Assessment of Social Vulnerability for River-Floods in Germany

The assessment of social vulnerability unveils hidden weaknesses and strengths of the human society towards a certain stressor or hazard. In this study, vulnerability is analysed in its relation to the hazard posed by extreme river-floods. The study starts with an assessment of the varying impacts that river-floods typically produce in Germany. Severe cases of floods of the rivers Danube in 2002, the river Elbe in 2002 and 2006 and at the river Rhine in 1993 and 1995 affected large areas in Germany. The review of the published research reveals that few studies have tackled hidden issues of flood risk like social vulnerability here. At the county level, this study develops a pilot approach on how to identify and compare social vulnerability along river-channels in Germany. The concept enables later cross-validation with data and studies from other sources and other spatial levels. The theoretical foundation of this vulnerability assessment is the base-line for the methodological development of the vulnerability indicators which capture the exposure, susceptibility and capacities of social groups concerning river-floods. One important cornerstone of this study is a Social Susceptibility Index (SSI) map based on population characteristics for counties in Germany. This map is based on a composite index of three main indicators for social susceptibility in Germany - fragility, socio-economic conditions and regional conditions. These indicators have been identified by a factor analysis of selected demographic variables obtained from the Federal Statistical Office. Therefore, these indicators can be updated annually based on a reliable data source. The influence of the susceptibility patterns on disaster outcome is shown by an independent second data set of a real case event. It comprises a survey of flood-affected households in three federal states. By using logistic regression, it is demonstrated that the theoretically presumed indications of susceptibility are correct and that the indicators are valid. It is shown that indeed certain social groups like the elderly, the financially weak or the urban residents are susceptible groups. Additionally, the Social and Infrastructure Flood Vulnerability Index (SIFVI) map combines both social and infrastructure vulnerability as well as flood exposure scenarios and demonstrates the integration of hazard and vulnerability information. The SIFVI map is thus the first comprehensive map of its kind for Germany that identifies vulnerable counties and delivers validation. As part of the DISFLOOD project, this study is furthermore an example of how theoretically and methodologically a multi-disciplinary research can be carried out.Abschätzung von sozialer Verwundbarkeit für Flusshochwasser in Deutschland Die Abschätzung von sozialer Verwundbarkeit hat zum Ziel, potentielle Schwächen und Stärken der Gesellschaft gegenüber einem bestimmten Hazard, hier Hochwasser an Flüssen, aufzudecken. Die Studie beginnt mit einem Überblick über typische Auswirkungen von Hochwasser an Flussläufen in Deutschland. Hochwasser schweren Ausmaßes traten zuletzt an der Donau 2002, an der Elbe 2002 und 2006 und am Rhein 1993 und 1995 auf. Die Auswertung wissenschaftlicher Studien zeigt, dass nur wenige Ansätze bislang hierzu existieren, die soziale Verwundbarkeit behandeln. Die vorliegende Arbeit ist eine Pilotstudie darüber, wie soziale Verwundbarkeit auf Landkreisebene für ganze Flussläufe in Deutschland erkannt und verglichen werden kann. Das Konzept ermöglicht unter anderem eine spätere Kreuzvalidierung mit Quellen und Studien auf anderen räumlichen Ebenen. Das theoretische Konzept der Verwundbarkeitsabschätzung ist der Unterbau für eine Entwicklung von Verwundbarkeits-Indikatoren, welche die Exponiertheit, Anfälligkeit und Kapazitäten sozialer Gruppen gegenüber Hochwasser erfassen.  Ein Hauptbestandteil dieser Studie ist eine Karte der sozialen Anfälligkeit für Landkreise in Deutschland, welche aufgrund von statistisch erfassten Bevölkerungsmerkmalen erstellt wurde.  Diese Karte basiert auf drei Hauptindikatoren, welche für soziale Anfälligkeit in Deutschland identifiziert werden – Fragilität, sozio-ökonomische Bedingungen und regionale Bedingungen. Diese Indikatoren stammen aus einer Faktorenanalyse demographischer Daten des Statistischen Bundesamtes und können jährlich aktualisiert werden. Die Muster, die durch die Faktorenanalyse aufgedeckt werden, konnten mittels logistischer Regression aufgrund einer unabhängigen Datenbasis für einen realen Hochwasserkatastrophenfall bestätigt werden. Dieser unabhängige zweite Datensatz besteht aus einer Befragung betroffener Haushalte in drei Bundesländern. Die Ergebnisse zeigen, dass in der Tat bestimmte soziale Gruppen wie etwa die Älteren, die finanziell Schwächergestellten oder Stadteinwohner anfälliger sind. Ein kombinierter Index für Soziale Verwundbarkeit und die Verwundbarkeit von Infrastruktur gegenüber Hochwasser zeigt die Integrationsfähigkeit von Hazard- und Verwundbarkeitsinformationen auf. Als Teil des multidisziplinären Projekts DISFLOOD wird hiermit die erste validierte Karte sozialer Verwundbarkeit auf Landkreisebene in Deutschland vorgestellt

