Based on many data sources, such as basic geographic information, land use and cover information and statistic data of irrigation areas, the authors picked agricultural irrigation areas in the middle reaches of Heihe river as a study area and analyzed the spatial-temporal distributions of ecological water requirement with Penman-Monteith equation and NDVI data. Considering the real water diversion and consumption per unit grain yield, the efficiency of water allocation was also analyzed. The results show that the annual potential evapotranspiration is between 800 and 1200 mm and the peak occurs between June and August. Average annual potential evapotranspiration is between 614 and 999 mm while maximum of demand appears from April to August. Ecological water requirement reduces from southeast to northwest gradually which is relatively larger along the Heihe river. Ground water plays major role in water diversion while underground water is minor. The yield of water diversion is the largest in 2008 and irrigation areas which have more water diversions flock around the Heihe river. Overall, water resource allocation overthere is fair good. Water supply-demand rate around Heihe river is generally greater than 1 while it is opposite in Shandan and Minle. Nearly 80% of the irrigation areas can be considered as efficient or relative efficient regions. There are four irrigation districts are inefficient and only one is short of water diversion. Therefore, adjustment of water diversion in some certain regions with promotion of water saving technology can enhance the efficiency of water allocation roundly. The results provide feasible reference to improve the efficiency of water allocation in arid area.
The dust event on May 25–26, 2014 in Wuhan Hubei province was studied by integrating multiplex information including mass concentration, metal element contents of atmospheric particle, vertical particle extinction, backward trajectory, surface meteorological parameters and synoptic analysis. The results show that the dust came from the sandstorm occurred in southern Xinjiang Taklamakan desert and Inner Mongolia Badan Jaran desert and Teng Ko Erh desert and then transported to east and south of China with cold air blowing. The PM10 mass concentration decried along the trajectory, with hourly average exceeding 2000 μg/m3, 1000 μg/m3 and 500 μg/m3 in Lanzhou, Yinchuan and Wuhan respectively. During the dust event, coarse particle was dominant, PM10 concentration increasing rapidly, and proportion of PM2.5 to PM10 decreased to about 35%. The concentrations of dust trace element Ca, V, Ba and Fe increased by about 4 times, percentages of the total element concentration doubled and the concentrations of As, Se, Cr, Cu, Zn and Pb from local anthropogenic sources were 1/5–2/5 of previous levels, percentages of the total element concentration decreasing significantly. Two evident dust deposition processes were recorded by Lidar, and the maximum area of extinction appeared near surface around 500 m with the max value at 0.086 km-1. This paper pilots the analysis method of transporting air pollution using combination of meteorological and environmental measurements.
