  In this paper we assess the snow cover and its dynamics for the western river
basins of the Indus River system and their subbasins located in Afghanistan,
China, India and Pakistan for the period 2001-2012. First, we validate the
Moderate Resolution Imaging Spectroradiometer (MODIS) daily snow products from
Terra and Aqua against the Landsat Thematic Mapper/Enhanced Thematic Mapper
plus data set, and then improve them for clouds by applying a validated non
spectral cloud removal technique. The improved snow product has been analysed
on a seasonal and annual basis against different topographic parameters
(aspect, elevation and slope). Our results show a decreasing tendency for the
annual average snow cover for the westerlies influenced basins (upper Indus
basin, Astore, Hunza, Shigar and Shyok) and an increasing tendency for the
monsoon influenced basins (Jhelum, Kabul, Swat and Gilgit). Seasonal average
snow cover decreases during winter and autumn, and increases during spring and
summer, which is consistent with the observed cooling and warming trends during
the respective seasons. Subbasins at relatively higher latitudes/altitudes show
higher variability than basins at lower latitudes/middle altitudes.
Northeastern and northwestern aspects feature greater snow cover. The mean end
of summer regional snow line altitude (SLA) zones range from 3000 to 5000 m asl
for all basins. Our analysis provides an indication of a descending end of
summer regional SLA zone for most of the studied basins, which is significant
for the Shyok and Kabul basins, thus indicating a change in their water
resources. Such results are consistent with the observed hydroclimatic data,
recently collected local perceptions and glacier mass balances for the
investigated period within the UIB. Moreover, our analysis shows a significant
correlation
