Impact of physico‐geographical factors and climate variability on flow intermittency in the rivers of water surplus zone

Abstract

AbstractClimate change is inevitably altering the hydrological regime of water bodies. The interest in changing behaviour of intermittent rivers is increasing in many countries. This research was focused on intermittent rivers (rivers which naturally, periodically cease to flow) in Lithuania. The purpose of this research was to provide an overview of flow intermittency phenomena according to available data in a historical period and to evaluate the impact of catchment geographical features and climate variability on zero‐flow events. The calculated indices of flow intermittency showed that the selected rivers had very different flow regimes. The threshold for the separation of typically intermittent rivers from only occasionally intermittent ones was suggested. Multiple linear regression analysis defined the crucial role of catchment size and watercourse slope on the river cessation process in Lithuania. The applied non‐parametric Wilcoxon–Mann–Whitney test revealed the significance of the relationship between precipitation (in June–September) and zero‐flow duration. Flow intermittency phenomena in Lithuanian rivers were linked to a low‐frequency teleconnection pattern (SCAND index). A methodology of estimating the relation between river intermittency and large‐scale atmospheric circulation pattern (based on SCAND index) was created. The generated regression equations between flow intermittency indices and catchment characteristics might be useful for the estimation of zero‐flows in ungauged river catchments. The main aspect of future investigations might be related to forecasting flow intermittency using modern hydrological models and climate scenarios as well as the defined relationships between zero‐flow indices and physico‐geographical features of river catchments.