Study On The Changes Of Spatial Pattern And The Regulations Of Ecological Water Demand In Momoge Wetlands

Wetlands play an important role in local climate regulation, living environment improvement, pollution purification, runoff regulation, and it is a crucial support for the sustainable development of economy and society. However, because of the un-reasonable excavation and utilization of Momoge wetlands in recent years, lots of ecological and environmental problems emerge. It is of certain guidance and practice for wetlands restoration and rational development of natural resources to study on the changes of spatial pattern, the reason of degeneration and the control scheme of environmental water supplement in Momoge national nature reserve.Based on four multiple-temporal Landsat TM images on the same period in the year of 1988,2001,2007,2015, the landscape indexs of Momoge wetlands are extracted, which are used to analyse wetland changes. Based on 60 years of meteorological datas from 1951 to 2010, the impact of climate changes on wetlands is studied. At the end of the paper, the moderate and minimum water demand are calculated, and a control scheme of environmental water supplement at different precipitation probability is given. The main conclusions in this paper are as follows:(1) Momoge wetlands area diminished sharply between 1988 and 2007, afterwards became a little enlarging by the year of 2015. The surface area of water body has decreased, while the area of salina has grown. The wetlands diversity index decreased and the fragmentation index became larger, which indicated that the damage of the structure and function in Momoge wetlands increased, with biodiversity shrinking. The climatic factors like temperature, precipitation, evaporation and river runoff have great influence on wetlands areas. Since 1950s, climate change had a negative effect on wetlands, and then the negative effect reduced gradually. On the other hand, human activity is another driving force for wetland change, which impacts wetland greatly and directly.(2) The grey relational grade analysis model is developed in the paper, Three correlative factors that largely influence the study object are qualified.They are annual rainfall of Momoge wetland, flow volume of Nen River and Taoer River which are near the Momoge wetland. Then the three factors are applied in the GM(0, N) model to predict wetland areas. In addition, the simulation results of grey models are compared with those of multiple linear regressive model, which reveals that the modified GM(0,N) model has an advantage in a practical application.(3) According to the calculation of the paper, the moderate water demand of Momoge wetland is 9.98×108m3, the minimum water demand is 4.63×108m3. The combinations of wetness-dryness encountering among annual rainfall of Momoge wetland, flow volume of Nen River and Taoer River are analyzed, choosing four negative scenarios. The GM(0, N) model is applied to predict wetland areas of the four scenarios, the water supplement is calculated accordingly. The diversion ability of the existing projects is is limited, it is proposed that the use of flood resources should be reinforced, some diversion projects should be built to recharge Momoge wetland from Taoer River.