Master plan and no-regret measures for urban drainage

Trinidad and Tobago is prone to flooding in both urban and rural areas. This flooding leads to significant loss in terms of access, property, agriculture and human health, and to the degradation of Trinidad’s quality of life. A consortium consisting of Witteveen+Bos, Trintoplan and EcoEngineering has created a strategic drainage plan, a final design, and tender documents for urgent, no-regret urban drainage management measures.

At the request of the Development Bank of Latin America (CAF), Witteveen+Bos:

• Prepared a strategic drainage plan which guides the government and CAF in formulating a joint investment programme to implement urgent flood control measures;
• Created final designs and tender documents for the urgent, no-regret flood control measures that were included as recommendations in the strategic drainage plan.

Collecting and analysing the existing literature and studies posed a challenge due to differing levels of detail. The selection of the urgent no-regret flood control measures was also complex. The main reason for this was the differing criteria that needed to be considered – relating to effectiveness as well as technical, cost-related, environmental and/or stakeholder-related aspects – which generated contradictions and dilemmas. As well as this, the situation surrounding corona meant that sessions with external stakeholders and internal meetings had to be conducted digitally, because of travel restrictions.

The starting point for the strategic drainage plan consists of short- and medium-term flood control measures. Witteveen+Bos formulated these for each catchment area using existing literature, earlier studies, and our own research. The strategy for each catchment area was subsequently discussed with the government and CAF and then adopted. Using the strategic drainage plan as a basis, CAF approved financing for the urgent, no-regret control measures.