Abstract
Because of the shortage of water resources, the phenomenon of groundwater over-extraction is widespread in many parts of the world, which has become a hot issue to be solved. The traditional idea of water resources management only considering blue water (stream flow) cannot meet the demand of sustainable utilization of water resources. Blue water accounts for less than 40% of total rainfall, while green water (evapotranspiration) accounts for more than 60% of total rainfall. In the natural environment, vegetation growth mainly depends on green water, which is often neglected. Obviously, the traditional water resources management without considering green water has obvious deficiencies, which cannot really reflect the regional water consumption situation in the water resources management. And only by limiting water consumption can achieve the real water-saving. In addition, the mode of water resources development and utilization has changed from “supply according to demand” to “demand according to supply”. In this background, for many regions with limited water resources, it is impossible to rely on excessive water intake for development, and sustainable development of regional can only be realized by truly controlling water demand. This paper chooses Shijin Irrigation District in the North China Plain as the research area, where agricultural water consumption is high and groundwater over-extraction is serious and ecological environment is bad. In order to alleviate this situation, comprehensive regulation of water resources based ET is necessary. Therefore, this paper focuses on the concept of ET water resources management and includes green water into water resources assessment. Based on the principle of water balance, the target ET value of crops in the study area is calculated, and the ET value is taken as the target of water resources regulation. The actual water consumption is calculated by Penman-Monteith formula, and reduction of crop water consumption is obtained according to the difference between actual ET and target ET. The reduction in crop water consumption leads to a reduction in demand for water supply, which reduces groundwater extraction. The results of this study can provide necessary technical support for solving the problem of groundwater over-extraction and realizing real water-saving.
Highlights
Because of the shortage of water resources, the phenomenon of groundwater over-extraction is widespread in many parts of the world, which has become a hot issue to be solved
The results showed that the modern water resource management strategy based on ET can avoid the waste of water resource, and improve the efficiency of water resource utilization
Based on the principle of water balance, the target ET value of crops in the study area is calculated, and the ET value is taken as the target of water resources regulation
Summary
Because of the shortage of water resources, the phenomenon of groundwater over-extraction is widespread in many parts of the world, which has become a hot issue to be solved. The traditional idea of water resources management only considering blue water (stream flow) can't meet the demand of sustainable utilization of water resources. Blue water and green water resources participate in the operation of environment and ecosystem as well as social production, affecting the storage of groundwater resources and food production, especially in arid and semi-arid areas with water shortage. The use of blue and green water for water resource management is to comprehensively consider the water balance among land, water and ecosystem, and solve the conflict between future food production demand and ecosystem balance (Falkenmark et al 2004). The traditional water resource management only considers the surface water and groundwater, that is, blue water, and ignores the green water resources that support rain-fed agriculture and maintain the balance of land ecosystem. The annual flow of green water on the earth's surface is about 72500km3 /
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