Floods are the most destructive natural phenomenon, by the total number of casualties, and value of property damage, compared to any other type of natural disaster. However, some of the most destructive flash floods are related to dam breaches or complete collapses, that release the large amounts of water, affecting inhabited areas. Worldwide, numerous dams have almost reached or surpassed the estimated construction life span, and pose an increasing risk to structure stability. Considering their continuous degrading state, increasing rainfall aggressiveness, due to climatic changes, technical error, or even human error, there are numerous, potential causes, for which dams could develop breaches and completely fail. This study aims to portray a comparative perspective of flood impact, with real-life consequences, measured by quantifiable parameters, generated from computer simulations of different breach sizes. These parameters include the total flooded surface, water velocity, maximum water depth, number of affected buildings, etc. The analysis was undergone by means of HEC-RAS based 2D hydraulic modeling and GIS, depending on high-accuracy Lidar terrain data and historical hydrological data. As a case study, Drăcșani Lake with the associated Sulița earthfill embankment dam was chosen, being one of the largest and oldest artificial lakes in Romania.
This research aimed to identify flooded areas following the July 2010 floods, using Landsat 7-ETM + satellite imagery and a more efficient way to extract water bodies. By computing several indices, such as MNDWI, NDWI, NDVI, AWI, WRI and NDMI, it was concluded that, in the present case, the NDWI index was most effective, the data obtained having a very good accuracy. The studied area was the Jijia River Slobozia-Dângeni sector, the Landsat 7-ETM + images were taken on July 3, 2010. The flow rate at this time at the Dângeni station was 473 cm, decreasing compared to July 1, 2010 when the share reached 579 cm. The flooded area obtained is 15.80 km2, the maximum extension of the flood area on July 3, 2010 being approx. 1 km on the localities of Durneşti and Sapoveni. The study found 143 houses in 19 localities flooded. Of the total flooded areas, the largest share is held by arable land (44.58%), with a surface area of 7.04 km2.
Water quality is a very important aspect in the perspective of durable, urban and rural development. At European level, several directives were implemented, with the purpose of regulating the degree of pollution for water sources. Both surface and underground water resources in Romania are being affected by pollutants, such as nitrites, phosphorus, generated through irrational usage of chemical fertilizers, but also through the discharge of urban waste water directly into river courses. The spatiotemporal analysis of water quality in North-Eastern Romania, for Suceava, Ozana and Tazlau drainage basins, was based, in the current study, on the water quality index that has been applied (WQI), and also the variation rate of water quality (R). The results have pointed out the fact that there are no substantial differences concerning water quality, on a North-South direction, but a decrease in the values of these parameters can be observed from upstream, to downstream, for each basin. WQI is associated with a Good Water Quality class, for Suceava river basin (with a value of 39.78), and also for Tazlau basin (with a value of 33.31), but Ozana basin has a value of 16.09, being associated with an Excellent Water Quality class. The results generated by the calculation of the water quality variation rate have emphasized the fact that 57% of the analyzed parameters reveal a worsening tendency, in Suceava and Tazlau drainage basins, while Ozana basin has a value of only 28%.
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