| Water resource shortage and eco-environment degeneration has become one of the most serious problems in the world. It is important to rationally manage the limited water resource and protect the ecosystem in the wetland, for wetland is the multi-purpose ecosystem with eco-benefit and utilization value. This paper presents a case study on the relationship between eco-environment and water in Zhalong wetland. The result from this study can be summarized as follows:(1) The eco-environmental functions and the negative changes of Zhalong Wetland are analyzed according to the relevant data and the result of field survey. Wetland cover change and the fragmentation of wetland patches are analyzed by remote sensing in 1986-2002. Finally, the restoration measures of the wetland are put forward.(2) The methods of the Kendall's rank verification, etc, are used to analyze characteristics of the climate and water cycle factors in Zhalong Wetland in recent 40 years. The evaporation model coupled with monthly maximum temperature, minimum temperature, humidity and wind speed at 2 meter height is established. The reason that the annual average evaporation shows degressive tendency with increasing of average temperature, is explained by the model. The wetland degradation reasons include two sides: human activity and regional climate change. The wetland degradation reason is supposed by analyzing the change trend of the region climate and water cycle factors. Although average temperature shows significant increasing trend, the annual average evaporation shows significant degressive trend, the humidity shows significant increasing trend, and the precipitation, runoff have no evident change. The change trends above mentioned are helpful to Zhalong Wetland, therefore the climate change has no negative influence to the study site. The wetland degradation is caused by human activity: occupying water resources and destroying surface of Zhalong Wetland.(3) The concept wetland eco-environmental water requirement is presented. The eco-environmental water requirement can be divided into two parts: ecological water storage and ecological water consumption according to the connotation. A model for determining the eco-environmental water requirement based on ecological water area method is suggested and applied to analyze the situation in Zhalong Wetland. The ecological water area coefficient is determined according to the analysis on the amount of water area in a long time series and comparison with the health situation of the eco-system. On this basis the safety threshold of eco-environmental water requirement can be obtained in terms of three grades: minimum, medium and ideal. The monthly average minimum water storage, medium water storage and ideal water storage as well as the minimum water consumption, medium water consumption and ideal water consumption are calculated. The processes of monthly water requirements are obtained accordingly. The result shows that the variation of eco-environmental water requirement accords with the natural hydrology condition in this wetland. The calculating method of minimum and medium water consumption is proposed under different rainfall frequency.(4) The wetland water environment system is a grey system. Thus, Grey Clustering Method is applied to the evaluation of the water environment quality in the wetland, a superior evaluation system suitable for the wetland is proposed. Classification standard of water quality is based on the criterion GB 3838-2002, and pollution degree is divided into 5 levels. Moreover, whitenization weight function is used to describe the limit of water quality classification, clustering weight is calculated by reciprocal method, and finally a comprehensive grey mathematical model is presented. The model has been used to evaluate the water environment quality in Zhalong Wetland. The result indicates that the spatial-temporal water pollution is very serious in the area studied, which is caused by the mutual in teraction of water shortage, the pollutants over proof standard, and the internal pollution; while water shortage is the leading factor for the pollution.(5) Based on the analysis of healthy water cycle concept of wetland and its connotation, and the PSR (Pressure - State - Response) conceptual model of wetland healthy water cycle is proposed. Assessment indictor system of wetland healthy water cycle is established based on the model, too. The indictor system aims to explore relationships between the pressure and the wetland healthy water cycle change, and propose the corresponding improvement measures. The fuzzy pattern recognition model is applied to evaluate healthy water cycle of the wetland, and the method of calculating weighting of each indicator is analytic hierarchy process. Furthermore, the above theory and method have been applied to the case study of Zhalong Wetland to reveal their health grades and disadvantages. According to the choice principle of the indicators, the 9 indicators are selected. The five-grade assessment standard is adopted. The comparison shows that the evaluation result of this method is in accordance with the actual situation of Zhalong wetland. Finally, the measures of water resource management are proposed based on the characteristics of the water cycle in Zhalong Wetland.
|
PDF Full Text Request