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- Improving a DSM Obtained by Unmanned Aerial Vehicles for Flood ModellingPublication . Mourato, Sandra; Fernandez, Paulo; Pereira, Luísa; Moreira, MadalenaAccording to the EU flood risks directive, flood hazard map must be used to assess the flood risk. These maps can be developed with hydraulic modelling tools using a Digital Surface Runoff Model (DSRM). During the last decade, important evolutions of the spatial data processing has been developed which will certainly improve the hydraulic models results. Currently, images acquired with Red/Green/Blue (RGB) camera transported by Unmanned Aerial Vehicles (UAV) are seen as a good alternative data sources to represent the terrain surface with a high level of resolution and precision. The question is if the digital surface model obtain with this data is adequate enough for a good representation of the hydraulics flood characteristics. For this purpose, the hydraulic model HEC-RAS was run with 4 different DSRM for an 8.5 km reach of the Lis River in Portugal. The computational performance of the 4 modelling implementations is evaluated. Two hydrometric stations water level records were used as boundary conditions of the hydraulic model. The records from a third hydrometric station were used to validate the optimal DSRM. The HEC-RAS results had the best performance during the validation step were the ones where the DSRM with integration of the two altimetry data sources.
- Geostatistical analysis of settlements induced by liquefaction: case study river Lis Alluviums, PortugalPublication . Veiga, Anabela; Mourato, Sandra; Rodrigues, HugoIn the present work the result of the application of geostatistical methods to soil settlement data is presented. The settlements are induced by liquefaction as a result of an earthquake of magnitude 5.5. In the present paper the ArcGIS Geostatistical Analyst software was used, where a number of Kriging methods are available. Geostatistical analysis was performed on two phases: (i) modelling the semivariogram to analyse the surface properties and; (ii) application of a Kriging method. The best adjustment was obtained with a Gaussian model with a first order function trend removal. The settlement values were obtained from the analysis and treatment of results of SPT tests carried out on soils corresponding to alluvial soils in the urban centre of Leiria, Portugal. The results show a significant area where are expected large settlements that can generate significant damages in the building stock and infrastructures.
- Effectiveness of Nature-Based Solutions in Mitigating Flood Hazard in a Mediterranean Peri-Urban CatchmentPublication . Ferreira, Carla S.; Mourato, Sandra; Kasanin-Grubin, Milica; Ferreira, António J. D.; Destouni, Georgia; Kalantari, ZahraUrbanization alters natural hydrological processes and enhances runoff, which affects flood hazard. Interest in nature-based solutions (NBS) for sustainable mitigation and adaptation to urban floods is growing, but the magnitudes of NBS effects are still poorly investigated. This study explores the potential of NBS for flood hazard mitigation in a small peri-urban catchment in central Portugal, prone to flash floods driven by urbanization and short but intense rainfall events typical of the Mediterranean region. Flood extent and flood depth are assessed by manually coupling the hydrologic HEC-HMS and hydraulic HEC-RAS models. The coupled model was run for single rainfall events with recurrence periods of 10−, 20−, 50−, and 100−years, considering four simulation scenarios: current conditions (without NBS), and with an upslope NBS, a downslope NBS, and a combination of both. The model-simulation approach provides good estimates of flood magnitude (NSE = 0.91, RMSE = 0.08, MAE = 0.07, R2 = 0.93), and shows that diverting streamflow into abandoned fields has positive impacts in mitigating downslope flood hazard. The implementation of an upslope NBS can decrease the water depth at the catchment outlet by 0.02 m, whereas a downslope NBS can reduce it from 0.10 m to 0.23 m for increasing return periods. Combined upslope and downslope NBS have a marginal additional impact in reducing water depth, ranging from 0.11 m to 0.24 m for 10− and 100−year floods. Decreases in water depth provided by NBS are useful in flood mitigation and adaptation within the peri-urban catchment. A network of NBS, rather than small isolated strategies, needs to be created for efficient flood-risk management at a larger scale.
