Editing Geography of Tuvalu

{{Short description|none}} <!-- "none" is preferred when the title is sufficiently descriptive; see [[WP:SDNONE]] -->
{{Use dmy dates|date=October 2019}}
{{Infobox country geography
| name               = Tuvalu
| map                = Tv-map.png
| continent          = [[Pacific Ocean]]
| region             = [[Pacific Ocean|Western Pacific]]
| coordinates        = {{coord|5|41|S|176|12|E|type:country}}
| area ranking       = 191st
| km area            = 26.26
| percent land       = 100
| km coastline       = 24.14
| exclusive economic zone = {{convert|749790|km2|mi2|abbr=on}}
| borders            = None
| geographic center  =
| highest point      = [[Niulakita]] <br> {{convert|4.6|m}}
| lowest point       = [[Pacific Ocean]] <br> {{convert|0|m}}
| longest river      = 
| largest lake       = 
}}

The [[Pacific Ocean|Western Pacific]] [[archipelagic]] nation of [[Tuvalu]], formerly known as the Ellice Islands, is situated {{convert|4000|km|mi|sp=us}} northeast of [[Australia]] and is approximately halfway between Australia and [[Hawaii]]. It lies east-northeast of the [[Santa Cruz Islands]] (belonging to the [[Solomon Islands|Solomons]]), southeast of [[Nauru]], south of [[Kiribati]], west of [[Tokelau]], northwest of [[Samoa]] and [[Wallis and Futuna]] and north of [[Fiji]]. It is a very small [[island country]] of {{convert|26.26|km2|mi2|abbr=on}}. Due to the spread out islands it has the 38th largest [[Exclusive Economic Zone]] of {{convert|749790|km2|mi2|abbr=on}}. In terms of size, it is the second-smallest country in Oceania.<ref>Rodgers, K. A., and Carol Cantrell. The biology and geology of Tuvalu: an annotated bibliography. No. 1. Australian Museum, 1988.</ref>

The [[islands of Tuvalu]] consists of three [[reef]] islands and six [[atolls]], containing approximately {{convert|710|km2|mi2|abbr=on}} of reef platforms.<ref name="MM20048">{{cite report|last= Morris, C., & Mackay, K. |title = Status of coral reefs in the Southwest Pacific: Fiji, Nauru, New Caledonia, Samoa, Solomon Islands, Tuvalu and Vanuatu |year= 2008 |publisher= Status of coral reefs of the world (Townsville: Australian Institute of Marine Science)| volume=|pages=177–188|chapter= |issn= }}</ref> The reef islands have a different structure to the atolls, and are described as reef platforms as they are smaller tabular reef platforms that do not have a salt-water [[lagoon]],<ref name="PSK1">{{cite journal| last = Paul S. Kench, Murray R. Ford & Susan D. Owen |title= Patterns of island change and persistence offer alternate adaptation pathways for atoll nations (Supplementary Note 1) | journal = Nature Communications| volume = 9| issue = 1| pages = 605|date = 9 February 2018| doi = 10.1038/s41467-018-02954-1| pmid = 29426825| pmc = 5807422| bibcode = 2018NatCo...9..605K}}</ref> although they have a completely closed rim of dry land, with the remnants of a lagoon that has no connection to the open sea or that may be drying up.<ref name="CH-GA">{{cite journal |ref= Hedley |last1= Hedley |first1= Charles |title= General account of the Atoll of Funafuti |url= http://australianmuseum.net.au/Uploads/Journals/16686/487_complete.pdf |year= 1896 |journal= Australian Museum Memoir |volume= 3 |issue= 2 |pages= 1–72 |doi= 10.3853/j.0067-1967.3.1896.487 |access-date= 29 September 2013 |archive-date= 15 October 2013 |archive-url= https://web.archive.org/web/20131015112253/http://australianmuseum.net.au/Uploads/Journals/16686/487_complete.pdf |url-status= dead }}</ref> For example, [[Niutao]] has two lakes, which are brackish to saline; and are the degraded lagoon as the result of coral debris filling the lagoon.

The soils of Tuvalu's islands are usually shallow, porous, alkaline, coarse-textured, with carbonate mineralogy and high [[pH]] values of up to 8.2 to 8.9.<ref name="CBD5">{{cite web| last = | first = |title= Tuvalu Fifth National Report to the Convention on Biological Diversity|publisher= Government of Tuvalu|page=|year = 2016|url= https://www.cbd.int/reports/search/ | accessdate=11 November 2023}}</ref> The soils are usually deficient in most of the important nutrients needed for plant growth (e.g., nitrogen, potassium and micronutrients such as iron, manganese, copper and zinc), so garden beds need to be enhanced with [[mulch]] and fertiliser to increase their fertility.<ref name="CBD5"/> The [[List of islands of Tuvalu|Tuvalu islands]] have a total land area of only about 26&nbsp;km<sup>2</sup>, less than {{convert|10|sqmi|km2|-1|abbr=on}}.

The land is very low-lying, with narrow coral atolls. The highest elevation is {{convert|4.6|m|ft}} above sea level on [[Niulakita]]. Over 4 decades, there had been a net increase in land area of the islets of 73.5 ha (2.9%), although the changes are not uniform, with 74% increasing and 27% decreasing in size. The sea level at the Funafuti tide gauge has risen at 3.9&nbsp;mm per year, which is approximately twice the global average.<ref name="PSK2">{{cite journal| last = Paul S. Kench, Murray R. Ford & Susan D. Owen |title= Patterns of island change and persistence offer alternate adaptation pathways for atoll nations (Supplementary Note 2) | journal = Nature Communications| volume = 9| issue = 1| pages = 605|date = 9 February 2018| doi = 10.1038/s41467-018-02954-1| pmid = 29426825| pmc = 5807422| bibcode = 2018NatCo...9..605K}}</ref> The rising sea levels are identified as creating an increased transfer of wave energy across reef surfaces, which shifts sand, resulting in accretion to island shorelines,<ref name="PSK">{{cite journal| last = Paul S. Kench, Murray R. Ford & Susan D. Owen |title= Patterns of island change and persistence offer alternate adaptation pathways for atoll nations | journal = Nature Communications| volume = 9| issue = 1| pages = 605|date = 9 February 2018| doi = 10.1038/s41467-018-02954-1| pmid = 29426825| pmc = 5807422|bibcode= 2018NatCo...9..605K }}</ref> although this process does not result in additional habitable land.<ref name="ktm519">{{Cite news |url=https://kmt.news/2018/03/19/tuvalu-pm-refutes-aut-research/ |title=TUVALU PM REFUTES AUT RESEARCH |date=19 March 2018 |access-date=2019-03-26 |language=en-US |archive-date=26 March 2019 |archive-url=https://web.archive.org/web/20190326140508/https://kmt.news/2018/03/19/tuvalu-pm-refutes-aut-research/ |url-status=dead }}</ref> As of March 2018 [[Enele Sopoaga]], the prime minister of Tuvalu, stated that Tuvalu is not expanding and has gained no additional habitable land.<ref name="ktm519"/>

Tuvalu experiences two distinct seasons, a wet season from November to April and a dry season from May to October.<ref name=CFCT>{{cite web| title=Current and Future Climate of Tuvalu| work=[[Tuvalu Meteorological Service]], [[Australian Bureau of Meteorology]] & [[Commonwealth Scientific and Industrial Research Organisation]] (CSIRO)|date=2011|url= http://www.pacificclimatechangescience.org/wp-content/uploads/2013/06/4_PCCSP_Tuvalu_8pp.pdf |access-date=7 September 2015}}</ref> Westerly gales and heavy rain are the predominant weather conditions from November to April, the period that is known as ''Tau-o-lalo'', with tropical temperatures moderated by easterly winds from May to October.

==Geography==
{{wide image|Tuvalu banner Funafuti beach.jpg|800px|[[Funafuti]] wharf and beach (2013)||right}}

'''Location:'''
[[Oceania]], [[island]] group of nine islands comprising three [[reef]] islands and six true [[atolls]] in the South [[Pacific Ocean]].<ref name="MAP">{{cite web|url=https://www.mapsland.com/oceania/tuvalu|title= Maps of Tuvalu |access-date=15 January 2021}}</ref> The islands of Tuvalu are spread out between the [[latitude]] of [[5th parallel south|5°]] to [[10th parallel south|10° south]] and [[longitude]] of [[176th meridian east|176°]] to [[180th meridian|180°]], west of the [[International Date Line]].<ref name="MAP"/>

'''[[Geographic coordinates]]:''' {{coord|5|41|S|176|12|E|type:country}} to {{coord|10|45|S|179|51|E|type:country}}

'''Map references:'''
[[Oceania]]

'''Area:'''
<br>''total:''
26&nbsp;km<sup>2</sup>
<br>''land:''
26&nbsp;km<sup>2</sup>
<br>''water:''
0&nbsp;km<sup>2</sup>

'''Area – comparative:'''
0.1 times the size of [[Washington, DC]]

'''Land boundaries:'''
0&nbsp;km

'''Coastline:'''
{{convert|24.14|km|mi}}

'''Maritime claims:'''
<br>''contiguous zone:''
{{convert|24.14|nmi|km|0|abbr=on}}
<br>''exclusive economic zone:''
{{convert|749790|km2|mi2|abbr=on}} and {{convert|200|nmi|km|-1|abbr=on}}
<br>''territorial sea:''
{{convert|12|nmi|km|0|abbr=on}}

Tuvalu's [[Exclusive Economic Zone]] (EEZ) covers an oceanic area of approximately {{convert|749790|km2|mi2|abbr=on}}.<ref name="AJT">{{cite book |author1=A J Tilling  |author2=Ms E Fihaki |title= Tuvalu National Biodiversity Strategy and Action Plan |url= http://www.cbd.int/doc/world/tv/tv-nr-04-en.pdf|date=17 November 2009 |publisher= Fourth National Report to the Convention on Biological Diversity|page=7}}</ref>

On 29 August 2012 an ''Agreement between Tuvalu and Kiribati concerning their Maritime Boundary'', was signed by their respective leaders that determined the boundary as being seaward of [[Nanumea]] and [[Niutao]] in Tuvalu on the one hand and [[Tabiteuea]], [[Tamana, Kiribati|Tamana]] and [[Arorae]] in [[Kiribati]] on the other hand, along the [[geodesics]] connecting the points of latitude and longitude set out in the agreement.<ref name="Maritime">{{cite web|title =Agreement between Tuvalu and Kiribati concerning their Maritime Boundary |url= https://www.un.org/depts/los/LEGISLATIONANDTREATIES/PDFFILES/DEPOSIT/tuv_mzn98_2013_AgreementBetweenTuvaluandKiribati.pdf|date= 29 August 2012|publisher=U.N.}}</ref>

In October 2014 the prime ministers of Fiji and Tuvalu signed the ''Fiji-Tuvalu Maritime Boundary Treaty'', which establishes the extent of the national areas of jurisdiction between Fiji and Tuvalu as recognized in international law under the 1982 United Nations Convention on the Law of the Sea.<ref name="MOF2014">{{cite web |url= http://www.foreignaffairs.gov.fj/media-resources/media-release/748-fiji-tuvalu-maritime-boundary-treaty|title= Fiji Tuvalu Maritime Boundary Treaty |publisher=  Ministry of Foreign Affairs of Fiji|date= 17 October 2014|access-date=15 January 2021}}</ref><ref name="SPC2014">{{cite web |url= http://gsd.spc.int/media-releases/1-latest-news/594-fiji-and-tuvalu-sign-maritime-boundary-agreement|title= Fiji and Tuvalu sign maritime boundary agreement |publisher=  Secretariat of the Pacific Community (SPC) Geoscience Division|date= 24 October 2014|access-date=15 January 2021}}</ref>

'''Climate:'''
tropical; moderated by easterly trade winds (March to November); westerly gales and heavy rain (November to March).

