Study On Key Technology In Monitor And Prediction System Construction Of Drought Injury

In this dissertation, a farther research on points of field capacity and relative evaporation of drought monitor and prediction system construction has been done.It includes three main parts of this dissertation. In the first part, methods of ascertain field capacity was studied systematically both in China and aboard, and the physical meaning of each method as well as clarifying the applying conditions of each method was analyzed also. Based on the extant data, two methods of Point-estimation model and Coefficient-estimation model that can ascertain field capacity were discussed, the result shows that Point-estimation model has more advantage on field capacity research. As the lack of the extant data, a relative method was put forward: 217 earth units aimed at the drought monitor and prediction system were partitioned firstly, then based on analyzing of distribution rules and effect factor of china soil, a conclusion that can estimate the field capacity of each unit was put forward, and combine with the extant data, the distribution of the field capacity of China can be established.In the second part, the six kinds of representative soil in China were analyzed firstly, then based on the method that had be educed in the first part, with analysis of the main factor that effects the field capacity, including soil matrix, mellow degree, soil structure, soil texture and soil utilization, and combine with the extant data and result of model method, the field capacity of the six representative areas was ascertained. Lastly, with frame of reference of the six areas, the field capacity of each unit of China was ascertained.In the third part, based on the theory of surface energy balance, the remote sensing data and meteorologic data were pretreated first. Then the 13 indexes were calculated based on the result of pretreatment, and the relative evaporation was ascertained, the water condition of each soil unit was estimated also, thus the purpose of drought monitor and prediction was achieved. At the end of the third part, the result of the land surface energy balance system was contrasted with the result of soil drought monitor developed by the Information Centre of Water Ministry, and the result of comparison shows that the theory of surface energy balance was a useful method in the construction of drought monitor and prediction system.