- A new approach for computing a flood vulnerability index using cluster analysisPublication . Fernandez, Paulo; Mourato, Sandra; Moreira, Madalena; Pereira, LuísaA Flood Vulnerability Index (FloodVI) was developed using Principal Component Analysis (PCA) and a new aggregation method based on Cluster Analysis (CA). PCA simplifies a large number of variables into a few uncorrelated factors representing the social, economic, physical and environmental dimensions of vulnerability. CA groups areas that have the same characteristics in terms of vulnerability into vulnerability classes. The grouping of the areas determines their classification contrary to other aggregation methods in which the areas' classification determines their grouping. While other aggregation methods distribute the areas into classes, in an artificial manner, by imposing a certain probability for an area to belong to a certain class, as determined by the assumption that the aggregation measure used is normally distributed, CA does not constrain the distribution of the areas by the classes. FloodVI was designed at the neighbourhood level and was applied to the Portuguese municipality of Vila Nova de Gaia where several flood events have taken place in the recent past. The FloodVI sensitivity was assessed using three different aggregation methods: the sum of component scores, the first component score and the weighted sum of component scores. The results highlight the sensitivity of the FloodVI to different aggregation methods. Both sum of component scores and weighted sum of component scores have shown similar results. The first component score aggregation method classifies almost all areas as having medium vulnerability and finally the results obtained using the CA show a distinct differentiation of the vulnerability where hot spots can be clearly identified. The information provided by records of previous flood events corroborate the results obtained with CA, because the inundated areas with greater damages are those that are identified as high and very high vulnerability areas by CA. This supports the fact that CA provides a reliable FloodVI.
- Study of the requirements of an autonomous system for surface water quality monitoringPublication . Barros, M.; Granchinho, P.; Ferreira, C.; Neves, P.; Magalhães, H.; Santos, L.; Lopes, B.; Marques, J.; Pinho, H.; Mourato, SandraIn recent years, there has been increasing awareness of the preservation, protection and sustainable use of natural resources. Water resources, being one of the most important natural resources, face major threats due to contamination by pollutants of various types and origins. Maintaining the quality of water resources requires more robust, reliable and more frequent monitoring than traditional techniques of data collection based on sporadic, discontinuous and manual processes. The management of large geographical areas, the insufficient spatiotemporal discretization of the values of samples collected by traditional processes and the unpredictability of natural phenomena, require a new approach to data collection procedures. This article, which is the result of ongoing research, defines the technical requirements and technologies used in a continuous and regular monitoring of surface water quality in freshwater systems, whose data acquisition system helps to identify the sources of pollution and the contaminants flow along the waterways. The design of a versatile real-time water quality monitoring system, which, due to its environmental constraints should be based on renewable energies and wireless transfer of energy, will contribute to improve the management and effective protection of water resources.
- Interannual variability of precipitation distribution patterns in Southern PortugalPublication . Mourato, S.; Moreira, M.; Corte‐Real, J.Southern Portugal is characterized by an irregular distribution of precipitation which is highly variable from year to year, requiring a clear ascertaining if the pattern of the precipitation is changing due to climate variability or climate change. In this paper, the authors applied several statistical methods to annual and seasonal time series of precipitation during the period 1931-2006, in order to detect trends and evaluate the variability in the frequencies of occurrence of dry and wet periods and also to assess spatial distribution patterns. The statistical methods include homogeneity tests, Mann-Kendall test, simple moving averages and cluster analysis. In spring, the authors detected a lack of homogeneity in the precipitation time series and a significant decreasing trend of precipitation was identified, by using simple moving averages and the Mann-Kendall test. Cluster analyses also confirmed the results and identified significant trends in the interannual and spatial distributions of dry, normal and wet years. It is concluded that the annual precipitation regime in the North interior sector is becoming drier, as the winter and spring also become drier. The only season in which a precipitation increase is observed is at fall and near the sea, but even for that region springs are also becoming drier.
- A Generalized Dynamic Programming Modelling Approach for Integrated Reservoir OperationPublication . Rani, Deepti; Mourato, Sandra; Moreira, MadalenaIn water resource systems, the demands at each reservoir are generally known. However, in the integrated operation of a system involving inter-basin water transfers, the import/export of water among various reservoirs also plays an important role in the sustainable and optimal management of available water. Generally, a trial and error approach is adopted to simulate a system for integrated operation. Prior information on water resettlements among reservoirs would be helpful for facilitating the integrated management of these systems. In the present study, a generalized inventory-based dynamic programming model is developed to evaluate the water transfers between reservoirs in the Alqueva subsystem. The model offers guidelines on water transfers among reservoirs and estimates the overall amount of water to be pumped from the Alqueva reservoir to subsidize the shortfalls in the Alqueva subsystem. The proposed methodology may be adapted to other complex systems to promote integrated operations, and the model may be useful for design and operational purposes.
