ABSTRACT LULC change simulation process Water pollution, such as nutrient enrichment in waterbodies due to human activities, can cause the formation of harmful algal blooms (HABs). Land use land cover (LULC) change may exacerbate the water pollution process by altering hydrological and water quality responses of a watershed. This study investigated changes in runoff, sediment yield, and chlorophyll-a loading into the Ohio River Basin at Ironton (ORBI) due to LULC alterations using the Soil and Water Assessment Tool (SWAT). The SWAT model was calibrated and validated against streamflow (R2 = 0.74–0.78; NSE = 0.67–0.73) and sediment concentrations (R2 = 0.52–0.63; NSE = 0.43–0.59) with acceptable accuracies. Twelve LULC scenarios were developed, including a decrease of forest lands and an increase of agriculture and urban land areas by 5, 10, 15, 20, 25, and 50%. At the subwatershed level, the results indicated that increased runoff (462%) and chlorophyll-a loads (960%) occurred when forestlands were converted to urban areas by 50%, whereas increased sediment (29%) occurred when agriculture replaced forest by 50%. This indicates that increased urbanization leads to reduced infiltration and increased nutrient runoff due to impervious surface, increasing the risk of HABs. The spatial representation of hydrological parameters demonstrated increased risk in the southern subbasins of ORBI, which could be helpful to the development of HABs prevention and management strategies.
Nepal et al. (Tue,) studied this question.