Water balance of lake-catchment systems with transformed water distribution

Abstract

Purpose – The purpose of this paper is to assess the scale of changes in the distribution of water and their influence on the components of the hydrological balance in two lake catchments situated in the Leczna-Wlodawa Lake District. Design/methodology/approach – In order to estimate the scale of man-made modification of water distribution an analysis of published cartographic materials was used. The maps cover time-scale of over 150 years. The analysis was completed by territorial research carried out during water years 2007-2009. The elements of water balance equation were calculated on the basis of daily water levels, discharge, precipitations and lake volumes. Evaporation was calculated as the difference of balance gains and losses (runoff deficit). Findings – The study has shown high permanent human pressure on lake-catchment systems under study, since the 50 of the nineteenth century. Naturally drainless lakes were connected to the system of surface runoff, which modified radically directions and pace of water circulation. The most pronounced hydrologic changes of the lake-catchment systems under study occurred in the 60 of the twentieth century. Human pressure on water conditions resulted in changes of water balance elements relation (increased surface inflow and outflow). Originality/value – In the ecosystems with zonal watersheds, even slight modification of water distribution may lead to radical changes in the structure of lake-catchment systems’ water balance. The paper is first in polish literature that documents major water divide translocation, as well as bifurcation in the drainage area of the highest cascade lake. Man-made modifications cause natural ecosystems degradation, especially in the areas built with peat-bogs.