The U.S. Geological Survey Forecast Mekong project is providing technical assistance and information to aid management decisions and build science capacity of institutions in the Mekong River Basin. A component of this effort is to produce a synthesis of the effects of dams and other engineering structures on large-river hydrology, sediment transport, geomorphology, ecology, water quality, and deltaic systems. The Mississippi River Basin (MRB) of the United States was used as the backdrop and context for this synthesis because it is a continental scale river system with a total annual water discharge proportional to the Mekong River, has been highly engineered over the past two centuries, and the effects of engineering have been widely studied and documented by scientists and engineers. The MRB is controlled and regulated by dams and river-engineering structures. These modifications have resulted in multiple benefits including navigation, flood control, hydropower, bank stabilization, and recreation. Dams and other river-engineering structures in the MRB have afforded the United States substantial socioeconomic benefits; however, these benefits also have transformed the hydrologic, sediment transport, geomorphic, water-quality, and ecologic characteristics of the river and its delta. Large dams on the middle Missouri River have substantially reduced the magnitude of peak floods, increased base discharges, and reduced the overall variability of intraannual discharges. The extensive system of levees and wing dikes throughout the MRB, although providing protection from intermediate magnitude floods, have reduced overall channel capacity and increased flood stage by up to 4 meters for higher magnitude floods. Prior to major river engineering, the estimated average annual sediment yield of the Mississippi River Basin was approximately 400 million metric tons. The construction of large main-channel reservoirs on the Missouri and Arkansas Rivers, sedimentation in dike fields, and protection of channel banks by revetments throughout the basin, have reduced the overall sediment yield of the MRB by more than 60 percent. The primary alterations to channel morphology by dams and other engineering projects have been (1) channel simplification and reduced dynamism; (2) lowering of channel-bed elevation; and (3) disconnection of the river channel from the flood plain, except during extreme flood events. Freshwater discharge from the Mississippi River and its associated sediment and nutrient loads strongly influence the physical and biological components in the northern Gulf of Mexico. Ninety percent of the nitrogen load reaching the Gulf of Mexico is from nonpoint sources with about 60 percent coming from fertilizer and mineralized soil nitrogen. Much of the phosphorus is from animal manure from pasture and rangelands followed by fertilizer applied to corn and soybeans. Increased nutrient enrichment in the northern Gulf of Mexico has resulted in the degradation of water quality as more phytoplankton grow, which increases turbidity and depletes oxygen in the lower depths creating what is known as the \"dead zone.\" In 2002, the dead zone was 22,000 square kilometers (km2), an area similar to the size of the State of Massachusetts. Changes in the flow regime from engineered structures have had direct and indirect effects on the fish communities. The navigation pools in the upper Mississippi River have aged, and these overwintering habitats, which were created when the pools filled, have declined as sedimentation reduces water depth. Reproduction of paddlefish may have been adversely affected by dams, which impede access to suitable spawning habitats. Fishes that inhabit swift-current habitats in the unimpounded lower Mississippi River have not declined as much as in the upper Mississippi River. The decline of the pallid sturgeon may be attributable to channelization of the Missouri River above St. Louis, Missouri. The Missouri River supports a rich fish community and remains relatively intact. Nevertheless, the widespread and long history of human intervention in river discharge has contributed to the declines of about 25 percent of the species. The Mississippi River Delta Plain is built from six delta complexes composed of a