Abstract
The application of hydrological and water quality models is an efficient approach to better understand the processes of environmental deterioration. This study evaluated the ability of the Annualized Agricultural Non-Point Source (AnnAGNPS) model to predict runoff, total nitrogen (TN) and total phosphorus (TP) loading in a typical small watershed of a hilly region near Taihu Lake, China. Runoff was calibrated and validated at both an annual and monthly scale, and parameter sensitivity analysis was performed for TN and TP before the two water quality components were calibrated. The results showed that the model satisfactorily simulated runoff at annual and monthly scales, both during calibration and validation processes. Additionally, results of parameter sensitivity analysis showed that the parameters Fertilizer rate, Fertilizer organic, Canopy cover and Fertilizer inorganic were more sensitive to TN output. In terms of TP, the parameters Residue mass ratio, Fertilizer rate, Fertilizer inorganic and Canopy cover were the most sensitive. Based on these sensitive parameters, calibration was performed. TN loading produced satisfactory results for both the calibration and validation processes, whereas the performance of TP loading was slightly poor. The simulation results showed that AnnAGNPS has the potential to be used as a valuable tool for the planning and management of watersheds.
Highlights
Non-point source pollution occurs when rainfall or irrigation water runs over land or through the ground, picks up pollutants and deposits them into rivers, lakes, or coastal waters or introduces them into ground water [1]
Upon completion of the data entry using the AnnAGNPS Data Input Editor, runoff was calibrated by adjusting Curve Number (CN) for all landuse categories
According to Lenhart [51], Fertilizer rate, Fertilizer organic, Canopy cover and Fertilizer inorganic can be classified as high sensitive parameters for total nitrogen (TN) output, whereas Residue mass ratio, Fertilizer rate, Fertilizer inorganic, and Canopy cover are highly sensitive parameters for total phosphorus (TP) output
Summary
Non-point source pollution occurs when rainfall or irrigation water runs over land or through the ground, picks up pollutants and deposits them into rivers, lakes, or coastal waters or introduces them into ground water [1]. It is an important environmental and water quality management problem, and non-point sources presently account for the majority of water quality problems [2]. In the last four decades, several hydrological and water quality models have been developed to assist in understanding hydrologic systems and pollutant loadings [7], such as AnnAGNPS
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