Evaluating adaptation options to sea level rise and benefits to agriculture

Subtitle:the Ebro Delta showcase

Sea level rise (SLR) is threatening low-lying coastal areas such as river deltas. The Ebro river Delta (Spain) is rep-resentative of coastal systems particularly vulnerable to SLR due to significant sediment retention behind up-stream dams (up to 99%), thereby dramatically reducing the capacity for deltaic sediment accretion. Rice production is the main economic activity, covering 66% of the delta area, and is negatively affected by SLR because of flooding and soil salinization. Therefore, appropriate adaptation measures are needed to preserve rice produc-tion. We combined Geographic Information Systems and Generalized Linear Models to identify zones prone to flooding and increasing soil salinity, and to calculate the so-called sediment deficit, that is the amount of sedi-ment needed to raise the land to compensate flooding and soil salinization. We modelled SLR scenarios predicted by the IPCC Fifth Assessment Report, and analysed the economic feasibility (not the technical feasibility) of reintroducing fluvial sediments retained in the upstream river dam reservoirs into the delta plain, which can con-tribute to maintaining land elevation and rice production with SLR. To do this, the costs of the sediment reintro-duction measures and their benefits in terms of avoided loss of rice production income were evaluated with an approximate economic cost-benefit analysis. Results predicted that between 35 and 90% of the rice field area will be flooded in the best and worst SLR scenarios considered (SLR = 0.5 m and 1.8 m by 2100, respectively), with a sediment deficit of 130 and 442 million tonnes, with an associated cost of sediment reintroduction of 13 and 226 million euro . The net benefit of rice production maintenance was 24.6 and 328 euro /ha. The proposed ad-aptation measure has a positive effect on rice production and can be considered as an innovative management option for maintaining deltaic areas under SLR. (c) 2021 Elsevier B.V. All rights reserved.

Publication year:2022

Keywords:A1 Journal article

Accessibility:Open