Ioana Popescu

Parametric and physically based modelling techniques for flood risk and vulnerability assessment: A comparison

Floods are one of the most common and widely distributed natural risks to life and property. There is a need to identify the risk in flood-prone areas to support decisions for risk management, from high-level planning proposals to detailed design. There are many methods available to undertake such studies. The most accepted, and therefore commonly used, of which is computer-based inundation mapping. By contrast the parametric approach of vulnerability assessment is increasingly accepted. Each of these approaches has advantages and disadvantages for decision makers and this paper focuses on how the two approaches compare in use. It is concluded that the parametric approach, here the FVI, is the only one which evaluates vulnerability to floods; whilst although the deterministic approach has limited evaluation of vulnerability, it has a better science base.

River cross-section extraction from the ASTER global DEM for flood modeling

An approach to generate river cross-sections from the Advanced Spaceborne Thermal Emission and Reflection Radiometer Global Digital Elevation Model (ASTER GDEM) is discussed. The low resolution and the inadequate vertical accuracy of such global data present difficulties in differentiating features of hydraulic importance, which necessitate pre-processing of the DEMs before they are used. A vertical bias correction carried out by comparison of elevation points with a high accuracy terrain model produces a considerable improvement to the cross-sections obtained. In a situation where there are some flow/stage measurements at either end of the river reach, an optimization routine combined with a conceptual flow routing method can provide an additional tool to identify the parameters of an equivalent river section. The extracted cross-sections were used in a 1D river modeling tool HEC-RAS/GeoRAS to simulate flooding on a part of the Tisza River, Hungary. Model results are encouraging and show good potential for using the suggested method in the areas of topographic data scarcity.

Climate change impact on flood hazard, vulnerability and risk of the Long Xuyen Quadrangle in the Mekong Delta

The Vietnamese Mekong Delta (VMD) has an important role in terms of food security and socio-economic development of the region; however, it is one of many areas of the world vulnerable to floods resulting from sea level rise (SLR) due to climate change. Therefore, management of flooding is a priority at national and regional levels in Vietnam. The Long Xuyen Quadrangle is the most important region in the VMD in terms of agriculture and economy. In the present work, flood hazard, vulnerability and risk were assessed and mapped to identify the priority areas in the Long Xuyen Quadrangle for flood mitigation. A hydrodynamic model was used to simulate the flood event of 2000 when a flood of 20-year return period occurred and caused loss of human lives and extensive damage. The calibrated model was then used to simulate a possible flood event in 2050 due to SLR. The resulting flood depth of the simulation was used to prepare inundation maps and to analyse flood hazard in this region, as well. The flood vulnerability of the region was assessed using the coastal areas flood vulnerability index (FVI) method. The FVI was determined by district, and flood vulnerability maps were developed based on these data. The results indicate that the major part of the study area (35.4%) can be classified as being at high risk. It was also found that 32.7% of the area is under medium risk and only about 18.4% is under very low and low risk; 10.2% of the total area is not subjected to flood risk. We show that district level flood vulnerability maps are potentially useful for decision makers and the public in planning better measures for adaptation and mitigation of the negative impacts of flooding.

Application of a coastal modelling code in fluvial environments

XBeach is an open source, freely available two dimensional code, developed to solve hydrodynamic and morphological processes in the coastal environment. In this paper the code is applied to ten different test cases specific to hydraulic problems encountered in the fluvial environment, with the purpose of proving the capability of XBeach in rivers. Results show that the performance of XBeach is acceptable, comparing well to other commercially available codes specifically developed for fluvial modelling. Some advantages and deficiencies of the codes are identified and recommendations for adaptation into the fluvial environment are made.

An experience in knowledge mapping

Purpose – To improve access to implicit knowledge by tunnel construction engineers.Design/methodology/approach – The strategy was to strengthen the informal networks by improving codification and diffusion of this knowledge. Project members tried to do that by searching for ways that make sharing, expressing and retrieving knowledge easier. Therefore they looked at networks, documents, organizations etc. The results are realized in a working prototype. The prototype makes use of the concept of a knowledge map integrated with a database with grey literature.Findings – In general the evaluation of the Tunnel Center prototype has been positive in terms of the projects research questions.Research limitations/implications – The most important lesson learned is that information needs of the different user groups seem to differ more than was realized in the beginning. The project team is very keen to work on this problem in a possible next phase of the project.Practical implications – The knowledge developed in...

Linking SWAT and SOBEK Using Open Modeling Interface (OpenMI) for Sediment Transport Simulation in the Blue Nile River Basin

Computer models assist basin-scale decision making by taking into account upstream-downstream interdependencies. The SWAT (hydrological) model code was developed into an OpenMI-compliant version and linked with the SOBEK (hydrodynamic) model to extend SWATs simulations of basin-scale streamflow and sediment transport. The development of an OpenMI-compliant version of SWAT involved reorganizing the SWAT model code and wrapping it with the OpenMI wrapper utility. The modified SWAT model was linked to the SOBEK model and applied to simulate sediment transport in the Blue Nile River basin. The SWAT model simulated the streamflow and soil erosion in the upstream catchment, while the SOBEK model routed the streamflow and sediment downstream to the basin outlet. Prior to the linking, both the SWAT and SOBEK models were individually calibrated. The results showed that the coupled models simulated the observed hydrodynamics and sediment deposition due to backwater effects, which would not be possible with the SWAT model alone. The developed OpenMI-compliant SWAT model can further be linked to groundwater, climate change, and socioeconomic models to address integrated water resources management needs.

