MMHPP is one of the hydropower projects located in Marsyangdi River (Nepal). The reservoir has been suffering from severe sedimentation problems since its commissioning. The reservoir has already lost more than half of its storage capacity in less than four years of exploitation. There could be several reasons for this problem among which the most obvious one is the ignorance of large and meso-scale morphological feature of the river while selecting the site. The reservoir planform does not appear to be appropriate from the geomorphological point of view. With the help of a morphological model, namely Delft3D Flexible Mesh (D-FM) coupled with Real-Time Control tool (to simulate reservoir gate operation), we have replicated sedimentation process at the reservoir. Given a first modelling exercise of such complexity using D-FM, the result can be regarded as rather satisfactory. The overestimation by the model can be improved by calibrating the flow and sediment transport parameters in case more data is available. The result shows consistent model behaviour and observed trend (see Figure below as one of the examples).
This computation is a part of the work, titled “Significance of geomorphological processes for safety and sustainability of water infrastructures”, presented at International Symposium on River Sedimentation, Chengdu, China (16-20 September 2019).
Figure: Comparing observed (left) and simulated (right) sedimentation of the reservoir
The animation of one of the simulated cases can be found here
