Spatio-temporal distribution of irrigation water productivity and its driving factors for cereal crops in Hexi Corridor, Northwest China

The analysis of irrigation water productivity (IWP) can provide insights into taking measures to improve water-efficient irrigation. This study examines the temporal IWP trend of cereal crops over the Hexi Corridor in Northwest China by employing descriptive analysis, trend analysis, and change-point analysis. Spatial patterns of different typical years (dry, average and wet year) are analyzed by the spatial interpolation method and spatial autocorrelation method. The regional average IWP significantly increased from 0.51 kg/m3 to 1.29 kg/m3 during the period of 1981-2012 and no change point was detected. Spatial distribution of IWP reveals that IWP was higher in the plain oasis region, while lower in the mountainous and desert oasis region. The IWP ranged from 0.72 to 1.60 kg/m3 for the dry year 2004, 0.77-1.66 kg/m3 for the average year 2008, and 0.81-1.93 kg/m3 for the wet year 2011, respectively. No significant spatial autocorrelation was observed. By 2012, there were still 3.9% of the area with IWP less than 1.0 kg/m3, which implied an opportunity to increase IWP through better water management practices. The grey relational analysis of the influences of major driving factors (area supported by unit of irrigation water use, fertilization, agricultural film, agricultural pesticide, and annual mean temperature) on IWP showed that area supported by unit of irrigation water use, fertilization, and agricultural film had dominant impacts during the whole period.