Non-renewable groundwater resources: a ... - unesdoc - Unesco

Guidelines■ Groundwater resources whose replenishment takes very long in relation to the time-frameof human activity are conveniently termed ‘non-renewable groundwater resources’ – andthe volume of such groundwater stored in some aquifers can be huge. In these cases oneis usually dealing with ‘fossil (or palaeo) groundwater’, recharged in past, more humid,climatic regimes, but not all aquifer systems containing fossil groundwater are non-renewable.■ Development of non-renewable groundwater resources implies the ‘mining of aquiferstorage reserves’, and as such takes on particular social, economic and political sensitivities.But especially in many of the world’s more arid regions, the use of non-renewable groundwateroffers an opportunity to alleviate growing water scarcity, improve social welfare andfacilitate economic development. To constrain resource utilisation on grounds of not being‘physically sustainable’ in the long-term is simplistic and insufficient, since such developmentcan (and should) be considered socially-sustainable if certain criteria can be met and specificrisks can be managed.■ To meet the requirement of ‘social sustainability’ in respect of development of the nonrenewablegroundwater resource, the following criteria need to be addressed :• it should lead to clear improvements in social well-being and livelihoods;• the balance between short-term socio-economic benefits and longer-term ‘negativeimpacts’ must be positive;• an ‘exit strategy’ should exist, with an answer to the question ‘what comes after theaquifer becomes seriously depleted’;• the issue of inter-generational equity has to be considered.■ Concomitantly, it should be recognised that predicting the longer-term evolution of anygiven case of groundwater mining will be subject to significant uncertainty (as a result ofincomplete hydrogeological understanding, innovations in water technology, changingglobal agriculture and food markets, accelerated climate change, etc), which places limits onconventional resource management. This dictates the need to incorporate more flexible andadaptive risk-based approaches, which need to find political acceptance.■ In practice the utilisation of non-renewable groundwater tends to occur in two scenarios :• ‘planned aquifer depletion’ – whose management goal is orderly utilization of aquiferreserves (of a system with little pre-existing development) with expected benefits andpredicted impacts over a specified time-frame;• ‘excessive unplanned exploitation’ – with incidental depletion of aquifer reserves as aresult of intensive groundwater abstraction in areas with limited contemporary recharge.59