massive area of coastal wetlands that support the largest commercial fishery in the conterminous United States. Since the early 20th century, approximately 4,900 km2 of coastal lands have been lost in Louisiana. One of the primary mechanisms of wetland loss on the Plaquemines-Balize complex is believed to be the disconnection of the river distributary network from the delta plain by the massive system of levees on the delta top, which prevent overbank flooding and replenishment of the delta top by sediment and nutrient deliveries. Efforts by Federal and State agencies to conserve and restore the Mississippi River Delta Plain began over three decades ago and have accelerated over the past decade. Regardless of these efforts, however, land losses are expected to continue because the reduced upstream sediment supplies are not sufficient to keep up with the projected depositional space being created by the combined forces of delta plain subsidence and global sea-level rise.
","language":"English","publisher":"U.S. Geological Survey","publisherLocation":"Reston, VA.","doi":"10.3133/cir1375","collaboration":"Prepared in cooperation with the U.S. Department of State","usgsCitation":"Alexander, J.S., Wilson, R.C., and Green, W.R., 2012, A brief history and summary of the effects of river engineering and dams on the Mississippi River system and delta: U.S. Geological Survey Circular 1375, v., 43 p., https://doi.org/10.3133/cir1375.","productDescription":"v., 43 p.","onlineOnly":"Y","additionalOnlineFiles":"N","costCenters":[{"id":464,"text":"Nebraska Water Science Center","active":true,"usgs":true}],"links":[{"id":257319,"rank":100,"type":{"id":15,"text":"Index Page"},"url":"https://pubs.usgs.gov/circ/1375/","linkFileType":{"id":5,"text":"html"}},{"id":300769,"rank":101,"type":{"id":11,"text":"Document"},"url":"https://pubs.usgs.gov/circ/1375/C1375.pdf","text":"Report","size":"7.57 MB","linkFileType":{"id":1,"text":"pdf"},"description":"Report"},{"id":257322,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/cir_1375.gif"}],"scale":"2000000","projection":"Albers Equal-Area Conic","datum":"North American Datum of 1983","country":"United States;Canada","state":"Alabama;Alberta;Arkansas;Colorado;Georgia;Illinois;Indiana;Iowa;Kanas;Kentucky;Louisiana;Michigan;Minnesota;Mississippi;Missouri;Montana;Nebraska;New Mexico;New York;North Carolina;North Dakota;Ohio;Oklahoma;Pennsylvania;Saskatchewan;South Dakota;Tennessee;Texas;Virginia;West Virginia;Wisconsin;Wyoming","otherGeospatial":"Mississippi River Basin","geographicExtents":"{ \"type\": \"FeatureCollection\", \"features\": [ { \"type\": \"Feature\", \"properties\": {}, \"geometry\": { \"type\": \"Polygon\", \"coordinates\": [ [ [ -118,27 ], [ -118,50 ], [ -78,50 ], [ -78,27 ], [ -118,27 ] ] ] } } ] }","noUsgsAuthors":false,"publicationStatus":"PW","scienceBaseUri":"53cd497ae4b0b290850ef36d","contributors":{"authors":[{"text":"Alexander, Jason S. 0000-0002-1602-482X jalexand@usgs.gov","orcid":"https://orcid.org/0000-0002-1602-482X","contributorId":2802,"corporation":false,"usgs":true,"family":"Alexander","given":"Jason","email":"jalexand@usgs.gov","middleInitial":"S.","affiliations":[{"id":464,"text":"Nebraska Water Science Center","active":true,"usgs":true}],"preferred":false,"id":464558,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Wilson, Richard C. wilson@usgs.gov","contributorId":846,"corporation":false,"usgs":true,"family":"Wilson","given":"Richard","email":"wilson@usgs.gov","middleInitial":"C.","affiliations":[{"id":464,"text":"Nebraska Water Science Center","active":true,"usgs":true}],"preferred":true,"id":464557,"contributorType":{"id":1,"text":"Authors"},"rank":2},{"text":"Green, W. Reed","contributorId":87886,"corporation":false,"usgs":true,"family":"Green","given":"W.","email":"","middleInitial":"Reed","affiliations":[],"preferred":false,"id":464559,"contributorType":{"id":1,"text":"Authors"},"rank":3}]}} ,{"id":70004600,"text":"70004600 - 2012 - Vulnerability of riparian ecosystems to elevated CO2 and climate change in arid and semiarid western North America","interactions":[],"lastModifiedDate":"2012-06-08T17:03:14","indexId":"70004600","displayToPublicDate":"2012-06-07T00:00:00","publicationYear":"2012","noYear":false,"publicationType":{"id":2,"text":"Article"},"publicationSubtype":{"id":10,"text":"Journal