甘肃省农田水分平衡及其时空分布规律

Field Water Balance and Its Distribution in Gansu Province

采用农田水量平衡模型,以县域为基本单元,对甘肃省1961～2001年10种作物逐月天然状态下农田水分平衡时空分布规律进行了研究。结果表明:天然状态下,甘肃省多年平均农田需水量为121.06×108m3;亏水量为43.28×108m3;盈水量为0.62×108m3,降水不能满足作物生长需求。在25%、50%、75%三种降水保证率下,作物的亏水总量分为35.99×108m3、42.93×108m3、49.85×108m3,盈水量分别为0.61×108m3、0.11×108m3、0.00×108m3。农田水分亏缺是甘肃省农田水分平衡的主要特征。对大多数作物而言,亏水量集中于夏季,10种作物夏季亏水总量占全年亏水总量的60.2%。全生育期棉花水分盈亏的稳定性最强,水量盈亏变异系数为6.9%,麻类最差,变异系数高达43.6%。全省天然状态下,农田亏水量由东南向西北、高山向河谷递增,农田盈水量由东南向西北递减,农田水分满足率与农田水分盈亏波动性具有从东南向西北递减的趋势。

Researches on the field water balance in Gansu province have been carried out with an accurate soil-water balance model,taking land use and the precipitation into account along with comparisons of water demand and deficits of different crops.Results show that water demand for all crops on the farmland is 121.06 billion m3,the corresponding water deficit is 43.28 billion m3,and the surplus water is 0.62 billion m3.Precipitation can not meet water demand of the crops and is the main characteristic in Gansu province.For most crops,water deficit appears in summer, and the quantity reaches 60.20% of the total deficits.The Cv value of cotton is the smallest among the ten summer crops,and that of hemp is the greatest.The water deficit increases progressively from southeast to northwest,and the surplus water decreases progressively from southeast to northwest.Water satisfactory rate and Cv value of surplus and deficit show a decrea-sing trend from southeast to northeast.