This activity has created an action plan to reduce flood damage in the urban area of Riohacha, based on the concept of Sustainable Urban Drainage Systems (SUDS) and Urban River Restoration.

Fast facts:

• 450 households were interviewed for the system diagnostic which helped to calibrate the model in terms of topographical and hydrological conditions of the study area in order to get effective and efficient solution strategies.

The problem

The study area, a locality in the coastal city of Riohacha, Colombia, has a linear complex of four mixed wetlands (natural and intervened) which cross the urban area longitudinally in its totality and that delineate the main axis of drainage. In this basin, most of the population is exposed to significant flood events due to the lack of land management and response to disasters. 

The solution

A comprehensive plan supported by a dynamic flood modeling exercise with the use of MODCEL software which quantifies the system’s response to external forces and possible physical interventions. With a multi-criteria evaluation of solution alternatives, seven potential solutions were defined based on the Sustainable Urban Drainage Systems (SUDS) criteria and the Urban River Recovery:
i. “Flooded parks”, this is, semi-natural areas or sport facilities adapted to temporarily store water volumes without large damage.
ii. A “Green corridor” that will recover the natural drainage axis across the wetlands in the city.
iii. The morphological redesign of some wetlands to increase their storage capacity and to improve their draining characteristics.
iv. Reconnection to the historical natural wetland Laguna Salada with the Riito river.
v. A by-pass with underground drainage towards the lagoon El Padrón to divert excess flow from the upper basin.
vi. Lateral flaps in the lower culvert to avoid backflow in high seas and/or flood conditions, and low precipitation in the urban basin.
vii. New underground drainage solutions to address local floods and the fix of some current local drainage proposed by the community.

Most of their indications have already been incorporated in the local Territorial Management Planning (Plan de Ordenamiento Territorial, “POT”), the main legal instrument for land use regulation in any city in Colombia.

Helping the planet

Urban sprawl in developing countries represents major challenges for land management in flood situations. This project helps as an example to establish risk reduction measures for disasters caused by climate change.

Helping people

The project has a strong public participation process at both institutional and community levels. It will improve the drain system of the locality, enhancing the multiple hydraulic outputs and the reconnection to the wetlands system.

Scaling Up

The study plans the construction of a demonstrative pilot project to be visible and replicable in every context. As a pioneering city in the local management to adapt to climate change and territorial resilience, it has attracted important organizations of international cooperation to finance further projects.

Images owned by the activity partners, all rights reserved.