SATELLITE BASED SNOW COVER AREA MAPPING OVER NORTH WESTERN HIMALAYA
Assessment of Long-Term and Current Status (2016-17) of Snow Cover Area (SCA) in North Western Himalayan (NWH) River Basins using Remote Sensing:
During winter season of 2016-17, heavy snowfall has been recorded in many part of NWH. As per the reports appearing in various national and local agencies and media, anomalous temperature and high snowfall in early spring season in entire NWH has broken last 30 years records at many places. This triggered the present study of assessing the status of SCA in NWH region and comparing it with last 15 years records.
Space based remote sensing has proven capability of mapping and monitoring SCA with high temporal and spatial resolution. Hence, in the present study 8-day Snow cover product from MODIS (MOD10A2) were used to analyse the current and past 15 years SCA status at sub-basin scale in the NWH region. Fraction snow cover is estimated as long-term (2001-2017) temporal SCA of all the NWH sub-basins and SCA of year 2016-17 has been compared with long-term mean SCA of each basin for respective time period.
Main Highlights of this study:
- Maximum SCA as percentage of total basin area for Upper Indus, Lower Indus, Gilgit, Sulmar, Jhelum, Chenab, Shyok, Shaksgam, and upper part of Sutlaj, Beas and Ganga sub-basins estimated to be in the range of 75 to 95% during winter season of 2016-17.
- Maximum SCA in Upper Ganga, Beas, Chenab and Jhelum sub-basins is observed in 2nd week of January 2017. However, in the sub-basins located in higher latitudes viz. Upper Sutlaj, Lower Indus, Shyok, Sulmar sub-basins maximum SCA is observed in 2nd week of February 2017 and Gilgit & Shaksgam sub-basins in 3rd week of February 2017.
- The maximum SCA observed for year 2017 in all these sub-basins is approximately 10 to 50% higher as compared to SCA of same time period in 2016.
- NWH region has also received one of the highest snowfall deposits in early March of 2017 with average 8% higher SCA as compared to previous year.
- The ground observed data from field instruments installed by IIRS in Beas basin reveals an increase in snow depth at these locations in the order of 1 to 1.5 m during January to March of 2017, as compared to same time period of year 2016.
Possible Implications & Further study areas
It is expected that, the increased SCA, snow depth will produce higher snow melt/discharge during upcoming spring and summer season in these sub-basins.
- On the benefits: Enhanced Hydro-power generation, reservoir storage and irrigation projects - possibilities with a proper planning.
- On the Concerns: Hydrological disasters due to heavy snowfall leading to higher SCA in spring season increases the probability of flash floods, landslide, sudden increase in river flow and associated hazards.
- Further study: These aspects can be studied in detail with the help of suitable hydrological models if hydro-meteorological data, snow depth, snow water equivalent, snow density, baseline topographical data, location of water resources projects, etc., of NWH region are made available.
Detailed Report of this study is available at: Download PDF