Shawn: A new approach to simulating wireless sensor networks

We consider the simulation of wireless sensor networks (WSN) using a new approach. We present Shawn, an open-source discrete-event simulator that has considerable differences to all other existing simulators. Shawn is very powerful in simulating large scale networks with an abstract point of view. It is, to the best of our knowledge, the first simulator to support generic high-level algorithms as well as distributed protocols on exactly the same underlying networks.Comment: 10 pages, 2 figures, 2 tables, Latex, to appear in Design, Analysis, and Simulation of Distributed Systems 200

Self-synchronized duty-cycling for sensor networks with energy harvesting capabilities: Implementation in Wiselib

In this work we present a protocol for a self- synchronized duty-cycling mechanism in wireless sensor net- works with energy harvesting capabilities. The protocol is im- plemented in Wiselib, a library of generic algorithms for sensor networks. Simulations are conducted with the sensor network simulator Shawn. They are based on the specifications of real hardware known as iSense sensor nodes. The experimental results show that the proposed mechanism is able to adapt to changing energy availabilities. Moreover, it is shown that the system is very robust against packet loss.Postprint (published version

The Geometric Maximum Traveling Salesman Problem

We consider the traveling salesman problem when the cities are points in R^d for some fixed d and distances are computed according to geometric distances, determined by some norm. We show that for any polyhedral norm, the problem of finding a tour of maximum length can be solved in polynomial time. If arithmetic operations are assumed to take unit time, our algorithms run in time O(n^{f-2} log n), where f is the number of facets of the polyhedron determining the polyhedral norm. Thus for example we have O(n^2 log n) algorithms for the cases of points in the plane under the Rectilinear and Sup norms. This is in contrast to the fact that finding a minimum length tour in each case is NP-hard. Our approach can be extended to the more general case of quasi-norms with not necessarily symmetric unit ball, where we get a complexity of O(n^{2f-2} log n). For the special case of two-dimensional metrics with f=4 (which includes the Rectilinear and Sup norms), we present a simple algorithm with O(n) running time. The algorithm does not use any indirect addressing, so its running time remains valid even in comparison based models in which sorting requires Omega(n \log n) time. The basic mechanism of the algorithm provides some intuition on why polyhedral norms allow fast algorithms. Complementing the results on simplicity for polyhedral norms, we prove that for the case of Euclidean distances in R^d for d>2, the Maximum TSP is NP-hard. This sheds new light on the well-studied difficulties of Euclidean distances.Comment: 24 pages, 6 figures; revised to appear in Journal of the ACM. (clarified some minor points, fixed typos

Assessment of contemporary Arctic river runoff based on observational discharge records

We describe the contemporary hydrography of the pan‐Arctic land area draining into the Arctic Ocean, northern Bering Sea, and Hudson Bay on the basis of observational records of river discharge and computed runoff. The Regional Arctic Hydrographic Network data set, R‐ArcticNET, is presented, which is based on 3754 recording stations drawn from Russian, Canadian, European, and U.S. archives. R‐ArcticNET represents the single largest data compendium of observed discharge in the Arctic. Approximately 73% of the nonglaciated area of the pan‐Arctic is monitored by at least one river discharge gage giving a mean gage density of 168 gages per 106 km2. Average annual runoff is 212 mm yr−1 with approximately 60% of the river discharge occurring from April to July. Gridded runoff surfaces are generated for the gaged portion of the pan‐Arctic region to investigate global change signals. Siberia and Alaska showed increases in winter runoff during the 1980s relative to the 1960s and 1970s during annual and seasonal periods. These changes are consistent with observations of change in the climatology of the region. Western Canada experienced decreased spring and summer runoff