'''Terrain:'''
low-lying and narrow coral atolls.

'''Elevation extremes:'''
<br>''lowest point:''
[[Pacific Ocean]] 0 m
<br>''highest point:''
unnamed location, {{convert|4.6|m|ft}} on [[Niulakita]].

'''Extreme points:'''
[[File:Tuvalu - Funafuti - Approach.jpg|thumb|right|300px|''[[Geographic coordinate system|Lat. and Long.]] {{Coord|-8.32|179.13 |display=inline}} <span style="color:darkblue;">([[Funafuti]])</span>'']]
This is a list of the extreme points of [[Tuvalu]], the points that are farther north, south, east or west than any other location:

* Northernmost point – [[Lakena]] [[islet]], [[Nanumea]]
* Easternmost point – [[Niuoko]] islet, [[Nukulaelae]]
* Southernmost point – [[Niulakita]]
* Westernmost point –  [[Lakena]] islet, [[Nanumea]]

{{see also|Islands of Tuvalu|List of villages and neighbourhoods in Tuvalu}}

'''Natural resources:'''
fish. coconut

'''Land use:'''
<br>''arable land:''
0%
<br>''permanent crops:''
60%
<br>''forest:''
33.3%
<br>''other:''
6.7% (2022 est.)

'''Irrigated land:'''
0 km<sup>2</sup>

==Trees and shrubs==

===Most common trees===
Thaman (2016) described about 362 species or distinct varieties of vascular plants that have been recorded at some time on Tuvalu, of which only about 59 (16%) are possibly indigenous.<ref name="RT2016">{{cite journal |author= Thaman, Randolph|date= October 2016 |title= The Flora of Tuvalu: Lakau Mo Mouku o Tuvalu|journal= Atoll Research Bulletin | issue=611 |pages= xii-129 |doi=10.5479/si.0077-5630.611|s2cid= 89181901 |doi-access= free }}</ref> The most common trees found on all islands are [[coconut]] (''Cocos nucifera'') stands, [[hibiscus]] (''Hibiscus tiliaceus''), [[papaya]] (''Carica papaya''), [[pandanus]] (''Pandanus tectorius''), salt bush (''[[Scaevola taccada]]''), ''[[Premna serratifolia]]'', ''[[Tournefortia]] samoensis'', zebra wood (''[[Guettarda speciosa]]''), Kanava (''[[Cordia subcordata]]''), (beach cordia) and terminalia (''[[Terminalia (plant)|Terminalia]] samoensis''). Indigenous broadleaf species, including Fetau (''[[Calophyllum inophyllum]]''), make up single trees or small stands around the coastal margin.<ref name="TCAP-F53">{{cite report|last= FCG ANZDEC Ltd |title = Tuvalu Coastal Adaptation Project: Environmental and Social Impact Assessment - Funafuti |date= 7 October 2020 |publisher= The Pacific Community |pages=53|chapter= |url= https://www.adaptation-undp.org/Tuvalu-Coastal-Adaptation-Project-TCAP-ESIA-Funafuti |access-date=6 February 2021}}</ref> While [[Coconut]] palms are common in Tuvalu, they are usually cultivated rather than naturally seeding and growing. Tuvaluan traditional histories are that the first settlers of the islands planted [[Coconut]] palms as they were not found on the islands.

The two recorded mangrove species in Tuvalu are the common Togo (''[[Rhizophora stylosa]]'') and the red-flowered mangrove Sagale (''[[Lumnitzera|Lumnitzera littorea]]''), which is only reported on Nanumaga, Niutao, Nui and Vaitupu. Mangrove ecosystems are protected under Tuvaluan law.<ref name="TCAP-NN66">{{cite report|last= FCG ANZDEC Ltd |title = Tuvalu Coastal Adaptation Project: Environmental and Social Impact Assessment - Nanumaga and Nanumea |date= 7 August 2020 |publisher= The Pacific Community |pages=66|chapter= |url= https://www.adaptation-undp.org/Tuvalu-Coastal-Adaptation-Project-TCAP-ESIA-Nanumaga-Nanumea |access-date=6 February 2021}}</ref>

The land cover types found on Funafuti include inland [[forest|broadleaf forest]] and woodland, coastal [[Littoral zone|littoral]] forest and scrub, [[Mangrove forest|mangroves]] and wetlands, and coconut woodland and agroforest.<ref name="CBD5"/>

===Native broadleaf forest===
[[File:Beach of Nanumea Atoll.jpg|thumb|upright|200px|''[[Scaevola taccada]]'' and ''[[Guettarda speciosa]]'' grow near the beach on Nanumea Atoll]]
[[File:Fualifeke Islet, Funafuti Atoll.jpg|thumb|right|200px|[[Fualefeke]] Islet]]

The native broadleaf forest is limited to 4.1% of the vegetation types on the islands of Tuvalu.<ref name="RBA">{{cite web|author= Randy Thaman, Feagaiga Penivao, Faoliu Teakau, Semese Alefaio, Lamese Saamu, Moe Saitala, Mataio Tekinene and Mile Fonua| work= Rapid Biodiversity Assessment of the Conservation Status of Biodiversity and Ecosystem Services (BES) In Tuvalu|title= Report on the 2016 Funafuti Community-Based Ridge-To-Reef (R2R) |date = 2017|url= https://www.sprep.org/attachments/VirLib/Tuvalu/r2r-biorap.pdf| access-date=25 May 2019}}</ref> The islets of the [[Funafuti Conservation Area]] have 40% of the remaining native broadleaf forest on [[Funafuti]] atoll. The native broadleaf forest of Funafuti would include the following species, that were described by [[Charles Hedley]] in 1896,<ref name="CHF">{{cite book|last1= Hedley|first1= Charles|title= General account of the Atoll of Funafuti|url= http://australianmuseum.net.au/Uploads/Journals/16686/487_complete.pdf|year= 1896|publisher= Australian Museum Memoir 3(2): 1–72|pages= 30–40|access-date= 29 September 2013|archive-date= 15 October 2013|archive-url= https://web.archive.org/web/20131015112253/http://australianmuseum.net.au/Uploads/Journals/16686/487_complete.pdf|url-status= dead}}</ref> which include the Tuvaluan name (some of which may follow [[Samoan plant names]]):

* ''Fala'' or Screw Pine, (''[[Pandanus]]'')
* ''Puka'' or ''pouka'', (''[[Hernandia]] peltata'')
* ''Futu'', (''[[Barringtonia asiatica]]'')
* ''Fetau'', (''[[Calophyllum inophyllum]]'')
* ''Ferra'', (''[[Ficus]] aspem''), native fig 
* ''Fau'' or ''Fo fafini'', or woman's fibre tree (''[[Hibiscus tiliaceus]]'')
* ''Lakoumonong'', (''[[Wedelia]] strigulosa'')
* ''Lou'', (''[[Cardamine]] sarmentosa'')
* ''Meili'', (''[[Polypodium]]''), fern 
* ''Laukatafa'', ''[[Asplenium nidus]]'', bird's-nest fern
* ''Milo'' or ''miro'', (''[[Thespesia populnea]]'')
* ''Ngashu'' or ''Naupaka'', (''[[Scaevola taccada]]'')
* ''Ngia'' or ''Ingia'', (''[[Pemphis]] acidula''), bush
* ''Nonou'' or ''nonu'', (''[[Morinda citrifolia]]'')
* ''Pukavai'', ([[Pisonia grandis]]) 
* ''Sageta'', (''[[Dioclea (plant)|Dioclea]] violacea''), vine
* ''Talla talla gemoa'', (''[[Psilotum]] triquetrum''), fern
* ''Tausunu'' or ''tausoun'', (''[[Heliotropium foertherianum]]'')
* ''Tonga'' or ''tongo'', (''[[Rhizophora mucronata]]''), found around swamps
* ''Tulla tulla'', (''[[Triumfetta]] procumbens''), whose prostrate stems trailed for several feet over the ground
* ''Valla valla'', (''[[Premna tahitensis]]'')
The blossoms that are valued for their scent and for use in flower necklaces and headdresses include: ''Fetau'', (''[[Calophyllum inophyllum]]''); ''Jiali'', (''[[Gardenia taitensis]]''); ''Boua'' (''[[Guettarda speciosa]]''); and ''[[Crinum]]''.<ref name="CHF"/>

[[Donald Gilbert Kennedy]], the resident District Officer in the administration of the [[Gilbert and Ellice Islands]] Colony from 1932 to 1938, identified other trees found in the broadleaf forest:<ref name="K1931">{{cite book|last1= Kennedy|first1= Donald|title= The Ellice Islands Canoe Journal of the Polynesian Society Memoir no. 9|url= http://www.jps.auckland.ac.nz/document//Memoirs_%28Additional%29/No._9%3A_Field_Notes_on_the_Culture_of_Vaitupu%2C_Ellice_Islands%2C_by_D._G._Kennedy/The_Ellice_Islands_Canoe%2C_p_71-100/p1|year= 1931|publisher= Journal of the Polynesian Society|pages= 71–100|access-date= 13 April 2019|archive-date= 6 October 2022|archive-url= https://web.archive.org/web/20221006034408/https://www.jps.auckland.ac.nz/document/Memoirs_%28Additional%29/No._9%3A_Field_Notes_on_the_Culture_of_Vaitupu%2C_Ellice_Islands%2C_by_D._G._Kennedy/The_Ellice_Islands_Canoe%2C_p_71-100/p1|url-status= dead}}</ref>

* ''Pua'', ([[Guettarda speciosa]]) 
* ''Kanava'', ([[Cordia subcordata]])

Charles Hedley (1896) identified the uses of plants and trees from the native broadleaf forest as including:<ref name="CHF1">{{cite book|last1= Hedley|first1= Charles|title= General account of the Atoll of Funafuti|url= http://australianmuseum.net.au/Uploads/Journals/16686/487_complete.pdf|year= 1896|publisher= Australian Museum Memoir 3(2): 1–72|pages= 40–41|access-date= 29 September 2013|archive-date= 15 October 2013|archive-url= https://web.archive.org/web/20131015112253/http://australianmuseum.net.au/Uploads/Journals/16686/487_complete.pdf|url-status= dead}}</ref>
 
