Contents preface (VII) introduction 1—37

14
PLANNING OF WATER RESOURCE
PROJECTS
14.1. GENERAL
The main aim of all water resource development is to improve the economic and environmental conditions for human living. A water resource project may serve one or more purposes and, accordingly, can be either single-purpose or multipurpose. In most cases, a project would be of a dual or multipurpose type. As such, the entire project needs to be investigated as a unit before the design requirement of a single component, such as a dam, can be finalised. A water resource project may serve one or more of the following purposes:
(i) Irrigation,
(ii) Power development, (iii) Flood control,

(iv) Industrial water supply,

(v) Domestic and municipal water supply, (vi) Recreation,

(vii) Fish and wild life preservation and promotion, and (viii) Navigation.

In almost every water resource project, dam and reservoir are key components of the project. Dams impound water, divert water from a stream, or raise the water level. In exceptional cases, dams may be constructed to impound water-borne sediments and water having a damaging chemical quality. Dams contribute immensely in reducing poverty and impacts of floods and droughts besides rejuvenating rivers in dry season. Dams also enable recharge of ground water and growth of more biomass. A reservoir is a fresh-water body created or enlarged by the building of dams, barriers or excavations (1).
It is seldom that a water resource project consists of only a dam and reservoir facility. In a flood control project, levees and other channel control works, besides the dam and reservoir, are usually desirable. Water resource projects for power development and water supply (for irrigation, domestic, municipal, and industrial purposes) have a combination of project components to accomplish the desired objectives. Therefore, dams must be planned, designed, and constructed to operate efficiently and harmoniously with other components of the project to achieve maximum benefits at minimum cost. The economic, environmental and social feasibilities, and justification of dam must be examined in combination with those of other project components, and the total project must be evaluated and judged for its feasibility. If the evaluation of a project proposal does not show justification for its construction, it may be