Study Of Ecllogical And Environmental Water Demand In Degenerative Wetland Of Yellow River Delta

With the reducing of water resource from Yellow River and the influence of human activity, the wetland of Yellow River Delta had degraded, such as the area of wetland shrinking, biodiversity reducing, and other serious environmental problems, which had already threatened the stabilization and sustainability of ecosystem. Because water is one of the most important factors of the wetland generation and development, the water resources must be adequate in regarded wetland recovery.The recovery area of wetland in Yellow River delta was selected as the studied area in the paper. Through field investigation and experimental analysis, the ecological effects were clarified. Using water depth data from field investigation by ERDAS and ARCGIS software, the eco-environment water requirements for wetland recovery was estimated in this paper. The conclusions are as follows:(1) Field investigation revealed that the moisture condition had progressed a lot. The wet land area had been enlarged, and the vegetation succession was going on, which brought the increase of the eco- biodiversity.(2) Remote sensing images of 2004 and 2007 were interpreted with ERDAS and ARCGIS software. The results showed that the wetland environment deteriorated in 2007 comparing that in 2004. The area of reedy, grassland, water surface and woodlands were reduced and the area of alkaline land increased. The degenerative wetland area was 1.22×10~8m~3.(3) The soil Physical and chemical indexes including soil moisture, pH, soil organic matter, the soil nitrogen and the phosphor were analysed. The soil samples were collected from the areas of different recovery term (recovery for 7years, 5years and not recovery). The results showed that soil moisture, pH, and soil organic matter in recovery area for 7 years were highest, and then in recovery area for 5 years, those in unrecovered area were lowest, which revealed that the recovery effects were obvious. But the change of soil nitrogen and the phosphor were not distinct. (4) The correlation analysis between vegetation coverage and soil moisture, soil organic matter, water depth, soil pH, the nitrogen and phosphor were analysed. The relations of vegetation coverage and soil moisture, soil organic matter, water depth, soil pH were significant. The correlation between the nitrogen and phosphor were insignificant.(5) The water requirement of degraded wetland recovery was estimated by ERDAS and ARCGIS software, using the water depth data obtained by field investigation. The water requirement of degraded wetland recovery in spring was 2.05×10~8m~3/a, and which in summer was 2.23×10~8m~3/a. According to correlation of water depth and vegetation analysis, the smallest depth of vegetation was 34cm, the proper depth of vegetation was 46cm, and the maximum depth of vegetation was 60cm. The minimum water requirement of Yellow River degenerate wetland was 2.08×10~8m~3/a, the proper water requirement of Yellow River degenerate wetland was 2.232×10~8m~3/a, and the maximum water requirement of Yellow River degenerate wetland was 2.40×10~8m~3/a.