Tasks for planning a water resources project

The important tasks for preparing a planning report of a water resources project would include the following:

•         Analysis of basic data like maps, remote sensing images, geological data, hydrologic data, and requirement of water use data, etc.

•         Selection of alternative sites based on economic aspects generally, but keeping in mind environmental degradation aspects.

•         Studies for dam, reservoir, diversion structure, conveyance structure, etc.

o   Selection of capacity.

o   Selection of type of dam and spillway.

o   Layout of structures.

o   Analysis of foundation of structures.

o   Development of construction plan.

o   Cost estimates of structures, foundation strengthening measures, etc.

•         Studies for local protective works – levees, riverbank revetment, etc.

•         Formulation of optimal combination of structural and non-structural components (for projects with flood control component).

•         Economic and financial analyses, taking into account environmental degradation, if any, as a cost.

•         Environmental and sociological impact assessment.

Of the tasks mentioned above, the first five shall be dealt with in detail in this course. However, we may mention briefly the last two before closing this chapter.

Engineering economy in water resources planning

All Water Resources projects have to be cost evaluated. This is an essential part of planning. Since, generally, such projects would be funded by the respective State Governments, in which the project would be coming up it would be helpful for the State planners to collect the desired amount of money, like by issuing bonds to the public, taking loans from a bank, etc. Since a project involves money, it is essential that the minimum amount is spent, under the given constraints of project construction. Hence, a few feasible alternatives for a project are usually worked out. For example, a project involving a storage dam has to be located on a map of the river valley at more than one possible location, if the terrain permits. In this instance, the dam would generally be located at the narrowest part of the river valley to reduce cost of dam construction, but also a couple of more alternatives would be selected since there would be other features of a dam whose cost would dictate the total cost of the project. For example, the foundation could be weak for the first alternative and consequently require costly found treatment, raising thereby the total project cost. At times, a economically lucrative project site may be causing submergence of a costly property, say an industry, whose relocation cost would offset the benefit of the alternative. On the other hand, the beneficial returns may also vary. For example, the volume of water stored behind a dam for one alternative of layout may not be the same as that behind another. Hence, what is required is to evaluate the socalled Benefit-Cost Ratio defined as below:

The annual cost and benefits are worked out as under.

Annual Cost (C): The investment for a project is done in the initial years during construction and then on operation and maintenance during the project's lifetime. The initial cost may be met by certain sources like borrowing, etc. but has to be repaid over a certain number of years, usually with an interest, to the lender. This is called the Annual Recovery Cost, which, together with the yearly maintenance cost would give the total Annual Costs. It must be noted that there are many nontangible costs, which arise due to the effect of the project on the environment that has to be quantified properly and included in the annual costs.

Assessment of effect on environment and society

This is a very important issue and all projects need to have clearance from the Ministry of Environment and Forests on aspects of impact that the project is likely to have on the environment as well as on the social fabric. Some of the adverse (negative) impacts, for which steps have to be taken, are as follows:

•         Loss of flora and fauna due to submergence.

•         Loss of land having agricultural, residential, industrial, religious, archaeological importance.

•         Rehabilitation of displaced persons.

•         Reservoir induced seismicity.

•         Ill-effect on riverine habitats of fish due to blockage of the free river passage

There would also be some beneficial (positive) impacts of the project, like improvement of public health due to availability of assured, clean and safe drinking water, assured agricultural production, etc. There could even be an improvement in the micro-climate of the region due to the presence of a water body.