Abstract:The present paper describes a methodological framework that combines ecosystem services (flood protection, education, art/culture, recreation and tourism) with economic analysis for selection of multifunctional measures for flood resilience. The framework includes active stakeholder participation and it consists of the four main components: (1) identification and valuation of ecosystem services pertinent to the project site under various mitigation scenarios, including baseline (pre-mitigation conditions); (2) evaluation of most effective flood mitigation measures through hydrodynamic simulations, and evaluation of economic viability using cost-benefit analysis; (3) selection of measures through consideration of ecosystem services, and solicitation of stakeholders' inputs; (4) development of the conceptual landscape design. Application of the framework was demonstrated in a case study of Ayutthaya Island, Thailand. Results of our research suggest that taking a holistic perspective of ecosystem services and economic assessments, marshalled through active stakeholder participation, has the potential to achieve more ecologically sustainable and socially acceptable solutions for flood protection in areas with cultural heritage. However, there is still a considerable challenge in taking this framework to a full-scale practical implementation, and this mainly relates to the selection of indicators that can enable proper application of ecosystem services.

Floods cause considerable damages worldwide and mitigation of their adverse effects through effective protection measures is needed. Along with the commonly applied “grey” infrastructure, “green” measures that can offer additional benefits, such as ecosystem services, are increasingly being considered lately. While the recent research tendencies are focused on the effectiveness and the value of green measures in urban areas, this paper presents a comprehensive financial evaluation of green and grey flood mitigation scenarios for a smaller rural watershed. A micro-scale damage model that builds on the hydrodynamic modeling of hazard, detailed asset identification, and damage assessment is presented and applied for evaluation of benefits from various flood mitigation measures in the Tamnava watershed in Serbia. Four scenarios are considered: (1) existing flood protection system; (2) green scenario involving new detention basins; (3) grey infrastructure enhancement by rising of the existing levees and diverting flood discharges; and (4) green-grey scenario that combines scenarios (2) and (3). The benefits (loss reduction) are the greatest with the green scenario and marginally higher with the combined green-grey scenario. The results suggest that for small rural watersheds, a holistic, integrative approach that includes both types of infrastructure can provide the most effective flood risk mitigation.

<p>Urbanization and climate change are making societies around the world more vulnerable to flooding. Effective and sustainable adaptation measures are needed to counteract the impacts of these changes and Nature-Based solutions have gained considerable attention for both mitigation and adaptation methods of flood risk reduction. However, methodologies to evaluate their performance and upscale their implementation are lacking. Performance evaluation in particular is an important process for decision-makers to be able to decide on the most desirable measures to be implemented. The present research aims to develop a methodology for evaluating the effectiveness of NBS in reducing flood risk. The hydrological model (HEC-HMS) and 1D-2D hydrodynamic model (HEC-RAS) were coupled to create probabilistic inundation depth maps. A detailed flood damage model is then built and applied to estimate damage with and without the measures. The flood damage model was developed within the model builder in ArcGIS so that it can be easily replicated with many scenarios. Four measures were selected for the analyses, namely; reforestation, retention ponds, riparian buffer stripes, and bridge removal. This methodology has been applied to the case study of the Tamnava River Basin in Serbia within the EU-funded RECONECT project.</p>

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