Flood Risk Evaluation in Urban Spaces: The Study Case of Tormes River (Salamanca, Spain)

Abstract

The expansion of cities towards flood zones, and the increasingly frequent episodes of torrential rains arising from global warming, mean that the population is becoming more exposed to floods. Due to this, a correct assessment of flood events is of great help in the development of preventive actions, planning and resource management, or interventions. For this reason, in this work we aim to establish guidelines to assess the hazard, exposure, and vulnerability of the population and its properties to flood events, using Hec-Ras for the simulation of the flood and ArcGis and GeoHecRas to treat geographic information and prepare the cartography. The study was focused on the Tormes River in Salamanca (Spain). We studied three return periods with different probabilities of occurrence and intensity, corresponding to 5, 100, and 500 years. The flow corresponding to each episode was calculated, along with the extension, speed, and depth that would be achieved in each case. Then, the probability of occurrence was delimited, as well as the magnitude, allowing us to obtain different hazard maps. In addition, the areas of greatest hazard to people and property were established for each event. Regarding the exposure, the areas and land use, infrastructure, and buildings that would be flooded in each case were identified, quantifying the extension or length of the affected properties at the different levels of hazard in each case. Additionally, the vulnerability of the different buildings and exposed infrastructure was studied. Finally, the flood risk was estimated by combining these three components.

Multitemporal Analysis of Soil Sealing and Land Use Changes Linked to Urban Expansion of Salamanca (Spain) Using Landsat Images and Soil Carbon Management as a Mitigating Tool for Climate Change

“…To avoid the most serious impacts of soil occupation and soil sealing, we propose to protect the high-quality soils and to guide urban development towards those soils of lower quality, as long as the opportunities to develop or redevelop the indoor of the urban area are exhausted. On the other hand, natural risk analyses were not taken into account in the city expansion processes, since up to 187 Ha were identified and built in flood zones, which was demonstrated in more detail in previous studies [80]. In short, the urban expansion has not followed rigorous sustainable criteria: the invasion of restrictive areas (with risks to the population and higher agro-environmental quality) has increased 2.5 times from 1985 to 2018.…”

“…In Salamanca and its surroundings, the natural risks are flooding, and to a lesser extent, rockfall. To establish the areas affected by flood risk, the data from a previous study are used [80], while the areas affected by rockfall are delimited by field work and the study of the slopes and dips of the terrain. These areas were weighted according to risk: (Very high: 5; High: 4; Moderate: 3; Low: 2; Very low: 1; Non-existent: 0).…”

Flood Risk Assessment of the Wadi Nu’man Basin, Mecca, Saudi Arabia (During the Period, 1988–2019) Based on the Integration of Geomatics and Hydraulic Modeling: A Case Study

“…The records also revealed that these stations cover a period of 39 years, 54 years, 25 years, and 47 years, respectively. The depth of the rain was determined in various return periods (5,10,20,25,50, and 100 years) using the Hyfran [36], and various statistical distributions, such as normal, log-normal, log-Pearson type III, Pearson type III, Gumbel, and exponential, and the Komogorov model, used to verify the results, were applied. It was concluded that the method (log-normal) is the most suitable for use in the four stations (Figures 7 and 8) ( Table 3).…”

Spatial assessment of flash‐flood vulnerability in the Moldova river catchment (N Romania) using theFFPI

“…Identifying areas at risk of being affected by flash floods can contribute to the reduction of economic and human losses (Criado, Martínez‐Graña, San Román, & Santos‐Francés, 2019; Sima & Șerban, 2015). In this context, Smith (2003) has developed a method for identifying areas with high potential for flash flood recordings called Flash Flood Potential Index (FFPI).…”