Analysis of the national piezometric network of Tunisia
The regular observation of groundwater levels began in Tunisia more than sixty years ago. The national groundwater level network consists presently of almost 3,700 monitoring points (wells, boreholes and piezometers), monitoring 148 aquifers with some long-term series of about fifty years. To characterize the national piezometric network, two types of indicators were defined: a) indicators connected with the intrinsic quality of the existing networks, and b) indicators describing the need for additional information for network consolidation. Quality indicators relate to space density, monitoring duration, functioning, spatial coverage of the network by piezometers, exploitation control and temporal evolution of the network. Consolidation indicators relate to piezometric variation, exploitation or overexploitation rates, resources and aquifer area. Based on these indicators, the classification highlights aquifers having the best quality networks and those requiring a network consolidation. The global synthesis highlights aquifers requiring priority actions in terms of rationalization of the piezometric network. The results obtained at the end of this analysis agree well with the present situation as observed in the field.