| Eco-hydrological process is one of the most important processes in the nature, impacting water balance, ecosystem health and human activities in the basin. The loess Plateau is an area with serious water and soil loss and fragile ecosystem because of its unique geographic condition and historical human activities. According to the practice requirement of ecosystem repair and water resources management right now, the eco-hydrological simulation application in large basins is the bottleneck in basin level eco-hydrological researches.This paper presents an application of biophysical based distributed eco-hydrological model system based on RHESSys (Regional Hydro-Ecological Simulation System) in the Jinghe River Basin of Loess Plateau. The ecological simulation and parameters’ uncertainties of the model were tested and the model applications of two spatial levels were conducted in the Jinghe River Basin. Based on the eco-hydrological model, the vegetation ecological water use and the water and soil conservation effects on stream flow were calculated and evaluated.First, a review of researches on eco-hydrological interactions, eco-hydrological simulations, vegetation ecological water use and water and soil conservation effects on hydrology wascarried out based on present global researches results. The main researches shortages of the eco-hydrological simulation and vegetation ecological water use in the Loess plateau were addressed, and the theories and approaches of eco-hydrological interaction simulations were evaluated.Second, the eco-hydrological model were constructed based on RHESSys with several modification according to realities of the Loess Plateau, including adding stream routing module, reservoir operation module and soil and water conservation modules. The eco-hydrological model and distributed hydrological model Water and Energy transfer Processes in Large basin (WEP-L) were both applied in the Jinghe River Basin to evaluate the hydrological simulation results and ecological simulation effects on hydrological simulation, and the Generalized Likelihood uncertainty Estimation (GLUE) approach were used to evaluate the parameters uncertainties of both models. The results shows that RHESSys model can applied in big basin of the Loess Plateau and reflect the vegetation dynamic effects on hydrological processes, and improve the base flow simulation precision, but the simulation precision on flood season need to be improved. Third, eco-hydrological model RHESSys was applied in two pair catchments in the Jinghe River Basin, one of which was reforested since1950s and the other one wasn’t. The reforestation effects on runoff, soil moisture and ecosystem were evaluated and discussed. The results showed the runoff of reforested catchment is smaller than the control catchment, and the runoff differences are larger in the flood season. The deep soil moisture and ground water recharge of the reforested catchment were less than the control catchment. The Net Primary Production (NPP)/BOIMASS of reforested catchment decreased at first, then became stable. According to the Budyko curves of both catchments, this area is water limited. The reforested catchment reaches its eco-hydrological stable after about40years since reforestation.At last, an approach of vegetation ecological water use calculation based on eco-hydrological processes was proposed. The vegetation ecological water use of Jinghe River Basin was calculated and analyzed by this approach. The soil and water conservation effects on stream flow were evaluated by eco-hydrological model. The results showed that the soil and water conservation decrease the.stream flow, and the effects increase by time.The main innovations of this paper are:(1) modifing eco-hydrological model to apply in large basins;(2) proposing a method to distinguish eco-hydrological stable of artificial forest growth, evaluated the eco-hydrological effects of artificial forest, and revealing the water limitation situation of the Loess Plateau;(3) proposing a vegetation ecological water use calculation method, and analyzing the vegetation ecological water use of the Jinghe River Basin spatially and temporally.This research is of great importance not only in eco-hydrological simulation, but also in effect evaluation of soil and water conservation, and supporting ecological construction and water resources planning. |
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