关键词: 波文比能量平衡法, 蒸渗计, 蒸散, 雨养农业, 春小麦

Abstract: Observation and experiment on the evapotranspiration rates(ET) of farmland were conducted in Dingxi Arid Meteorology and Ecological Environment Experimental Station, Institute of Arid Meteorology, CMA in 1993,1994 and 1996 by using Lysimeter technique and Bowen ratio-energy balance method(BREB). The results show that the BREB overestimated ET by about 20%, which can satisfy the accuracy demands in the semi-arid rainfed agricultural region. Moreover, the error in the BREB calculations of ET is smaller during non-advective periods than in advective periods. The agreement between the BREB method and Lysimeter technique on ET is better, but the Lysimeter technique underestimated ET because water and energy exchange is separated between Lysimeter and around field, and the exact error need to be confirmed by more observation study.

Key words: Bowen ratio-energy balance method, Lysimeter, evapotranspiration, rainfed agriculture, spring wheat