A water pricing model for urban areas based on water accessibility.

Water resource, with properties of scarcity, is one of the vital resource endowments. Like land resources, the prices of these resource endowments should be correlated to their locations to follow fair and reasonable principles. The current water price systems are mainly policy-oriented fixed regimes. And the water use was charged according to the regional-average situation with scarce consideration of the fine-scale geographical water accessibility. With a combination of the water accessibility and the current water pricing regime, this paper first proposed a novel water pricing model, the Water Price at Grid-scale (WPG) model, to dynamically allocate water prices to fine grids for urban residents. The WPG model was examined in the case study of the Han River Basin in the Hubei province of China. The specific results were: (1) the Pgrid of Tier I is between 0.66 and 3.94 yuan/m³, the Pgrid of Tier II is between 0.57 and 5.44 yuan/m³, and the Pgrid of Tier III is between 0.47 and 6.94 yuan/m³ in the study area. (2) the grids with more water acquisition generally have lower water prices than others and vice versa. (3) the average water prices in tiers obtained by the WPG model are generally higher than that derived from the current water pricing system. The results proved that the proposed WPG model spatially allocates the three-tier water prices into grids of urban areas. The WPG framework can be adopted in any society by involving its water price regimes and adjusting the scale of grids and the pricing year. This study provided a new viewpoint of domestic water pricing involving fine-scale water accessibility. The WPG model has great potential to ease water shortage pressure in water-limited societies and can be utilized and loaded into the current smart-city network for efficient and fine-scale water resource management.

Monitoring vegetation change and their potential drivers in Yangtze River Basin of China from 1982 to 2015.

Monitoring vegetation change and their potential drivers are important to environmental management. Previous studies on vegetation change detection and driver discrimination were two independent fields. Specifically, change detection methods focus on nonlinear and linear change behaviors, i.e., abrupt change (AC) and gradual change (GC). But driver discrimination studies mainly used linear coupling models which rarely concerned the nonlinear behaviors of vegetation. The two diagnoses need be treated as sequential flow because they have inner causality mechanisms. Furthermore, ACs concealed in time series may induce over/under-estimate contributions from human. We chose the Yangtze River Basin of China (YRB) as a study area, first separated ACs from GCs using breaks for additive and seasonal trend method, then discriminated drivers of GCs using optimized Restrend method. Results showed that (1) 2.83% of YRB were ACs with hotspots in 1998 (30.2%), 2003 (10.4%), and 2002 (7.6%); 66.7% of YRB experienced GC with 94.8% of which were positive; and (2) climate induced more area but less dramatic GCs than human activities. Further analysis showed that temperature was the main climate driver to GCs, while human-induced GCs were related to local eco-policies. The widely occurring ACs in 1998 were related to the flooding catastrophe, while the dramatic ACs in sub-basin 12 in 2003 may result from urbanization. This paper provides clear insights on the vegetation changes and their drivers at a relatively long perspective (i.e., 34 years). Sequential combination of specifying different vegetation behaviors with driver analysis could improve driver characterizations, which is key to environmental assessment and management in YRB.

Modeling the water-satisfied degree for production of the main food crops in China.

Water resources are one of the important factors that influence regional crop production and the food security of humans. Most traditional models of crop water demand analysis are built on the basis of a certain crop or macroscopic analysis, which neglect regional crop allocation and the difference of water demand in different crop growing periods. In this paper, a new assessing model, the satisfied degree of crop water requirement, is developed to assess the impacts of water resources on production of six main food crops in China. The six main food crops are spring wheat, winter wheat, corn, early season rice, middle-season rice and late rice. The results show that: (1) there are serious risks of water shortage in China, even in south China with its abundant precipitation; (2) the satisfied degree of crop water demand represents great temporal-spatial changes. On spatial distribution the risks are high in major bases of food production due to influences of cropping system and crop-combinations. Northwest China is a special interesting case. In seasonal fluctuation water shortage is severe in March and September. These risks seriously restrict food production in China. The results also show that the strategic measures of water resources management must be chosen carefully to deal with food security and regional sustainable development in China.