* '''Food plants''': [[Coconut]]; and ''Ferra'', native fig (''[[Ficus]] aspem'').<ref name="CHF1"/>
* '''Fibre''':  [[Coconut]]; ''Ferra''; ''Fala'', Screw Pine, ''[[Pandanus]]''; ''Fau'' or ''Fo fafini'', or woman's fibre tree (''[[Hibiscus tiliaceus]]'').<ref name="CHF1"/>
* '''Timber''': ''Fau'' or ''Fo fafini''; ''Pouka'', (''[[Hernandia]] peltata''); ''Ngia'' or ''Ingia'', (''[[Pemphis]] acidula''); ''Miro'', (''[[Thespesia populnea]]''); and ''Tonga'', (''[[Rhizophora mucronata]]'').<ref name="CHF1"/>
* '''Dye''': ''Valla valla'', (''[[Premna tahitensis]]''); ''Tonga'', (''[[Rhizophora mucronata]]''); and ''Nonou'', (''[[Morinda citrifolia]]'').<ref name="CHF1"/>
* '''Scent''': ''Fetau'', (''[[Calophyllum inophyllum]]''); ''Jiali'', (''[[Gardenia taitensis]]''); and ''Boua'' (''[[Guettarda speciosa]]''); ''Valla valla'', (''[[Premna tahitensis]]''); and [[Crinum]].<ref name="CHF1"/>
* '''Medicinal''': ''Tulla tulla'', (''[[Triumfetta]] procumbens''); ''Nonou'', (''[[Morinda citrifolia]]''); ''Tausoun'', (''[[Heliotropium foertherianum]]''); ''Valla valla'', (''[[Premna tahitensis]]''); ''Talla talla gemoa'' (''[[Psilotum]] triquetrum''); ''Lou'', (''[[Cardamine]] sarmentosa''); and ''Lakoumonong'', (''[[Wedelia]] strigulosa'').<ref name="CHF1"/>

Thaman (1992) provides a literature review of the ethnobiology of the Pacific Islands.<ref name="Thaman">{{cite journal| last = Thaman | first =R.R. |title= Batiri Kei Baravi: The Ethnobotany of Pacific Island Coastal Plants |journal= Atoll Research Bulletin |issue=361 |publisher=National Museum of Natural History, [[Smithsonian Institution]]|date = May 1992| volume =361 | pages =1–62 | doi =10.5479/si.00775630.361.1 |url= http://repository.si.edu/bitstream/10088/5070/1/00361.pdf| access-date=8 February 2014}}</ref>

==Climate and natural hazards==

===El Niño and La Niña===
Tuvalu experiences the effects of [[El Niño]] and [[La Niña]] that flow from changes in ocean temperatures in equatorial and central Pacific. [[El Niño]] effects increase the chances of tropical storms and [[cyclones]]; while [[La Niña]] effects increase the chances of drought conditions in Tuvalu. On 3 October 2011, drought conditions resulted in a state of emergency being declared as water reserves ran low.<ref name="SPC2011">{{cite web|url= http://reliefweb.int/report/tuvalu/tuvalu%E2%80%99s-crippling-drought-offers-important-lessons-pacific|title= Tuvalu's crippling drought offers important lessons to the Pacific  |work= Secretariat of the Pacific Community|date= 6 October 2011|access-date=24 April 2015}}</ref><ref name=Tele>{{cite news| url=https://www.telegraph.co.uk/news/worldnews/australiaandthepacific/tuvalu/8804093/Tuvalu-to-run-out-of-water-by-Tuesday.html| location=London | work=The Telegraph| first1=Matthew| last1=Benns| title=Tuvalu 'to run out of water by Tuesday'| date=3 October 2011}}</ref><ref name=AM>{{cite web| first= Alistair |last= Macrae|url=http://www.abc.net.au/unleashed/3497128.html|title= Tuvalu in a fight for its life| date =11 October 2011|publisher=The Drum – Australian Broadcasting Corporation |access-date=12 October 2011}}</ref> Typically the islands of Tuvalu receive between 200mm to 400mm of rainfall per month, however a weak [[La Niña]] effect causes a drought by cooling the surface of the sea around Tuvalu.

{{see also|2011 Tuvalu drought}}

===Tropical cyclones===
Severe [[tropical cyclone]]s are usually rare, but the low level of islands makes them very sensitive to sea-level rise. Tuvalu experienced an average of three cyclones per decade between the 1940s and 1970s, however eight occurred in the 1980s.<ref name="JCon">{{cite journal| last=Connell |first=John |url=http://scholarspace.manoa.hawaii.edu/bitstream/10125/38764/1/v27n1-1-36.pdf |title=Vulnerable Islands: Climate Change, Techonic Change, and Changing Livelihoods in the Western Pacific  |journal=The Contemporary Pacific|volume=27|issue=1 |year=2015|pages=1–36|doi=10.1353/cp.2015.0014 }}</ref> The impact of individual cyclones is subject to variables including the force of the winds and also whether a cyclone coincides with high tides. A warning system, which uses the [[Iridium satellite constellation|Iridium]] satellite network, was introduced in 2016 in order to allow outlying islands to be better prepare for natural disasters.<ref>{{cite web|publisher=[[Radio New Zealand]] |date=10 June 2016|access-date=10 June 2016|title=Tuvalu to introduce new early warning system|url=http://www.radionz.co.nz/international/pacific-news/306132/tuvalu-to-intoduce-new-early-warning-system}}</ref>

George Westbrook recorded a cyclone that struck [[Funafuti]] on 23–24 December 1883.<ref name="BKE">{{cite journal |author= McLean, R.F. and Munro, D. |url= http://uspaquatic.library.usp.ac.fj/gsdl/collect/spjnas/index/assoc/HASH0199.dir/doc.pdf |title= Late 19th century Tropical Storms and Hurricanes in Tuvalu |journal= South Pacific Journal of Natural History |volume= 11 |year= 1991 |pages= 213–219 |access-date= 13 April 2019 |archive-date= 10 April 2019 |archive-url= https://web.archive.org/web/20190410113306/http://uspaquatic.library.usp.ac.fj/gsdl/collect/spjnas/index/assoc/HASH0199.dir/doc.pdf |url-status= dead }}</ref><ref name="H83">{{cite book |last1=Resture|first1= Jane |title= Hurricane 1883 |url= http://www.janeresture.com/hurribebe/hurricanebebe2.htm|publisher= Tuvalu and the Hurricanes: 'Gods Who Die' by Julian Dana as told by George Westbrook}}</ref> A cyclone struck Nukulaelae on 17–18 March 1886.<ref name="BKE"/> Captain [[Edward H. M. Davis|Edward Davis]] of HMS ''Royalist'', who visited the Ellice Group in 1892, recorded in the ship's diary that in February 1891 the Ellice Group was devastated by a severe cyclone.<ref name="JEC">{{cite web| last = Resture | first = Jane|title= Tuvalu and the hurricanes|date =17 May 2004|url= http://www.janeresture.com/hurribebe/index.htm| access-date=23 April 2014}}</ref> A cyclone caused severe damage to the islands in 1894.<ref name="TAH2">{{cite book |first1=Pasoni |last1=Taafaki |editor-first1=Hugh |editor-last1=Laracy |title= Tuvalu: A History|year= 1983 |publisher= Institute of Pacific Studies, University of the South Pacific and Government of Tuvalu|page=27 |chapter=Chapter 2 – The Old Order}}</ref>

[[Image:Tuvalu Meteorology Service.jpg| thumb|left|275px| [[Tuvalu Meteorological Service]], [[Fongafale]], [[Funafuti]] atoll]]
[[Cyclone Bebe]] caused severe damage to [[Funafuti]] during the [[1972–73 South Pacific cyclone season]].<ref name="JRBebe">{{cite web| last =Resture| first =Jane|title=Hurricane Bebe Left 19 People Dead And Thousands Misplaced In Fiji and Tuvalu| publisher= Janeresture.com|date =14 October 2022| url=https://www.janeresture.com/hurricane-bebe/| access-date=3 December 2023}}</ref><ref name="PIM1973-5">{{cite web| last =| first =  | work= 44(5) Pacific Islands Monthly |title=Life bounce back in the Ellice|date =1 May 1966|url=https://nla.gov.au/nla.obj-336976092/view?sectionId=nla.obj-340950828&partId=nla.obj-337014010#page/n22/mode/1up| access-date=2 October 2021}}</ref> Funafuti's [[Pukasavilivili|Tepuka Vili Vili]] [[islet]] was devastated by [[Cyclone Meli]] in 1979, with all its vegetation and most of its sand swept away during the cyclone.<ref name=KFCA>{{cite web|title=Kogatapu Funafuti Conservation Area | publisher=Tuvaluislands.com |url= http://www.tuvaluislands.com/islands/funafuti_kogatapu.html |archive-url= https://web.archive.org/web/20080708191258/http://www.tuvaluislands.com/islands/funafuti_kogatapu.html |url-status= usurped |archive-date= 8 July 2008 |access-date=28 October 2011}}</ref> [[Cyclone Gavin]] was first identified during 2 March 1997, and was the first of three tropical cyclones to affect Tuvalu during the 1996–97 cyclone season with Cyclones [[Cyclone Hina|Hina]] and [[Cyclone Keli|Keli]] following later in the season. [[Cyclone Ofa]] had a major impact on Tuvalu in late January and early February 1990.<ref name="STD">{{cite report|author=Koop, Neville L|author2=Fiji Meteorological Service|type=Mariners Weather Log|date=Winter 1991|title=Samoa Depression|oclc=648466886|volume=35|issue=1|publisher=United States National Oceanic and Atmospheric Administration's National Oceanographic Data Service|issn=0025-3367|page=53|editor=DeAngellis, Richard M}}</ref> On [[Vaitupu]] Island around 85 percent of residential homes, trees and food crops were destroyed, while residential homes were also destroyed on the islands of [[Niutao]], [[Nui (atoll)|Nui]] and [[Nukulaelae]]. The majority of the islands in Tuvalu reported damage to vegetation and crops especially bananas, coconuts and breadfruit, with the extent of damage ranging from 10 to 40 percent. In [[Funafuti]] sea waves flattened the Hurricane Bebe bank at the southern end of the airstrip, which caused sea flooding and prompted the evacuation of several families from their homes. In Nui and Niulakita there was a minor loss of the landscape because of sea flooding while there were no lives lost. Soon after the systems had impacted Tuvalu, a Disaster Rehabilitation Sub-Committee was appointed to evaluate the damage caused and make recommendations to the National Disaster Committee and to the Cabinet of Tuvalu, on what should be done to help rehabilitate the affected areas.

