Using Remote Sensing Data to Identify Restorable Wetlands for Agricultural Nitrate Removal in the UMRB

Abstract

Restored wetlands have great potential to reduce nitrogen (N) pollution from excess agricultural fertilizer. There is specific interest in the Upper Mississippi River Basin (UMRB), where groundwater, surface water, and downstream catchments experience increased N loading as a result of agricultural intensification. This contributes to contamination of drinking water, coastal aquatic toxicity, and enhanced eutrophication. However, many historical (defined here as legacy) wetlands were drained in the conversion of the UMRB’s landscape for agricultural and urban use. To this day, the true extent of their loss is unknown.

This study's primary goal is to identify legacy wetlands in the UMRB to aid targeted restoration efforts and policy decisions on agriculture, water quality, and conservation. We aim to (1) identify the total loss of drained legacy wetlands across the UMRB and (2) determine the size and distribution of legacy wetlands. To detect legacy wetlands throughout the UMRB, we plan to use a bare-earth digital elevation model and intersect it with soil data from the USDA’s Soil Survey Geographic Database (SSURGO). To prevent accounting for existing wetlands, the output layer will be overlaid with the National Wetlands Inventory (NWI), and the National Land Cover Database (NLCD), to ensure the sites exist on cropland. This process will be automated and applied to sites across the UMRB. The findings of this research intend to assist in developing wetland restoration techniques to increase nitrate removal from agricultural landscapes in the UMRB.