Fishery Resources, Environment, and Conservation in the Mississippi and Yangtze (Changjiang) River Basins

<em>Abstract</em>.—The lower Mississippi River encompasses the 1,535-km reach extending from the confluence with the Ohio River at Cairo, Illinois to the Gulf of Mexico. Waters of the lower Mississippi River have historically inundated vast areas of adjacent floodplain during spring flood pulses. Additionally, processes of land building within the river’s deltaic plain supported vast forests and diverse freshwater and salt-marsh habitats. Flood pulses provided a mechanism of lateral exchange of energy and nutrients between the aquatic and terrestrial habitats, while sediment loads continually rebuilt and supported the deltaic plain. As human populations and agriculture expanded throughout the lower Mississippi Valley, construction of flood-protection levee systems and commercial navigational structures severely decreased the connectivity between the lower Mississippi River and its floodplain. The current lower Mississippi River floodplain is more than 90% reduced in area compared to historical conditions. Fluvial dynamics, which are the driving forces that stimulate floodplain function and create diverse habitats, appear to have been altered throughout approximately 80% of the river. As a result, the hydrograph, thermograph, sedimentation patterns, nutrient dynamics, and vegetation communities within the lower Mississippi River floodplain have experienced major changes through time, with many large alterations occurring during the past century. In addition, because most of the sediment load of the lower Mississippi River now enters the northern Gulf of Mexico, land building and associated processes are much reduced in the river’s deltaic plain. This process has allowed intrusion of saltwater into coastal habitats, which has heavily impacted vegetation communities. This paper reviews the consequences of river modification to lower Mississippi River floodplain, current efforts towards restoring the floodplain and deltaic plain, and proposes future strategies towards restoring portions of the historical floodplain.

2007 ◽  
Author(s):  
Colin Thorne ◽  
Oliver Harmar ◽  
Chester Watson ◽  
Nick Clifford ◽  
Richard Measures ◽  
...  

1961 ◽  
Vol 26 (3Part1) ◽  
pp. 317-323 ◽  
Author(s):  
William G. Haag

AbstractNo archaeological remains which the majority of specialists will accept as Archaic have been found in the Mississippi Valley from the mouth of Ohio River to the Gulf of Mexico. Despite this, the literature reflects a general acceptance of the belief that the Archaic stage is well represented in the Lower Valley. The presence of concentrated Archaic populations in northern Alabama and western Tennessee and Kentucky has given comparative support to these expectations and has provided part of the source for some of the hypothetical statements in the literature of what the Lower Valley Archaic ought to be like. Although the failure of writers to agree on a definition of Archaic which will satisfy the evidence in all of the areas of Eastern United States has contributed to the problem of identifying Archaic materials in the Lower Valley, the lack of these remains can best be explained by the geology of the region. The cutting and filling of the Alluvial Valley during the Pleistocene changes in sea level have removed or buried all of the surfaces that might have been occupied by Archaic peoples. The surface of the Alluvial Valley is everywhere less than 5000 years old. Possible Late Archaic sites are located on old stable beach ridges or near enough to the Pleistocene terraces not to have been included in the general pattern of Recent coastal subsidence. It is concluded that Archaic or earlier materials are absent in the Lower Alluvial Valley of the Mississippi River. Neither Tchefuncte nor Copell are accepted as Archaic; Poverty Point is viewed as transitional from an Upper Archaic tradition to some phase of the Formative stage. Poverty Point materials may not be expected to be found in quantity along the Gulf Coast of the Mississippi Delta region.


Author(s):  
Michael W. Babcock ◽  
Stehen Fuller

This paper estimates the demand for corn and soybean shipments on the Ohio River during the 1992-2004 period. Using monthly data, OLS (with Newewy-West standard errors) parameters estimates were obtained for the explanatory variables. Results indicate that Ohio River corn and soybean shipments are significantly and positively affected by one month lagged shipments, corn and soybean stocks in the Ohio River production region, and corn and soybean exports from lower Mississippi River Gulf ports. Some empirical support was found for a significant negative relationship between Ohio River corn and soybean shipments and ocean shipping freight rates from lower Mississippi River Gulf ports to Japan. Indiana corn prices did not significantly affect Ohio River corn and soybean shipments.


Author(s):  
Y. Jun Xu

Abstract. Many river deltas in the world are vibrant economic regions, serving as transportation hubs, population centres, and commercial hotspots. However, today, many of these deltaic areas face a tremendous challenge with land loss due to a number of factors, such as reduced riverine sediment supply, coastal land erosion, subsidence, and sea level rise. The development of the Mississippi River Deltaic Plain (MRDP) in southeast Louisiana, USA, over the past century is a good example. Since 1932, approximately 4877 km2 of the coastal land of MRDP has become submerged. The lower Mississippi River main channel entering the Gulf of Mexico has become an isolated waterway with both sides losing land. In contrast, large open water areas in the Mississippi River’s distributary basin, the Atchafalaya River basin, have been silted up over the past century, and the river mouth has developed a prograding delta feature at its two outlets to the Gulf of Mexico. The retrospective analysis of this paper makes it clear that the main cause of the land loss in the MRDP is not the decline of riverine sediment, but the disconnection of the sediment sources from the natural flood plains. Future sediment management efforts in the MRDP should focus on restoring the natural connection of riverine sediment supplies with flood plains, rather than solely using channelized river diversion. This could be achieved through controlled overbank flooding (COF) and artificial floods in conjunction with the use of a hydrograph-based sediment availability assessment.


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