Article"},"seriesTitle":{"id":1837,"text":"Global Change Biology","active":true,"publicationSubtype":{"id":10}},"title":"Vulnerability of riparian ecosystems to elevated CO2 and climate change in arid and semiarid western North America","docAbstract":"Riparian ecosystems, already greatly altered by water management, land development, and biological invasion, are being further altered by increasing atmospheric CO2 concentrations ([CO2]) and climate change, particularly in arid and semiarid (dryland) regions. In this literature review, we (1) summarize expected changes in [CO2], climate, hydrology, and water management in dryland western North America, (2) consider likely effects of those changes on riparian ecosystems, and (3) identify critical knowledge gaps. Temperatures in the region are rising and droughts are becoming more frequent and intense. Warmer temperatures in turn are altering river hydrology: advancing the timing of spring snow melt floods, altering flood magnitudes, and reducing summer and base flows. Direct effects of increased [CO2] and climate change on riparian ecosystems may be similar to effects in uplands, including increased heat and water stress, altered phenology and species geographic distributions, and disrupted trophic and symbiotic interactions. Indirect effects due to climate-driven changes in streamflow, however, may exacerbate the direct effects of warming and increase the relative importance of moisture and fluvial disturbance as drivers of riparian ecosystem response to global change. Together, climate change and climate-driven changes in streamflow are likely to reduce abundance of dominant, native, early-successional tree species, favor herbaceous species and both drought-tolerant and late-successional woody species (including many introduced species), reduce habitat quality for many riparian animals, and slow litter decomposition and nutrient cycling. Climate-driven changes in human water demand and associated water management may intensify these effects. On some regulated rivers, however, reservoir releases could be managed to protect riparian ecosystem. Immediate research priorities include determining riparian species' environmental requirements and monitoring riparian ecosystems to allow rapid detection and response to undesirable ecological change.","largerWorkType":{"id":2,"text":"Article"},"largerWorkTitle":"Global Change Biology","largerWorkSubtype":{"id":10,"text":"Journal Article"},"language":"English","publisher":"Wiley","publisherLocation":"Hoboken, NJ","doi":"10.1111/j.1365-2486.2011.02588.x","usgsCitation":"Perry, L., Andersen, D., Reynolds, L., Nelson, S.M., and Shafroth, P.B., 2012, Vulnerability of riparian ecosystems to elevated CO2 and climate change in arid and semiarid western North America: Global Change Biology, v. 18, no. 3, p. 821-842, https://doi.org/10.1111/j.1365-2486.2011.02588.x.","productDescription":"22 p.","startPage":"821","endPage":"842","costCenters":[{"id":291,"text":"Fort Collins Science Center","active":true,"usgs":true}],"links":[{"id":257332,"rank":0,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"},{"id":257328,"rank":9999,"type":{"id":10,"text":"Digital Object Identifier"},"url":"https://dx.doi.org/10.1111/j.1365-2486.2011.02588.x","linkFileType":{"id":5,"text":"html"}}],"otherGeospatial":"North America","volume":"18","issue":"3","noUsgsAuthors":false,"publicationDate":"2011-12-08","publicationStatus":"PW","scienceBaseUri":"505bc382e4b08c986b32b208","contributors":{"authors":[{"text":"Perry, Laura G.","contributorId":45565,"corporation":false,"usgs":true,"family":"Perry","given":"Laura G.","affiliations":[],"preferred":false,"id":350824,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Andersen, Douglas C. doug_andersen@usgs.gov","contributorId":2216,"corporation":false,"usgs":true,"family":"Andersen","given":"Douglas C.","email":"doug_andersen@usgs.gov","affiliations":[{"id":291,"text":"Fort Collins Science Center","active":true,"usgs":true}],"preferred":false,"id":350823,"contributorType":{"id":1,"text":"Authors"},"rank":2},{"text":"Reynolds, Lindsay V.","contributorId":102732,"corporation":false,"usgs":true,"family":"Reynolds","given":"Lindsay