a b s t r a c tIn recent years, the frequency and intensity of drought in China are on the rise, and most of the major grain producing provinces are situated in the drought-prone areas, so agricultural drought has become one of the main factors restricting the agricultural production in China. In this paper, with Henan province being taken as the research area, the change trend of agricultural drought area of Henan province was analyzed, and the spatial-temporal evolution characteristics of Henan province were evaluated based on the regional agricultural drought index. The research showed that the inter-annual change of agricultural drought index showed a decreasing trend year by year (tendency rate was -0.12/10a), indicating that the drought degree decreased year by year. The east and south of North Henan, east and north of Eastern Henan, and north and east of Central Henan were mild drought-prone areas; the east of Western Henan, west and north of North Henan, and west of Central Henan were moderate drought-prone areas; the west of North Henan, west of Western Henan, and north of South Henan were severe drought-prone areas.
The water consumption system is a typical dissipative structure system, and its evolution can be described with information entropy. Meanwhile understanding the principal driving factors in the evolution of water consumption is essential for water consumption prediction and management. Firstly, the information entropies of water consumption in China were calculated from 1997 to 2010. Secondly, the principal driving factors were extracted using principal component analysis. Finally, based on the principal driving factors, the water consumption system was predicted. The results showed that the entropies can be divided into two stages: an entropy increasing period (1997–2002) and an entropy convergence period (2003–2010). On a national scale, the entropies in the majority of provinces are focused between 0.6 and 1.1. The principal driving factors were population, gross domestic product, food production, command irrigation area, and urban consumption levels. Chinese water consumption structure will develop an inverted ‘U’-shape curve and water consumption levels are expected to plateau during 1997 to 2020. The system is gradually becoming more orderly through coordination and self-organization.
The assessment of water use benefits is complex as it involves economic, ecological and social domains. The index system of the benefits assessment is multi-object and semistructural including both quantitative and qualitative indices. Based on the theory of variable fuzzy, the benefits assessment system in an irrigation district in Shanxi province, northwestern China is built. Using the two-level variable fuzzy decision-making model and the improved multi-level decision-making model, the benefits of water use in the irrigation district are assessed in three level years of 1997, 2005 and 2015. The results show that the benefits are gradually increasing, and the multi-level variable fuzzy decision-making model is superior to two-level model which makes the calculation results more stable. Moreover, the multilevel model can not only be used to optimize the different schemes but also to assess the grade of each scheme, with which to support the decision-making for the sustainable development of water use in the irrigation district.
Keywords-variable fuzzy model; water use benefits;multiobjective decision making; benefits assessment; irrigation districtI.
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