Study On The Model Of Xinanjiang In Karst Area Watershed Based On Cell Nested Grid

In order to better solve the problems of insufficient accuracy of long-term runoff prediction and low practicality of flood forecasting model in traditional aggregate hydrological model in the southwest karst area watershed.This paper combines the theoretical approaches of distributed hydrological forecasting model and conceptual hydrological forecasting model to construct a distributed Xinanjiang model with a view to providing theoretical guidance for flood prevention and development of karst area watersheds.The paper carries out the research of daily and monthly scale runoff and field flood forecasting with the catchment area above Pingtang hydrological station in Chengbi River basin,and the main work and research results are as follows.(1)Research on daily and monthly scale runoff prediction of Pingtang hydrological station based on the Grid Xinanjiang model.The results show that the model can better simulate the daily and monthly scale runoff process at Pingtang station,and the fitting effect is better for the high flow process,and the simulation effect is better than that for the dry water year,the annual runoff depth qualification rate is 91%.The daily runoff prediction accuracy reaches the standard of class B,and the monthly runoff prediction accuracy reaches the standard of class A.The results show that the model can better simulate the daily and monthly scale runoff process at Pingtang station,and the simulation effect is better than that for the dry water year.(2)Based on the Grid Xinanjiang model,the karst and non-karst cells are divided,and the rainfall distribution coefficient ? is introduced to construct the cell nested Grid Xinanjiang model and to predict the daily and monthly runoff at Pingtang hydrological station.The results show that the model can better simulate the daily and monthly runoff processes at Pingtang station,and the simulation effect of daily runoff high flow process and daily runoff low flow process in dry water year is more significant than that of the Grid Xinanjiang model,the qualification rate of annual runoff depth is 91%,the accuracy of daily runoff prediction reaches the standard of class B,and the accuracy of monthly runoff prediction reaches the standard of class A.Simulated values of extreme runoff at daily and monthly scales are strongly correlated with measured values.It can be seen that the model can be applied to the daily and monthly runoff simulation at Pingtang Station in Chengbi River Basin.(3)Research on the field flood prediction of Pingtang station based on the cell nested grid Xinanjiang model.The results show that the pass rate of field flood is 75% and the forecast accuracy reaches the standard of class B.The model simulates better the field flood with high rainfall level,single-peak type and large flood level;the correlation between the simulated and measured values of flood production and confluence is strong.It can be seen that the model can be applied to the simulation of field floods in Pingtang station.The results can provide technical support for long-and short-term runoff prediction and reservoir scheduling in the southwest karst area basin.