Improvement potential of the integrated water resources management in the mining basin of Gafsa

The phosphate mining basin of Gafsa is part of the south-western dry area of Tunisia. It covers 3250 km2, representing 42% of the entire governorate of Gafsa area and 38% of its total population. The area is characterised by water resources scarcity as well as high variability of rainfall. The water demand is in continual increase due to many factors such as the industrial, agricultural and socio-economic development. The confrontation between available resources and water demand for all sectors in the phosphate basin shows that the current global balance is in surplus. Taking into account the fact that all the sectors have neither the same requirement of water quality nor the same added value of the pumped water, it seems then necessary to review the current resources allowance model in order to establish rational exploitation plans so as to face the water demand increase. In the local context of the Gafsa phosphate mining basin, the treated waste water seems to constitute potential additional water resource that should be considered to reduce the groundwater resources overexploitation.

The conventional water resources in the “mining basin” of Gafsa, are threatened on a quantitative and qualitative basis. More efforts, in terms of water use efficiency improvement in all sectors and of the mobilisation of the non-conventional resources notably treated waste water, are needed. Beyond the water resource protection, the use of treated waste water would contribute to soil and water conservation improvement and to a better ecological promotion. However, the increase of the exploitation, even in an optimised way, to satisfy the ever increasing demands by various sectors would not necessarily guarantee the conservation of the water quality and the exploitable reserves volumes. Therefore, the consideration of the variability of salinity and water exploitable reserves must be considered to establish sustainable solutions for the whole system. Acknowledgments The authors express their gratitude to the European Commission for funding the Elmaa Project (INCO-CT-2005-015410) and all the participants for their help and commitment.