Sediment management will continue to be an issue for hydropower facilities, as well as other infrastructure, in the Kaligandaki basin due to its geologic and climatic setting. However, watershed management can provide a useful mechanism to control excess erosion and sedimentation from anthropogenic activities, which can increase operation and maintenance costs and reduce the useful life of the facility. Understanding the major sediment sources and different strategies to mitigate these are critical for planning a catchment management program that addresses these problems in an integrated way.
The study illustrated by this e-book demonstrates the important role that hydrologic modeling and scenarios analyses can play in identifying and prioritizing the most cost-effective areas to invest in sediment control measures. The SWAT hydrologic model allowed for a characterization of the areas of high sediment load across the basin, and also highlighted the need for better sediment monitoring to refine this understanding. The analysis of land management options and modeling of their potential impacts allowed for identification of the most effective areas for sediment management, as well as the areas where non-structural land management is not likely to be a cost-effective option. The vulnerability analysis of mitigated versus unmitigated road construction helped to map the areas where the greatest attention should be paid to proper engineering and enforcement of new road construction practices.
| CAT | Catchment area treatment |
| DEM | Digital elevation model |
| DHM | Department of Hydrology and Meteorology |
| DoI | Department of Irrigation |
| HRU | Hydrologic response unit, used in watershed modeling |
| InVEST | Integrated Valuation of Ecosystem Services and Tradeoffs, a modeling software suite |
| IWMI | International Water Management Institute |
| LULC | Land use and land cover |
| NEA | Nepal Electricity Authority |
| SALT | Sloping land agricultural technologies |
| SDR | Sediment Delivery Ratio model, part of the InVEST software suite |
| SWAT | Soil and Water Assessment Tool, a watershed hydrologic model |
| USLE | Universal Soil Loss Equation |
| VDC | Village Development Committee |
This e-book was produced by Urvashi Narain, Kavita Macleod, Csaba Boros, and Hrishi Patel from the World Bank, with input from Adrian L. Vogl and Stacie Wolny from the Natural Capital Project.
This report underlying this e-book was prepared by a core team composed of Adrian L. Vogl, Stacie Wolny, and Phil Hartger from the Natural Capital Project, Pennan Chinnasamy and Aditya Sood from the International Water Management Institute, and Urvashi Narain, Zhiyun Jiang, Annu Rajbhandari and Kavita Macleod from the World Bank. Contributions were also received from Durga Prasad Sangraula and Dinesh Lamichhane from the Institute of Engineering, Pulchowk Campus.
The team is very grateful for the support and overall guidance of Madhav Belbase, Joint Secretary, Water and Energy Commission Secretariat (WECS), Ministry of Energy, Government of Nepal, and Har Raj Neupane, Project Coordinator, Kaligandaki “A” Rehabilitation Project, Nepal Electricity Authority. The team also thanks Annette Dixon (Regional Vice President, World Bank), Qimiao Fan (Nepal Country Director, World Bank), Takuya Kamata (Nepal Country Manager, World Bank), Karin Kemper (Senior Director, World Bank), Julia Bucknall (Director, World Bank) and Kseniya Lvovsky (Practice Manager, World Bank) for their encouragement and support.
The team would like to extend special thanks to the many experts and stakeholders who provided assistance with data and knowledge of local conditions and who attended stakeholder consultation meetings in March and September 2016 in Kathmandu. These include staff from theNepal Electricity Authority (NEA), the Department of Roads (North-South Kaligandaki Highway), the Department of Hydrology and Meteorology, the Ministry of Land Reform and Management, the Water and Energy Commission Secretariat, the Department of Electricity Development, the Department of Soil Conservation and Watershed Management, the District Soil Conservation Office, Syanjha District, the World Wildlife Fund – Nepal, the World Bank – Nepal, and the Institute of Engineering, Pulchowk Campus. The team also thanks Raj Bista, Arjun Kandel, Prahlad Raut and Pashupati Gautam of NEA for their valuable support during field visits.
The team gratefully acknowledges the financial support provided for this report by the South Asia Water Initiative (SAWI) – a partnership between the World Bank and the governments of United Kingdom, Australia and Norway, and the Korean Green Growth Trust Fund (KGGTF) of the World Bank. SAWI works to improve the management of the major Himalayan river systems of South Asia for sustainable, fair and inclusive development, and climate resilience.