Quantifying hydrologic alteration in an area lacking current reference conditions—The Mississippi alluvial plain of the south‐central United States

Abstract

Quantifying hydrologic alteration in the Mississippi Alluvial Plain (MAP) of the southcentral United States is particularly difficult because of the lack of current reference, or even relatively undisturbed, streams and associated streamflow data. Impacts, such as water withdrawals for agriculture, weirs, dams, channelization, and other forms of regulation, within the MAP increased substantially beginning around 1960 suggesting that streamflow has since been altered. Using historical streamflow and climate data and explanatory variables, the U.S. Geological Survey developed random forest regression models to estimate expected reference monthly streamflows (pre-1960) at 76 sites in the MAP and two adjacent Level III Ecoregions. To compensate for the lack of current reference stream sites in the study area, the pre-1960 streamflow data were used as a surrogate to estimate current streamflow conditions without anthropogenic influence (inferring current reference conditions). Overall, nearly every site within the study area had less zero-flow days than what historically has been observed and there were more low-pulse spells. However, the frequency of floods remained relatively consistent.

Catchment scale assessment of drought impact on environmental flow in the Indus Basin, Pakistan

“…Nature Conservancy has developed the IHA (http://www.nature.org/), which has been successfully used to quantify the alterations in river flows (Lee et al, 2014;Nature Conservancy, 2007;Rahman et al, 2020b;Richter et al, 1996). Assessing the hydrological alterations in river flows is extremely important for sustainable water resource management, quantifying anthropogenic impacts on river flow and associated ecology, and maintaining a healthy ecosystem (Hart and Breaker, 2019;Lytle and Poff, 2004;Poff and Zimmerman, 2010). IHA is gaining more attention nowadays and has been used in several hydrological applications, including ecology, water resources management, assessing alterations in streamflow, and others (Lee et al, 2014;Mathews and Richter, 2007;Rahman et al, 2020b).…”