Change of water productivity of wheat at different scales in oasis irrigation districts

Water productivity is an integrated index that evaluated agriculture production level and scientific and rationality of agricultural water. According to the data of meteorological, irrigation water use, irrigation area and crop yields of Hongshuihe irrigation districts from 1995 to 2006 in Minle County, Gansu Province, the variations of irrigation water productivity of wheat at four different scales which consist of farm scale, lateral canal scale, main canal scale and irrigation district scale were analyzed. The results indicated that the average values of irrigation water productivity of wheat calculated for different scales and different years were difference, the datum at farm scale was 1.414 kg/m3, lateral canal scale was 1.013 kg/m3, main canal scale was 1.089 kg/m3 and irrigation districts scale was 0.894 kg/m3. Also, differences of irrigation water productivity were bigger in years for different scales. The water saving irrigation project was put in practice in Hongshuihe irrigation districts in 2001. The average of irrigation water productivity of wheat was promoted obviously from 2001 to 2006 than that from 1995 to 2000. And the average from 2001 to 2006 was raised by 7.9%, 19.4%, 16.5%, 7.4%, respectively for farm scale, lateral canal scale, main canal scale and irrigation district scale, which showed that water saving was obvious benefit at lateral canal scale and main canal scale. At the same time the results also showed that water saving was considerable potential at irrigation district scale. Therefore the emphases of research works for agriculture water saving will be in irrigation district scale in the future.