Geomorphology Effects on Nutrient Retention in Restored Floodplains at the Wabash and Tippecanoe Confluence
Geomorphology Effects on Nutrient Retention in Restored Floodplains at the Wabash and Tippecanoe Confluence

Abstract

Agricultural production is a major contributor to excess nitrogen (N) and phosphorus (P) in receiving aquatic streams, leading to adverse impacts on aquatic ecosystems. Modification of hydrology through tile drainage and channelization of the river network has led to more rapid downstream nutrient and sediment transport. Floodplains have demonstrated the potential to retain a significant amount of nutrients and sediments, although this retention may vary across the floodplain due to elevation variations and the hydrological connectivity across the floodplain area. Understanding the effect of floodplain geomorphology on nutrient and sediment retention could expand our knowledge in spatial variation in floodplain mitigation. The objective of this project is to characterize the spatial variation of inorganic N and P after a flood event, across lateral and longitudinal transects in three restored floodplains at the confluence of the Wabash and Tippecanoe rivers near West Lafayette, Indiana. To estimate the nutrient retention, we use ion-exchange resin bags that capture soluble reactive phosphorus, ammonium, and nitrate. Sediment tiles were installed to determine the sediment fluxes and particle size after a flood event. Future analysis will determine the effect of the floodplain geomorphology in the nutrient concentrations and sediment loadings from riverine waters, providing management guidance in the designing systems for optimal nutrient retention.