Екстремно висок отток във високопланинските речни басейни на Рила

Екстремно висок отток във високопланинските речни басейни на Рила

Калин Сейменов

Extremely high flow within the Alpine catchments in the Rila Mountain

Kalin Seymenov

Abstract

The study of high flow characteristics within the Alpine catchments represents one of the most challenging tasks for the modern hydrological science, because of high vulnerability response of these areas to the global and regional climate changes, including to the proven positive air temperature trends. The current picture of the hydro-climatic processes in the Rila Mountain – the highest mount within the Balkan Peninsula, is not exception. Study area covers eight Alpine catchment areas, located above 1600 m sea level in the Rila Mountain. The aim of this research is to perform a spatio-temporal analysis of the extremely high streamflow characteristics within the researched drainage basins. Study period includes six years in the beginning of the XXІ century: there are very dry (2001), very wet (2005) and four normal water years. The analysis is based of Threshold level method (TLM) with fixed constant threshold value: 5th percentile of all discharge daily data for the given term. Results obtained show the number of extremely high streamflow events ranges from 6 to 26 – for the catchments of the Stara River at Kostenets and the Blagoevgradska Bistritsa River at Bistritsa, respectively. The maximal duration of these events varies from 15 (for the Mesta River at Yakoruda) do 39 days (the Stara River at Kostenets), but the oneweek extremely high flow periods are most typical here (a frecquency to 88% of all cases). The temporal analysis shows a concentration of studied hydrological events during the spring season (in the months of April, May and June), when occurs also a high streamflow phase, due to the snow melting and rainfalls. An exception of this statement is the wettest year in Bulgaria from the beginning of this century – 2005. Then because of heavy prolonged rainfalls during the months of July, August and September, were detected sharp peaks of the hydrographs. Present work establishes some spatial differences of extremely high flow characteristics (time of occurring, duration, frequency) in study area due to the slopes exposition peculiarities. Results obtained supplement previous scientific works and give new information about the risk hydrological processes within the mountainous catchment areas in Bulgaria.

Keywords: extremely high flow, alpine catchments, Rila Mountain, threshold level method

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Начин на цитиране / Citation

На български:

Сейменов К (2019) Екстремно висок отток във високопланинските речни басейни на Рила. Известия на Българското географско дружество 40: 17–23. https://geography.bg/publication/magazines/item/415-vol40-2019-3 

English:

Seymenov K (2019) Extremely high flow within the Alpine catchments in the Rila Mountain. Journal of the Bulgarian Geographical Society 40: 17–23. https://geography.bg/publication/magazines/item/415-vol40-2019-3