The Economics of Reservoir Sedimentation: A Case Study of Mahaweli Reservoirs in Sri Lanka

Abstract

Bene® ts of water resource projects often fall short of original expectations owing to sedim entation of reservoirs. This study estimates the cost of reservoir sedimentation in M ahaweli reservoirs including impact on hydropower production, irrigation w ater supply, extra cost of water puri® cation and loss of ® sheries yields. The present value of the cost of sed im entation is estimated to be U S$26 406 62 0. Of the different types of costs, lost hydropower production is the m ost signi® cant as it accounts for 66.6% of the total cost. The bene® ts of prevention of reservoir sedimentation alone are inadequate to com pensate for the costs involved. Using soil erosion control measures at farm level offers a better solution for reservoir sedimentation com pared with de-silting. A mong the available erosion control methods, stoned terrace is the least-cost solution to reservoir sedimentation.

Conserving reservoir water storage: An economic appraisal

“…For example, Southgate and Macke [1989] use $2.5/m 3 as a unit cost of dredging for the case of Dominica Republic. Gunatilake and Gopalakrishnan [1999] report a unit cost of desilting as high as $15/m 3 for Sri Lanka. On the other hand, Kawashima et al [2003] suggests the presence of scale economy in sediment dredging.…”

“…The economic impact of reservoir sedimentation has been mainly studied in the context of off-site benefits of watershed management. This is due to the fact that sediment that flows into the reservoir can be reduced by the introduction of soil control at the watershed level [e.g., Crowder, 1987;Veloz et al, 1985;Southgate and Macke, 1989;de Janvry et al, 1995;Wang et al, 1998;Gunatilake and Gopalakrishnan, 1999]. While watershed management only mitigates the rate of sedimentation, reservoir level sediment management, such as dredging and/or sediment flushing, allows for recovering the lost storage and for retaining its usefulness as long as possible.…”

Decision-making in soil conservation: application of a behavioral model to potato farmers in Sri Lanka

“…It is generally recognized as the most serious environmental problem in the upper watershed areas of the central mountain region in Sri Lanka (Gunatilake and Gopalakrishnan, 1999;Stocking, 1992). Past studies on the land degradation problem in Sri Lanka (see Chisholm et al, 1999) indicate the magnitude of the degradation problems in different agroecosystems.…”

Monitoring Riverbank Erosion in Mountain Catchments Using Terrestrial Laser Scanning

“…Soil erosion has several on-site and off-site impacts on the environment: (1) loss of fertile soil with important consequences on agriculture [1]; (2) silting of reservoirs that reduces the storage capacity and interferes with dam operations [2][3][4]; (3) migration of pollution in which sediment transport is considered a means of transport for contaminants [5,6]; (4) increase of flood risk [7] and debris flow events [8]; and (5) geomorphic evolution of river beds [9] with possible impacts on the surrounding structures. At the basin scale, sediment production is the result of the complex interaction between different geomorphic processes: splash erosion, sheet erosion, rill erosion, gully erosion, bank erosion as well as mass movements [10].…”