Abstract: Snowcover coverage, snowcover depth and snowmelt water volume of the Kumalake River basin were calculated using EOS/MODIS satellite data form June to September of 2002-2008. The paper also analyses the following three aspects with meteorological and hydrological stations data: first, the relationship between the change of snow cap and meteorological factors during snowmelt periods in 2002-2008; second, 15 effective temporal intervals of maximum temperature during the period of flood peak of 1990-2008; third, effective temporal intervals influenced by 12 hours precipitation. In the 7 flood peaks (2002-2008), 4 of them are type of snowmelt dominance (2003, 2006, 2007, and 2008) and 2 of them are type of snowmelt secondary dominance (2002, 2005). In the flood peaks of 2002 and 2005, precipitation is the dominant factor in 2002 while snowmelt is the dominant factor in 2005. Based on former analysis, following results were obtained: Firstly, snowmelt is the dominant factor in flood peaks during 2002-2008. When the snow cap in the mountain area was over 0.55 billion m3 and the height of 0 ℃ layer raised up to 4 500 m for more than 4 days, the snowmelt water from Kumalake River Basin reached up to 0.18-1.03 billion m3. The change of 0 ℃ level height of the Kumalake River Basin in summer indicates snowmelt flood well; Secondly, the snowmelt water of real snowcover in Kumalake River Basin in 2002-2008 reached up to 9.88×108 t, and the maximum possible snowmelt water was less than 11.18 ×108 t on hypothesis that all of the snowcover in the Kumalake River Basin was melted. The theoretically maximum possible snowmelt water was 17.55 ×108 t in this historical period. The snowwater equivalent produced by all of snowcover was melted was less than 17.75×108 t. The estimation of snowmelt water equivalent obtained from actually observed data and theoretical calculation can supply the support for estimating the maximum flood amounts due to snowcover melt in this mountain area.

Key words: MODIS, remote sensing, snowfall, snowmelt, Kumalake River