Study On Hydrology And Water Quality Process Simulation Based On Hspf Model

HSPF model which has a good performance of hydrology and water quality simulation in different regions is widely used in foreign. However, it has limited use in China. To further explore the applicability of it in different regions of China, we need to develop experimental research in different regions. Water pollution problems in Taihu Lake region are comparison serious, and the western hilly region is main runoff-producing area. Therefore, selecting this watershed to simulate hydrological and water quality process has important significance.Using the Zhongtian River watershed which located in the western hilly region of Tai Lake as the study area, we developed the hydrology and water quality simulation based on HSPF model in small watershed scale and then evaluated the adaptability of the model in this region. The main conclusions are as follows:(1)5hydrological sensitivity parameters AGWRC, UZSN,INFILT, LZSN, and DEEPFR were determined by using the relative sensitivity method which is based on perturbation analysis. Combined with an overview of study area and relevant references, we selected and adjusted the sensitivity parameters of water quality module. Sediment simulation parameters included PERLND(KRER、JRER、KSER、JSER、KGER、JGER), IMPLND (KEIM、JEIM), RCHRES (KSAND、EXPSND、TAUCS、TAUCD).The sensitivity parameters of total nitrogen included KDSAM, KADAM, KAM, KNI, KTAM20, KNO320and KNO220. The sensitivity parameters of phosphate included KDSP, KADP, KIMP and KMP.(2) The hydrological results showed good agreement with simulated and measured values in annual runoff, storm runoff and daily runoff simulation period. And in annual runoff simulation period, it showed good agreement with percent differences of-6.39%, -8.76%and9.66%, respectively, which were all below10%during the calibration period, and the simulation results were in a good range with percent differences of-13.31%and5.22%during the validation period. The Nash-Sutcliffe (Ens) coefficients reached0.87and0.69, respectively, and relative errors were1.63%and4.14%, which met the simulation requirements and could reflect the variation of annual runoff in Zhongtian River watershed. In storm runoff simulation period, correlation coefficients of runoff simulation were0.965and0.847. And in daily runoff simulation period, correlation coefficient increased to0.584, which showed a good correlation. The results show that the HSPF model in the study area has better adaptability to watershed runoff simulation which has scientific significance to the simulated hydrological processes in the region.(3) The water quality simulation results showed simulation value of sediment and nitrogen and phosphorous nutrients were anastomose to measured value, which were within the allowable range in the5sub-water shed. The Ens of sediment, total nitrogen (TN) and PO4-P reached0.61,0.58and0.89, respectively, and relative errors were34.21%,18.91%and53.05%during the calibration period. In validation period, the Ens reached0.54,0.51and0.88, respectively, and relative errors were40.09%,29.15%and30.37%, which met the simulation requirements and could reflect the variation of runoff and water quality in Zhongtian River watershed. The results show that the HSPF model also has better adaptability to water quality simulation.(4) Estimated and analyzed the non-point source pollution load in the study area from2005to2010by using the calibrated and calibrated HSPF model, and then discussed the time distribution characteristics of the non-point source pollution load. The results showed that the annual variation of non-point pollutant load output had a more obvious positive correlation with rainfall in2005to2010, and there was a big difference between wet year (2009) and dry year (2007). The sediment output in wet year was1.83times than it in dry years, and concentration of TN and PO4-P were maintained at a high level in wet years, which were5.04t and44.98kg. And sediment and TN load in dry year were both the lowest in all the six years. So one can see the wet years and wet months are the critical period of soil erosion loss and N P pollutants loss in Zhongtian River watershed, which are particularly important to the control of non-point source pollution.