Assessment of freshwater scarcity using a model based on supply and demand law

Abstract

The main goal of this work is to provide an analysis methodology for assessment of water scarcity problems based on supply and demand. To this end, we must first determine what can be considered as supply and demand in the water scarcity problem. Although some variables involved are physical, economical or demographical, in our approach social factors are also included. This leads us to objectify water demand standards in relation to acceptable welfare levels. Within this approach, water scarcity will appear when demand reaches a higher value than supply. Two supply levels are defined based on other works. Demand is calculated within several scenarios. These scenarios represent the outcome of political or management decisions taken to reach a welfare standard. A special scenario will represent, simply, the continuation of the current state of affairs. The variables needed to calculate demand are obtained through a multilevel model where the lowest level is formed by disciplinary models and the highest level takes into account social and political factors. The methodology is applied to the countries of the gulf of Guinea. Its application to Côte d’Ivoire is described in detail and results are given for the other eight countries of the area. To summarize the results, two indexes are suggested. With this methodology, it is possible to divide the region of the gulf of Guinea in three areas of different freshwater capacity, giving new insight with regards previous studies that did not state differences between the countries of the region.