Developing and managing floodplains in a context of global change - COSTEA

The project aims to identify and design nature-based solutions to control environmental risks (flooding and pollution) in the Gharb floodplain, Morocco, where wetlands and intensive irrigated agriculture coexist.
Flooded pathway after heavy rain © P. Silvie, CIRAD
Flooded pathway after heavy rain © P. Silvie, CIRAD

Flooded pathway after heavy rain © P. Silvie, CIRAD


The Gharb floodplain in Morocco, which is subject to summer droughts, saline intrusions and winter flooding, began its agricultural development in the 1920s with the construction of irrigation and drainage networks. However, the plain's limited natural capacity to drain floodwater to the ocean makes it particularly vulnerable to the flooding caused by winter rains in the Sebou watershed, which causes significant crop losses. On the plain, several more or less temporary wetland zones act as a buffer with respect to flooding and play an agricultural role, particularly for pastoralism, and an ecological role, as a biodiversity reserve and natural agricultural effluent purification system. The COSTEA project aims to exploit their multifunctionality, in interaction with developed, irrigated zones, using a new ecological engineering approach that remains largely undeveloped in this context.


The project includes five work packages:

  • understanding the vulnerability and functionalities of the wetlands,
  • characterizing the surface and subsurface hydrology of the floodplains and their hydraulic infrastructures,
  • identifying socioeconomic and environmental trade-offs between proposed green and grey infrastructures,
  • conducting territorial consultations,
  • monitoring and cross-capitalization by combining research results from the COSTEA structuring action projects in Cambodia and Ecuador.

Expected impacts

  • A wider community, including farmers and institutional players, will be aware of the environmental and socioeconomic benefits of merjas (marshes).
  • Closer cooperation will have been built between Moroccan institutions in charge of the environment and of agriculture.
  • In the longer term, with additional financial investment, development of the Gharb floodplain in line with the project's recommendations should serve to reduce the negative impacts of flooding on crops and thus improve food security for the population groups concerned.

Contract partner

Institut Agronomique et Vétérinaire Hassan II, Rabat (Morocco)