Development of the Generalized Numerical Model of the Seepage in the Surroundings of Kruonis PSHP and Simulation Results

Abstract

Kruonio HAE aukštutinis baseinas (AB) yra sudarytas vietinėje reljefo pakilumoje, apribojant ištisine beveik 7 km ilgio damba 300 ha plotą, todėl geofiitracįjos AB aplinkoje problema yra aktuali. Reikšmingiausi šios problemos sprendimo rezultatai gauti skaitmeninio modeliavimo būdu 1995-1999 m. Naudotas aktyvios geofiltracijos bendrasis modelis, apimantis ~25 km2 teritoriją, ir du atskiri submodeliai. Jų pagrindu 1999 m. sudarytas bendrasis modelis. Jis kalibruotas pagal sukauptą ir apibendrintą Kruonio HAE aplinkos geofiltracijos natūrinių stebėjimų medžiagą, o po to panaudotas geofiltracijos prognozei, kai AB vandens lygis bus pakeltas iki maksimalaus projektinio - 153,50 altitudės. Vandens lygis baseine taps didesnis už natūralų gruntinių vandenų lygį nuo kelių iki 40 metrų. Apskaičiuoti prognozuojami gruntinio vandens lygiai, debitai, gyliai ir vandens lygio pokyčiai (AVL). Be to, nustatytos veikliosios (jautriausios) hidrografinio tinklo atkarpos, apskaičiuoti filtracinio vandens debitai jose. Apibendrinus prognozės rezultatus nustatyta, kad geofiltracijos KHAE AB aplinkoje esminių pokyčių nenumatoma; atkreiptas dėmesys į zonas, kur tie pokyčiai gali būti ryškesni, ir pabrėžiamas tolesnių geofiltracijos stebėjimų būtinumas

The upper basin (UB) of the Kruonis Pumped Storage Hydropower Plant (PSHP) is situated in a local relief rise surrounding an area of 300 hectares by a levee of almost 7 km length. In the basin water level is higher than the natural groundwater level ranging from several up to 40 meters. Therefore, the problem of the seepage in UB surroundings is actual. Most significant results of the problem solution were obtained by numerical simulation in 1995-1999. The simulation was carried out by the main model covering the territory of the active seepage of~ 25 km2, and by two separate submodels. On the basis of the above models the generalized model was worked out in 1999. It was calibrated by the materials of seepage field investigations in the surroundings of Kruonis PSHP. It was used for the seepage prognosis, when in the UB water level was raised to its maximum design level 153,50. Prognosed levels, level changes, depths and flow rates of the groundwater were calculated. In addition, the active (most sensitive) reaches of the hydrographic network were exposed and their flow rates were calculated. Analysis of the prognosis results showed that the essential changes of seepage in surroundings of the UB of Kruonis PSHP are not expected; the attention should be paid to some individual zones where the changes are more possible. The above conclusions coincide well with results of the field investigation in 2002 when UBWL reached the maximum altitude 153.50. The new seepage situation is still under dynamic stabilization. Further seepage investigations are required