Wolfgang Dorner

Evaluating cartographic design in flood risk mapping

In order to mitigate flood hazards and to minimize associated losses, technical protection measures have been additionally and increasingly supplemented by non-technical mitigation, i.e. land-use planning activities. This is commonly done by creating maps which indicate such areas by different cartographic symbols, such as colour, size, shape and typography. Hazard and risk mapping is the accepted procedure when dealing with natural hazards and is therefore required in the European Member States in order to meet the demands of the European Flood Risk Directive. However, available information is sparse concerning the impact of such maps on different stakeholders, i.e. specialists in flood risk management, politicians and affected citizens. The lack of information stems from a traditional approach to map production which does not take into account specific end-user needs. In order to overcome this information shortage the current study used a circular approach such that feedback mechanisms originating from different perception patterns of the end user would be considered. Different sets of small-scale as well as large-scale risk maps were presented to different groups of test persons in order to (1) study reading behaviour as well as understanding and (2) deduce the most attractive components that are essential for target-oriented communication of cartographic information. Therefore, the method of eye tracking was applied using a video-oculography technique. This resulted in a suggestion for a map template which fulfils the requirement to serve as an efficient communication tool for specialists and practitioners in hazard and risk mapping as well as for laypersons. Taking the results of this study will enable public authorities who are responsible for flood mitigation to (1) improve their flood risk maps, (2) enhance flood risk awareness and, therefore, (3) create more disaster-resilient communities.

Flood Risk and Flood hazard maps – Visualisation of hydrological risks

Hydrological models are an important basis of flood forecasting and early warning systems. They provide significant data on hydrological risks. In combination with other modelling techniques, such as hydrodynamic models, they can be used to assess the extent and impact of hydrological events. The new European Flood Directive forces all member states to evaluate flood risk on a catchment scale, to compile maps of flood hazard and flood risk for prone areas, and to inform on a local level about these risks. Flood hazard and flood risk maps are important tools to communicate flood risk to different target groups. They provide compiled information to relevant public bodies such as water management authorities, municipalities, or civil protection agencies, but also to the broader public. For almost each section of a river basin, run-off and water levels can be defined based on the likelihood of annual recurrence, using a combination of hydrological and hydrodynamic models, supplemented by an analysis of historical records and mappings. In combination with data related to the vulnerability of a region risk maps can be derived. The project RISKCATCH addressed these issues of hydrological risk and vulnerability assessment focusing on the flood risk management process. Flood hazard maps and flood risk maps were compiled for Austrian and German test sites taking into account existing national and international guidelines. These maps were evaluated by eye-tracking using experimental graphic semiology. Sets of small-scale as well as large-scale risk maps were presented to test persons in order to (1) study reading behaviour as well as understanding and (2) deduce the most attractive components that are essential for target-oriented risk communication. A cognitive survey asking for negative and positive aspects and complexity of each single map complemented the experimental graphic semiology. The results indicate how risk maps can be improved to fit the needs of different user groups. Recommendations were developed of how to provide stakeholder-oriented information on hydrological risks.

Photogrammetric Point Clouds for GIS-Based High-Resolution Estimation of Solar Radiation for Roof-Top Solar Systems

Solar radiation is the main factor that must be considered when predicting solar systems energy output. Especially in built-up areas the use of Digital Surface Models (DSM) and analysis with Geographic Information Systems (GIS) has gained popularity for these predictions in recent years. However, the identification of small objects and their impact in the shadowing of solar systems is a very important factor that cannot be entirely acquired by models from common available Light Detection and Ranging (LiDAR) data. Thus higher resolutions DSMs are required. These can be generated from photogrammetric point clouds derived from Unmanned Aerial System (UAS) based large scale image flights. This paper presents a comparison between a common available resolution DSM generated from standardized LiDAR data and a DSM with very high resolution from photogrammetric point clouds. The added value of using high-resolution DSMs for solar radiation estimation for PV rooftop-systems is discussed with a focus on elevation, slope, aspect and on the suitability for selection of usable roof-top areas. Although DSMs with resolutions up to 1 cm have been generated, the results show that a DSM of 25 cm is enough for considering all small roof-top objects that are relevant for estimation of solar radiation.

