Study On Dynamic Prediction Of Soil Moisture And Water Demand In The Main Reaches Irrigation Area Of Yellow River

Agricultural irrigation water in the Yellow River is about 80%of the total water consumption of the Yellow River,which is the main body of the economic water of the Yellow River.The accurate prediction of the water demand process of the Yellow River is the difficult point to realize the fine adjustment of the water resources in the Yellow River.In this paper,the temporal and spatial distribution of water for Yellow River diversion,which was based on the historical water diversion data,the key period of water demand and the influence factors of water diversion in the main reaches irrigation area of yellow river were analyzed.On the basis of these,a statistical model for water diversion prediction in the main reaches irrigation area of yellow Yellow River is establish,ed.At the same time,the spatial distribution information of the soil water condition was obtained in real time by using the remote sensing technology,which was used to study the change mechanism of soil water content under the influence of rmulti-factors and the method of dynamic prediction of soil drought condition,and establish a model for forecasting the water demand in the typical irrigation area.It provides theoretical support for accurately obtaining and forecasting agricultural water demand infortmation and optimizing the Yellow River dispatching scheme.The main results are as follows:(1)On the basis of the comparison of the measured data,the method of stepwise regression,the selection regression method based on the fuzzy close degree,the BP neural network method and the support vector machine method were used to select the suitable prediction model of annual Yellow River diversion and the forecast model of monthly Yellow River in Ningxia,Inner Mongolia and Henan Henan and Shandong of the Yellow River.(2)The soil drought monitoring index(CI)for remote sensing was proposed,and information such as crop type,crop growth period and crop water supply status of the crop in the irrigation area could be comprehensively described.Combined with the measured soil water content data of the station,the inversion formula of average soil water content in irrigation area based on TVDI was established,and the remote sensing monitoring index of soil moisture in different growth stages of wheat based on CI was analyzed and established.Remote sensing image could directly monitor soil moisture in irrigation area.(3)The principle of water consumption balance,time series model,grey model and neural network model were used to predict the dynamic change process of soil moisture in irrigation area,and the method suitable for dynamic prediction of soil moisture in Yellow River diversion irrigation area was selected.The method of calculating the crop water requirement with the characteristic air temperature as the main input parameter was established,and the effective precipitation method and the forecast formula of the crop water utilization were established through the test research,and the available method was provided for the determination of the input parameters of the dynamic prediction model of the soil condition.(4)The model of water demand for Yellow River diversion in typical irrigation area was constructed,which was based on the raster data of current soil moisture content obtained by RS,According to the groundwater buried depth type,soil type,engineering distribution,crop planting type and so on,the calculation unit was divided and the data processing and calculation were carried out.The calculated results were in good agreement with the actual Yellow River diversion results.