In March 2015 [[Cyclone Pam]], the Category 5 cyclone that devastated [[Vanuatu]], caused damage to houses, crops and infrastructure on the outer islands.<ref name="TSP11">{{cite web| work= Tuvalu Solar Project Team Blog |title= Wild weather in Tuvalu |date =11 March 2015|url= http://www.powersmarttuvaluproject.blogspot.co.nz/| access-date=15 March 2015}}</ref><ref name="SBS15">{{cite web| work= SBS Australia |title= Flooding in Vanuatu, Kiribati and Tuvalu as Cyclone Pam strengthens |date =13 March 2015|url= http://www.sbs.com.au/news/article/2015/03/13/flooding-vanuatu-kiribati-and-tuvalu-cyclone-pam-strengthens | access-date=15 March 2015}}</ref><ref name="RNZI14">{{cite web| work= Radio New Zealand International |title= State of emergency in Tuvalu  |date =14 March 2015|url= http://www.radionz.co.nz/international/pacific-news/268612/state-of-emergency-in-tuvalu| access-date=15 March 2015}}</ref><ref name="RNZI15">{{cite web| work= Radio New Zealand International |title= 45 percent of Tuvalu population displaced – PM|date =15 March 2015|url= http://www.radionz.co.nz/international/pacific-news/268686/45-percent-of-tuvalu-population-displaced-pm| access-date=15 March 2015}}</ref> A state of emergency was subsequently declared on 13 March.<ref name="FenS15">{{cite web|title=Press Release issued by the Office of the Prime Minister |publisher=Fenui News |date=13 March 2015 |url=https://www.un.int/tuvalu/sites/www.un.int/files/Tuvalu/Documents/GA/fenui_mar_13_2015_special_edition.pdf |access-date=17 November 2018}}</ref><ref>{{cite web|publisher=Radio New Zealand International|date=14 March 2015|access-date=15 March 2015|title=State of emergency in Tuvalu|url=http://www.radionz.co.nz/international/pacific-news/268612/state-of-emergency-in-tuvalu}}</ref> An estimated 45&nbsp;percent of the nation's nearly 10,000&nbsp;people were displaced, according to [[Prime Minister of Tuvalu|Prime Minister]] [[Enele Sopoaga]].<ref name=rnzi>{{cite news|title=45 percent of Tuvalu population displaced – PM |url=http://www.radionz.co.nz/international/pacific-news/268686/45-percent-of-tuvalu-population-displaced-pm |work=[[Radio New Zealand International]] |date=15 March 2015 |access-date=15 March 2015}}</ref><ref name="RNZI17">{{cite web| work= Radio New Zealand International |title= International assistance due today in Tuvalu|date =17 March 2015|url= http://www.radionz.co.nz/international/pacific-news/268866/international-assistance-due-today-in-tuvalu| access-date=17 March 2015}}</ref> The three northern islands, [[Nanumea]], [[Nanumanga]] and [[Niutao]] were badly affected by flooding as the result of storm surges. More than 400 people from the northern island of Nanumanga were moved to emergency accommodation in the school buildings, as well as another 85 families from [[Nukulaelae]] in the south of Tuvalu. On [[Nui (atoll)|Nui]] the storm surges contaminated the water supplies and damaged septic tanks and grave sites. The central islands of [[Vaitupu]] and [[Nukufetau]] were also affected by flooding caused by storm surges.<ref name="TuvaluReport">{{cite report|work=International Federation of Red Cross and Red Crescent Societies|publisher=ReliefWeb|date=16 March 2015|access-date=17 March 2015|title=Emergency Plan of Action (EPoA) Tuvalu: Tropical Cyclone Pam|url=http://reliefweb.int/sites/reliefweb.int/files/resources/MDRTV001dref.pdf}}</ref><ref name="RNZI19">{{cite web| work= Radio New Zealand International |title= One Tuvalu island evacuated after flooding from Pam|date =18 March 2015|url= http://www.radionz.co.nz/international/pacific-news/268988/one-tuvalu-island-evacuated-after-flooding-from-pam| access-date=18 March 2015}}</ref><ref name=RW22>{{cite web|url= http://reliefweb.int/report/tuvalu/tuvalu-tropical-cyclone-pam-situation-report-no-1-22-march-2015 |title=Tuvalu: Tropical Cyclone Pam Situation Report No. 1 (as of 22 March 2015)| date =22 March 2015|publisher= Relief Web |access-date= 25 March 2015}}</ref> The Situation Report published on 30 March reported that on Nukufetau all the displaced people have returned to their homes.<ref name=RW30>{{cite web|url= http://reliefweb.int/report/tuvalu/tuvalu-tropical-cyclone-pam-situation-report-no-2-30-march-2015 |title=Tuvalu: Tropical Cyclone Pam Situation Report No. 2 (as of 30 March 2015)| date =30 March 2015|publisher= Relief Web |access-date= 30 March 2015}}</ref>

Nui suffered the most damage of the three central islands (Nui, Nukufetau and Vaitupu);<ref name="UNDP">{{cite web| work= United Nations Development Programme|title= Forgotten paradise under water|date =1 May 2015 |url= https://undp.exposure.co/forgotten-paradise-under-water| access-date=8 June 2015}}</ref> with both Nui and Nukufetau suffering the loss of 90% of the crops.<ref name=RW30/> Of the three northern islands (Nanumanga, Niutao, Nanumea), Nanumanga suffered the most damage, with 60–100 houses flooded and damage to the health facility.<ref name=RW30/><ref name=WHO04>{{cite web|url=http://reliefweb.int/report/tuvalu/tuvalu-situation-update-3-april-2015  |title=Tuvalu situation update: Securing health from disastrous impacts of cyclone Pam in Tuvalu| date =3 April 2015 |publisher= Relief Web/World health Organisation – Western Pacific Region |access-date= 8 June 2015}}</ref> [[Vasafua]] islet, part of the [[Funafuti Conservation Area]], was severely damaged by Cyclone Pam. The coconut palms were washed away, leaving the islet as a sand bar.<ref name="VIV">{{cite web| last =Wilson  | first =David  | work= Tuvalu-odyssey.net |title= Vasafua Islet vanishes |date = 4 July 2015|url= http://www.tuvalu-odyssey.net/vasafua-islet-vanishes/ | access-date=22 July 2015}}</ref><ref name="TO13">{{cite web| last =Endou  | first = Shuuichi  | work= Tuvalu Overview (Japanese) |title= バサフア島、消失・・・(Vasafua Islet vanishes)|date = 28 March 2015|url= http://www.tuvalu-overview.tv/blog/news/3253/ | access-date=22 July 2015}}</ref>

Despite passing over {{convert|500|km|mi|round=5|abbr=on}} to the south of the island nation, [[Cyclone Tino]] and its associated convergence zone impacted the whole of Tuvalu between January 16&nbsp;- 19 of 2020.<ref name="Tuvalu SWB 1">{{cite report|title=Special Weather Bulletin Number 1 for Tuvalu January 16, 2020 10z|publisher=Fiji Meteorological Service|date=January 16, 2020}}</ref><ref name="Swept">{{cite news|title="It swept right over": Tuvalu inundated by waves whipped up by Cyclone Tino|url=https://www.rnz.co.nz/international/pacific-news/407611/it-swept-right-over-tuvalu-inundated-by-waves-whipped-up-by-cyclone-tino |access-date=February 8, 2020|work=[[Radio New Zealand]] |date=January 20, 2020}}</ref>

===Tsunami===
[[Nui (atoll)|Nui]] was struck by a giant wave on 16 February 1882;<ref name="TAH10">{{cite book |first1=Sotaga |last1=Pape |editor-first1=Hugh |editor-last1=Laracy |title= Tuvalu: A History (Chapter 10) Nui|year= 1983 |publisher= Institute of Pacific Studies, University of the South Pacific and Government of Tuvalu|pages=76|chapter=10}}</ref> earthquakes and volcanic eruptions occurring in the basin of the [[Pacific Ocean]] and along the Pacific [[Ring of Fire]] are a possible cause of a [[tsunami]]. There is [[2007 Solomon Islands earthquake#Tectonic summary|earthquake activity in the Solomon Islands]], where earthquakes occurred in relation to the New Hebrides Trench,<ref name="TCAP-F50">{{cite report|last= FCG ANZDEC Ltd |title = Tuvalu Coastal Adaptation Project: Environmental and Social Impact Assessment - Funafuti |date= 7 October 2020 |publisher= The Pacific Community |pages=50|chapter= |url= https://www.adaptation-undp.org/Tuvalu-Coastal-Adaptation-Project-TCAP-ESIA-Funafuti |access-date=6 February 2021}}</ref><ref name="TCAP-NN61">{{cite report|last=  FCG ANZDEC Ltd |title = Tuvalu Coastal Adaptation Project: Environmental and Social Impact Assessment - Nanumaga and Nanumea |date= 7 August 2020 |publisher= The Pacific Community |pages=61|chapter= |url= https://www.adaptation-undp.org/Tuvalu-Coastal-Adaptation-Project-TCAP-ESIA-Nanumaga-Nanumea |access-date=4 February 2021}}</ref> and movement along the boundary of the [[Pacific Plate]] with, respectively, the [[Indo-Australian Plate|Indo-Australia]], [[Woodlark Plate|Woodlark]], and Solomon Sea plates.<ref name=USGSSummary>{{Cite web |url=https://earthquake.usgs.gov/eqcenter/eqinthenews/2007/us2007aqbk/ |title=Magnitude 8.1 – SOLOMON ISLANDS – Summary|work=USGS Earthquake Hazards Program |access-date=2 April 2007| archive-url= https://web.archive.org/web/20070406185859/http://earthquake.usgs.gov/eqcenter/eqinthenews/2007/us2007aqbk/| archive-date= 6 April 2007 | url-status= live}}</ref>

Tuvalu has the third lowest tsunami risk of Pacific Island countries, with a maximum tsunami amplitude of 1.6m for a 2000-year return period (comparatively, the highest is 5.2m for PNG, and the lowest is 1m for Nauru).<ref name="TCBD">{{cite report |first1=C. |last1=Thomas |last2=Burbidge |first2=D |title =A Probabilistic Tsunami Hazard. Assessment of the Southwest Pacific Nations. Geoscience Australia Professional Opinion No.2009/02. Rereleased 2011/11 |year= 2009 |publisher=  Geoscience Australia (GA)|pages=|chapter= |url= http://www.ga.gov.au/webtemp/image_cache/GA20154.pdf |access-date=12 February 2021}}</ref> The assessment of the tsunami risk of Tuvalu was that major source of risk was activity associated with the New Hebrides trench. The orientation of the trench vis-à-vis the islands of Tuvalu results in the conclusion that most of the energy originating from New Hebrides trench is likely to be directed towards the southern islands of Tuvalu, so that the tsunami risk is lower for the northern islands when compared to the southern islands.<ref name="TCBD"/><ref name="TCAP-F50"/><ref name="TCAP-NN61-1">{{cite report|last=  FCG ANZDEC Ltd |title = Tuvalu Coastal Adaptation Project: Environmental and Social Impact Assessment - Nanumaga and Nanumea |date= 7 August 2020 |publisher= The Pacific Community |pages=61|chapter= |url= https://www.adaptation-undp.org/Tuvalu-Coastal-Adaptation-Project-TCAP-ESIA-Nanumaga-Nanumea |access-date=12 February 2021}}</ref>

