Suchergebnisse

Abstract. Intertidal wetlands, such as mangroves in the tropics,
are increasingly recognized for their role in nature-based mitigation of
coastal flood risks. Yet it is still poorly understood how effective they
are at attenuating the propagation of extreme sea levels through large
(order of 100 km2) estuarine or deltaic systems, with complex geometry
formed by networks of branching channels intertwined with mangrove and
intertidal flat areas. Here, we present a delta-scale hydrodynamic modelling
study, aiming to explicitly account for these complex landforms, for the
case of the Guayas delta (Ecuador), the largest estuarine system on the
Pacific coast of Latin America. Despite coping with data scarcity, our model
accurately reproduces the observed propagation of high water levels during a
spring tide. Further, based on a model sensitivity analysis, we show that
high water levels are most sensitive to the mangrove platform elevation and
degree of channelization but to a much lesser extent to vegetation-induced
friction. Mangroves with a lower surface elevation, lower vegetation density,
and higher degree of channelization all favour a more efficient flooding of
the mangroves and therefore more effectively attenuate the high water levels
in the deltaic channels. Our findings indicate that vast areas of
channelized mangrove forests, rather than densely vegetated forests, are
most effective for nature-based flood risk mitigation in a river delta.