Work Package 4: Morphodynamics of the Karnali River and erosion of vegetated floodplains
The objective of this work package is to understand and quantify human impact on floodplain reworking and associated vegetation cover. With this, our work aims to find hydrological links between river discharge regime, groundwater system in the national park and the tiger habitat in nature reserves in Nepal and Northern India.
The Karnali fluvial fan is one of a row of fluvial fans and megafans located at the foot of the Himalayan mountain range in what is called the Terai Arc Landscape (TAL). The presence of the abundant grassland cover in TAL river floodplains, which is indispensable for deer and therefore for tiger, used to be assured by fire, overbank flows, and river planform dynamics. However, the natural river channel migration over these fans has been largely disturbed by various human induced disturbances such as the construction of levees, channelization associated with hydropower, water offtake for irrigation, and gravel and sand mining in the river floodplain. Climate change exacerbates these pressures through, for instance, reduced average precipitation.
All these changes affect not only the river discharge regime but also the sediment flux to the fluvial fans. A river responds to such change by changing its forms like the planform configuration and channel slope. This response affects floodplain vegetation cover (grassland and forest), which in turn affects the river planform again by, for instance, increased stabilisation of the riverbanks. In this WP we will especially look at the Karnali river at Chisapani where the river splits into the western Kauriala River and eastern Geruwa River.
This Work Package is Lead by dr. ir. Astrid Blom, Delft University of Technology, Delft, the Netherlands