Review on spring floods 2013

Spring floods in the middle part of Daugava river started unusually late this year – at the middle of April. It was one of main factors, determinating remarkable height of the flood level and scope of flooded areas this year. During the time period between 14th and19th of April, most grandiose seasonal nature spectacle in Latvia was observed in Daugava downstream Daugavpils – spring ice drift, accompanied by formation of heavy ice jams both upstream and downstream Dviete floodplain.

One of such ice jams was observed at Līksna inflow in Daugava at the afternoon of April 18, when ice masses stopped at Vaikuļāni hydrological post. As a result a rapid increase of water level and flooding of lowest parts of the floodplain started upstream the ice jam - in Līksna and Svente parishes of Daugavpils municipality. When ice jam at Vaikuļāni disbanded and ice drifted further down into the direction of Glaudānu sala, water level slightly decreased, still it was a temporary effect, followed by gradual rise of water level due to continuous influx of snow melting waters from upper parts of Daugava basin.

During this time period flood waters of Daugava, pieces of ice and different kind of debris (parts of trees etc.) were continuously transported into Dviete floodplain area. Hence a water flow, opposite to usual direction of current, was observed in Dviete river not only at the bridge near Dviete village, but also at Sloboda bridge in Bebrene parish.

Due to rapid increase of water level in Dviete floodplain, the ice of Skuķu lake was pulled out together with frozen reeds with their roots. Clusters of flowing reeds and remnants of bushes, cut in winter, were moved to arable lands and roads. Roads and bridges were damaged by flood currents in Dviete floodplain - the road from Dviete to Bebrene was flooded and eroded, the basement of embankment of the bridge over Dviete river at Dviete village was eroded as well. Flood currents formed also the popular „Dviete whirlpool" on the road Dviete - Dunava, exposed to heavy erosion.

Maximal water level in Daugava at Vaikuļāni and in Dviete floodplain were observed 8-10 days later than usual - on April 23-24. Highest flood level of this year in Dviete floodplain at Sloboda bridge was observed on April 23 (91.67 m above sea level), not reaching the absolute maximum of spring floods in 1931 (93.47 m above sea level) for almost two meters. Still not only most of the area of nature park, but also all ground-water monitoring wells at the vicinity of Putnu sala, including the pole for water level measuring with a length of 4.5 m, situated vertically, disappeared under the water.

Maximal flood level in Daugava at Vaikuļāni was observed on April 24 at 12:00 a.m. (713 cm above zero line of the post or 91.94 m above sea level). Analyses of historical hydrological data on highest observed flood levels in Daugava at Vaikuļāni shows that so high flood water level previously is registered here in 1970 (723 cm), while in Daugavpils it was registered in 1962. Peak of flood level in 2013 did not reach the highest historically registered level at Vaikuļāni hydrological post (898 cm in 1951) – it was about 1.75 meters lower.

After the culmination of spring floods a gradual decrease of water level took place both in Daugava and its floodplain. Ordinary current to the direction of Daugava was observed in Dviete river again. Decrease of water level was much slower, than the increase. Gradual decrease of water level and recede of flood waters from Dviete floodplain continued during all May and is not completed also at the beginning of June, because the water level in Dviete river and in Daugava downstream Daugavpils still is higher than in low-water period of summer.

Dāvis Gruberts

03.06.2013.