Impact of climate change on water resources in South Sikkim, India

The Intergovernmental Panel on Climate Change (IPCC) estimates that the global mean temperature has increased by 0.6 ± 0.2⁰C since 1861 and predicts an increase of 2 to 4⁰ C over the next 100 years. The direct effect of climate change on groundwater resources depends on the variation in the volume and distribution of groundwater and its recharge. Ingty and Bawa (2012) have summarized the detailed observation of climate change and its impact on biodiversity and natural resources in the Lachen valley, Sikkim using weather-based indicator of climate change like lesser snowfall, shifts in seasonal timing, uneven rainfall, accelerated glacial melt, and drying of water sources. South Sikkim is the most drought-prone area of the state and this is worst hit district by climate change. In Sikkim, more than three-fourths people feel that the water resources are drying up and out of them 60.2% believe that there is less snow at present time rather than the past. The subsurface aquifers are mainly recharged by precipitation or through the interaction of surface water bodies like lakes, glaciers, streams and rivers. But due to the effect of climate change the rate of precipitation and snow cover melting, the water scarcity problem had started. According to Indian Meteorological Department (Namthang AWS, South Sikkim), the annual precipitation has decreased from 2533 mm to 1503 mm. Spring is the main source of water in South Sikkim and most of the spring have become seasonal or dried. The average spring discharge data in the year 2000 was 100.18 l/m and after ten years it decreased by 26.12 l/m. With the decrease in precipitation and spring discharge, the agriculture productivity also get affected and it affect the socio-economic condition of South district. This study looks into various factors impacting the discharge at springs highlighting the effect of climate change induced precipitation pattern and land cover dynamics using SLURP (Semi-distributed Land Use based Runoff Processes).