Integrated modelling and the impacts of water management on land use

River systems and the quantity and quality of water depend on the catchment, its structure and land use. In central Europe especially land is a scarce resource. This causes conflicts between different types of land use, but also with the interests of flood protection, nature conservation and the protection of water resources and water bodies in the flood plain and on a catchment scale. ILUP – Integrated Land Use Planning and River Basin Management was a project, funded by the European Union, to address the problems of conflicting interests within a catchment. It addressed the problems of conflicting land use from a hydrological perspective and with regard to the resulting problems of water management. Two test river basins, Vils and Rott, both with a catchment size of about 1000 square kilometres, were considered for the German part of the project. Objective of the project was to identify means of managing land use with regard to water management objectives and adapt planning strategies and methodologies of water management authorities to the new needs of catchment management and planning. Catchment models were derived to simulate hydrological processes, assess the safety of dams and improve the control strategy of detention reservoirs with regard to land use in the lower system. Hydrodynamic models provided the basis to assess flood prone areas, evaluate flood protection measures and analyze the impacts of river training and discharge on morphology. Erosion and transport models were used to assess the impacts of land use on water quality. Maps were compiled from model results to provide a basis for decision making. In test areas new ways of planning and implementation of measures were tested. As a result of model scenarios in combination with the socio economic situation in the catchment new methods of land management and land use management were derived and implemented in model areas. The results of the project show that new ways of managing land use in river catchments are necessary to fulfil quantitative and qualitative criteria of new European legal regulations. The paper presents means to use hydrological models and data as a basis of land use planning and river basin management.

A review of spatial localization methodologies for the electric vehicle charging infrastructure

Abstract With view to the high share of the transport sector in total energy consumption, e-mobility should play an important role within the transition of the energy systems. Policymakers in several countries consider electric vehicles (EV) as an alternative to fossil-fueled vehicles. In order to allow for the development of EV, the charging infrastructure has to be set up at locations with high charging potential, identified by means of various criteria such as demand density or trip length. Many methodologies for locating charging stations (CS) have been developed in the last few years. First, this paper presents a broad overview of publications in the domain of CS localization. A classification scheme is proposed regarding modeling theory and empirical application; further on, models are analyzed, distinguishing between users, route or destination centricity of the approaches and outcomes. In a second step, studies in the field of explicit spatial location planning are reviewed in more detail, that is, in terms of their target criteria and the specialization of underlying analytical processes. One divergence of these approaches lies in the varying level of spatial planning, which could be crucial depending on the planning requirements. It is striking that almost all CS locating concepts are proposed for urban areas. Other constraints, such as the lack of extensive empirical EV traffic data for a better understanding of the driving behavior, are identified. This paper provides an overview of the CS models, a classification approach especially considering the problem’s spatial dimension, and derives perspectives for further research.

Proving the ecosystem value through hydrological modelling

Ecosystems provide valuable functions. Also natural floodplains and river structures offer different types of ecosystem functions such as habitat function, recreational area and natural detention. From an economic stand point the loss (or rehabilitation) of these natural systems and their provided natural services can be valued as a damage (or benefit). Consequently these natural goods and services must be economically valued in project assessments e.g. cost-benefit-analysis or cost comparison. Especially in smaller catchments and river systems exists significant evidence that natural flood detention reduces flood risk and contributes to flood protection. Several research projects evaluated the mitigating effect of land use, river training and the loss of natural flood plains on development, peak and volume of floods. The presented project analysis the hypothesis that ignoring natural detention and hydrological ecosystem services could result in economically inefficient solutions for flood protection and mitigation. In test areas, subcatchments of the Danube in Germany, a combination of hydrological and hydrodynamic models with economic evaluation techniques was applied. Different forms of land use, river structure and flood protection measures were assed and compared from a hydrological and economic point of view. A hydrodynamic model was used to simulate flows to assess the extent of flood affected areas and damages to buildings and infrastructure as well as to investigate the impacts of levees and river structure on a local scale. These model results provided the basis for an economic assessment. Different economic valuation techniques, such as flood damage functions, cost comparison method and substation-approach were used to compare the outcomes of different hydrological scenarios from an economic point of view and value the ecosystem service. The results give significant evidence that natural detention must be evaluated as part of flood mitigation projects. In addition can be stated that the loss of detention due to land use and dikes can be called an externality and results in economic inefficiencies.