Regional Hydrogeological Model of Latvia for Management of Its Groundwater Resources

The countries of the world and of the European Union are developing hydrogeological models (HM) where, by means of computer modelling, the information necessary for the groundwater management is obtained. In 1996, Riga Technical University (RTU), upon assignment of the former State Geological Survey, established regional HM REMO for the central part of Latvia. REMO does not match demands of a modern water management for the whole country, the HM plane approximation step of 4000 meters is too crude. In 2010, RTU started the project of HM that includes the whole territory of Latvia and border areas of neighbouring countries. The project is co-financed by the European Regional Development Fund. HM accounts for 25 geological layers and its plane approximation step is 500 meters. HM have to be established, during 2010-2012, as the element of the Latvian Shared Environmental Information System. It is supported by the Latvian Environment, Geology and Meteorology Centre. HM will comprise geological and hydrogeological information provided by the centre. To ensure compatibility with models of other countries, the commercial program Groundwater Vistas is used for running HM. It contains software tools applied for groundwater modelling worldwide. For the establishment and calibration of HM, innovative methods are used: the map of the ground surface elevations (digital relief) serves as a boundary condition; the aeration zone is a formal aquitard; the actual geometry of HM may not be used in the initial phase of the model establishment. The model data will be used for regional evaluation of the groundwater flow distributions, especially, in areas bordering the neighbouring countries and the Baltic Sea. HM will provide data for establishment of local HM that are used for determination of the permissible productivity of well fields, for modelling contaminant migration and for evaluation of effectiveness of measures used for restoration of groundwater resources.