| The karst groundwater resources serve as a very important source of water for daily life in the karst peak forest area of Zuojiang,Guangxi,and provide important support for the realization of socio-economic development and ecological civilization construction in the region.However,However,the ground and underground karst development is intense in this area.,the temporal and spatial distribution of precipitation is uneven,drought and flood disasters are frequent,which severely restrict the socio-economic development.The temporal and spatial variation of groundwater resources in karst arid and dry areas is not yet clear,and the conditions for groundwater storage and exploitation and utilization of underground rivers need to be ascertained.Therefore,in order to ensure a more rational and sustainable development and utilization of karst water resources in the region,it is imperative to quantitatively study and analyze the relationship between groundwater and surface water in the region and scientifically evaluate karst groundwater resources.The SWAT distributed hydrological model based on the physical mechanism can fully consider the spatial variability of different hydrological factors on the karst water resources through the spatial dispersion of the underlying surface;the open source state allows researchers to develop the mechanism of karst water formation.Constantly deepen understanding,improve and improve the model with the aid of computer language.Therefore,the application of distributed watershed hydrological model in karst areas has great potential and advantages.In this paper,the Chongzuo area of Zuojiang in Guangxi province is selected as the typical study area,using SWAT to establish a hydrological model with karst water as the main body.The total area is 12857.90 km2,of which the area of karst area is7573.65 km2.The study area is divided into 147 subbasins,764 hydrological response units,using monthly runoff simulation,the preheating period is two years,the simulation period is from January 2011 to December 2015.Considering the special structure of surface karst zone in karst area,the function module of surface karst zone is added.By comparing the basic flow values of the improved SWAT simulation with the original model,the improved base flow value has a half month to one month lag effect compared with the original base flow value,and the improved instability coefficient is exponentially decreasing.which better characterized the lag effect produced by the base flow recharge and more accurately portrayed the physical mechanism of the karst water production flow.The identified model can well reflect the distribution of karst water and the characteristics of water resources in the study area.the monthly runoff R2 and ENSare all above 0.5.The method for evaluating groundwater resources in highly karst areas was explored,and some progress was made in solving the difficult problems of quantitative assessment of water resources in the karst areas of Southwest China.On the basis of model runoff fitting,based on the principle of water balance,the soil water and groundwater resources were evaluated and calculated in the study area.The total water resources in the basin were 87.61?108m3,and the annual average groundwater recharge was 51.39?108m3.The dry-seasonal runoff modulus method calculates that the annual mineable resources are no more than 16.92?108m3.In addition,Taking the watershed as the unit,the groundwater resources（recharge resources and recoverable capacity）of different types of subbasins are calculated respectively.The composition of karst water resources in underground river subsystems was divided into fast flow and slow flow components. |