===Climate data===

{{Weather box
|location = [[Funafuti]] (Köppen Af)
|single line = Yes
|collapsed = Yes 
|metric first = Yes
|width = auto 
|Jan record high C = 33.8
|Feb record high C = 34.4
|Mar record high C = 34.4
|Apr record high C = 33.2
|May record high C = 33.9
|Jun record high C = 33.9
|Jul record high C = 32.8
|Aug record high C = 32.9
|Sep record high C = 32.8
|Oct record high C = 34.4
|Nov record high C = 33.9
|Dec record high C = 33.9
|year record high C = 34.4
|Jan high C = 30.7
|Feb high C = 30.8
|Mar high C = 30.6
|Apr high C = 31.0
|May high C = 30.9
|Jun high C = 30.6
|Jul high C = 30.4
|Aug high C = 30.4
|Sep high C = 30.7
|Oct high C = 31.0
|Nov high C = 31.2
|Dec high C = 31.0
|year high C = 30.8
|Jan mean C = 28.2
|Feb mean C = 28.1
|Mar mean C = 28.1
|Apr mean C = 28.2
|May mean C = 28.4
|Jun mean C = 28.3
|Jul mean C = 28.1
|Aug mean C = 28.1
|Sep mean C = 28.2
|Oct mean C = 28.2
|Nov mean C = 28.4
|Dec mean C = 28.3
|year mean C = 28.2
|Jan low C = 25.5
|Feb low C = 25.3
|Mar low C = 25.4
|Apr low C = 25.7
|May low C = 25.8
|Jun low C = 25.9
|Jul low C = 25.7
|Aug low C = 25.8
|Sep low C = 25.8
|Oct low C = 25.7
|Nov low C = 25.8
|Dec low C = 25.7
|year low C = 25.8
|Jan record low C = 22.0
|Feb record low C = 22.2
|Mar record low C = 22.8
|Apr record low C = 23.0
|May record low C = 20.5
|Jun record low C = 23.0
|Jul record low C = 21.0
|Aug record low C = 16.1
|Sep record low C = 20.0
|Oct record low C = 21.0
|Nov record low C = 22.8
|Dec record low C = 22.8
|year record low C = 16.1
|precipitation colour = green
|Jan precipitation mm = 413.7
|Feb precipitation mm = 360.6
|Mar precipitation mm = 324.3
|Apr precipitation mm = 255.8
|May precipitation mm = 259.8
|Jun precipitation mm = 216.6
|Jul precipitation mm = 253.1
|Aug precipitation mm = 275.9
|Sep precipitation mm = 217.5
|Oct precipitation mm = 266.5
|Nov precipitation mm = 275.9
|Dec precipitation mm = 393.9
|year precipitation mm = 3512.6
|unit precipitation days = 1.0 mm
|Jan precipitation days = 20
|Feb precipitation days = 19
|Mar precipitation days = 20
|Apr precipitation days = 19
|May precipitation days = 18
|Jun precipitation days = 19
|Jul precipitation days = 19
|Aug precipitation days = 18
|Sep precipitation days = 16
|Oct precipitation days = 18
|Nov precipitation days = 17
|Dec precipitation days = 19
|year precipitation days = 223
|Jan humidity = 82
|Feb humidity = 82
|Mar humidity = 82
|Apr humidity = 82
|May humidity = 82
|Jun humidity = 82
|Jul humidity = 83
|Aug humidity = 82
|Sep humidity = 81
|Oct humidity = 81
|Nov humidity = 80
|Dec humidity = 81
|year humidity = 82
|Jan sun = 179.8
|Feb sun = 161.0
|Mar sun = 186.0
|Apr sun = 201.0
|May sun = 195.3
|Jun sun = 201.0
|Jul sun = 195.3
|Aug sun = 220.1
|Sep sun = 210.0
|Oct sun = 232.5
|Nov sun = 189.0
|Dec sun = 176.7
|year sun = 
|Jand sun = 5.8
|Febd sun = 5.7
|Mard sun = 6.0
|Aprd sun = 6.7
|Mayd sun = 6.3
|Jund sun = 6.7
|Juld sun = 6.3
|Augd sun = 7.1
|Sepd sun = 7.0
|Octd sun = 7.5
|Novd sun = 6.3
|Decd sun = 5.7
|yeard sun = 6.4
|source 1 = [[Deutscher Wetterdienst]]<ref name = FunafutiDWD>
{{cite web
| url = http://www.dwd.de/DWD/klima/beratung/ak/ak_916430_kt.pdf
| title = Klimatafel von Funafuti / Tuvalu (Ellice-Inseln)
| work = Baseline climate means (1961–1990) from stations all over the world
| publisher = Deutscher Wetterdienst
| language = de
| access-date = 22 November 2016}}</ref>
}}

==Environment==

===Island, reef and lagoon habitats===
[[File:Nukufetau.jpg|thumb|right|240px|[[Nukufetau]] atoll.]]
{{see also|Coral reefs of Tuvalu|Protected areas of Tuvalu}}

Tuvalu consists of three [[reef]] islands and six true [[atolls]]. Its small, scattered group of [[atolls]] have poor soil and a total land area of only about 26.26&nbsp;square kilometres (less than 10&nbsp;sq.&nbsp;mi.) making it the fourth smallest country in the world. The islets that form the atolls are very low-lying.  [[Nanumaga]], [[Niutao]], [[Niulakita]] are [[reef]] islands and the six true atolls are [[Funafuti]], [[Nanumea]], [[Nui (atoll)|Nui]], [[Nukufetau]], [[Nukulaelae]] and [[Vaitupu]]. [[Funafuti]] is the largest [[atoll]] of the nine low [[reef]] islands and atolls that form the Tuvalu volcanic island chain. It comprises numerous islets around a central lagoon that is approximately {{convert|25.1|km|mi|abbr=off}} (N–S) by {{convert|18.4|km|mi|abbr=off}} (W-E), centred on 179°7’E and 8°30’S. On the atolls an annular reef rim surrounds the lagoon, with several natural reef channels.<ref name="FSN">{{cite journal| last =McNeil | first =F. S. |title= Organic reefs and banks and associated detrital sediments|journal=Am. J. Sci.|volume= 252|issue=7|pages= 385–401 | year = 1954|bibcode=1954AmJS..252..385M|doi=10.2475/ajs.252.7.385|doi-access=free}}</ref> A standard definition of an ''atoll'' is "an annular reef enclosing a lagoon in which there are no promontories other than reefs and islets composed of reef detritus".<ref name="FSN"/> The northern part of the Funafuti lagoon has a deep basin (maximum depth recorded of 54.7 m) basin, and the southern part of the lagoon has very narrow shallow basin.<ref name="SOPAC">{{cite web |title= EU-SOPAC Project Report 50: TUVALU TECHNICAL REPORT High-Resolution Bathymetric Survey Fieldwork undertaken from 19 September to 24 October 2004 |publisher= Pacific Islands Applied Geoscience Commission c/o SOPAC Secretariat|date=October 2018 |url= ftp://ftp.gouv.nc/sig/PUBLIC/club_geomatique/2017/GT_donnees_geo_maritimes_22_06_2017/Rapport_de_leve_CPS.pdf| access-date=21 October 2019 }}</ref>

The eastern shoreline of [[Fongafale]] in the Funafuti lagoon (''Te Namo'') was modified during World War II; several piers were constructed, beach areas filled, and deep water access channels were excavated. These alternations to the reef and shoreline have resulted in changes to wave patterns with less sand accumulating to form the beaches as compared to former times; and the shoreline is now exposed to wave action.<ref name="TN">{{cite web| work=tuvaluislands.com |title= Fogafale: Then and Now (1941 & 2003)|url=  http://www.tuvaluislands.com/maps/fogafale_1.html|archive-url=  https://web.archive.org/web/20060209040631/http://www.tuvaluislands.com/maps/fogafale_1.html|url-status=  usurped|archive-date=  9 February 2006| access-date=14 June 2015}}</ref> Several attempts to stabilize the shoreline have not achieved the desired effect.<ref name="RC">{{cite web|first=Ralf|last=Carter|title=Wind and Sea Analysis – Funafuti Lagoon, Tuvalu|date=4 July 1986|url=http://prdrse4all.spc.int/data/wind-and-sea-analysis-funafuti-lagoon-tuvalu|work=South Pacific Regional Environmental Programme and UNDP Project RAS/81/102 (Technical. Report No. 58 of PE/TU.3)|access-date=2 January 2020}}</ref>

The rising population results in increased demand on fish stocks, which are under stress;<ref name="RevLT">{{cite web|last=Lusama|first=Tafue|date=29 November 2011|title=Tuvalu plight must be heard by UNFCC|url=http://www.abc.net.au/unleashed/3701422.html|access-date=29 November 2011|publisher=The Drum – Australian Broadcasting Corporation}}</ref> although the creation of the [[Funafuti Conservation Area]] has provided a fishing exclusion area that helps sustain fish populations across the Funafuti lagoon. Population pressure on the resources of Funafuti and in-adequation sanitation systems have resulted in pollution.<ref name="Krales"/><ref name="FB">{{cite news| url=https://www.theguardian.com/global-development/poverty-matters/2011/mar/04/tuvalu-sustainable-way-of-life-disappears | location=London | work=[[The Guardian]] | first1=Florent | last1=Baarsch | title=Warming oceans and human waste hit Tuvalu's sustainable way of life | date=4 March 2011|access-date=24 October 2011}}</ref> The Waste Operations and Services Act 2009 provides the legal framework for the waste management and pollution control projects funded by the European Union that are directed to organic waste composting in eco-sanitation systems.<ref name="TWWSP">{{cite web|url= http://ec.europa.eu/europeaid/documents/aap/2009/af_aap_2009_tuv.pdf |title= Tuvalu / Water, Waste and Sanitation Project (TWWSP): CRIS FED/2009/021-195, ANNEX | date =2009|work=European Union|access-date=24 October 2011}}</ref>

Surveys were carried out in May 2010 of the reef habitats of Nanumea, Nukulaelae and Funafuti (including the Funafuti Conservation Area) and a total of 317 fish species were recorded during this ''Tuvalu Marine Life'' study. The surveys identified 66 species that had not previously been recorded in Tuvalu, which brings the total number of identified species to 607.<ref name=TMLSY>{{cite web|author1=Sandrine Job |author2=Daniela Ceccarelli | title = Tuvalu Marine Life Synthesis Report|date = December 2011| work= Alofa Tuvalu project with the Tuvalu Fisheries Department| url= http://www.alofatuvalu.tv/US/05_a_tuvalu/05_page_tml/livret2light.pdf| access-date=3 December 2013}}</ref><ref name=TMLScR>{{cite web|author1=Sandrine Job |author2=Daniela Ceccarelli | title = Tuvalu Marine Life Scientific Report|date = December 2012| work= Alofa Tuvalu project with the Tuvalu Fisheries Department| url= http://www.alofatuvalu.tv/US/05_a_tuvalu/05_page_tml/livret4light.pdf| access-date=3 December 2013}}</ref>

The terrestrial invertebrates are land and shore crabs, including ''Paikea'' (''[[Discoplax rotunda]]''), ''Tupa'' (''[[Cardisoma carnifex]]''), ''Kamakama'' (''[[Grapsus albolineatus]]''), a range of hermit crabs, ''Uga'' (''[[Coenobita]] spp'') and the coconut crab, ''Uu'' (''[[Coconut crab|Birgus latro]]'').<ref name="TCAP-NN66"/> Also important are a range of land snails, misa (''[[Melampus (gastropod)|Melampus]] spp'') used to make shell [[Lei (garland)|leis]] (ula) and [[Art of Tuvalu|traditional handicrafts]],<ref name="RBA1">{{cite web|author= Randy Thaman, Feagaiga Penivao, Faoliu Teakau, Semese Alefaio, Lamese Saamu, Moe Saitala, Mataio Tekinene and Mile Fonua| work= Rapid Biodiversity Assessment of the Conservation Status of Biodiversity and Ecosystem Services (BES) in Tuvalu|title= Report on the 2016 Funafuti Community-Based Ridge-To-Reef (R2R) |date = 2017|url= https://www.sprep.org/attachments/VirLib/Tuvalu/r2r-biorap.pdf| access-date=13 February 2021}}</ref> which includes the decoration of mats, fans and wall hangings.<ref name="ATP">{{cite web| last =Tiraa-Passfield | first = Anna |title= The uses of shells in traditional Tuvaluan handicrafts| publisher= SPC Traditional Marine Resource Management and Knowledge Information Bulletin #7|date = September 1996|url= http://www.spc.int/DigitalLibrary/Doc/FAME/InfoBull/TRAD/7/TRAD7_02_Tiraa.pdf| access-date=13 February 2021}}</ref>

