Environment, Climate Change and Watershed Management
Environment, Climate Change and Watershed Management tests climate policy, adaptation and mitigation, and the hydrological reasoning behind watershed treatment. Nepal's mountain terrain makes glacial lake outburst flood, landslide and flood risk central.
Core rules and concepts
- Climate Change Policy, 2076 (2019), the National Adaptation Plan (2021-2050) and Nepal's NDC set the policy frame; Nepal has announced a net-zero target for 2045.
- Mitigation reduces greenhouse gas sources or increases sinks: forest restoration, REDD+, renewable energy and improved cookstoves. Adaptation reduces vulnerability: early warning, climate-smart agriculture, water harvesting and resilient infrastructure.
- Watershed processes include interception, infiltration, evapotranspiration, runoff and erosion. A watershed is a catchment, not just a river.
- Watershed treatment combines biological measures such as afforestation and grass strips, engineering measures such as check dams and gabions, and bioengineering such as brush layering and live check dams.
- GLOF risk requires glacial lake monitoring, early warning and downstream land-use planning.
Worked example
A 500 ha watershed receives 1,500 mm annual rainfall. Rainfall volume = 500 ha x 10,000 square metres/ha x 1.5 m = 7,500,000 cubic metres. If the runoff coefficient is 0.40, annual runoff = 0.40 x 7,500,000 = 3,000,000 cubic metres. The reasoning: convert hectares to square metres, convert rainfall to metres, multiply to get volume, then apply the runoff coefficient. The same logic is used to size a check dam or estimate water yield.
Traps
Do not confuse mitigation with adaptation. Do not treat all forests as equal carbon sinks; growth rate, age and management matter. Do not ignore GLOF and sediment in mountain watersheds. Do not reduce watershed management to building dams; biological measures are usually the first line.