Long-term changes of the river runoff in Latvia

The study of changes in river discharge is important for the development of efficient water resource management systems, as well as for the development and validation of climate change impact models. The discharge regime of rivers and their long-term changes in Latvia were investigated. Four major types of river discharge regimes, which depend on climatic and physico-geographic factors, were characterized. These factors are linked to the changes observed in river discharge. Periodic oscillations of discharge intensity, and low- and high-water flow years are common for the major rivers in Latvia. A main frequency of about 20 and 13 years was estimated for the studied rivers.