Hydrologic response on atmospheric drought

Abstract

The main aim of the study concerns the influence of climatic and hydrological droughts formation and intensity of droughts In 6 agricultural catchments located in lowlands of Central Poland. The behaviour of the catchments has been examined with respect to the rate of streamflow during the most severe droughts which occurred in 1966-1995 period. Low flow events were separated according to the selected threshold flow criterion. Uniform truncation criterion of Q70% was applied on daily flow duration curves. The first stage of the study was indication of water supply deficit in selected catchments by the analysis climatic water balance (CWB). Potential evapotranspiration was calculated by Thom-Olivier formula. Next the relationship Of cumulated curve of climatic water balance versus discharge reduction curve (Q% discharge expressed as the percentage of time of given discharge) was analysed. The conclusion of the analysis is that the catchments with more impermeable surface need large atmospheric feeding deficit (CWB) to reach the same low flow level as the catchment with relatively more permeable surface. Climatic water balance and discharge reduction values are highly correlated