Hydrometeorological dynamics and driving mechanism of runoff and water quality in the Taohe River basin,Gansu Province
In the context of climate change and intensive human activities,the water environment problem of wa-tershed is still one of the severe challenges faced by watersheds management in China and abroad. The Taohe River basin is a typical alpine ecologically fragile basin in China,and the study of changes in water environment elements and their driving mechanisms in Taohe River basin is of great significance to the management of water environment in Taohe River basin. In this paper,the characteristics of precipitation and temperature change trends and mutation features in the Taohe River basin during the period 1990—2018 were analyzed by statistics,linear fitting and M-K trend and mutation tests. The land use transfer matrix was used to analyze the land use change characteristics of the Taohe River basin in 1990 and 2018,and the hydrological and meteorological dy-namic characteristics of the Taohe River basin were revealed. On this basis,the SWAT hydrological model data-base was constructed by DEM,land use,soil and meteorological data,and the monthly scale simulation of run-off and water quality in the Taohe River basin was carried out. The model divided the Taohe River basin into 24 sub-basins. The meteorological data of temperature,precipitation,relative humidity,wind speed and solar radi-ation were input,and the weather generator was constructed by SWAT-Weather. The runoff simulation period was 1988—2018,and 1988—1989 was set as the preheating period. Due to the limited measured data,the DO simulation period is 2015—2018,and the NH3-N simulation period is 2018. The simulation calibration and veri-fication were carried out by using the SUFI-2 calibration method in SWAT-CUP,and the R2,NSE and PBIAS indexes were selected to evaluate the simulation accuracy of the model. In order to improve the accuracy of the simulation,22 runoff-related parameters and 37 water quality-related parameters were selected. Based on the simulation results of SWAT model,the temporal and spatial variation trend of runoff in Taohe River basin is ana-lyzed by using water yield index and Slope trend. Finally,by setting different input conditions of precipitation,temperature and land use type,the scenario simulation was carried out for climate change,land use change and comprehensive change of climate and land use,and the driving mechanism of runoff and water quality in Taohe River basin is analyzed based on the scenario simulation results. The results show that:(1) During the past 30 years in the Taohe River basin,The interannual variation of precipitation fluctuates greatly,and the overall trend is upward,with a linear trend of 20.16 mm·(10a)-1;There is no significant mutation in temperature,and the overall trend is upward,with a linear trend of 0.55 ℃·(10a)-1. The land use types in the Taohe River basin are mainly agricultural land,grassland and forest land. All land use types have changed,but the area changed slight-ly. (2) The SWAT model has good applicability to simulate long-term monthly runoff in the Taohe River basin;the R2 and NSE are generally above 0.6,and the absolute value of PBIAS remains within 15％ The accuracy of monthly scale short-term simulation of DO is relatively high,and the accuracy of monthly scale short-term simu-lation of NH3-N is slightly lower,but the results in the middle and lower reaches meet the simulation accuracy re-quirements. The water yield in the upper reaches of the Taohe River basin is the highest,and the trend of in-crease is larger. The water yield in the middle and lower reaches is negatively correlated with the trend of in-crease in water yield. (3) Runoff is positively correlated with and controlled by precipitation,but negatively cor-related with temperature. The runoff yield of each land use is agricultural land>grassland>forest land. The concentration of NH3-N is negatively correlated and controlled by temperature,but positively correlated with pre-cipitation. The conversion of agricultural land to forest land and agricultural land to grassland significantly re-duce the concentration of NH3-N. The concentration of DO is negatively related to temperature. and is almost un-affected by the other factors.
SWAT modelTaohe River basinwater environment driving mechanismland use and climate change
万方数据
维普
