Sustainability
of Groundwater Resources and its Indicators (Proceedings of symposium S3 held during the
Seventh IAHS Scientific Assembly at Foz do Iguaçu, Brazil, April 2005). IAHS
Publ. 302, 2006, 67-77.
Fluxes, numerical models and sustainability of
groundwater resources
Maciek W. Lubczynski
ITC, International Institute for Geoinformation Science and Earth Observation, PO Box 6, Enschede 7500 AA, The Netherlands
Abstract Management of groundwater resources in a sustainable manner requires understanding of hydrological processes in space and time. Therefore the spatio-temporal complexity of subsurface fluxes is discussed with regard to their use in numerical models and their importance in judgement of sustainability. Sustainability of groundwater resources depends on two types of constraints: anthropogenic, resulting from human impact, and hydrogeological. Four hydrogeological constraints of sustainability: net recharge, aquifer storage, aquifer transmissivity and groundwater quality are important in groundwater management. The most important is the net recharge which represents the difference between recharge and groundwater evapotranspiration. In arid and semiarid areas, recharge and groundwater evapotranspiration are largely spatially and temporally dependent. In such conditions sustainability of groundwater resources can only be well evaluated by fully-transient models i.e. with spatio-temporally variable fluxes defined on the basis of long-term monitoring data. The standard management of aquifer storage can be undertaken successfully by using partially-transient models based on model calibration with excessive pumping abstraction and related drawdowns. Two, modelling studies from Spain (fully transient model of Sardon area) and Botswana (partially transient model of Serowe area) with different hydrogeological conditions and different degrees of socio-economic impact, are analysed with regard to sustainability of groundwater resources. In this analysis, the advantages but also the complexity of fully-transient models with spatio-temporally variable fluxes are emphasized and compared.
Key words
fluxes;
groundwater; numerical models; vulnerability