Study And Application Of A Distributed Hydrological Model On The Loess Plateau

The construction of the water and soil conservation has achieved great benefit in the Loess Plateau in recent decades while the effect of sediment and water decreasing induced by the water and soil conservation measures is different according to different researches. This make it difficult to evaluate the status and effect of the construction of the water and soil conservation. The distributed hydrological model received more and more concern by its remarkable characteristic of dealing with the heterogeneity inside the watershed and is considered as an effective tool to study the effect of the water and soil conservation measures. The current distributed hydrological models can not effectively simulate the changed hydrological process with the construction of the silt-trapping dam due to their large scale or improper calculation method . A new model is needed.An integrated grid based distributed hydrological model THIHMS-SW (TsingHua Integrated Hydrological Model System-for Small Watershed) is developed to adapt to the special conditions of of the Loess Plateau, with focus on the soil movement in saturated-unsaturated zone by numerical solving of Richards Equation to obtain more accurate simulation of infiltration and runoff, and the coupling of water and sediment at the scale of grid. Modeling of water and soil conservation measures especially the silt-trapping dam is also considered. Continuous simulation of eight years under the condition without much human activity disturbance are carried out in the Chabagou small watershed and the results indicate that the model works well, and the efficiency coefficients are all higher than 0.70. Continuous simulations of three years under the condition of hundreds of the silt-trapping dams installed are also carried out and fairly good results are obtained.Long-term continuous simulations in 0.5 hourly temporal resolution with topsoil being discretized into different layers were carried out in the...