An inter‐basin backwater overflow (the Buhai Brook and the Ezer reservoir on the Jijia River, Romania)

Abstract

During the last few years, the north‐western part of Romania has been affected by catastrophic floods with most of the watercourses reaching their highest recorded discharges. This study reports the generation of a numerical terrain model and the simulation of a backwater phenomenon at elevation steps according to the volume of water accumulated at the confluence of the Buhai Brook with the Jijia River. The hydrological data are complemented by rainfall data and the careful recording of the flood behaviour during the entire period of its development. The main aim of the study is to identify the causes of the backwater phenomenon and to highlight the material damage inflicted on the town of Dorohoi. At the same time, the study uses cartographic model that was developed to establish which areas are at risk of flooding at various levels of probability. The catastrophic flood began on the Buhai Brook, a slow‐flowing stream that drains the areas to the west of the town of Dorohoi and discharged into the upstream sector of the Jijia confluence. The flood caused two types of backwater waves: one behind the bridges and the houses built on the floodplain and a second that followed the course of the main stem (Jijia) upstream from the confluence, flooding the Ezer Lake, which was created specifically to attenuate such floods. The spillway backwater phenomenon was inter‐basin as it did not occur in a single hydrographic basin. The causes of the catastrophic flash flood and of the inter‐basin backwater overflow are natural but also reflect anthropogenic influence. After the lake filled, the discharge into the Jijia was controlled and the flooding downstream was thus greatly diminished. Though fortuitous, the backwater flooding was important in mitigating the impact of the flood wave from the Jijia River. Copyright © 2013 John Wiley & Sons, Ltd.

Using High-Density LiDAR Data and 2D Streamflow Hydraulic Modeling to Improve Urban Flood Hazard Maps: A HEC-RAS Multi-Scenario Approach

“…In this study, we developed a method for flood vulnerability assessment under real (average discharge) and mathematical (calculated discharge) hydrological data based on HEC-RAS, LiDAR data, and 2D hydraulic modeling. Different from other studies [23][24][25][26][27]47], which provide flood hazard maps based on hydrological data calibrated at river basin scale [23,24,26,27], we developed for the first time in the study area flood hazard maps adapted to local environment settings and calculated discharge. In this context, four 2D streamflow hydraulic scenarios (s1-s4) were computed in order to test the flood mitigation capacity of hydro-technical constructions located downstream on the Bistriţa River (North East Romania) ( Figure 1a).…”

Historic flood events in NE Romania (post-1990)

“…After the movement of inhabitants from the mountainous regions and forest restitutions, Romania witnessed the emergence of flood events at increasingly high levels and frequencies, with floods occurring in 1991, 2006, 2008, 2010(Cojoc, Romanescu, & Tirnovan, 2015Romanescu, Zaharia, Sandu, & Juravle, 2015). At the same time, historical flows at hydrometric stations located in the Siret basin were recorded at Dragesti, with 2884 m³/s in 2010, and Lungoci, with 3110 m³/s in 1991; flows in the Prut basin were recorded at Radauti-Prut, with 2310 m³/s in 2010, and at Andrieseni, with 460 m³/s in 2005, on the Jijia River (Romanescu & Stoleriu, 2013a, 2013bRomanescu, Stoleriu, & Romanescu, 2011). We managed to map the historical floods that occurred in the Siret and Jijia River basins ( The main features of the flood events in the Siret lower basin are reported in Figure 3.…”

Exceptional floods in the Prut basin, Romania, in the context of heavy rains in the summer of 2010

“…The processed data were portrayed as histograms that illustrate the evolution of water levels during the floods, including the CA (warning level), CI (flood level), and CP (danger level) flood threshold levels before and after the flood, the daily and monthly runoff, and the hourly variations of run-off during the backwater. For an exact assessment of the damage and the flooded surface area, observations and field measurements were conducted on the major floodplains of the Volovat, Baseu, Jijia, Sitna, Miletin, Bahluet, Bahlui, Elan, and Chineja rivers (Romanescu et al, 2012;Romanescu and Stoleriu, 2013b;MihuPintilie and Romanescu, 2011).…”