Contents preface (VII) introduction 1—37

14.5. SELECTION OF A PROJECT PLAN
Planning may be defined as the systematic consideration of a project from the original statement of purpose through the evaluation of alternatives to the final decision on a course of action. Planning of water resource project begins with some definite idea about its main purpose. It is usually economical to have a multipurpose rather than a single-purpose project. From economic considerations, the best project plan is the one for which the ratio of combined project benefits

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and the total project cost is maximum. The time required to construct a dam and then to first fill the reservoir before the start of the project operation is usually very large (several years) and, hence, the interest on the investment up to the start of the project operation should also be added to the investment costs. The cost of a dam and other major project features and also the benefits for at least three different sizes (the smallest, the largest and an intermediate) of the project are worked out. Using these computations, size-benefit and size-cost curves for different possible functions are prepared. A proper analysis of all this information would yield the size and functions of the project which would result in maximum benefit-cost ratio.
Generally, the needs for water services, power, and flood control in any given region continue to grow due to the increasing population. Therefore, it appears to be uneconomical to build large and costly projects far in advance of their needs. As such, physical and design conditions permitting, a project can also be constructed in stages. Because of the growing concern for environmental conditions, it is essential to take into account the environmental effects of alternative plans. Usually, there is an improvement in the environmental conditions due to the availability of water service and flood protection facilities. However, there are some adverse environmental effects of water resource projects which affect (i) scenic beauty, and (ii) wildlife (both land and aquatic species). These effects, however, cannot be measured. A planner can, therefore, only select an alternative with more favourable or less unfavourable effects.
In making a choice of suitable alternatives, some kind of compromise is always made. These compromises may be in the form of fixing stream flows, acquisition of land to be used as wildlife tracts, siting project features to the advantage of scenic views, and providing access to areas having enjoyment potential. The following method (1) is suggested for this purpose.
Alternative plans of the proposed water resource project, having different amounts of environmental impact but accomplishing other objectives of the project, are prepared. The first step would be to make an inventory of the existing conditions of various important environmental qualities of the water resource system under consideration. These environmental factors may be ranked in order of their importance. The second step in the preparation of alternative plans would be to estimate the future environmental conditions without the project development. These conditions may be the same as the existing ones, or may be degraded or improved. The third step would be to prepare an ‘‘optimum economic water resource project plan alternative’’ without considering environmental impacts except those which are positively controlling environmental impacts. Similarly, an ‘‘optimum environmental water resource project plan alternative’’ would be prepared wherein an attempt would be made to minimise all adverse environmental impacts and still achieve some of the project objectives. If the second alternative results in significantly reduced accomplishments of the project objectives or greatly increased cost compared to that of the first alternative, the second alternative is discarded in favour of a third alternative plan. The third alternative plan would be so prepared that it would reflect a compromise between the two extreme alternatives and seek to avoid or minimise the important adverse environmental impacts while accomplishing all or most of the project objectives of the first alternative.

The role of the planner of a water resource project is to select the best of all possible alternatives. Various methods of optimization, collectively called systems analysis, are, therefore, obvious tools for this purpose. Because of large number of constraints involved, one has to often make several simplifying assumptions in order to obtain the best possible alternative. Besides, deficiencies of the input data will make determination of the true optimum a difficult task. Nevertheless, systems analysis is still the best method of determining the best possible alternative out of several feasible alternatives.

PLANNING OF WATER RESOURCE PROJECTS