- Water Resources Impact Assessment Under Climate Change Scenarios in Mediterranean WatershedsPublication . Mourato, Sandra; Moreira, Madalena; Corte-Real, JoãoClimate models project a reduction in annual precipitation and an increase in temperature, which may lead to runoff shortages and a consequent water availability reduction, in some Mediterranean regions, such as southern Portugal. The impacts on water availability under different climate change scenarios are assessed using SHETRAN, a physically-based and spatially-distributed hydrological model. SHETRAN is calibrated and validated against daily runoff measurements at outlet and internal sections and against phreatic surfaces using a multi-basin, multi-location and multi-response approach. Nash-Sutcliff efficiency, volume deviation and coefficient of determination ranged, respectively, from 0.58 to 0.76, 0.59 to 0.79 and −9 to 15 %, in the calibration period, and from 0.54 to 0.75, 0.54 to 0.77 and −14 to 12 %, in the validation period. Three GCM and two RCM are used for control (1961–1990) and scenario (2071–2100) periods, under the A2 SRES emission scenario. Observed bias in the climate models’ projected precipitation and temperature are corrected with three bias correction methods. For the scenario period the climate models project a change in precipitation from +1.5 to −65 % and an increase in temperature from +2.7 to +5.9 °C. This trend in climate change projection is reflected in the annual runoff that decreases drastically, between 13 and 90 %, in southern Portugal by the end of the century. The runoff reduction is greater in all watersheds in Autumn and Spring with higher agreement between models and bias correction methods. The runoff decrease seems greater in the Guadiana river basin which is already under significant water stress. © 2015, Springer Science+Business Media Dordrecht.
- Heating and Cooling Degree-Days Climate Change Projections for PortugalPublication . Andrade, Cristina; Mourato, Sandra; Ramos, JoãoClimate change is expected to influence cooling and heating energy demand of residential buildings and affect overall thermal comfort. Towards this end, the heating (HDD) and cooling (CDD) degree-days along with HDD + CDD were computed from an ensemble of seven high-resolution bias-corrected simulations attained from EURO-CORDEX under two Representative Concentration Pathways (RCP4.5 and RCP8.5). These three indicators were analyzed for 1971-2000 (from E-OBS) and 2011-2040, and 2041-2070, under both RCPs. Results predict a decrease in HDDs most significant under RCP8.5. Conversely, it is projected an increase of CDD values for both scenarios. The decrease in HDDs is projected to be higher than the increase in CDDs hinting to an increase in the energy demand to cool internal environments in Portugal. Statistically significant linear CDD trends were only found for 2041-2070 under RCP4.5. Towards 2070, higher(lower) CDD (HDD and HDD + CDD) anomaly amplitudes are depicted, mainly under RCP8.5. Within the five NUTS II regions projections revealed for 2041-2070 a decrease in heating requirements for Algarve and Lisbon Area higher in Faro, Lisboa and Setúbal whereas for North and Center regions results predicts an increase in cooling energy demand mainly in Bragança, Vila Real, Braga, Viana do Castelo, Porto and Guarda, higher under RCP8.5.
- An interactive Web-GIS fluvial flood forecast and alert system in operation in PortugalPublication . Mourato, Sandra; Fernandez, Paulo; Marques, Fábio; Rocha, Alfredo; Pereira, LuísaFloods are one of the natural disasters not preventable, affecting people and causing significant damage to economic activities and infrastructures. Thus, it is of foremost importance to, within a disaster risk-reduction strategy, develop a useful flood forecast and alert system to prevent people from suffering flood disasters and mitigate its consequences. This article presents the Flood Forecast and Alert System in operational mode since 2019 for the Águeda river basin located in Portugal's centre region. This system is technologically advanced, differing from others since it uses a coupled real-time hydrologic and 2D hydrodynamic modelling supported on numerical weather prediction and a high-resolution digital terrain surface model. The system components are automatically activated and linked: i) a rainfall forecasting model (WRF), ii) a hydrological model (HEC-HMS), iii) a hydraulic model (HEC-RAS 2D), and a iv) Web-GIS platform. The hydrological model is forced with forecast precipitation for the next three days and updated every 6 h, which is crucial to generate pre-flood hazard maps. It also includes a Web GIS service for flood hazard dissemination available for civil authorities and citizens. A flood forecast and alert system is highly relevant to the community since, by enhancing knowledge, it provides the authorities responsible for assessing and managing the flood risk, responsiveness to disasters and timely decision-making, which is even more evident in the context of climate change.