Integrating knowledge to assess coastal vulnerability to sea-level rise: The development of the DIVA tool

Abstract

This paper describes the development of the DIVA tool, a user-friendly tool for assessing coastal vulnerability from subnational to global levels. The development involved the two major challenges of integrating knowledge in the form of data, scenarios and models from various natural, social and engineering science disciplines and making this integrated knowledge accessible to a broad community of end-users. These challenges were addressed by (i) creating and applying the DIVA method, an iterative, modular method for developing integrating models amongst distributed partners and (ii) making the data, scenarios and integrated model, equipped with a powerful graphical user interface, directly and freely available to end-users.

Introduction

Knowledge on coastal vulnerability enables scientists and policymakers to anticipate impacts that could emerge as a result of sea-level rise and other effects of climate change. It can thus help to prioritize management efforts that need to be undertaken to minimize risks or to mitigate possible consequences. In view of the high natural and socio-economic values that might be threatened or lost in coastal zones (Nicholls et al., 2007), it is therefore important to identify the types and magnitude of problems that different coastal areas may have to face, as well as possible solutions.

Global vulnerability assessments carried out by Hoozemans et al. (1993) and Baarse (1995) suggest that some 189 million people presently live below the once-per-1000-years storm-surge level. They estimate that, under current conditions, an average of 46 million people per year experience storm-surge flooding. Hoozemans et al. (1993) estimate that this number would rise to over 100 million people per year, assuming 1 m of sea-level rise and 30 years of socio-economic development. The assessment also projects that, under the same scenario, 59% of coastal wetlands will be lost.

These global vulnerability assessments played a central part in the preparation of the World Coast Conference 1993 and several IPCC reports. They have also been used extensively for further academic analyses, including integrated assessment modelling. However, with the widespread use of the global assessments, their limitations have become increasingly apparent. These limitations include the following:

• The obsolescence and low spatial resolution of underlying data sources;

• the limited number of scenarios used;

• the reliance of global mean sea-level rise as the only driver of coastal vulnerability;

• the non-consideration of bio-geophysical and socio-economic dynamics and feedback;

• arbitrary and rather simplistic assumptions regarding adaptation.

To address these limitations and thus provide updated policy-relevant information on coastal vulnerability involves two major challenges. First, knowledge in the form of data, scenarios and models from different natural, social and engineering science disciplines needs to be integrated in a much more comprehensive way than had ever been done for coastal vulnerability. This is particularly true for the feedbacks between natural and social systems, as well as including adaptation. Second, the integrated knowledge must be made available in a form that allows a diverse community of end-users and policy-makers to answer the specific questions they are confronted with.

This paper presents the systematic approach by which the EU-funded project DINAS-COAST (Dynamic and Interactive Assessment of National, Regional and Global Vulnerability of Coastal Zones to Sea-Level Rise) has addressed these challenges. The project developed an innovative, modular and iterative approach for integrating knowledge about coastal subsystems. This approach was then applied to produce the tool called DIVA (Dynamic and Interactive Vulnerability Assessment), a dynamic, interactive and flexible software tool that enables its users to produce quantitative information on a range of coastal vulnerability indicators, for user-selected climatic and socio-economic scenarios and adaptation strategies, on national, regional and global scales, covering all coastal nations. DIVA 1.5.5 was released on a CD-ROM in 2006 (DINAS-COAST Consortium, 2006) and is freely available for download from http://www.pik-potsdam.de/diva.

The purpose of this paper is not to give a full description of the integrated model itself. Rather the purpose is to present the process by which the integrated model was developed. In so doing, we hope to contribute to the methodological advancement of transdisciplinary, integrative science by providing the rapidly growing number of researchers active in this field with insights and tools that would enable many to tackle similar challenges. A detailed account of the integrated model can be found in the technical documentation that comes along with the tool (DINAS-COAST Consortium, 2006) and the academic literature (Hinkel, 2005, Hamilton et al., 2005, Brander et al., 2006, Vafeidis et al., 2006, Hinkel and Klein, 2007, McFadden et al., 2007a, McFadden et al., 2007b, Vafeidis et al., 2008).

The remainder of the paper is organized as follows. Section 2 presents a brief overview of the evolution of methodologies applied for assessing the vulnerability of coastal zones to sea-level rise. Section 3 analyses the requirements that resulted from the two challenges outlined above. Section 4 then presents the method designed to address these challenges, that is, the method applied to develop the DIVA tool. Section 5 presents the tool's structure and components. Section 6 briefly presents some results of DIVA and compares these with results obtained by Hoozemans et al. (1993) and Baarse (1995). Section 7 discusses lessons learned in developing DIVA, and their significance to transdisciplinary science in general, and to vulnerability assessment in particular. Finally, Section 8 presents conclusions and proposes activities for future work.