Changes in hydrology and suspended-sediment transport in the Mississippi River Basin over the past century

Simon, Andrew, Artita, Kimberly, Simon, Gail, Darby, Stephen and Leyland, Julian (2020) Changes in hydrology and suspended-sediment transport in the Mississippi River Basin over the past century Mississippi. United States Army Corps of Engineers 297pp. (doi:10.21079/11681/37073).

Abstract

Since about 1900, widespread changes in hydrology across the Mississippi River Basin have occurred, resulting in important changes in the delivery of water and sediment to the Lower Mississippi River (LMR). This is due to a combination of natural and anthropogenic factors. There have been increases in annual precipitation and 1- to 7-day totals over large parts of the basin. Changes in seasonal distributions were also identified, as were increases in hurricane-related rainfall. Streamflow to the LMR has increased significantly over the past 100 years. Median water yields have increased across most of the mid-continent and decreased in the western-most parts of the Missouri and Arkansas River basins. Suspended-sediment loads to the LMR have dramatically declined. The Lower Mississippi River is receiving about 500 million tonnes per year less suspended sediment today than in the 1940s (616 Mt/y to 98 Mt/y). Human impacts on hydrology and sediment transport throughout the basin are important. In the mid-continent, water yield per unit precipitation showed increases, but markedly decreased in the western parts of the basin. Decreases can be attributed to the construction of thousands of dams, associated flow regulation, withdrawals for agriculture, and to a lesser extent, the increased evaporation behind impoundments.

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Contributors

Author: Stephen Darby

Author: Julian Leyland

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