| A large amount of meltwater was retained as glacier meltwater continuously flowing into glacial lake, which resulted in lake area expansion and water level rising, adjusted the cycle process of melting water in glaciated zone, modified the water storage and life cycle of glacial lake, and produced far-reaching effects on hydrological processes and glacial lake outburst flood (GLOF) hazards in the glaciated regions. In this paper, we propose to estimate lake storage of different types of glacial lake classified by their hydrologic connection with their mother glaciers. Heterogeneity of glacial lake distribution and changes and its controlling factors were discussed using glacial lake inventories of 1990,2000 and 2013 in the China. Furthermore, based on Landsat TM/ETM+/OLI imagery and SRTM DEM, aerial survey topographical map and field surveyed data, this has motivated the development of empirical relationships to predict lake volume given a measurement of lake surface area obtained from satellite imagery and analyzed the meltwater retention effect by computing the increment volume of glacier-fed lake.In addition, glacial lake volume of various types, drainage basin, elevation and mountain was calculated.The results through research show that:(1) According to thesize (< 0.1 km2,0.1-1 km2 and>1 km2), glacial lake is divided into three different scales and the different scale glacial lake volume-area estimate model is developed by different lake scale. Different regional extent, lake fitting formula is significant variations and a power-exponent function relation is more suitable for large area of water gauge such as the whole of western China in glaciated zone.Fitting different scale power-exponent function relation in this paper, find that the average error is smaller, but large fluctuations and the estimates of lake volume are smaller than the actual measurement result. (2) In 2013, meltwater storage resources with glacial lake area<0.1 km2 is 10.63±0.54×109 m3, and glacial lake area>0.1 km2 and<1 km2 is 7.59±0.25×109 m3 and meltwater storage is 9.26±0.05×109 m3 with glacial lake area?0.1 km and total water storage resources is 9.26 ±0.05×109 m3for western China in glaciated zone. (3) During the past 23 years, the lake storage has expanded at an average rate of 17.9% or 0.78%/a each year. (4) Examining decades, the average expansion rate of lake storage (0.85%/a) over 1990-2000 was about 1.3 times that (0.67%/a) of 2000-2013, indicating accelerated glacier meltwater loss trends around the transition year 2000 in the Western China glaciated areas. (5) In 2013, the most abundant water reserves (15.00±0.43×109 m3 or 56.1%) and the fastest rates (1.50%/a) were the Ganges, Brahmaputra river basin (50) and the flow zone in the central Asia (5X), respectively. (6) Given the elevation, the most glacial lake was located in4300-5300 mm and the less glacial lake was situated out of 3500-5700. (7) Discrepant water storage expansion of different types of glacial lake implies contrasting signals of climate change in the Chinese. Fewer direct climatic signals can be inferred from changes of supraglacial lakes. Ice-contacting lakes characterized by the fast expansion rate (1.57%/a) depicts accelerated glacier shrinkage caused by climate warming. Non-glacier-fed lakes expansion at the rate of 0.54%/a reflect an apparent increase of precipitation in the mountains. |
PDF Full Text Request