V.","affiliations":[],"preferred":false,"id":350826,"contributorType":{"id":1,"text":"Authors"},"rank":3},{"text":"Nelson, S. Mark","contributorId":59283,"corporation":false,"usgs":true,"family":"Nelson","given":"S.","email":"","middleInitial":"Mark","affiliations":[],"preferred":false,"id":350825,"contributorType":{"id":1,"text":"Authors"},"rank":4},{"text":"Shafroth, Patrick B. 0000-0002-6064-871X shafrothp@usgs.gov","orcid":"https://orcid.org/0000-0002-6064-871X","contributorId":2000,"corporation":false,"usgs":true,"family":"Shafroth","given":"Patrick","email":"shafrothp@usgs.gov","middleInitial":"B.","affiliations":[{"id":291,"text":"Fort Collins Science Center","active":true,"usgs":true}],"preferred":true,"id":350822,"contributorType":{"id":1,"text":"Authors"},"rank":5}]}} ,{"id":70003872,"text":"70003872 - 2012 - New Eclipidrilus species (Annelida, Clitellata, Lumbriculidae) from southeastern North America","interactions":[],"lastModifiedDate":"2021-01-06T13:04:21.260197","indexId":"70003872","displayToPublicDate":"2012-06-07T00:00:00","publicationYear":"2012","noYear":false,"publicationType":{"id":2,"text":"Article"},"publicationSubtype":{"id":10,"text":"Journal Article"},"seriesTitle":{"id":3814,"text":"Zootaxa","onlineIssn":"1175-5334","printIssn":"1175-5326","active":true,"publicationSubtype":{"id":10}},"title":"New Eclipidrilus species (Annelida, Clitellata, Lumbriculidae) from southeastern North America","docAbstract":"Three new species of Lumbriculidae from southeastern North America are attributed to Eclipidrilus Eisen. All are small worms (diameter 0.2–0.5 mm), having semi-prosoporous male ducts with the atria in X, and spermathecae in IX. Eclipidrilus breviatriatus n. sp. and E. microthecus n. sp. have crosshatched atrial musculature, similar to some E. (Eclipidrilus) species, but they differ from congeners in having small, compact spermathecal ampullae. Eclipidrilus macphersonae n. sp. has a single, median atrium and spermatheca. The new species have been collected only in Sandhills and Middle Atlantic Coastal Plain streams of North Carolina.
","language":"English","publisher":"Magnolia Press","doi":"10.11646/zootaxa.3194.1.4","usgsCitation":"Fend, S.V., and Lenat, D.R., 2012, New Eclipidrilus species (Annelida, Clitellata, Lumbriculidae) from southeastern North America: Zootaxa, v. 3194, no. 1, p. 51-67, https://doi.org/10.11646/zootaxa.3194.1.4.","productDescription":"17 p.","startPage":"51","endPage":"67","costCenters":[{"id":148,"text":"Branch of Regional Research-Western Region","active":false,"usgs":true}],"links":[{"id":381900,"type":{"id":24,"text":"Thumbnail"},"url":"https://pubs.usgs.gov/thumbnails/outside_thumb.jpg"}],"country":"United States","state":"North Carolina","geographicExtents":"{\n \"type\": \"FeatureCollection\",\n \"features\": [\n {\n \"type\": \"Feature\",\n \"properties\": {},\n \"geometry\": {\n \"type\": \"Polygon\",\n \"coordinates\": [\n [\n [\n -75.89355468749999,\n 36.527294814546245\n ],\n [\n -81.6943359375,\n 36.56260003738545\n ],\n [\n -84.24316406249999,\n 35.137879119634185\n ],\n [\n -80.9912109375,\n 35.137879119634185\n ],\n [\n -80.6396484375,\n 34.813803317113155\n ],\n [\n -79.5849609375,\n 34.70549341022544\n ],\n [\n -78.57421875,\n 33.797408767572485\n ],\n [\n -76.5966796875,\n 34.88593094075317\n ],\n [\n -75.6298828125,\n 35.746512259918504\n ],\n [\n -75.89355468749999,\n 36.527294814546245\n ]\n ]\n ]\n }\n }\n ]\n}","volume":"3194","issue":"1","noUsgsAuthors":false,"publicationDate":"2012-02-15","publicationStatus":"PW","scienceBaseUri":"505a6514e4b0c8380cd72af8","contributors":{"authors":[{"text":"Fend, Steven V. 0000-0002-4638-6602 svfend@usgs.gov","orcid":"https://orcid.org/0000-0002-4638-6602","contributorId":3591,"corporation":false,"usgs":true,"family":"Fend","given":"Steven","email":"svfend@usgs.gov","middleInitial":"V.","affiliations":[{"id":438,"text":"National Research Program - Western Branch","active":true,"usgs":true}],"preferred":true,"id":349234,"contributorType":{"id":1,"text":"Authors"},"rank":1},{"text":"Lenat, David R.","contributorId":23500,"corporation":false,"usgs":true,"family":"Lenat","given":"David","email":"","middleInitial":"R.","affiliations":[],"preferred":false,"id":349235,"contributorType":{"id":1,"text":"Authors"},"rank":2}]}} ]}