Flood impact on the Spanish Mediterranean coast since 1960 based on the prevailing synoptic patterns

Assessing current and future available resources to supply urban water demands using a high-resolution SWAT model coupled with recurrent neural networks and validated through the SIMPA model in karstic Mediterranean environments

Hydrological simulation in karstic areas is a hard task due to the intrinsic intricacy of these environments and the common lack of data related to their geometry. Hydrological dynamics of karstic sites in Mediterranean semiarid regions are difficult to be modelled mathematically owing to the existence of short wet episodes and long dry periods. In this paper, the suitability of an open-source SWAT method was checked to estimate the comportment of a karstic catchment in a Mediterranean semiarid domain (southeast of Spain), which wet and dry periods were evaluated using box-whisker plots and self-developed wavelet test. A novel expression of the Nash-Sutcliffe index for arid areas (ANSE) was considered through the calibration and validation of SWAT. Both steps were completed with 20- and 10-year discharge records of stream (1996-2015 to calibrate the model as this period depicts minimum gaps and 1985-1995 to validate it). Further, SWAT assessments were made with records of groundwater discharge and relating SWAT outputs with the SIMPA method, the Spain's national hydrological tool. These methods, along with recurrent neural network algorithms, were utilised to examine current and predicted water resources available to supply urban demands considering also groundwater abstractions from aquifers and the related exploitation index. According to the results, SWAT achieved a "very good" statistical performance (with ANSE of 0.96 and 0.78 in calibration and validation). Spatial distributions of the main hydrological processes, as surface runoff, evapotranspiration and aquifer recharge, were studied with SWAT and SIMPA obtaining similar results over the period with registers (1980-2016). During this period, the decreasing trend of rainfalls, characterised by short wet periods and long dry periods, has generated a progressive reduction of groundwater recharge. According to algorithms prediction (until 2050), this declining trend will continue reducing groundwater available to meet urban demands and increasing the exploitation index of aquifers. These results offer valuable information to authorities for assessing water accessibility and to provide water demands in karstic areas.

Atmospheric circulation types and floods' occurrence; A thorough analysis over Greece

Floods have a direct impact on the society and the environment, causing human losses, affecting individual incomes and national economic activity including infrastructure damages. Atmospheric circulation is strongly related to both mean and extreme climate, with the latter being the driving force of adverse phenomena, such as inundations. The overarching goal of the research is the identification of those atmospheric circulation patterns that are associated with catastrophic flood events over Greece. An updated atmospheric classification scheme consisted of 12 circulation types (5 anticyclonic and 7 cyclonic) is implemented to detect and highlight the flood-dominant circulation types over the domain of interest. It is established that for a 7-year period (from 2012 to 2018), where reliable flood inventories are available as a derivative of the European Union (EU) Flood Directive implementation process, the dominant circulation type is the cyclonic type C with its center to be located over the Cyclades area. The study also reveals that during the most severe floods, the prevailing cyclonic types are substantially deeper than their mean anomaly field. Finally, out of the 14 River Basin Districts of Greece, Thrace (EL14) is the more flood prone area, while Eastern Macedonia (EL11) is far less flood affected. The introduced Floods' Frequency Vulnerability index (FFVI) showed that in the case of significant floods, Western Peloponnese (EL01) and Epirus (EL05) are the most vulnerable River Basin Districts. The proposed methodology of coupling circulation types with flood occurrences can be applied in all EU Member-States and set the base of effective floods' prediction mechanisms at River Basin Districts scales.

Review of the Impacts of Climate Change on Ports and Harbours and Their Adaptation in Spain

Climate change is one of the issues of greatest concern to today’s society. The increase in temperatures has affected sea levels, polar masses and extreme events, among others. There are many scientific studies that analyze the impacts of climate change on coastal communities, but most of them focus on beach erosion and coastal recession. Scientific literature on the effects of climate change on ports and harbors and their adaptation is much less abundant. Ports are essential for the economy and society of their cities, so studying the impact of climate change on them is an urgent need. The Mediterranean and the Spanish Mediterranean coast is one of the areas that will be most affected by climate change in the future. In addition, the Spanish economy depends a lot on its tourism and, thus, on its coastal cities. Therefore, the study of the impact of climate change on Spanish ports and coastal communities is essential. This article presents a review of the studies carried out until now on the effects of climate change on Spanish ports, and it identifies research gaps and weaknesses and suggests new research lines.

Flood Risk and Exposure: The Case of the Tajuña Valley (Madrid, Spain)

This paper aims to update the exposure to flood risk in a catchment area of the Community of Madrid (Spain) linked to primary sector activities, albeit affected by the urban expansion of the capital. This research starts with the updating of the flood inventory, encompassing episodes documented between 1629 and 2020. The inadequate occupation of the territory means that floods continue to cause significant damage nowadays. It is worth highlighting the two recent floods (2019) that occurred just 15 days apart and caused serious damage to several towns in the basin. The areas at risk of flooding are obtained from the National Floodplain Mapping System, and the maximum and minimum floodable volume in the sector of the Tajuña River basin with the highest exposure to flooding has been calculated. The Sentinel 2 image in false colour (RGB bands 11-2-3, 11-8-3 and 12-11-8) and its transformation to colour properties (Intensity, Hue and Saturation) has made it possible to determine the extension of the riparian vegetation and the irrigated crops located in the alluvial plain. The SPOT 6 image with higher spatial resolution has allowed us to update the mapping of buildings located in areas at risk of flooding. Finally, based on cadastral data, a detailed cartography of built-up areas in areas at risk of flooding is provided. They affect buildings built mainly between the 1960s and 1990s, although the most recent buildings are built on agricultural land in the alluvial plain, even though current regulations prevent the occupation of these lands.

A Rapid Method to Estimate the Different Components of the Water Balance in Mediterranean Watersheds

The sustainable management of water resources, whether surface or underground, requires the identification of the flows involved and the possibility of achieving the water balance of the water resource. These require knowledge of the main flow components with a sufficient level of accuracy. Hydrological simulation models are valuable tools for studying flow at the watershed scale but rely on data that are rarely available; therefore, they require the implementation of field investigations. There is thus a need for simple and practical tools for studying the functioning of a watershed and identifying the different components of the flows. In this paper, a method that uses only weather data, volumes of water abstraction by pumping or diversion, and flows measured at the outlet is proposed. The use of cumulative multi-year curves of measured flows or rainfall provides an assessment of the unknown flows that can take place in the watershed, as well as the order of the respective magnitudes of fast and slow flows. Its application to 20 French Mediterranean watersheds shows that it is possible to properly estimate the order of magnitude of losses or gains linked to karst flows and irrigation input. External inflows or outflows can represent up to 150% of the flow measured at the outlet. The annual volumes estimated by using this method are indeed very close (R2 = 93%) to those provided by existing knowledge. The proposed method can constitute a first approach for the quantification of flows and help to guide the implementation of field investigations and more sophisticated approaches such as hydrological modelling.