中文摘要：

选取位于黄土高原北部水蚀风蚀交错区的六道沟流域为研究区,以FAO56推荐的参考作物的蒸散发计算公式和Penman-Monteith公式,利用观测的气象数据,以1 h为时间步长分别计算参考作物的蒸散发ET0、草地植被的蒸散发ET以及水分有效性参数ma（ma=ET/ET0）。2006年的计算结果表明：年ET0略高于年降雨量;ET占年降雨量的37%,雨季集中降雨发生后ET明显增加;年中大部分时间ma〈0.4,其年平均价值为0.34;研究结果可为黄土高原北部水蚀风蚀交错区土壤水分的动态功能分析、土壤水分与农作物生长的关系等研究提供基础数据。

英文摘要：

The study area is the Liudaogou Basin which is located at the wind-water erosion crisscross region of the northern Loess Plateau.The reference crop evapotranspiration（ET0） was estimated by Penmen method which was recommended by FAO56 and the evapotranspiration over the grassland（ET） was estimated by Penmen-Monteith equation using the observed meteorological data with time unit of 1 h.The soil moisture availability factor was defined by ma=ET/ET0.The calculated results in 2006 indicated that total ET0 was slightly more than the total yearly precipitation and ET accounted for 37 % of that,ET increased distinctly after the intensive rainfall event in the rainy season;Most of ma was less than 0.4 and its annual mean was 0.34.The results are looked forward to provide basis for studies on dynamic functional analysis of soil moisture,relationship between soil water and crop growth at wind-water erosion crisscross region of the northern Loess Plateau.