Abstract:
Since the fully implemented of Xiaowan Reservoir in 2008,an artificial riparian zone with a vertical height of 60 m has been created.The comprehensive action of periodical submerged-exposed and storm runoff causes severe soil erosion and ecological degradation,which prone to cause the bank collapse and landslide.Understanding the spatial distribution characteristics of water level fluctuating zone (WLFZ) in Xiaowan Reservoir would provide an important prerequisite for investigation of ecological changes,which could provide guiding significance for the ecological regulation and restoration of the area.Based on GF-1 and Google Earth image data,the different counties,elevations,slopes and aspects of the riparian zone area were investigated by using ArcGIS spatial analysis function.The results showed that the total area of WLFZ in Xiaowan Reservoir is 87.03km2,with 48.46km2 in mainstream (Lancang River) and 48.46km2 in tributary (Heihui River).Three prefectures (cities) of Yunnan Province is involved,including 32.84km2 in Dali,26.65km2 in Lincang and 27.54km2 in Baoshan.Most of the WLFZs are distributed at 11901200m,12101220m and 12301240m,with the area is all over 18km2 and taking over 60% of the total.WLFZs in Xiaowan Reservoir is mainly below 35,and the area of gentle slopes at less than 15 is 26.12km2 and accounting for about 30% of total WLFZ area,which mainly distributed in the mainstream of Lancang River.WLFZ area with slope between 1535 is 43.79km2,which takes over half proportion of the total area.In conclusion,WLFZ area of flat slope,northeast,southwest slope accounting for 17.55%,13.39% and 13.20% of total WLFZ area,respectively.Meanwhile,a series of problems such as vegetation degradation,landscape diversity decrease,severe soil erosion,serious sediment deposition,frequent geological disasters,pollutants detention,fragile ecological environment arise by the formation of WLFZ in Xiaowan Reservoir.