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Table1. Changes in annual runoff according to different climate change scenarios (percentages) River Station HADMID HADMIN HADMAX HAMMID HAMMIN HAMMAX Ahja Ahja 26 13 31 39 21 51 Ahja Koorvere 36 24 40 48 32 59 Avijo Mulgi 24 11 30 41 21 54 Emajõgi Tartu 46 33 51 60 42 72 Kääpa Kääpa 30 16 36 48 27 61 Kunda Sämi 15 5 19 27 13 36 Piiga009 Piigaste 18 7 22 31 15 41 Põltsamaa Pajusi 23 11 28 37 19 46 Pungerja Roostoja 22 10 28 38 20 49 Purtse Lüganuse 18 6 23 33 15 43 Tagajõgi Tudulinna 22 9 28 40 20 52 Võhandu Räpina 26 14 31 40 22 51 Võhandu Himmiste 29 16 33 42 24 54 Not only total increase of annual runoff is important but also its seasonal distribution. In most of the impact studies, the consequences of a greenhouse effect for runoff are analysed and discussed, while seasonal patterns of runoff have received less attention, especially concerning their regularity. Modelling results demonstrate a possibility of enormous changes in seasonal runoff on the eastern part of Estonia. The results below (Figures 1–3) illustrate geographical differences in the sensitivity of runoff to climate change. Maximum runoff is more sensitive than minimum runoff. For the studied rivers, the modelled annual curve of runoff is similar to baseline. A decrease of modelled runoff in spring and its increase in autumn is typical to all river basins, especially to the rivers of North-Estonia. Figures 1–3 demonstrate a variety of runoff responses to climate change in different landscape regions. Observed curves of monthly runoff for the baseline period (1961–1990) and modelled curves for the year 2100 are presented. In addition to the medium climate change scenarios HADMID and HAMMID, HADMIN as the lowest change scenario and HAMMAX as the highest one are demonstrated. Võhandu River basin is located in South-East Estonia in the region of the most continental climate. There, changes in annual course of runoff will be the less remarkable (Fig. 1). The runoff maximum in spring will move by a month earlier, but will not decrease. ECHAM3TR model indicates even an increase of the maximum.
mm/day 1.60 1.40 1.20 1.00 0.80 0.60 0.40 0.20 0.00 Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Jan Baseline HADMID HADMIN HAMMID HAMMAX Fig. 1. Changes in monthly runoff in Võhandu River (station Räpina). Modelled data for Emajõgi River basin (Fig. 2) have the highest increase in runoff. But the predicted seasonal variations of discharge are quite similar to the previous example. The increase in winter runoff and its maximum in March in case of Emajõgi River basin is higher. It is caused by a fact that this river has the largest catchment area and runoff is naturally regulated by Lake Võrtsjärv. 1.60 1.40 mm/day 1.20 1.00 0.80 0.60 0.40 0.20 0.00 Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Jan Baseline HADMID HADMIN HAMMID HAMMAX Fig. 2. Changes in monthly runoff in Emajõgi River basin (station Tartu). The Kunda River basin is typical to a limestone plateau and a karst region in North Estonia. It has a great groundwater inflow that makes slower the runoff decrease after spring maximum, and higher the level of runoff minimum in summer. Both the maximum in spring and minimum in summer will be shifted earlier in case of climate change (Fig. 3). The increase of runoff in autumn will be significant in Kunda River basin.
Page 1 and 2: LIFE-Environment project “Viru-Pe
Page 3: Climate change scenarios used in mo
Page 7 and 8: Tagajõgi- 0.69 0.74 0.71 0.74 Tudu
Page 9: will start not in June but in May.

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