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The influence of wet lands drainage on Jura river basin runoff changes
Date Issued |
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2011 |
Installation of drainage systems has changed agricultural land use, landscape and hydrographical network a lot. The conditions for the formation both of surface and groundwater runoff changes too. There are 2.3 million of hectares of drained lands in Lithuania and makes about 80-90 percent of lands which could be drained in some rivers watershed. Such intense drained areas in Lithuania give a theoretical assumption, that during long term have changed runoff of rivers due to changes of water balance components. The purpose of the work was to evaluate the influence of wet lands drainage area on watershed runoff during different periods of the year. The Jura river watershed in the western part of the Republic of Lithuania was chosen for the research. At the moment drained land area makes 70-84 % of Jura watershed wet lands area. Five year periods averages of river runoff coefficients were calculated and shown for different periods. It was found out runoff coefficient during spring period (March – May) has downward trend, i.e while drained land area increases runoff coefficient during spring month decreases. The hypothesis of reduction river runoff during dry periods due increase drained land cannot be proved as it was found out there is no significant correlation between drained land area and runoff during June – September (r – 0.025). There is strong direct correlation between annual runoff and drained land area in Akmena and Jura (by Taurage) basins, i.e. more as 50 % of annual runoff are influenced by drainage.