Spatiotemporal Variations in Dry-Wet Climatic Variables over the Urumqi-Changji Region of Xinjiang
新疆乌-昌地区干湿气候要素时空变化分析

Urumqi City and Changji Hui national autonomous prefecture (Urumqi-Changji region) is located in the northern slope of the Tianshan Mountains and southern edge of the Junggar Basin of Xinjiang. The precipitation is extremely less and evaporation is high over this region. Dry climate and water shortage are the major factors restricting local socio-economic development, especially agricultural production and environmental protection. To investigate characteristics of dry-wet climate change in the past 49 years in the Urumqi-Changji region, based on monthly climate data from 1961 to 2009 at 16 meteorological stations across the Urumqi-Changji region, fundamental characteristics of spatial-temporal change in various dry-wet climate variables, such as annual precipitation, potential evapotranspiration (ETo), dry-wet index, and water deficiency, were comprehensively analyzed using methods of linear regression, Mann-Kendall test, three-dimensional and quadratic trend surface simulation, and inverse distance weighting interpolation. Results show that the dry-wet climate is completely different for varying regions in the Urumqi-Changji region. In general, the annual precipitation and dry-wet index are larger in the Tianshan Mountain areas and western areas than in plain and eastern areas. ETo and water deficiency are generally larger in plain and eastern areas than in the Tianshan mountain areas and western areas in the Urumqi-Changji region. A climate wetting trend was evident in recent 49 years. The annual precipitation and dry-wet index showed a significant increasing trend at a rate of 13.843 mm/10a and 0.016/10a, respectively, showing a significantly abrupt increase in 1990 and 1987, respectively. ETo and water deficiency showed a significantly decreasing trend at a rate of -16.07mm/10a and -29.909mm/10a, respectively, with abrupt decreases occurring in 1983 and 1986, respectively. In general, the climate showed an obvious wetting trend over the recent 49 years. The increasing range of precipitation and the dry-wet index in the Tianshan Mountain areas was larger than in plain areas. The decreasing range of ETo and water deficiency in central plain areas was larger than in the Tianshan mountain areas and Gurbantunggut desert edge areas. It was found that the climate has become humid, which would lead to increases in water resources, decreases in evapotranspiration from farmland and natural vegetation, reductions in crop water requirement, and be conducive to easing fierce contradictions between water supply and demand and improving the fragile environment over the study region.