| Guanzhong area is always most developed area in agriculture for ancient China, and it was the political, economic and cultural center of whole China in Qin, Han and Tang Dynasty. However, Guanzhong area is located in the semi-arid areas, belongs to the water resources shortage area. The per capita water resources is only 17.3% of Chinese average level. In the other hand, because Guanzhong area is a plain area, there are less water reservoirs, the ability of water resources regulation is weak corresponding. The drought is most frequent and serious natural disaster in this area.According to the Chinese developing plan, the Xi’an city, the core city of Guanzhong area, will play a very important role. The whole Guanzhong area faces to a historic chance. Hence, it is necessary to find a scientific method to against drought, to reduce losses, to improve the ability for early warning in Guanzhong area.In this paper, the temporal-spatial characters of rain, surface water resources, and ground water are carefully analyzed, and the total quantity of water resources with available water resources are discussed. The annual precipitation of Guanzhong rangs from 550 mm to 700 mm, when the evaporation rangs from 1200 mm to 1400 mm. the distribution of precipitation in Guanzhong is extremely imbalance. In spatial aspect, the precipitation is shown tends to degression from south to north, from west to east. In temporal aspect, the 60%-75% precipitation and 50%-65% runoff are generated in four months, June to September. And the runoff in Guanzhong is decreasing in recent years.In drought research, drought frequency index and drought accumulative damage index of Guanzhong are calculated based on drought statistic data from 1949 to 1995. Through this research, it is obviously that drought is very frequent in Guanzhong. There are 280 times drought are recorded from 1949 to 1995, and 35.6% drought occurred in summer. After cluster analysis by K-means method, the drought frequency figure and drought accumulative damage figure of Guanzhong were drawn, which give a direct understand for temporal-spatial distribution characters of drought in Guanzhong.For drought monitoring, remote sensing method has more advantages than the traditional monitoring methods, such as bigger monitoring geography scale, timing and lower cost. In this paper, the MODIS data was chosen for drought monitoring data, and Normalized Difference Drought Index(NDDI) was chosen for monitoring index. The details of data acquisition, data preproccess and data analysis were introduced step by step in this paper.For drought early warning, the Fuzzy available set method is used for drought assessment. In this assessment system, the drought frequency index, drought accumulative damage index, remote sense drought monitoring index and meteorological index are considered comprehensively. According to the assessments, the corresponding color warning is issued to alert every stakeholder.At last the imbalance between water resources supply and demand at different precipitation runoff probability were analyzed, the research unit is administrative county(or district), the temporal scale is month. In this part, every month available water source was calculated for every county, which could be the significant consult to water allocation in drought.The main innovation of this paper is historic factor and human’s activity factor were considered in drought assessment, especially drought accumulative damage index is the first time introduced. Drought accumulative damage index is a comprehensive index, it reflects regional disparity on drought resistance ability and allocation efficiency of water resource in different drought levels.Further more, this paper established a simple, operable and effective drought assessment and early warning system for Guanzhong, which contribute to improve the management level of water resource when drought. This system changes the drought deal with strategies from result management as processing management. This research is an important reference for Guanzhong economic stability and people’s property safety. |
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