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

Abstract

Climate 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.

Climate Change Impact on Hydropower Resources in Gauged and Ungauged Lithuanian River Catchments

“…The central Lithuanian hydrological region will experience the greatest decline of runoff according to all projections and in both the near and far future periods. This finding corresponds with a previous study [51] that highlighted vulnerability and a high risk of an increasing number of rivers drying up in response to climate change in this particular hydrological region.…”

Patterns of Past and Future Droughts in Permanent Lowland Rivers

“…These findings broadly support the results of other studies, suggesting that the identified specifics of river catchments from different hydrological regions and climatic conditions help analyze and project extreme hydrological phenomena in the conditions of changing aridity [28,29,34,69,70]. SPI and RDI parameters showed that in most cases, the number of dry months and the minimum value of the index increased with an extension of the accumulation period.…”

“…This tendency is identified in the past and future due to specific conditions of river feeding sources (the smallest amount of precipitation and groundwater feeding in the C-LT region). This could be the reason why almost all Lithuanian intermittent rivers are located in this region [69]. In the future, the hydrological droughts are expected to be more extreme in the C-LT region, and the number of intermittent rivers may even increase.…”

Spatial and Temporal Patterns of Low-Flow Changes in Lowland Rivers

“…Summer flows projections in the studied rivers showed a decreasing tendency [27,28]. The ongoing signs of climate change led to the investigation of intermittent rivers, which are particularly sensitive to any alterations in meteorological conditions or any anthropogenic disturbances [29].…”