Abstract:

In order to explore the water supply guarantee and food security of rice in the hilly irrigation area of southern China, the daily meteorological data of long time series in Maweizao irrigation area were collected, and the rainfall in the growing season of rice was taken as the object to analyze and determine the typical years and their characteristic values. Subsequently, based on the FAO Penman-Monteith method and the water balance method, the water requirement of rice crops and the net irrigation water requirement in the field were calculated. Then, the GIS technology was used to analyze the net irrigation water supply and the spatial characteristics of water supply guarantee in the irrigation area. Combined with soil moisture content and crop yield test, the correlation between net irrigation water supply, soil moisture content and rice yield were obtained. The results showed that, taking late rice as an example, the net irrigation water requirements of the field in normal year, medium drought year and dry year were 415mm, 455mm and 560mm respectively. In dry year, the ratio of net irrigation water to net irrigation water in the field was less than 40 %, 40 % ~60 %, 60~80 % and more than 80 %, respectively, accounting for 26.11 %, 10.16 %, 13.33 % and 50.4 % of the total area of the irrigation area, and the grain yield was 0~200,200~300,200~300 and 400~500 kg / mu, respectively. The research results will provide reference for the confirmation of agricultural water rights and the total amount of agricultural water use in large and medium-sized irrigation areas.

Key words: intraseasonal rainfall, net irrigation water requirement in the field, net irrigation water available, water supply security