UNSYMMETRICAL DEPRESSION CONES OF DOLOMITE EXCAVATION QUARRIES THAT ARE SITUATED CLOSE TO LARGE SURFACE WATER BODIES IN LATVIA.

The case is considered when at the Koknese district in Latvia the hydrogeological situation for dolomite excavation quarries is heterogeneous. The place geological build is complex and the quarries are situated close to large surface water bodies represented by the Daugava river and by the Urgu reservoir. The depression cones of the quarries were obtained by using the local hydrogeological model (HM). The primary data for creating the local HM were provided by the regional HM of Latvia LAMO4. The Groundwater Vistas 7 (GV) system was applied to run HM. The original method for obtaining the depression cone was used. It did not applied any data on the undisturbed and disturbed (active quarries) groundwater heads To obtain the depression cone, the quarry drawdown was applied as the boundary condition. The quarry depression cones are unsymmetrical, especially explicitly, for the quarries that are situated beside the Urgu reservoir. Interdependence of the quarries was estimated. The impact of groundwater sources in supporting the quarry drainage flow was found. The flow was supported mainly by the Daugava river (~50%) and the Urgu reservoir (~80%). The drainage flow for the related uniform situation was considerably smaller and it was supported by the flow through the HM border. The results considered in the paper may be useful for specialists dealing with obtaining of depression cones when conditions of a place are heterogeneous. [ABSTRACT FROM AUTHOR]