Evaluating the Effects of Future Land use/Land cover and Agricultural Conservation Practices Scenarios on Streamflow and Water Quality in the Maumee River Watershed

Abstract

Lake Erie's water environment has been a growing concern due to its severe water eutrophication problems which primarily caused by the accumulation of nutrients, particularly phosphorus, from both point and nonpoint source pollutants originating from the Maumee River Watershed (MRW). Despite global studies on the watershed's nutrient dynamics, the complex interactions between land use and land cover (LULC), agricultural conservation practices (ACPs), and their effects on the water environment remain inadequately understood within the MRW. In our study, we designed seven future scenarios involving LULC and ACPs to explore their impacts on the MRW. We employed the Land Change Modeler (LCM) and SWAT+ (Soil and Water Assessment Tool_Plus) to simulate future scenarios of LULC changes and to model the hydrological conditions of the watershed from 2046 to 2065, respectively. ACPs were set up in SWAT+, and we also incorporated meteorological data under the RCP8.5 scenario as future climatic conditions. We selected four hydrological parameters—streamflow (Q), Total Suspended Solids (TSS), Soluble Reactive Phosphorus (SRP), and Total Phosphorus (TP)—to analyze the impacts of various LULC and ACP scenarios on MRW. Our research found that ACP scenarios have a more significant impact on MRW's streamflow and water quality, but the effects of LULC changes are also non-negligible. We further analyzed the impacts of different LULC scenarios on the MRW's water environment in greater depth, both temporally and spatially, and found that different LULCs have more pronounced effects at the spatial scale. Although different LULC scenarios can mitigate impacts to varying degrees in different areas, our study also identified that the most significant LULC types on the water environment are open spaces and agricultural lands. Therefore, we suggest that the ideal future development model for MRW should involve managing open spaces reasonably and reducing fertilizer input in agricultural lands, while moderately increasing the proportion of open spaces and medium to high-intensity urban land in urbanized areas and reducing the area of agricultural land in the watershed. This model would effectively improve MRW's streamflow and water quality while accommodating agricultural, economic, and population growth needs.