14.6.3. Pre-construction Investigations The final adoption of provisionally selected project site and its size and functions begins after the project has been approved and funded for construction. It is essential that final designs consider any new information which might have been obtained or received during the time interval between feasibility investigation and the final design. For example, an extreme low runoff season or a flood of large magnitude might have occurred during this intervening period and this may necessitate changes in the estimates of the critical dry year project water supplies or of the frequency of occurrence of a flood of given magnitude.
For pre-construction planning, more detailed and accurate topographic maps and additional geological investigations are usually necessary to reduce uncertainties about foundation conditions and construction material. This is also true of other basic data needed for planning of dams and reservoirs.
