Water scarcity period in the Don River basin

By Maria Kireeva

Don is one of the biggest rivers on the European territory of Russia. Its basin has the same area as Sweden or Iraq. Simultaneously this region is a centre of industry and especially agriculture. Rivers are also important source of water for drinking and municipal water supply, hydropower engineering and fisheries. For this reason the extreme hydrological drought that took place on this territory from 2007 to 2015 was a very serious problem.  River flow data analysis showed that this water scarcity period was the longest multiyear drought in the Don River basin during the whole period of observation (1880-2015). The observed annual flow for the main river and its biggest tributaries had a probability of occurrence of about 0.8 – 0.9 (or less then 40 % of the normal).  The extreme low flow situation led to dramatic increasing of phytoplankton concentration, which resulted in change of water quality from oligotrophic to eutrophic. Furthermore, significant reduction of fish stocks was observed.

Extremly low water level on the 30/10/2017 in the Don river, Rostov Area for World Fifa Cap 2018.

One of the main goals now is to investigate the key drivers  of the severe drought event. Research has identified that the river flow was not significantly affected by anthropogenic factors. Water intake and indirect losses, which are connected with human surface transformation, form less than 5 percent of the annual flow. This figure is too small to play a significant role on the water decline. At the same time climatic changes, particularly the decrease in precipitation and rise in transpiration, are likely responsible for the reduced flow. Correlation coefficient between observed river flow and the climatic water balance (i.e. difference between precipitation and evaporation) is more than 0.75.  Moreover a temperature shift led to interannual flow redistribution: spring flow reduced to about 40 percent of normal, while flow in the winter months increased by 10-20%.

However, in the past two years the river flow in the Don River basin has again increased to normal levels. This gives hope that this hazardous hydrological situation in the region is over, at least for the time being.