Editing River delta (section)

=== Tidal freshwater deltas ===
A tidal freshwater delta<ref>{{Cite web|url=http://pasternack.ucdavis.edu/research/projects/tidal-freshwater-deltas/|title=Gregory B. Pasternack – Watershed Hydrology, Geomorphology, and Ecohydraulics :: Tidal Freshwater Deltas|website=pasternack.ucdavis.edu|language=en|access-date=2017-06-12|archive-date=2018-09-30|archive-url=https://web.archive.org/web/20180930094738/http://pasternack.ucdavis.edu/research/projects/tidal-freshwater-deltas/|url-status=live}}</ref> is a sedimentary deposit formed at the boundary between an upland stream and an estuary, in the region known as the "subestuary".<ref>{{cite thesis |last=Pasternack |first=G. B. |year=1998 |title=Physical dynamics of tidal freshwater delta evolution |type=PhD dissertation |publisher=The Johns Hopkins University |oclc=49850378 }}</ref> Drowned coastal river valleys that were inundated by rising sea levels during the late [[Pleistocene]] and subsequent [[Holocene]] tend to have dendritic estuaries with many feeder tributaries. Each tributary mimics this salinity gradient from its brackish junction with the mainstem [[estuary]] up to the fresh stream feeding the head of tidal propagation. As a result, the tributaries are considered to be "subestuaries". The origin and evolution of a tidal freshwater delta involves processes that are typical of all deltas<ref name=":0" /> as well as processes that are unique to the tidal freshwater setting.<ref>{{Cite journal|last1=Pasternack|first1=Gregory B.|last2=Hilgartner|first2=William B.|last3=Brush|first3=Grace S.|date=2000-09-01|title=Biogeomorphology of an upper Chesapeake Bay river-mouth tidal freshwater marsh|journal=[[Wetlands (journal)|Wetlands]]|volume=20|issue=3|pages=520–537|doi=10.1672/0277-5212(2000)020<0520:boaucb>2.0.co;2|bibcode=2000Wetl...20..520P |s2cid=25962433 |issn=0277-5212}}</ref><ref>{{Cite journal|last1=Pasternack|first1=Gregory B|last2=Brush|first2=Grace S|date=2002-03-01|title=Biogeomorphic controls on sedimentation and substrate on a vegetated tidal freshwater delta in upper Chesapeake Bay|journal=[[Geomorphology (journal)|Geomorphology]]|volume=43|issue=3–4|pages=293–311|doi=10.1016/s0169-555x(01)00139-8|bibcode=2002Geomo..43..293P}}</ref> The combination of processes that create a tidal freshwater delta result in a distinct morphology and unique environmental characteristics. Many tidal freshwater deltas that exist today are directly caused by the onset of or changes in historical land use, especially [[deforestation]], [[intensive agriculture]], and [[urbanization]].<ref>{{Cite journal|last1=Pasternack|first1=Gregory B.|last2=Brush|first2=Grace S.|date=1998-09-01|title=Sedimentation cycles in a river-mouth tidal freshwater marsh|journal=[[Estuaries and Coasts]]|language=en|volume=21|issue=3|pages=407–415|doi=10.2307/1352839|issn=0160-8347|jstor=1352839|s2cid=85961542|url=http://www.escholarship.org/uc/item/61w6m8kc|access-date=2018-09-08|archive-date=2019-02-07|archive-url=https://web.archive.org/web/20190207072632/https://escholarship.org/uc/item/61w6m8kc|url-status=live}}</ref> These ideas are well illustrated by the many tidal freshwater deltas prograding into [[Chesapeake Bay]] along the east coastline of the United States. Research has demonstrated that the accumulating sediments in this estuary derive from post-European settlement deforestation, agriculture, and urban development.<ref>{{cite journal | last1 = Gottschalk | first1 = L. C. | year = 1945 | title = Effects of soil erosion on navigation in upper Chesapeake Bay | journal = Geographical Review | volume = 35 | issue = 2| pages = 219–238 | doi=10.2307/211476| jstor = 211476 | bibcode = 1945GeoRv..35..219G }}</ref><ref>{{cite journal | last1 = Brush | first1 = G. S. | year = 1984 | title = Patterns of recent sediment accumulation in Chesapeake Bay (Virginia-Maryland, U.S.A.) tributaries | journal = [[Chemical Geology]] | volume = 44 | issue = 1–3| pages = 227–242 | doi=10.1016/0009-2541(84)90074-3| bibcode = 1984ChGeo..44..227B }}</ref><ref>{{cite journal | last1 = Orson | first1 = R. A. | last2 = Simpson | first2 = R. L. | last3 = Good | first3 = R. E. | year = 1992 | title = The paleoecological development of a late Holocene, tidal freshwater marsh of the upper Delaware River estuary | journal = [[Estuaries and Coasts]] | volume = 15 | issue = 2| pages = 130–146 | doi=10.2307/1352687| jstor = 1352687 | s2cid = 85128464 }}</ref>