Construction And Application Of Distributed Hydrologic Model NEHM

As a modern study way of hydrological studies, forest hydrological model has complementary functions with traditional research methods and special ones. The development of forest hydrological models synchronize with that of computers’. From the early black-box model to distributed hydrological model with highly physical simulation, forest distributed hydrological model can predict hydrological response under natural conditions or human disturbance, which lays the foundation for the understanding of hydrological mechanism. The model has an important guiding significance to ecological reconstruction, so was got highly attention and rapid development.Taking the watershed of Han Yue forest station in Yu Lin River of Dai Ling forest bureau in Xiao Xing’an Mountains as a research object, watershed distributed forest hydrological model-NEHM(Northeast Hydrology Model) was constructed, which was based on the technologies of "3S", databases, computer programming language and DEM, referred to hydrological model constructing characteristics abroad and at home, according to the laws of forest hydrology and snow and frozen soil characteristics, to simulate hydro-dynamic process and provide effective forecasting and evaluating method in the forest hydrological cycle of Xiao Xing’an Mountains. According to the region subcompartment table, NEHM obtains vegetation parameters to make up for past model’s shortcomings of vegetation spatial and temporal distribution. The model simulate runoff response in specific vegetation, topography, soil freezing and thawing and snow characteristics in order to reveal the laws of ecosystem vegetation changing on regulation of hydrological processes. Moreover, the model has great significant in objective evaluation of forest vegetation hydrology.Based on2004observed data of Yu Lin River hydrological stations, the research simulated daily runoff process of the typical catchment of Tang Wang River Basin in Xiaoxing’ an Mountains by NEHM and compared with the results about annual total amount of surface runoff and daily surface runoff. The results showed that the simulated and measured values of annual total amount of surface runoff are close. They also showed that the linear regression coefficient (R2) and Nash-Sutcliffe model efficiency system (Ens) of simulated and measured values of daily surface runoff are both higher than0.75and the effects of simulation are relatively good. All above reveal that NEHM can simulate hydrological dynamic process exactly, so as to guide the allocation of water resources in this region. Based on the above analysis, according to "Runoff Data of Experiment Station in Heilong Jiang Province" and "River Hydrological Data in Heilong Jiang Province", the simulations of land surface streamflow amount in observation station grids with various precipitations scenes were conducted by NEHM, and NEHM could give exactly expression to the effects of rainfall scenes to hydrologic process. Rainfall and runoff had positive correlation, but exited a certain lag. Finally, the effect of slope position on interflow was simulated by NEHM. The result showed that the size of incremental and increment of subsurface flow had negative correlation. The paper made detailed exploration to further research on distributed hydrological model and lay the foundation for its development.