An Approach for Prioritizing Natural Infrastructure Practices to Mitigate Flood and Nitrate Risks in the Mississippi-Atchafalaya River Basin

Abstract

Risks from flooding and poor water quality are evident at a range of spatial scales and climate change will exacerbate these risks in the future. Natural infrastructure (NI), consisting of structural or perennial vegetation, measures that provide multiple ecosystem benefits have the potential to reduce flood and water quality risks. In this study, we intersected watershed-scale risks to flooding and nitrate export in the Mississippi-Atchafalaya River Basin (MARB) of the central U.S. with potential locations of seven NI practices (row crop conversion, water, and sediment control basins, depressional wetlands, nitrate-removal wetlands, riparian buffers, and floodplain levees and row crop change) to prioritize where NI can be most effective for combined risk reduction at watershed scales. Spatial data from a variety of publicly-available databases were analyzed at a 10 m grid cell to locate NI practices using a geographic information system (GIS). NI practices were presented at the regional basin scale and local Iowa-Cedar watershed in eastern Iowa to show individual practice locations. A prioritization scheme was developed to show the optimal watersheds for deploying NI practices to minimize flooding and water quality risks in the MARB. Among the 84 HUC4 basins in the MARB, 28 are located in the Upper Mississippi and Ohio Rivers basins. The Wabash and Iowa-Cedar basins (HUCs 0512 and 0708, respectively) within these basins were found to rank among the uppermost quintile for nearly all practices evaluated, indicating widespread opportunities for NI implementation. Study results are a launching point from which to improve the connections between watershed scale risks and the potential use of NI practices to reduce these risks.

Slowing Down Quick Runoff—A New Approach for the Delineation and Assessment of Critical Points, Contributing Areas, and Proposals of Measures to Reduce Non-Point Water Pollution from Agricultural Land

“…different landscapes within a watershed area [40][41][42][43][44][45]. At the same time, structural water retention measures provide an enhanced water storage capacity; therefore, they may generally be more effective for water quality improvements than agrotechnical measures [40][41][42].…”

“…In numerous cases, and especially in practice, runoff reduction interventions and water quality improvement measures are separately propounded or adopted solely for the selected individual measures [35][36][37][38][39]. Nevertheless, several complex approaches have been documented in the literature [40][41][42][43][44]. A comprehensive method utilized for identifying priority areas on a large scale, including agricultural drainage, was presented in a study conducted by [41], which assessed runoff and nitrate leaching processes using the SWAT model and GIS tools in risky areas, and accordingly positioned and evaluated seven types of structural measures in the study.…”

“…Nevertheless, several complex approaches have been documented in the literature [40][41][42][43][44]. A comprehensive method utilized for identifying priority areas on a large scale, including agricultural drainage, was presented in a study conducted by [41], which assessed runoff and nitrate leaching processes using the SWAT model and GIS tools in risky areas, and accordingly positioned and evaluated seven types of structural measures in the study. On the other hand, the authors in [42] described a common lack of water quality benefits presented in the studies generally describing the principles and function of flood and runoff mitigation measures.…”

“…Several studies agreed that mitigation measures are the most effective method when designed and implemented as a mutually interconnected system of different measures in different landscapes within a watershed area [40][41][42][43][44][45]. At the same time, structural water retention measures provide an enhanced water storage capacity; therefore, they may generally be more effective for water quality improvements than agrotechnical measures [40][41][42].…”

“…Several studies agreed that mitigation measures are the most effective method when designed and implemented as a mutually interconnected system of different measures in different landscapes within a watershed area [40][41][42][43][44][45]. At the same time, structural water retention measures provide an enhanced water storage capacity; therefore, they may generally be more effective for water quality improvements than agrotechnical measures [40][41][42]. Thus, the main aim of this study is to describe a method that is applicable to areas of varying scales and hydrological units to jointly address the attenuation of surface and subsurface runoff while considering the water quality.…”