Sensitivity Analysis of the Regulation Study of a Reservoir Enlargement

The objective of this work is to quantify the influence of the main input variables in the regulation study of a water resources system, through a sensitivity analysis, in the particular case of the enlargement of a reservoir.

When valuing the utility of a new hydraulic infrastructure, for example a reservoir or its enlargement, it is usual to study the increase in water supply guarantee that it would achieve in the water demands of the exploitation system. For this, a regulation study is carried out where a wide data set must be introduced. A part of such data is subject to uncertainty: water contributions, urban and agricultural demands, siltation and evaporation in reservoirs, leaks in channels...

Sensitivity analysis, very common in financial economics, tries to set different future scenarios (optimistic, realistic or pessimistic) instead of a single future scenario, to study the influence of each type of data on the results and make decisions with a better perspective of the risks that are assumed and the probabilities of success.

Thus, this paper will analyze the effect on the water supply guarantee of the modification of the data subject to uncertainty, setting various study scenarios. Special attention will be paid to the uncertainties introduced by climate change on water contributions in the rivers and on evaporation in the reservoirs. Likewise, demand management measures to reduce the demands of water by means of the reduction of leaks in the water transport channels or by increasing the efficiency of the harvesting systems, both urban and agricultural, will be analyzed.

A basic "test" case is developed, and, as an example of application, a complete sensitivity analysis will be carried out from a real regulation study, in order to detect which data have a greater influence on supply guarantees.

The AQUATOOL computer tool is used, a development environment for Decision Support Systems (SSD) for watershed planning and management of water resource systems. In particular, SIMGES module is used, a general simulation model for river basin or complex water resources systems management.