Analysis of Probable Flows Based on the Rainfall-Runoff Model for Flood Scenarios: a Case Study of the Losse River Catchment (Germany)

Abstract

Directive 2007/60/EC [1] sets the framework of actions aimed at restricting the negative consequences connected with floods within the European Union. The implementation of the Directive in the Polish legal system was regulated by the amended "Water Law" Act of 5 January 2011 [2], which required member states to construct flood hazard maps and flood risk maps showing the potential adverse consequences associated with different flood scenarios by December 2013. Some of the first EU projects testing the methodology of developing such maps were the LABEL [3] and Flood Wise projects [4]. The methodology for compiling such maps in Poland was specified by a regulation [5]. Flood hazard maps contain information Pol. J. Environ. Stud. Vol. 25, No. 4 (2016), 1403-1413 AbstractThe procedure of the rainfall-runoff (R-R) model, based on the instantaneous unit hydrograph (IUH) method and used to calculate the probable flows in 8 profiles of the Losse river (on the stretch from 5+476 to 7+596 km) for three flood scenarios (Qextreme, Q1% and Q10%), has been presented in this work. A computer program developed by the author was used to conduct the analyses, enabling the flows to be simultaneously calculated for each of the analyzed profiles in response to 10 rainfall events of varying duration and a given exceedance probability.The obtained values of probable flows were recalculated into corresponding water table levels using the WSP-ASS program (Water Level Program). The extent of the flooding and water depths for three flood scenarios were calculated based on the levels of the water table and terrain elevation data ("Digital Terrain Model"). As a final effect of the analyses, flood hazard maps for the analyzed stretch of the Losse River were constructed, enabling the consequences of flooding to business activities, the infrastructure, the environment, and human health and life to be assessed.

Influence of environmental factors on retention of extensive green roofs with different substrate composition

“…On the basis of values of water available to plants (pF2.0-pF4.2) as well as a given thickness of the substrate equal to 15 cm, the maximum water volume which can be retained by this [36]. For the GR1 substrate it amounted to 15.03 dm 3 , whereas for GR2 9.80 dm 3 . Based on a conventional approach relying on determining atmospheric precipitation suggested and assumed in other studies of the "green roof" type, rainfall events separated by six or more hours are classified as independent events [1,32,34,[37][38].…”

“…Green roofs in particular, have gained considerable attention in recent years as a potential cost-effective way to mitigate urban flood risk [1][2][3][4][5]. They are defined as roofs which are partially or completely covered with a growing medium (substrate) and vegetation (excluding pot vegetation) [5][6][7][8][9].…”

Long-Term Impact of Sediment Deposition and Erosion on Water Surface Profiles in the Ner River

“…The flow module of the model is initially calibrated implementing (1) water surface elevations from the flood hazard maps of the ISOK project [23] and (2) The set of maximum flows tested include 10-, 100-and 500-year floods. Such a set of flows was taken as the basis of the ISOK project [23] and it is very common in scientific works [28]. They correspond to probabilities of exceedance of 10%, 1%, and 0.2%, respectively.…”

Role of drainage layer on green roofs in limiting the runoff of rainwater from urbanized areas

“…The progressing development of cities is changing natural areas into impermeable surfaces, leading to a change in the hydrological cycle [ATALLAH et al 2018;BARSZCZ 2016;BERNDTSSON 2010;MROWIEC, SOBCZYK 2014;ROMANIAK 2017]. Moreover, the aging infrastructure in cities, urbanization rate and climate change, by the degraded hydrological cycle, may constitute a threat to urban drainage.…”