Research On Soil Water Resources Assessment And Efficient Utilization

Haihe River Plain is the production base of agriculture and commodity grain in china. Water resources shortage is a restrict to the sustainable development of the national economy in the area. The water use for the agricultural production accounts for 70% of total water in the area. Soil water can be directly used in the crop growth, and the farmland irrigation water is only essential supplyment to the insufficient soil water recharged by precipitation, which cannot meet the crop water requirement. To alleviate the situation of shortage of regional water resources, the key is to reduce farmland water consumption and improve water production efficiency in agriculture, which demands the regional agricultural production and farm structure form should be in accordance with the "suitable water development" principle, to adapt to the situation of soil water resources of the area. Therefore research on soil water resources assessment and efficient uitilization has important theoretical and practical significance for the agricultural production to reduce consumption of traditional water resources(gravity water,) and to ease the contradiction between supply and demand of water resources in the area. In this paper, taking Baoding plain as an example, we have studied the soil water resource evaluation and high efficient utilization in farmland. The main study contents and results are as follows:(1) Analysis and description of basic theory research on soil water resources evaluation. The relationship between soil water resources and soil water and concept and characteristics of soil water resources has been analyzed. Research content, evaluation index and evaluation method of soil water resources have been explained. The concepts and methods about water resources evaluation layer are cleared. The model calculating the soil water resources quantity of Baoding plain is put forward in the light of water balance principle. This model focuses upon the following problems: firstly, in order to calculate the surface flow that does not produce soil water, the hydrological model of runoff yield in excess of infiltration is applied; secondly, the hydrological model of runoff yield at natural storage is used to calculate the water quantity of infiltration out of the assessment layer that recharge water amounts to underneath the assessment layer; and thirdly, the canopy interception model is utilized to measure the ineffective rainfall.(2) Study on quantity evaluation of soil water resources in Baoding plain. The model of soil water resources evaluation has been applied to calculate the soil water resources in Baoding region. The model needs the following different parameters, such as the daily precipitation, based on the rainfall of different hydrological years in Baoding plain, determined by the precipitation frequency according to 1956-2012 years of precipitation record series of rainfall stations in Baoding plain; invalid rainfall, calculated by canopy interception model; surface runoff, based on runoff over infiltration model; and water amounts of underneath the assessment layer, based on the runoff yield model. Annual variation of soil water resources quantity is measured by the difference between the daily precipitation and above daily loss, and the soil water resources in Baoding plain is concluded. The temporal and spatial distributioan of soil water resources are cleared, which is the theoretical foundationt to adjust regional planting structure and improve water use efficiency.(3) Study on control experiments of Soil water resources in field. According to the characteristics of natural precipitation in Baoding plain, plastic mulch field experiment has been done to study the influence of plastic mulch on the soil water resources amount and utilization. First, the ratio from rainfall to soil water resources has been calculated by using the change of soil water contents in the soil layer of cotton root before and after rainfall, and the results indicate that the ratio of film mulching has been increased; second, the effect on soil water consumption is cleared on the base of water balance equation; third, the appraise model under the condition of same production is set up based on the theory of virtual water.(4) Study on regulation system of soil water resources utilization. According to the difference between the soil water resources amount and water requirement during the growth period of main crop, and in accordance with the "suitable water development" principle, soil water resources regulation system are put forward. Soil water resources regulation system includes the macroecosmic regulation and microcosmic regulation.