===Environment – climate change issues===
{{Main|Climate change in Tuvalu}}
Since there are no streams or rivers and groundwater is not potable, most water needs must be met by catchment systems with storage facilities; beachhead erosion because of the use of sand for building materials; excessive clearance of forest undergrowth for use as fuel; damage to coral reefs from the bleaching of the coral as a consequence of the increase of the ocean temperatures and acidification from increased levels of carbon dioxide; Tuvalu is very concerned about global increases in greenhouse gas emissions and their effect on rising sea levels, which threaten the country's underground water table. Tuvalu has adopted a national plan of action as the observable transformations over the last ten to fifteen years show Tuvaluans that there have been changes to the sea levels.<ref name=NAP>{{cite web| title=Tuvalu's National Adaptation Programme of Action|work=Department of Environment of Tuvalu |date=May 2007|url= http://unfccc.int/resource/docs/napa/tuv01.pdf|access-date=7 September 2015}}</ref>

Because of the low elevation, the islands that make up this nation are threatened by current and future [[sea level rise]].<ref name="Krales">{{cite web| first= Amelia Holowaty|last=Krales|url= http://green.blogs.nytimes.com/2011/10/18/as-danger-laps-at-its-shores-tuvalu-pleads-for-action/|title=As Danger Laps at Its Shores, Tuvalu Pleads for Action| date =18 October 2011|work= The New York Times – Green: A Blog about Energy and the Environment|access-date=24 October 2011}}</ref> The highest elevation is {{convert|4.6|m|ft}} above sea level on [[Niulakita]],<ref name="JL">{{cite journal|first=James|last=Lewis|title =Sea level rise: Some implications for Tuvalu |journal=The Environmentalist|volume=9|issue=4|pages=269–275| date =December 1989|doi=10.1007/BF02241827|s2cid=84796023 }}</ref> which gives Tuvalu the second-lowest maximum elevation of any country (after the [[Maldives]]). However, the highest elevations are typically in narrow storm dunes on the ocean side of the islands which are prone to over topping in tropical cyclones, such as occurred on [[Funafuti]] with [[Cyclone Bebe]].<ref name="bom2">{{cite book |last1=  |first1= |title= Tropical Cyclones in the Northern Australian Regions 1971–1972|url= |format= |accessdate=  |year=1975|publisher= Bureau of Meteorology, Australian Government Publishing Service |location= |language= |isbn=|oclc= |doi= |id= |page= |pages=|chapter=|quote= |bibcode= }}</ref>

[[File:Ocean side Funafuti.jpg|thumb|left|300px|Ocean side of [[Funafuti]] atoll showing the storm dunes, the highest point on the atoll.]]

Tuvalu is mainly composed of coral debris eroded from encircling reefs and pushed up onto the islands by winds and waves.<ref name="NG15">{{cite web| last = Warne | first = Kennedy | work= National Geographic  |title= Will Pacific Island Nations Disappear as Seas Rise? Maybe Not – Reef islands can grow and change shape as sediments shift, studies show |date =13 February 2015|url= http://news-beta.nationalgeographic.com/2015/02/150213-tuvalu-sopoaga-kench-kiribati-maldives-cyclone-marshall-islands/|archive-url= https://web.archive.org/web/20150214031223/http://news-beta.nationalgeographic.com/2015/02/150213-tuvalu-sopoaga-kench-kiribati-maldives-cyclone-marshall-islands/|url-status= dead|archive-date= 14 February 2015| access-date=14 February 2015}}</ref> Paul Kench at the [[University of Auckland]] in New Zealand and Arthur Webb at the [[South Pacific Applied Geoscience Commission]] in [[Fiji]] released a study in 2010 on the dynamic response of reef islands to sea level rise in the central Pacific. Tuvalu was mentioned in the study, and Webb and Kench found that seven islands in one of its nine atolls have spread by more than 3 per cent on average since the 1950s.<ref name="new-rep">{{cite magazine|first=Bradford |last=Plumer |title=Pacific Islands Defying Sea-Level Rise—For Now | date=7 June 2010 |url=https://newrepublic.com/blog/the-vine/75348/pacific-islands-defying-sea-level-rise-least-now |magazine= New Republic |access-date=11 October 2015}}</ref> One island, [[Funamanu]], gained 0.44 hectares, or nearly 30 per cent of its previous area. In contrast, [[Tepuka Vili Vili]] has suffered a net loss in area of 22 percent since 1896. The shape and orientation of the reef has also changed over time.<ref name="NG15"/>

Further research by Kench et al., published in 2018 identifies rising sea levels as creating an increased transfer of wave energy across the reef surfaces of the atolls of Tuvalu, which shifts sand, resulting in accretion to island shorelines. Over 4 decades, there had been a net increase in land area of the islets of 73.5 ha (2.9%), although the changes are not uniform, with 74% increasing and 27% decreasing in size.<ref name="PSK"/> However, this process does not result in additional habitable land.<ref name="ktm519"/>

The storm surge resulting from a [[tropical cyclone]] can dramatically shift coral debris. In 1972 Funafuti was in the path of [[Cyclone Bebe]]. Tropical Cyclone Bebe was a pre-season [[tropical cyclone]] that impacted the [[Gilbert Islands|Gilbert]], [[Tuvalu|Ellice Islands]], and [[Fiji]] island groups.<ref name="BOM1975">Bureau of Meteorology (1975) ''Tropical Cyclones in the Northern Australian Regions 1971–1972'' Australian Government Publishing Service</ref> The storm surge created a wall of coral rubble along the ocean side of [[Fongafale]] and [[Funafala]] that was about {{convert|10|mi}} long, and about {{convert|10|to|20|ft|m}} thick at the bottom.<ref name="HB72">{{cite web |last=Resture|first= Jane|title= Hurricane Bebe 1972 |url= http://www.janeresture.com/hurribebe/hurricanebebe2.htm|date=5 October 2009 |work= Tuvalu and the Hurricanes: 'The Hurricane in Funafuti, Tuvalu' by Pasefika Falani (Pacific Frank)|access-date=15 February 2015}}</ref> The cyclone knocked down about 90% of the houses and trees on Funafuti and contaminated sources of drinking water as a result of the system's storm surge and fresh water flooding.

Tuvalu is affected by [[perigean spring tide]] events which raise the sea level higher than a normal [[high tide]].<ref name="BBC">{{cite news|first=David|last=Shukman|title=Tuvalu struggles to hold back tide|date=22 January 2008|work=[[BBC News]] |url=http://news.bbc.co.uk/2/hi/science/nature/7203313.stm|access-date=5 August 2008}}</ref> The highest peak tide recorded by the [[Tuvalu Meteorological Service]] was {{convert|3.4|m|ft}} on 24 February 2006 and again on 19 February 2015.<ref>{{cite web|publisher=[[Radio New Zealand]] |date=24 February 2015|access-date=17 March 2015|title=Tuvalu surveys road damage after king tides|url=http://www.radionz.co.nz/international/pacific-news/266995/tuvalu-surveys-road-damage-after-king-tides}}</ref> As a result of historical sea level rise, the [[king tide]] events lead to flooding of low-lying areas, which is compounded when sea levels are further raised by [[La Niña]] effects or local storms and waves.<ref name="PDV-24-2-15">{{cite news |last1= Eliuta|first1= Niuone |title= Science says Tuvalu will drown within decades; the reality is worse |url=https://devpolicy.org/science-says-tuvalu-will-drown-within-decades-the-reality-is-worse-20240215/ |access-date=15 February 2024 |work=PolicyDevBlog|date=15 February 2024}}</ref> In the future, sea level rise may threaten to submerge the nation entirely as it is estimated that a sea level rise of {{convert|20|–|40|cm|in|abbr=off}} in the next 100 years could make Tuvalu uninhabitable.<ref name ="Patel">{{cite journal | vauthors = Patel SS | year = 2006 | title = A sinking feeling | url = http://www.scidev.net/pdffiles/nature/tuvalu.pdf | journal = Nature | volume = 440 | issue = 7085| pages = 734–736 | doi = 10.1038/440734a | pmid = 16598226 | bibcode = 2006Natur.440..734P | s2cid = 1174790 }}</ref><ref name="staff.acecrc.org.au">Hunter, J. A. 2002. [http://staff.acecrc.org.au/~johunter/tuvalu.pdf Note on Relative Sea Level Change at Funafuti, Tuvalu] {{webarchive |url=https://web.archive.org/web/20111007232502/http://staff.acecrc.org.au/~johunter/tuvalu.pdf |date=7 October 2011 }}. Retrieved 13 May 2006.</ref>

Tuvalu experiences westerly gales and heavy rain from October to March – the period that is known as ''Tau-o-lalo''; with tropical temperatures moderated by easterly winds from April to November. Drinking water is mostly obtained from rainwater collected on roofs and stored in tanks; these systems are often poorly maintained, resulting in lack of water.<ref name="PAK">{{cite web|first=P.A. |last=Kingston |title=Surveillance of Drinking Water Quality in the Pacific Islands: Situation Analysis and Needs Assessment |year=2004 |url=https://pacific-data.sprep.org/dataset/drinking-water-quality-pacific-island-countries/resource/43881d9e-831b-488e-b0a5 |work=Situation Analysis and Needs Assessment, Country Reports, WHO |access-date=2 January 2020}}</ref> Aid programs of Australia and the European Union have been directed to improving the storage capacity on Funafuti and in the outer islands.<ref name="10EDF">{{cite web|url=https://ec.europa.eu/europeaid/countries/tuvalu_en|title=Tuvalu – 10th European Development Fund|work=Delegation of the European Union|access-date=2 January 2020}}</ref>

===Borrow Pits Remediation (BPR) project===
When the airfield, which is now [[Funafuti International Airport]], was constructed during World War II. The coral base of the atoll was used as fill to create the runway. The resulting [[borrow pit]]s impacted the fresh-water [[aquifer]]. In the low areas of Funafuti the sea water can be seen bubbling up through the porous coral rock to form pools with each high tide.<ref name=ML2005>{{cite web| first=Monise |last=Laafai |url= http://www.tuvaluislands.com/photos/2006_tides/2006tides.html|archive-url= https://web.archive.org/web/20060419190352/http://www.tuvaluislands.com/photos/2006_tides/2006tides.html|url-status= usurped|archive-date= 19 April 2006|title=Funafuti King Tides | date = October 2005|access-date=14 October 2011}}</ref><ref name=MKM>{{cite web|first= Moya K.|last= Mason|url= http://www.moyak.com/papers/tuvalu-climate-change.html |title= Tuvalu: Flooding, Global Warming, and Media Coverage |access-date=13 October 2011}}</ref><ref name="AHK1">{{cite web| last = Holowaty Krales | first =Amelia | title= Chasing the Tides, parts I & II |date= 20 February 2011 |url=http://ameliaholowatykrales.blogspot.com.au/2011_02_01_archive.html|access-date=20 November 2012}}</ref> Since 1994 a project has been in development to assess the environmental impact of transporting sand from the lagoon to fill all the borrow pits and low-lying areas on [[Fongafale]]. In 2013 a feasibility study was carried out and in 2014 the Tuvalu Borrow Pits Remediation (BPR) project was approved, so that all ten borrow pits would be filled, leaving Tafua Pond, which is a natural pond.<ref>{{cite web|last= Silafaga Lalua Melton|title= 73 years of waiting finally pays off for Funafuti | date =28 October 2014|url= https://www.facebook.com/permalink.php?story_fbid=357292681098580&id=333658940128621&substory_index=0|publisher= Fenui News|access-date=1 April 2014}}</ref> The New Zealand Government funded the BPR project.<ref>{{cite web|title= Tuvalu to Benefit from International Dredging Aid| date =1 April 2014|url= http://www.sandandgravel.com/news/article.asp?v1=19459 |publisher= Dredging News|access-date=1 April 2014}}</ref> The project was carried out in 2015 with 365,000 sqm of sand being dredged from the lagoon to fill the holes and improve living conditions on the island. This project increased the usable land space on Fongafale by eight per cent.<ref>{{cite web |title= Coast contractor completes aid project in remote Tuvalu| date =27 November 2015|url= http://www.sunshinecoastdaily.com.au/news/coast-contractor-completes-aid-project-remote-tuva/2855272/|publisher= SunshineCoastDaily|access-date=28 November 2015}}</ref>

