Abstract:
This research paper proposes a new five-step protocol to enhance
the result of existing cloud removal algorithms using Moderate
Resolution Imaging Spectroradiometer (MODIS) daily snow cover
products (SCPs). The study has been carried out for the upper
Bhagirathi basin (up to Maneri Hydropower Project) located in the
Western Himalaya. Gafurov and B ardossy test employed to validate
the performance of the proposed method, followed by comparing
with the field observed snow cover duration (SCD) data.
The result shows that the mean overall accuracy of the proposed
method for cloud removal is about 95%. However, the cloud
removal method by Gafurov and Bardossy also achieved similar
mean overall accuracy but with the higher variability within the
individual images as compared with the variability within the
results obtained by the proposed method. SCD computed from
cloud removed SCPs matched significantly with the field observed
SCD for a point location, supporting the accuracy achieved by the
cloud removal method. This study also examines the spatiotemporal
variability of the snow cover in the study area during the
past 18 years (2000–2018). During the observation period, no specific
trend was observed for annual maximum snow cover, while
yearly minimum snow cover in the basin showed an increasing
trend since 2010. Seasonally, December and June month witnessed
significant changes. December experienced a declining
trend in snow cover between 3000–6000m a.s.l. covering 88% of
the basin area, whereas, June showed an increasing trend
between 4500 to 6000m (a.s.l.). This elevation range covers 61%
of the basin area, including core 86% of the glacier area within
the basin. September and October experienced the highest interannual
snow cover variability. Maximum snow cover month of
February and minimum snow cover month of August experienced
the least variability. The present study suggests significant elevation-
dependent increasing as well as the decreasing trend in the
snow cover with seasonal contrast, which may affect the glaciers
as well as the hydrological behavior of the basin.
