Long-term changes of river discharge regime in Latvia

Abstract

The study of changes in river discharge is important for regionai climate variability characterization and for development of an efficient water resource management system. The hydrological regime of rivers and their long-term changes in Latvia were investigated. Four major types of river hydrological regimes, which depend on climatic and physicogeographic factors, were characterized. These factors are linked to the changes observed in river discharge. Periodic oscillations of discharge, and low-and high-water flow years are common for the major rivers in Latvia, A main frequency of river discharge regime changes of about 20 and 13 years was estimated for the studied rivers. A significant impact of climate variability on the river discharge regime has been found.

Decadal oscillations of the aquatic chemistry of river waters in Latvia

“…2, the character of the variation of discharge values in the studied rivers obviously can be described as oscillated. Signs of oscillations with 20, 11, 8-9, 3-5 and 2 years long periods can be observed, that generally corresponds to the results of earlier studies (Glazacheva, 1988;Klavins et al, 2002a). Increase of water color, known also as brownification, was frequently reported in many lakes and rivers of the Northern hemisphere (Driscoll et al, 2003;Frey and Smith, 2005;Monteith et al, 2007;Erlandsson et al, 2008;Haaland et al, 2010), including Latvian rivers as well (Klavins et al, 2012).…”

“…At the same time river discharge regimes, surface water composition and flows of dissolved substances have not only linear trend of changes, but well expressed periodicity (Pekarova et al, 2003). Oscillations of the discharge intensity, with main frequency of about 20 and 13 years in rivers of Latvia, were reported by Klavins et al (2002a). Periodic oscillations of groundwater levels and levels of deeper underground aquifers in Latvia, with a main frequency of about 11 years, were reported by Levina et al (1995).…”

Climate Change and Energy Systems

“…For the period 1923-2007, trends have been found to be negative, indicating earlier peak discharges. The tendency for an earlier spring maximum discharge timing has been reported for stations throughout the Baltic region (Meilutytė-Barauskienė and Kovalenkovienė, 2007;Klavins et al, 2002;. However, for the periods 1941-2007 and 1961-2007 trends in the timing of the spring flood were found to be insignificant.…”

The Features of the Cyclical Fluctuations, Homogeneity and Stationarity of the Average Annual Flow of the Southern Buh River Basin

“…Furthermore, the presence of periodic cyclical fluctuations in annual average river flow is confirmed by studies many Ukrainian and foreign scientists (Pecarova et al, 2006;Mazvimavi&Wolski, 2006;Grebin, 2004). For example, scientists from Latvia, according to the results of own researches affirmed the presence of periodic oscillations of the discharge intensity on the major rivers of their country (Klavins et al, 2002). Ukrainian scientist Grebin V. relates the change annual flow Ukraine primarily with fluctuations of annual precipitation amounts (Grebin, 2004).…”