Instream constructed wetland capacity at controlling phosphorus outflow under a long‐term nutrient loading scenario: approach using SWAT model

Autor: Sohoulande Djebou, Clement D., Szogi, Ariel A., Novak, Jeff M., Stone, Kenneth C., Martin, Jerry H., Watts, Don
Zdroj: Modeling Earth Systems and Environment; 20230101, Issue: Preprints p1-14, 14p
Abstrakt: At the watershed scale, sustained applications of phosphorus (P) fertilizers on croplands cause unwanted P losses into aquatic systems and subsequent risks of water eutrophication. Nevertheless, instream constructed wetlands (ICWs) offer the possibility to control P transfer from land to water and maintain P concentration in water below levels that negatively affect aquatic life. However, including ICWs in long-term water quality conservation plans is arguable because their long-term functionality is still less known. To better understand this long-term functionality, this study used the soil and water assessment tool (SWAT) model to portend an ICW’s hydrological behavior and its capacity at controlling P release under exceptional climate conditions in the Southeastern Coastal Plain of the United States. Specifically, the model was calibrated and validated for stream and P flow using experimental ICW data and an assumption of a continuous corn-soybean rotation across an agricultural watershed. A multi-decadal simulation was used to evaluate monthly balances of dissolved P (ΔDP) and total P (ΔTP) under a variable climate spectrum and a continuous nutrient loading scenario. Analyses of monthly ΔDPand ΔTPtime series over consecutive decadal periods 2001–2010 and 2011–2020 showed signals of negative P balances at a probability of 0.18. Point biserial correlations analyses unveiled a significant relationship between monthly ICW’s P balances and precipitation variability at the watershed scale. The P releases were under control during low to moderate precipitation conditions, but extreme precipitation events caused abnormal P outflows. Hence, ICWs could be a sustainable option for long-term P outflow control under low to moderate hydrologic regimes.
Databáze: Supplemental Index
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