Model-Based Optimization of Downstream Impact during Filling of a New Reservoir: Case Study of Mandaya/Roseires Reservoirs on the Blue Nile River

The aim of this paper is to develop a methodology based on coupled simulation-optimization approach for determining filling rules for the proposed Mandaya Reservoir in Ethiopia with minimum impact on hydropower generation downstream at Roseires Reservoir in Sudan, and ensuring power generation at Mandaya Reservoir in Ethiopia. The Multi-Objective Optimization (MOO) approach for reservoir optimization presented in this paper is a combination of simulation and optimization models, which can assist decision making in water resource planning and management (WRPM). The combined system of reservoirs is set in MIKE BASIN Simulation model, which is then used for simulation of a limited set of feasible filling rules of the Mandaya reservoir according to the current storage level, the inflow, and the time of the year. The same simulation model is then coupled with Multi-Objective optimization Non-dominated Sorting Genetic Algorithm (NSGA-II), which is adopted for determining optimial filling rules of the Mandaya Reservoir. The optimization puts focus on maximization of hydropower generation in both the Mandaya and the Roseires Reservoirs. The results demonstrate that optimal release- (and correspondingly filling-) rules for Mandaya Reservoir which maximize the hydropower generation in both Mandaya and Roseires reservoirs can be found. These rules are determined along the Pareto frontier obtained by the optimization algorithm, which can serve as a decision support tool for choosing the actual filling rule. The results also showed that the NSGA- II is an efficient and powerful tool that could assist decision makers for solving optimization problems in complex water resource systems.

Integrated modelling for flood risk mitigation in Romania: case study of the Timis–Bega river basin

An integrated flood modelling approach has been applied in a demonstrator of a flood management system, which was developed within the framework of a collaborative project between Romania and the Netherlands. The developed demonstrator system had two objectives: (a) operational water management under extreme conditions when actions have to be taken quickly; (b) off-line analysis and design of flood mitigation measures and alternatives. This article presents the applied approach and the achieved results for meeting the second objective. The pilot basin for the development of the system was the Timis–Bega river basin, in which the rivers Timis and Bega were considered jointly. The system is based on modelling the flood generation and routing processes by combined development and application of hydrological and hydrodynamic models. The modelling system HEC-HMS was used for the hydrological model, HEC-RAS for the one-dimensional hydrodynamic model and SOBEK for the two-dimensional (2D) model used for downstream flood analysis and design of mitigation measures and alternatives. The 2D model includes alternatives of deliberate dike breaching as part of the analysis of the system response. The analysis presented is concentrated on a specific flood event that occurred in April 2005, which occurred due to dike breaches along the Timis river. The combination of models is first used for reconstruction of inundation patterns resulting during this flood event. Subsequently the models were used for testing flood mitigation alternatives of deliberate (planned) breaches of flood protection dikes located in the downstream part of the Timis river at the same location where they had occurred during the 2005 flood event, but at different times with respect to the arrival of the flood hydrograph. The demonstrated approach can enable decision-makers to analyse the behaviour of the physical system and design possible preventive and/or mitigation measures.

Shatt al Arab River system under escalating pressure: a preliminary exploration of the issues and options for mitigation

ABSTRACT This paper provides a broad description of the current state of hydrological and geographical characteristics of the Shatt al Arab River (SAR), and analyses the severe decline in water quantity and escalating levels of salinity. The analyses cover SAR as well as all contributing rivers and Mesopotamian Marshlands, which is essential to present a holistic picture of the issues. The analyses are based on the most recent data, though limited, on water availability, water resources development and management infrastructure, and water quality status. The study shows that the water inflows have significantly reduced and the water quality status has deteriorated to alarmingly high levels, especially from Basra to the river mouth. The crisis can only be averted through the cooperative water management initiatives taken by all the riparian countries, which require a paradigm shift from the current approach of unilateral water management planning to international cooperation and management on the shared water resources. The crisis mitigation strategies should find ways of increasing inflows and improving water quality from the upstream source rivers. At the same time, local measures are required to avoid drainage of poor-quality domestic and industrial effluents and highly saline water from the marshes into the SAR. These efforts should be supported by sound scientific information, which is also limited at the moment.

Distance Learning in Support of Water Resources Management: An Online Course on Decision Support Systems in River Basin Management

This paper presents the conceptualisation, design and implementation of an online course on the topic of Decision Support Systems in River Basin Management. The need for development of such a course has been recognised, as activities in the field of water resources planning and management increasingly depend on decision support methods such as simulation, optimisation and Multi Criteria Analysis (MCA). The online learning approach is particularly needed for continuous professional development and life-long learning of professionals active in this field, and especially for those coming from developing countries. The course was developed and implemented following the competence-based learning approach, supported by the EU FP 7 educational research project named TenCompetence, which also provided the learning platform for deploying and delivering the course. The paper presents the course design, implementation and evaluation by the course participants, with special focus on the course content and the developed learning resources. Participants’ evaluations show high appreciation for the course, but they also highlight areas for future improvements.