DEPRESSION CONE MIS-SHAPENNING DUE TO VARIABLE PERMEABILITY OF A DOLOMITE EXCAVATION AQUIFER IN LATVIA.

If the place hydrogeological conditions are uniform (invariable aquifer transmissivity, no impact of hydrogeological network) then the quarry depression cone and the pumping rate for the quarry draining can be obtained by using analytical methods. The dolomite aquifer at the Iecava district in Latvia included large impervious areas. Due to this fact, appliance of analytical methods cannot give the right depression cone. The local hydrogeological model (HM) was applied for obtaining the depression cone of the dolomite excavation quarry. The Groundwater Vistas (GV) system was used for running HM. For obtaining the depression cone, the original method was applied. To carry out the method, the fixed head boundary conditions on the HM area borderline were changed to the zero value. The only non-zero boundary condition for obtaining the depression cone was the quarry drawdown. It was found out that because of the dolomite aquifer irregular permeability, the cone depression isoline contours, including the borderline, were considerably deformed in comparison with the circles for the related uniform aquifer. The quarry drainage flow was considerably smaller than the one for the uniform aquifer. The results reported in the paper may be useful for specialists dealing with obtaining of depression cones for heterogeneous aquifers. [ABSTRACT FROM AUTHOR]