Assessment of hydrokinetic resources of small and medium-size rivers: the Lithuanian case

Abstract

The aim of the study is to assess hydrokinetic energy resources of small and medium-size rivers in Lithuania. The estimation of technical resources was carried out for river segments, where for average longterm runoff the flow velocity exceeded 0.4 m/s, and the average depth was more than 0.5 m. The results of hydrological studies were used to calculate the average flow rate and the relationship between flow velocity and river depth. The width and depth of the river channel was estimated in accordance with physical and geographical factors. Part of the favourable for use sites of rivers located within protected areas cannot be used for energy production because of the priority of environmental protection. Navigation, recreation and other factors also limit the use of streams for energy production. In addition, in winter due to ice phenomena, hydrokinetic devices in small and medium rivers should be protected from mechanical obstacles. Moreover, Lithuania is a flat country and available hydrokinetic resources of such plain rivers are very small. Their estimated capacity comprises 13.6 MW, and they can generate 79.4 GWh of electric energy per year.

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

“…According to the Köppen–Geiger climate classification system, Lithuania belongs to a humid continental climate and falls within a water surplus zone as the ratio between annual precipitation and evaporation reaches 1.47. It has over 22,000 rivers and streams with a total length of more than 76,000 km (Gailiušis, Jablonskis, & Kovalenkovienė, 2001). Although Lithuania is a relatively small country, its rivers differ in their hydrological behaviour.…”

Lietuvos upių ekologinio nuotėkio vertinimas

“…Tai trumpalaikio (paros ar savaitės) nuotėkio reguliavimo atvejis, kai gaminama pikinė energija. Išplėtotoje elektros energetikos sistemoje toks energijos būdas kartu su vėjo ar kinetinės energijos šaltiniais nebeaktualus [17,18]. Sezoninis ar daugiametis nuotėkio regu liavimas padidina reguliuotos upės sausmečio nuotėkį [9] per pavasario potvynį sukauptu van deniu.…”

Steponas Kolupaila's contribution to hydrological science development

“…Besides the water-level, temperature and ice-regime-change measurements, most of the stations were also recording water discharges. The collected data have been successfully used to optimise the country's hydrological station network: the majority of modern Lithuanian hydrological stations, which have been operating for more than 60 years, were established in places proposed by Kolupaila (Gailiušis et al, 2001;Jakimavičius, 2007). In the 1940s most hydrographic researches were summarised in the fundamental works (Kolupaila, 1933b(Kolupaila, , 1936a(Kolupaila, , 1940b, which became very popular and were updated and published repeatedly (Kolupaila, 1938a(Kolupaila, , 1950.…”

“…L. Bajorūnas, who was the first in Lithuania to defend a dissertation on a hydrological subject for a doctoral degree of engineering in 1943, later worked for a long time in Detroit as director of the US Lake Survey Great Lakes Research Center. Even the most significant Lithuanian hydrologists, hydroelectricity specialists and water management engineers (J. Burneikis, A. Barisas, J. Jablonskis, B. Gailiušis, P. Punys, K. Kilkus) state that their scientific ideas are based on basic knowledge which was formulated thanks to Kolupaila's hydrology school (Macevičius, 1992;Gailiušis et al, 2001;Kilkus, 2002;Kilkus and Valiuškevičius, 2006).…”

“…In 1920-1940 Kolupaila (using 1 : 84 000 and 1 : 300 000 scale maps) estimated length and catchment areas of all Lithuanian rivers whose length exceeded 5 km and also evaluated the river bed slope and network density of major part of Nemunas River basin (Macevičius, 1992;Gailiušis et al, 2001). The hydrographical research results were regularly published in academic journals (over 20 articles on this topic were published within 10 years) and presented at international conferences (Kollupailo, 1925b(Kollupailo, , 1929Kolupaila, 1927aKolupaila, , b, 1930a.…”