Research On The Ecological And Environmental Water Requirements Of The Highland And River Channel In The Yellow River Basin

A series of eco-environmental problems, for example, drying up of the river channel, riverbed deposition, and degradation of estuarine delta, are arising from excessive utilization of water resources in the Yellow River Basin. Therefore, how to ensure water requirement of the watershed ecosystem is a crucial factor for the ecosystem conservation. The research has studied the ecological and environmental water requirements of highland and river channel in the Yellow River Basin. Two aspects of research are included in this paper. One is to study the ecological and environmental water requirements of the basin theoretically from the point of view of the ecological conservation; the purpose is to analyze its spatial-temporal variation and ecological water shortage in the basin. The other is to study water required by ecosystem in water resources allocation of the basin from the point of view of ecological conservation and economic development; the aim is to realize the combination of its theory and application and to offer scientific foundation for rational water resources allocation of the basin. The following contents in detail are included in this research: 1. The concept, structure, formation, characters of watershed ecological and environmental water requirement has been studied. Especially, the ecological water requirements of highland and river channel ecosystems have been highlighted. Based on the relationship between ecological and environmental water requirement and ecosystem health, the grades of watershed ecological and environmental water requirements have been set up; the grade standards, which were dependent on the study area, have also been established. This provided theoretical foundations for the actual calculation of the ecological and environmental water requirements in the Basin. 2. In term of the highland ecological and environmental water requirement, the concepts, formations, characters, influence factors and relevant relations among the water requirement of plant, soil, and for soil conservation and improvement have been studied. Then the computing model of plant water requirement was established according to the relations among evapotraspiration and climate, vegetation, soil moisture; while the computing model of soil water requirements was established directly according to its definition. These computing methods were applied in the Yellow River Basin, and the results showed that these methods are suitable to the basin, and could be used to analyze its spatial-temporal distribution of the highland ecological and environmental water requirements. 3. The previous theory and computing methods of the ecological and environmental water requirements of river channel were summarized and appraised. The ecological base flow, water requirement for pollutant self-purification, water requirement for sand transportation and the flow requirement to the Bohai Sea were mainly studied according to the river characters and major ecological function of the Yellow River Basin. Finally, the computing methods suitable for applying in the basin were proposed by the author 4. To solve the problem that the ecological and environmental water requirements of river channel were calculated repeatedly among the different water resources districts, the Section Control Method were brought forward by the author to calculate the contribution of every water resources district to the ecological and environmental water requirements of river channel of the Yellow River Basin. Thus the ecological and environmental water requirements of every water resources district could be calculated based on results of water requirements of highland and river channel. The comprehensive calculation of the ecological and environmental gross water requirements of highland and river channel has been studied, and the calculation principles have been put forward. According to the principles, the calculation model has been established in the paper. 5. The method to estimating the ecological and environmental water requirements for water resources...