Effect Of Channel On Zhalong Wetland Degradation And Its Design For Wetland Restoration

The amount of water affected the formation, development, evolution and function of wetland. Lack of water was the main cause for wetland degradation. Wetland hydrology developed to a bad direction for wetland evolution was the primary cause of wetland degradation.Channels led to wetland degradation by influencing the hydrological pattern, water amount and so on. Recently, a lot of channels were built in Zhalong, which led to wetland drought and degradation. We wanted to take proper measurements to restore the degraded wetland according to the specific situation in Zhalong. However, the mechanism of the degradation was not very clear, which resulted in the lack of the scientific backing for the design of ecological restoration program. Thus, our object was to verify the effect mechanism of channels on wetland degradation, then design an effective program for wetland restoration. The domestic and foreign research progress was understood, the channel types were investigated, and the channel distribution in time and space was studied according to topographic map of1980. TM remote sensing image of1999, SPOT4remote sensing image and actual survey. Mann-Keddall time series analysis method and Mutations inspection method were used to analyze stream flow time series trends and point mutations in each hydrological station, and Frequency statistic method was used for degree of stream change. Based on these methods, the durations and frequency of wet and dry season in each hydrological station were analyzed statistically and the ratios of average flow in wet and dry season to mean annual runoff were calculated. The coefficient of uniformity Cy was used to describe the uneven runoff allocation within a year. Pearson Correlation Coefficient was used to analysis the relation between the input water amount in Zhalong Wetland and the surface area of water in the end of every year in recent5decades. Finally, we clarified the effect of runoff change on the area of wetland."3S" technologies and Landscape changes analysis software was used to analyze Fragmentation index and the amount of patches of wetland landscape in different years. Changes of water surface area, biodiversity and microtopgraphy in wetland were acquired from documents and literature. Researches such as channel distribution, the effect of channels on wetland hydrological connectivity, stream distribution, and coming water paths, and its ecological effect, we suggested that the key reason for Zhalong Wetland degradation was the lack of water due to the separation of channels. Then, a restoration on water supplement was designed according to the reason for degradation. First, the topographic map and remote sensing images of Zhalong Wetland was analyzed by computer and persons, meanwhile, hydrological distribution laws, separation of large hydraulic project and channels, distribution of plants and characteristics of birds’ habitat were took into account. According to that, Zhalong Wetland was separated into many relatively independent filling water units. Second. resource of replenishment water and replenishment points were determined by surveying the water resource in each water replenishment units. and according to many principles including using original hydraulic structure.choosing the shortest replenishment paths, and being easy to management. Third, according to the water level monitoring data in Zhalong Wetland and hydrographic stations, the amount of replenishment water and replenishment points were determined. At last, following the hydrological laws and previous water replenishment experience, the water replenishment patterns was determined.The results of this study would enrich the basic theories of Hydrology, Wetland Science and Ecology, which provides a scientific backing to Local government department for wetland restoration. It is significantly meaningful for theory and practice relating to wetland research.