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Land use change analysis at different periods has been very helpful for resource management and essential trends detection through time. In order to understand the changes of land use, we examine the level of land use and the strength of human activities on land use in the Yellow River Basin in recent years. Based on the analysis of the change of land use area in the study area, according to secondary divisions of water resources, importance index of land use change (Ci), proportion of land use change area (D) and vegetation index of forest and grassland (R) were used to analyze the direction and degree of land use change in eight regions of Yellow River Basin during 1980- 2015. It is found that land use in this basin underwent significant changes in the 35 years. The intensity of land changes in the Hekouzhen-Longmen section of the Yellow River Basin was the most intense. Although the degree of change in the eight sub- regions was relatively small, the absolute change area was large. The speed and degree of land use change were studied in four periods of 1980-1990, 1990-2000, 2000-2010 and 2010- 2015 by using single land use dynamic degree, comprehensive land use dynamic degree and land use degree. The results showed that compared with 1980, the area of built-up land and water changed significantly. By analyzing the rate of single land use change in different periods, the rate of desert and unused land, water and urban and rural industrial and residential land changed significantly. The other three types of land use were not noticeable because of larger base area. In terms of the study periods, the change rate during 2010-2015 was the highest, and presented an increasing trend over time. Through the analysis of land use change rate, there was an increasing trend in all the eight regions; however the increasing trend in Longyangxia region was the most obvious. Except Longyangxia and Huayuankou water resources divisions, the comprehensive index of land use degree in the entire Yellow River basin ranged from –2 to 2 from 1980 to 2015, indicating that the comprehensive level of land use in each division did not change much in this period. From this perspective, human activities have less impact on land use. The reason for this result is that the entire area of the Yellow River Basin is too large, and the areas with intense human activities are only distributed in densely populated towns and plains. In the 35- year period, human activities did not have a profound impact on forests, grasslands, and deserts. [ABSTRACT FROM AUTHOR]

At present, most of the drought researches are based on a single meteorological or hydrologic drought index which can not reflect the drought situation or social contradiction of supply and demand of water comprehensively. This paper studied the spatial and temporal distribution of drought in Shaanxi Province based on the method taking the social economic factors of drought into account. The natural meteorological factors are also taking into consideration. We established comprehensive drought evaluation index of Shaanxi Province with fuzzy comprehensive decision process on basis of meteorological data from 19 meteorological stations in Shaanxi from 1960 to 2013. The results showed that the spatial distribution of drought in Shaanxi Province is heterogeneous, the drought in the central Shaanxi (DI value is about 3) is more serious than in northern Shaanxi, and there is no drought in south Shaanxi at the same time where water resources are abundant. Drought occurrence frequency in Shaanxi Province is very high. The medium drought phenomenon mostly existed in the north and south (frequency approached to 80%-99.99%). The severe droughts occurred in the central Shaanxi more often (frequency approached to 79%). The method of water supply and demand evaluation considered the influence of social economy and the actual supply and demand contradiction. And the comprehensive meteorological drought index considered the effects of meteorological factors. The results of the two methods are basically identical, but only one type of drought index can not reflect the overall actual situation when there exists great difference of water quantity in different areas. In water shortage regions, the results of fuzzy comprehensive drought index are closer to the fact. In regions where water resource is extremely rich and water supply ability is strong, the results of water supply and demand method are closer to the fact. And in economic developed areas, social economy drought index is suggested. When doing researches of drought, it shall give full consideration to the natural meteorological factors and actual water supply ability. [ABSTRACT FROM AUTHOR]