| In the present study, a limiting factor regression model of the grain production was established based on the characteristics of water resource that are the key limiting factors for the cropping system in Zuli river basin with the aid of 3S (RS, GIS, GPS) technology. The spatial distribution of grain production throughout the basin was simulated by the model coupling with GIS. According to the statistical analysis of the total grain output and per capita grain yield from each villages and towns which were considered as discrete units, the present situation of grain demand and supply and food security was also discussed. The results showed that because dry farmland accounted for 92.74% of the total cropland area, the rainfed agriculture was the mainly type of farms in Zuli river basin, and the grain yield per unit area in dry farmland was only about 630.1～1 231.5 kg·hm-2, which was only about 1/4～1/5 of that in irrigated cropland (about 3 750～5 250 kg·hm-2). Furthermore, the grain yield was uneven in spatial distribution. And our research also indicated that total grain output of the whole basin was about 4.17×108 tons, and the grain yield per capita was 481.94 kg, implying that the total grain output of the whole basin could satisfy the consumption need of population under the existing condition. Although there were 16 villages and towns, accounting for 25.4% of those in the whole basin, where grain yield per capita was less than 395 kg, through internal grain allocation inside the basin, the balance of food supply and demand in basin could be achieved. |