DOI: 10.5593/sgem2017/31/S12.050


C. Boariu, C. Bofu, D.M. Pohrib, P. Cercel, T. Hraniciuc
Monday 11 September 2017 by Libadmin2017

References: 17th International Multidisciplinary Scientific GeoConference SGEM 2017, www.sgem.org, SGEM2017 Conference Proceedings, ISBN 978-619-7408-04-1 / ISSN 1314-2704, 29 June - 5 July, 2017, Vol. 17, Issue 31, 393-402 pp, DOI: 10.5593/sgem2017/31/S12.050


Along Bistrita River in the Eastern Carpathians is produced each year freezeup ice jams. Depending on the hydro and weather conditions these breakup jams have a larger or smaller spreading. Periodical ice jams cause damage and noticeable loss of lives. The article examines the area between the tail of Mountain Spring Lake (Poiana Largului) and Dorna Arini which has a length of about 80 km. Jams and ice accumulations occur usually in the downstream section between Poiana Largului and Borca. It would be preferable for ice jams to occur in an uninhabited area.
It is possible to fulfilment a structure hydro (threshold) to create the conditions of formation of ice blockage in a particular section?
By making hydraulic structure that allows the accumulation of ice, water flow changes. These changes can produce undesirable effects on water flow in the river bed (level rise compared to the previous situation). The calculation was performed for three types of flows (average of winter months, the multiannual average flow and 5% probability). Topographical measurements were made on the study. The bed roughness coefficient (Manning) was determined using measurements of flows and levels at hydrological stations in the area. Manning coefficient calibration was performed with MIKE software. Another issue to resolve is unlocking breakup jams in melting ice time safely. It is shown by theoretical considerations (nature of ice jam formation) and observations in the field as unlocking congestion ice does not cause negative effects in downstream
The article identifies an area of Bistrita river wherein is dimensioned a structure (threshold) through which ice accumulation is obtained without changing the character of flow. It proposed a criterion for assessing the minimum impact of threshold height about the character of flow. The two goals (block ice and minimal impact) can be fulfilled only under certain conditions. These conditions are identified.

Keywords: ice jam, hydraulic structure, minim impact