Validation of an agricultural non-point source (AGNPS) pollution model for acatchment in the Jiulong River watershed, China
LIU Jianchang , ZHANG Luoping , ZHANG Yuzhen , HONG Huasheng , DENG Hongbing
DOI:
Received July 15, 2007,Revised October 29, 2007, Accepted , Available online
Volume 20,2008,Pages 599-606
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This study tested and evaluated the agricultural non-point source (AGNPS) model for the Wuchuan catchment, a typical agricultural
area in the Jiulong River watershed, Fujian Province, China. The AGNPS model was calibrated and validated for the study area
with observed data on ten storms. The data on eight storms in 2002 were used for calibration while data on two storms were used for
validation of the model. Considering the lack of water quality data over a long-term series, a novel method, comparing an internal nested
catchment with its surrounding catchment, was used to supplement the less long-term series data. Dual calibration and validation of the
AGNPS model was obtained by this comparison. The results indicate that the correlation coe cients were 0.99 and 0.98 for runo , 0.94
and 0.95 for the peak runo rate of the large catchment and the small catchment, respectively, and 0.76 for the sediment of the small
catchment only. Each pair of correlation coe cients is homogeneous for the same event for the two catchments. With the exception of
the sediment yield and particulate phosphorus, the peak runo rate and other nutrients were well predicted. Sensitivity analysis showed
that the Soil Conservation Service curve number and rainfall quantity were the most sensitive parameters, which resulted in high output
variations. Erosivity and other parameters had little influence on the hydrological and quality outputs.
