Research On Evaluation And Prediction Model Of Soil Erosion In Yellow River Basin

A long time, the serious soil erosion of the Yellow River Basin not only causes the soil of the middle-up reach to be barren, and the environment to be deteriorated, but also as the primary cause initiates the serious siltation, frequent flood and sediment disasters in the downstream.The soil erosion is one kind of hydrodynamics process which corroded material follows the runoff, moving and transporting to basin export section. Affected by many factors, the basin sediment production mechanism is extremely complex. Because of the requirement of practice of soil erosion control, people should recognize the law of sediment yield, transportation, deposition process, and give the description and solution in mathematics expression. It can be predicted and evaluated the soil erosion and sediment yield through the mathematics expression, thus to meet the parameters requirements of basin planning, design and management. In this paper, a more detailed study about this has been done; the main point and innovation of the research are as follows:1. The study analyzes the model developing status quo of the soil erosion evaluation & prediction, points out the main problems that current existing, and put forward the objectives and content of the study on the numerical simulation of the soil erosion.2. This study is based on the needs of soil erosion control in the Loess Plateau and based on the integrated research all over the world, then propound the research scheme of setting up distributed soil erosion evaluation & prediction mathematical model of typical small watershed in the more sediment and coarse sand area of the Yellow River, which takes the erosion dynamics, geomorphology, hydrology, river dynamics theory as the instruction, take the Chabagou basin that has complete erosion slope to produce sand and channel system to transport water and sediment in this area as object of study, take the GIS as platform.3. The study presents automatic extraction method of the soil erosion environmental factors by using the RS/GIS, establishes index systems that enable the model to integrate well with GIS, and forms the analysis database of GIS, so as to further study the key technology of that GIS coupled well with soil erosion mathematical model.4. The study sets up the equation systems of slope flow simulation and its erosion and sediment yield, which based on the kinetic theory of water erosion and sediment yield. The evaluation & prediction model that based on GIS platform has been developed. The model is verified and modified by field measuring data; and finally the distributed mathematical model coupled with GIS was built, which can be used for predicting and evaluating soil erosion process of small basin in more sediment and coarse sand areas of the Loess Plateau.5. The paper reveals the coupling relationship of the erosion and sediment yield in slope and gully systems, and the study enables runoff to couple tightly with sediment yield and transport. The study puts forward the concept of equivalent roughness, and fixes the quantity of impact of soil and water conservation works on the runoff, so that the model can predict and evaluate the benefit of various soil and water conservation program. The study analyzes the uncertainty of the model by using GLUE method, determines the sensitivity parameters of the model, brings forward the spatial distribution of the sensitivity of the model parameters and confidence level of simulation results, and thus improves the scientific level of model prediction results.