Seite - 643 - in Book of Full Papers - Symposium Hydro Engineering

term economic performance of the scheme. Furthermore, the dam owner and operator does not wish the accumulation of sediments in the reservoir, especially since it believes that consolidated sediments would produce H2S, a detriment to the drinking water quality of the reservoir water. Numerical simulation indicated that if no sediment management measures are implemented, the reservoir storage will be depleted within approximately 50 years, i.e. the reservoir is non-sustainable. Several sediment management approaches have been developed for handling sedimentation [1], [2]. A preliminary assessment presented below indicated that almost all sediment management techniques can potentially convert the non-sustainable Moragolla reservoir into a sustainable infrastructure for the future generations. The conclusion is however rather generic, since the identification of the best suitable management strategy depends on several other boundary conditions and project development priorities. Fig. 1 Preliminary assessment of sediment management options for Moragolla reservoir (Source of underlying nomograph: [3]) For example, an important constraint is imposed by the fact that in the mid to upper reaches of Mahaweli River lives a fish called Labeo Fisheri which has been put on the IUCN Red List of Threatened Species. Therefore, any risk in terms of too high sediment concentrations that would endanger the habitat of the above- mentioned fish species are rendered as not acceptable. The objective of the paper is the presentation of the rapid screening for the available state-of-the-art sediment management techniques with purpose of the selection and specification of the optimum solution considering the necessary tailoring onto the project specific boundary conditions. 2. THE MORAGOLLA HPP PROJECT The envisaged Moragolla Hydropower project will be located in the central Highlands of Sri Lanka, approximately 22 km south of the city of Kandy and 130 0.1 1.0 10.0 100.0 1000.0 10000.0 100000.0 0.0001 0.001 0.01 0.1 1 10 Moragola Moragola CAP million m³ 4.66 MAF million m³/a 706 MAS million m³/a 0.17 CAP/MAF [years] 0.01 CAP/MAS [years] 27.4 643