Study Of The DEM-based Dagang Mountain Forest Watershed Distributed Hydrological Model And Its Validation

Study on hydrological function of forest ecosystem can help to understand the process and mechanism of water movement in forest ecosystem,and learn the effects of ecosystem structure and energy metabolism on hydrology.Moreover,it is helpful for us to understand correctly the role of the forest to protect water resources and conserve soil.Many researchers have focused on the hydrological characteristics of forests in tropics and subtropical climate regions,and especially there are many reports on the distributed hydrological model in forest watershed and its application research.Forest and water are important parts of forest ecosystem,in order to quantitatively examine the relationship between forest and hydrological of forest watershed in a subtropical humid region of China,in this study,the Dagang Mountain Forest Watershed in Jiangxi Province was selected as a study area,and geographical information system(GIS)and remote sensing(RS)technologies were applied to couple and integrate hydrological parameters with digital information on precipitation,air temperature,soil and vegetation.Based on an available Digital Elevation Model(DEM),the study developed the Dagang Mountain Forest Watershed(DMFW)model,and simulated and validated the hydrological process in Dagang Mountain Forest Watershed,discussing the influence of rainfall,temperature,vegetation and topography on the hydrological process of forest watershed.The main results are as follows:(1)This study established a basic database of Dagang Mountain Forest Watershed,including hydro-meteorological data,digital terrain elevation data,soil properties data,water system data,and land use and soil types data.Based on a DEM of the Dagang Mountain Forest Watershed,the watershed was discretized into 26 sub-watersheds based on the digital watershed,and 104 HRUs were then generated according to the land use type,soil type and gradient in each sub-watershed.(2)Based on a DEM of the Dagang Mountain Forest Watershed,which was generated using GIS and RS technologies,the DMFW model of China's subtropical forest watershed was developed.The DMFW model is composed of a canopy interception model,soil water holding model,evapotranspiration model,runoff yield model,water source division model,flow concentration model and other models.The DMFW model was able to accurately simulate the effects caused by factors such as rainfall,temperature,vegetation and terrain on the hydrological processes of the forest watershed.(3)Using measured data from 2010–2014,the DMFW model parameters and hydrological processes of the Dagang Mountain Forest Watershed were calibrated and validated.During the calibration period from 2010–2012,the coefficients of determination(R~2)were 0.82,0.85 and 0.83,and the NSE coefficients reached 0.81,0.85 and 0.86,respectively.During the validation period from 2013–2014,the R~2 values were 0.76 and 0.82,and the NSE coefficients reached 0.75 and 0.84,respectively.These results show that the DMFW model could satisfactorily simulate the hydrological processes of the Dagang Mountain Forest Watershed,yielding results consistent with the actual condition of the watershed.(4)This study coupled and integrated hydrological parameters with digital information on precipitation,air temperature,soil and vegetation based on a DEM of the Dagang Mountain Forest Watershed,and constituded the digital information database,which established an important foundation for distributed hydrological simulation.Meanwhile,according to the structure and characteristics of forest distribution of the Dagang Mountain Forest Watershed in Jiangxi Province in a subtropical humid region of China,and based on the traditional Xin'An River model,the DMFW model increased the interception and evaporation module and soil water module,which could basically reflect the hydrological characteristics of the forest watershed,so as to more objectively and accurately simulate the hydrological process under the action of forest vegetation.The physical mechanism of the hydrological cycle process in the DMFW model is explicit,and the parameters are relatively easy to obtain and have clear physical meanings,and it can provide new methods and scientific guidance for the study of hydrological characteristics of forest watershed in subtropical area.