===Tuvalu Coastal Adaptation Project (TCAP)===
The [[Tuvalu Coastal Adaptation Project]] (TCAP) was launched in 2017 for the purpose on enhancing the resilience of the islands of Tuvalu to meet the challenges resulting from higher sea levels.<ref name="GCF">{{cite web| last = Bouadze | first = Levan |title= Groundbreaking ceremony in Funafuti for Tuvalu's coastal adaptation|publisher= UNDP Pacific Office in Fiji |page=|date = 6 December 2022|url= https://www.undp.org/pacific/speeches/groundbreaking-ceremony-funafuti-tuvalus-coastal-adaptation | accessdate=1 November 2023}}</ref> Tuvalu was the first country in the Pacific to access climate finance from [[Green Climate Fund]], with the support of the [[United Nations Development Programme|UNDP]].<ref name="GCF"/> In December 2022, work on the Funafuti reclamation project commenced. The project is to dredge sand from the lagoon to construct a platform on [[Fongafale]], [[Funafuti]] that is {{convert|780|m|ft}} meters long and {{convert|100|m|ft}} meters wide, giving a total area of approximately 7.8 ha. (19.27 acres), which is designed to remain above sea level rise and the reach of storm waves beyond the year 2100.<ref name="GCF"/> The Australian [[Department of Foreign Affairs and Trade]] (DFAT) also provided funding for the TCAP. Further projects that are part of TCAP are capital works on the outer islands of [[Nanumea]] and [[Nanumaga]] aimed at reducing exposure to coastal damage resulting from storms.<ref name="GCF"/>

===Topographic and Bathymetric Survey===
In May 2019, TCAP signed an agreement with Fugro, for it to carry out an airborne [[Lidar|LIDAR (Light Detection and Ranging)]] survey across the nine [[islands of Tuvalu]].<ref name="LiDAR">{{cite web| last = | first = |title= Advanced Topographic and Bathymetric Survey to Support Tuvalu's Adaptation Efforts |publisher= UNDP|page=|date = 2 May 2019 |url= https://reliefweb.int/report/tuvalu/advanced-topographic-and-bathymetric-survey-support-tuvalu-s-adaptation-efforts | accessdate=8 November 2023}}</ref> LIDAR is a [[remote sensing]] method that uses light in the form of a pulsed laser that will produce high quality mapping of the reef and lagoon [[bathymetry]] (sea floor mapping to 50-meter depths) and accurate [[topography]] (land elevation data).<ref name="LiDAR"/> This aerial survey will provide high quality baseline data to assess the relationship between water levels and wave dynamics and their impact on the islands of Tuvalu.<ref name="LiDAR"/> The survey will also provide baseline data for shoreline monitoring, coastal vulnerability assessment and planning.<ref name="LiDAR"/>

===Controls on plastic waste and recycling of domestic waste===
From 1 August 2019, specific single-use plastic items are subject to a ban on importation into Tuvalu, an importation levy was also imposed on specific items, such as refrigerators and vehicles, to raise money to pay for their recycling or shipment out of the country when they cease to be usable.<ref name="LOC19">{{cite web| last = Buchanan | first = Kelly |title= Tuvalu: Ban on Single-Use Plastics Commences |publisher= Library of Congress |page=|date = 19 August 2019|url= https://www.loc.gov/item/global-legal-monitor/2019-08-19/tuvalu-ban-on-single-use-plastics-commences/| accessdate=8 November 2023}}</ref> The new rules are contained in two regulations: the Waste Management (Prohibition on the Importation of Single-Use Plastic) Regulation 2019 and the Waste Management (Levy Deposit) Regulation 2019, which regulations are made under the Waste Operations and Services Act 2009.<ref name="LOC19"/>

===Environment – international agreements===
Tuvalu is a party to:
[[Biodiversity]], [[United Nations Framework Convention on Climate Change|Climate Change]], [[Climate Change-Kyoto Protocol]], [[Desertification]], [[Hazardous waste|Hazardous Waste]], [[Law of the Sea]], [[Ozone Layer Protection]], [[Ship Pollution]], [[Whaling]]
<br>''signed, but not ratified:'' none

Tuvalu signed the [[Convention on Biological Diversity]] (CBD) in 1992, and ratified it in December 2002.<ref name="CBD">{{cite web| last = | first = |title= Tuvalu Sixth National Report to the Convention on Biological Diversity|publisher= Government of Tuvalu|page=|year = 2020|url= https://www.cbd.int/doc/nr/nr-06/tv-nr-06-en.pdf | accessdate=11 November 2023}}</ref><ref name="RT16">{{cite web|author= Compiled by Randy Thaman with assistance from Faoliu Teakau, Moe Saitala, Epu Falega, Feagaiga Penivao, Mataio Tekenene and Semese Alefaio | work= Ministry of Foreign Affairs, Trade, Tourism, Environment and Labour Government of Tuvalu |title= Tuvalu National Biodiversity Strategy and Action Plan: Fifth National Report to the Convention on Biological Diversity |date = 2016|url= https://www.cbd.int/doc/world/tv/tv-nr-05-en.pdf| access-date=25 May 2019}}</ref>

Tuvalu signed the [[Pacific Islands Cetaceans Memorandum of Understanding]] on 9 September 2010.

Tuvalu is a party to the [[Waigani Convention]] that bans the importation into forum island countries of hazardous and radioactive wastes and to control the transboundary movement and management of hazardous wastes within the south pacific region and is also a party to the [[Minamata Convention on Mercury]], [[Stockholm Convention on Persistent Organic Pollutants]], [[Vienna Convention for the Protection of the Ozone Layer]] and the [[Montreal Protocol]] on Substances that Deplete the Ozone Layer. Tuvalu is in the process of completing its accession to the [[Basel Convention]] to protect human health and the environment against the adverse effects that may result from the generation, transboundary movements and management of hazardous and other wastes.<ref name="wm20">{{cite web| last = | first = |title= Assessment of Legislative Frameworks Governing Waste Management in Tuvalu |publisher= Prepared by the Melbourne Law School at the University of Melbourne, Australia, with technical assistance from Monash University, on behalf of the Secretariat of the Pacific Regional Environment Programme (SPREP). |page=|date = November 2020|url= https://library.sprep.org/sites/default/files/2021-03/waste-legislation-Tuvalu.pdf| accessdate=8 November 2023}}</ref>

==Funafuti atoll==
===Structure of Funafuti atoll===
[[File:Funafuti bearbeitet.jpg|thumb|right|250px|Funafuti atoll]]

[[Funafuti]] [[atoll]] consists of a narrow sweep of land between {{convert|20|and|400|m|0|abbr=off}} wide, encircling a large lagoon (''Te Namo'') of about {{convert|18|km|0|abbr=in}} long and {{convert|14|km|0|abbr=in}} wide. The average depth in the Funafuti lagoon is about {{convert|20|fathom|m ft|abbr=off}}.<ref name="AC1">{{cite book |last=Coates|first=A. | title= Western Pacific Islands |year= 1970 |publisher= H.M.S.O.|pages=349}}</ref> With a surface of {{convert|275|km²|1|abbr=out}}, it is by far the largest lagoon in Tuvalu. The northern part of the lagoon has a deep basin (maximum depth recorded of 54.7 m) basin, and the southern part of the lagoon has very narrow shallow basin.<ref name="SOPAC"/> The land area of the 33 islets aggregates to {{convert|2.4|km²|1|abbr=out}}, less than one percent of the total area of the atoll.

The boreholes on [[Fongafale]] islet at the site now called ''Darwin's Drill'',<ref name="PDN">{{cite book |last1=Lal |first1=Andrick |title=South Pacific Sea Level & Climate Monitoring Project – Funafuti atoll |url=http://www.pacificdisaster.net/oip/FinalReport/Annex/3_Survey%20LDP/Survey_Diagrams_JPACE-TV.pdf |archive-url=https://web.archive.org/web/20140203011855/http://www.pacificdisaster.net/oip/FinalReport/Annex/3_Survey%20LDP/Survey_Diagrams_JPACE-TV.pdf |url-status=dead |archive-date=3 February 2014 |publisher=SPC Applied Geoscience and Technology Division (SOPAC Division of SPC) |pages=35 & 40}}</ref> are the result of drilling conducted by the [[Royal Society of London]] for the purpose of investigating the [[formation of coral reefs]] to determine whether traces of shallow water organisms could be found at depth in the [[coral]] of Pacific atolls. This investigation followed the work on [[The Structure and Distribution of Coral Reefs]] conducted by [[Charles Darwin]] in the Pacific. Drilling occurred in 1896, 1897 and 1898.<ref>{{cite news |url=http://nla.gov.au/nla.news-article17092086 |title=TO THE EDITOR OF THE HERALD |newspaper=[[The Sydney Morning Herald]] |date=11 September 1934 |access-date=20 June 2012 |page=6 |publisher=National Library of Australia}}</ref> Professor [[Edgeworth David]] of the [[University of Sydney]] was a member of the 1896 "Funafuti Coral Reef Boring Expedition of the Royal Society", under [[William Johnson Sollas|Professor William Sollas]] and lead the expedition in 1897.<ref>David, Mrs Edgeworth, ''Funafuti or Three Months on a Coral Atoll: an unscientific account of a scientific expedition'', London: John Murray, 1899</ref> However, the geologic history of atolls is more complex than Darwin (1842) and Davis (1928)<ref name="WMD1">{{cite journal| last = Davis, W.M. |title= The coral reef problem | journal = American Geographical Society Special Publication | volume = 9| issue = | pages = 1–596|date = 1928}}</ref> envisioned.<ref name="DRS">{{cite journal| last = Stoddart, D. R.|title= Theory and Reality: The Success and Failure of the Deductive Method in Coral Reef Studies–Darwin to Davis| journal = Earth Sciences History | volume = 13| issue =1 | pages = 21–34|date = 1994|doi= 10.17704/eshi.13.1.wp354u3281532021}}</ref><ref name="WRD">{{cite journal|last1= Dickinson |first1=William R. |title= Pacific Atoll Living: How Long Already and Until When?|url= https://www.geosociety.org/gsatoday/archive/19/3/pdf/i1052-5173-19-3-4.pdf|year= 2009 |journal= GSA Today |volume=19|issue=3|pages=4–10 |doi= 10.1130/GSATG35A.1 }}</ref> The survey of the atoll published in 1970 described its structure as being:

