Trends in flood risk management in deltas around the world

Are we going ‘soft’?

Abstract

Flood-risk management (FRM) is shaped by context: a society’s cultural background; physical
possibilities and constraints; and the historical development of that society’s economy,
political system, education, etc. These provide different drivers for change, in interaction with more
global developments. We compare historical and current FRM in six delta areas and their contexts:
Rhine/Meuse/Scheldt (The Netherlands), Pearl River (China), Mekong (Vietnam), Ganges/
Brahmaputra/Meghna (Bangladesh) Zambezi/Limpopo (Mozambique), and Mississippi (USA).
We show that in many countries the emphasis is shifting from ‘hard’ engineering, such as dikes,
towards non-structural ‘soft’ measures, such as planning restrictions or early warning systems,
while the ‘hard’ responses are softened in some by a ‘building with nature’ approach. However,
this is by no means a universal development. One consistent feature of the application of ‘hard’
FRM technology to deltas is that it pushes them towards a technological ‘lock-in’ in which fewer
and fewer ‘soft’ FRM alternatives are feasible due to increased flood risks. By contrast, ‘soft’
FRM is typically flexible, allowing a range of future options, including future hard elements if
needed and appropriate. These experiences should lead to serious reflection on whether ‘hard’
FRM should be recommended when ‘soft’ FRM options are still open.