ASSESSING GLOBAL WATER SCARCITY

There are currently several methods used to calculate water scarcity on a per-country basis. Some of the methods consider only physical water scarcity based on per capita availability or percent of available water currently used, while others include economic factors. As global population increases and water scarcity becomes a more pressing political issue, the importance of appropriate and accurate methods to calculate water scarcity will become critical.

In this study, a global, country-based, water scarcity database was constructed within a geographic information system (GIS) from data available from various reputable scientific agencies and organizations. The database includes estimates of the physical factors that determine water availability (including surface and ground water resources) as well as economic (i.e., gross domestic product) and demographic (i.e., population) indicators that may influence access and use of water. While many studies have looked at new ways to calculate water scarcity, no studies have quantitatively compared the different, commonly employed techniques for assessing water scarcity. The GIS framework allowed for a visual as well as quantitative comparison of these various techniques and rapid identification of areas of agreement and disagreement among the different methods.

Although for most countries there was agreement among the different water scarcity assessments, in some countries, like many in Central Africa, there were conflicting results in which a country was considered scarce by some techniques and not scarce by others. These inconsistencies have potentially serious policy implications as water scarcity assessments often influence food aid and economic allocations from international organizations and agencies. The efficacy of determining the appropriate indicators for water scarcity is thus extremely important. This study identified those areas where discrepancies among the various techniques existed and then considered the potential policy implications that a country's scarcity designation might have.