{{cquote| “[[Funafuti]] is an almost circular and conical submarine mountain 12,000 feet high, originally volcanic, and of immense geological age, much older than the relatively young and active mountains of the [[Vanuatu|New Hebrides]] and [[Solomon Islands|Solomons]]. At its base on the ocean bed it is 30 miles wide in one of the directions tested, and 28 miles wide on the other. It rises in a gentle slope which gradually steepens to a point 2,400 feet below water level, after which it rises at an angle of 80 degrees to 840 feet below water level. From this point it rises vertically, like an enormous pillar, till reaches the surface in the form of a reef enclosing a lagoon of irregular size, but of which the extremities give a measurement of 13.5 by 10.0 miles".<ref name="AC1"/>}}

===Aquifer salinization of Fongafale Islet, Funafuti===
The investigation of groundwater dynamics of [[Fongafale]] Islet, [[Funafuti]], show that [[tidal force|tidal forcing]] results in salt water contamination of the [[surficial aquifer]] during [[Perigean spring tide|spring tides]].<ref name="EAS">{{cite journal|author1=Nakada S. |author2=Yamano H. |author3=Umezawa Y. |author4=Fujita M. |author5=Watanabe M. |author6=Taniguchi M. |title= Evaluation of Aquifer Salinization in the Atoll Islands by Using Electrical Resistivity|journal=Journal of the Remote Sensing Society of Japan |volume=30 |year =2010 |pages=317–330|doi=10.11440/rssj.30.317 }}</ref> The degree of aquifer salinization depends on the specific [[topographic]] characteristics and the [[hydrologic]] controls in the sub-surface of the atoll. About half of Fongafale islet is reclaimed swamp that contains porous, highly permeable coral blocks that allow the tidal forcing of salt water.<ref name="GWD">{{Cite journal|vauthors=Nakada S, Umezawa Y, Taniguchi M, Yamano H |title= Groundwater dynamics of Fongafale Islet, Funafuti Atoll, Tuvalu |journal= Groundwater |volume= 50 |issue= 4 |date =Jul–Aug 2012 |pages=639–44 |doi= 10.1111/j.1745-6584.2011.00874.x |pmid=22035506|s2cid= 32336745 }}</ref> There was extensive swamp reclamation during World War II to create the air field that is now the [[Funafuti International Airport]]. As a consequence of the specific topographic characteristics of Fongafale, unlike other atoll islands of a similar size, Fongafale does not have a thick [[Lens (hydrology)|freshwater lens]].<ref name="GWD"/> The narrow fresh water and brackish water sheets in the sub-surface of Fongafale islet results in the [[taro]] swamps and the fresh groundwater resources of the islet being highly vulnerable to salinization resulting from the rising sea-level.<ref name="GWD"/>

In addition to the increased risk of salinized by the sea-level rise, the freshwater lens is at risk from over extraction due to the large population that now occupies Fongafale islet; the increased extraction can be exacerbated by a decrease of the rainfall recharge rate associated with the climate change.<ref name="EAS"/> Water pollution is also a chronic problem, with domestic wastewater identified as the primary pollution source.<ref name="AIW">{{cite journal| last = Fujita M., Suzuki J., Sato D., Kuwahara Y., Yokoki H., Kayanne, Y. |title= Anthropogenic impacts on water quality of the lagoonal coast of Fongafale Islet, Funafuti Atoll, Tuvalu|journal= Sustainability Science|volume= 8|issue= 3|pages= 381–390|year =2013 |url= https://link.springer.com/content/pdf/10.1007%2Fs11625-013-0204-x.pdf|doi= 10.1007/s11625-013-0204-x|s2cid= 127909606}}</ref>  Approximately 92% of households on Fongafale islet have access to septic tanks and pit toilets. However, these sanitary facilities are not built as per the design specifications or they are not suitable for the geophysical characteristics, which results in seepage into the fresh water lens and run off into coastal waters.<ref name="AIW"/>

On [[Funafuti]] and on the other islands, rainwater collected off the corrugated iron roofs of buildings is now the primary source of fresh water. On Funafuti a desalination unit that was donated by Japan in 2006 also provides fresh water.<ref name="JPDP">{{cite web|title = Japan Provides Desalination Plant to relieve Tuvalu's water problems |date =2 June 2006|url= http://www.fj.emb-japan.go.jp/pr_Japan_Provides_Desalination_Plant_to_relieve_Tuvalus_water_problems.html |publisher = Embassy of Japan in the Republic of the Fiji Islands |access-date=1 December 2011}}</ref> In response to the [[2011 Tuvalu drought|2011 drought]], Japan funded the purchase of a 100 m<sup>3</sup>/d desalination plant and two portable 10 m<sup>3</sup>/d plants as part of its Pacific Environment Community (PEC) program.<ref name="JNZ">{{cite web |title = Japan-New Zealand Aid Cooperation in response to severe water shortage in Tuvalu |date =4 November 2011|url= http://www.mofa.go.jp/announce/announce/2011/11/1104_01.html |publisher = Department of Foreign Affairs of Japan |access-date=1 December 2011}}</ref><ref name="J3">{{cite web |title = Japanese fund three desalination plants for Tuvalu |date = 17 October 2011 |url = http://www.desalination.biz/news/news_story.asp?id=6170&title=Japanese+fund+three+desalination+plants+for+Tuvalu |publisher = The International Desalination & Water Reuse Quarterly industry website |access-date = 1 December 2011 |archive-date = 7 May 2012 |archive-url = https://web.archive.org/web/20120507101412/http://www.desalination.biz/news/news_story.asp?id=6170&title=Japanese+fund+three+desalination+plants+for+Tuvalu |url-status = dead }}</ref> Aid programs from the European Union<ref name="10EDF"/><ref name="TWWSP1">{{cite web| url= http://ec.europa.eu/europeaid/documents/aap/2009/af_aap_2009_tuv.pdf |title= Tuvalu / Water, Waste and Sanitation Project (TWWSP): CRIS FED/2009/021-195, ANNEX | publisher=European Union|access-date=24 October 2011}}</ref> and Australia also provided water tanks as part of the longer-term solution for the storage of available fresh water.

===Aquifer salinization and the impact on Pulaka production===
Swamp taro (''[[Cyrtosperma merkusii]]''), known in Tuvalu as ''[[Pulaka]]'', is grown in large pits of composted soil below the water table,<ref name="GK">{{cite book|last=Koch|first=Gerd|title=The material culture of Tuvalu|publisher=Institute of Pacific Studies, [[University of the South Pacific]]|date=1983|page=46|url=https://books.google.com/books?id=w7aeiuIXVigC&pg=PA46|access-date=12 May 2010}}</ref> Pulaka has been the main source for [[carbohydrate]]s,<ref name="GK"/> it is similar to [[taro]], but "with bigger leaves and larger, coarser roots".<ref name="TARO">{{cite web |url= http://www.fao.org/WAIRdocs/x5425e/x5425e01.htm |title= Leaflet No. 1 – Revised 1992 – Taro |date= 1992 |publisher= [[Food and Agriculture Organization]] |access-date= 15 August 2012 |archive-date= 28 August 2009 |archive-url= https://web.archive.org/web/20090828014127/http://www.fao.org/Wairdocs/X5425E/x5425e01.htm |url-status= dead }}</ref>

In recent years the Tuvaluan community have raised concerns over increased salinity of the groundwater in pits that are used to cultivate pulaka.<ref name="root crop">{{cite news| url= http://www.rnzi.com/pages/news.php?op=read&id=42070 | publisher=[[Radio New Zealand]]| title= Tuvalu could lose root crop | date=17 September 2008| access-date = 10 May 2010}}</ref> Pits on all islands of Tuvalu (except [[Niulakita]]) were surveyed in 2006. [[Nukulaelae]] and [[Niutao]] each had one pit area in which salinity concentrations thought to be too high for successful swamp taro growth. However, on Fongafale in [[Funafuti]] all pits surveyed were either too saline or very marginal for swamp taro production, although a more salt tolerant species of [[taro]] (''Colocasia esculenta'') was being grown in Fongafale.<ref name="TTR">{{cite web| last = Webb| first = Dr Arthur| title = Tuvalu Technical Report: Assessment of Salinity of Groundwater in Swamp Taro (Cyrtosperma Chamissonis) "Pulaka" Pits in Tuvalu| publisher = Pacific Islands Applied Geoscience Commission, EU EDF8-SOPAC Project Report 75: Reducing Vulnerability of Pacific ACP States| date = March 2007| url = https://www.researchgate.net/publication/328175697| access-date = 2 January 2020}}</ref>

The extent of the salinization of the aquifer on Fongafale Islet is the result of both man-made changes to the [[topography]] that occurred when the air field was built in World War II by reclaiming swamp land and excavating coral rock from other parts of the islet. These topographic changes are exacerbated by the groundwater dynamics of the islet, as tidal forcing pushes salt water into the surficial aquifer during spring tides.<ref name="EAS"/>

The [[Lens (hydrology)|freshwater lens]] of each atoll is a fragile system. [[Tropical cyclone]]s and other storm events also result in wave wash over and extreme high water also occurs during spring tides. These events can result in salt water contamination of the fresh groundwater lens. Periods of low rainfall can also result in contraction of the freshwater lens as the coconut trees and other vegetation draw up the water at a greater than recharge than it can be recharged. The over extraction of ground water to supply human needs has a similar result as drought conditions.<ref name="GWD1">{{Cite journal|vauthors=Nakada S, Umezawa Y, Taniguchi M, Yamano H |title= Groundwater dynamics of Fongafale Islet, Funafuti Atoll, Tuvalu |journal= Groundwater |volume= 50 |issue= 4 |date =2012 |pages=639–44 |doi= 10.1111/j.1745-6584.2011.00874.x |pmid=22035506|s2cid= 32336745 }}</ref>

==See also==
* '''''<small>{{portal-inline|Tuvalu}}</small>'''''

==References==
{{reflist|30em}}

==Further reading==
* {{in lang|en}} {{cite web|last= Kench, Thompson, Ford, Ogawa and McLean |title = GSA DATA REPOSITORY 2015184 (Changes in planform characteristics of 29 islands located on Funafuti's atoll rim)| date =2015|url= https://www.geosociety.org/datarepository/2015/2015184.pdf |publisher= The Geological Society of America|access-date=22 January 2017}}
* {{cite web|author= Compiled by Randy Thaman with assistance from Faoliu Teakau, Moe Saitala, Epu Falega, Feagaiga Penivao, Mataio Tekenene and Semese Alefaio | work= Ministry of Foreign Affairs, Trade, Tourism, Environment and Labour Government of Tuvalu |title= Tuvalu National Biodiversity Strategy and Action Plan: Fifth National Report to the Convention on Biological Diversity |date = 2016|url= https://www.cbd.int/doc/world/tv/tv-nr-05-en.pdf| access-date=25 May 2019}}
* {{cite journal |author= Thaman, Randolph|date= October 2016 |title= The Flora of Tuvalu: Lakau Mo Mouku o Tuvalu|journal= Atoll Research Bulletin |issue= 611 |pages= xii-129 |doi=10.5479/si.0077-5630.611|s2cid= 89181901 |doi-access= free }}


{{CIA World Factbook}}{{Geography of Oceania}}
{{Tuvalu topics}}

[[Category:Geography of Tuvalu| ]]