Investigating the potential of using simple SuDS in informal settlements in Lagos, Nigeria to transition to a sustainable surface water management system

Abstract

Rapid urbanisation, coupled with climate change, highlights the underperformance and failure of current conventional water management systems. Flooding during the rainy season has become a yearly phenomenon for most countries across Africa, with the poor, living in slums or informal settlements being impacted the most. In order to better manage this problem, this research investigated the potential of adopting a sustainable alternative: sustainable surface water management (SSWM) systems. A transition framework was developed to deliver SSWM focused on informal settlements using sustainable drainage systems (SuDS) as the major driver. SSWM systems reduce runoff by treating stormwater as close as possible to its source, preferably on site. Presently, there appears to be a paradigm shift towards more SSWM practice in developed countries with the growing adoption of SuDS to replace or work in conjunction with, existing conventional drainage methods. However, less-developed countries (LDCs) such as those in West Africa still rely solely on conventional drainage methods.

Lagos, Nigeria was chosen as the study site, as it suffers regular flooding, is surrounded by informal settlements, and the existing drainage infrastructure is generally not fit for purpose. A mixed research method was adopted to collect data for this study. This entailed the administration of questionnaires, interviews and focus group meetings with relevant stakeholders, including residents, community leaders and government officials. Data was collected in 2 visits between April and August 2015 across 9 settlements in Lagos. The first visit comprised the administration of 150 questionnaires across the visited sites, and 76 of these were retrieved. Focus group meetings were also conducted to familiarise the respondents with SuDS. During the second visit, 154 questionnaires were retrieved of the 200 distributed, and interviews were carried out with 15 participants, including residents (formal and informal alike), community leaders and government officials.

The result from this study indicated that the informal settlers experienced more flooding episodes and also more severe incidences than those living in formal areas. Compared to the formal settlers, negative impacts were much worse and flood waters remained for longer periods in the informal settlements. Further findings showed that the government placed little or no emphasis on addressing these flooding issues in the informal areas. Additionally, the realisation that conventional systems are failing was highlighted in the results, as respondents indicated that blocked gutters were a major cause of flooding. It was also found that the informal residents were interested in the concept of SSWM and its implementation using SuDS in order to address the ongoing flooding issues. These findings clearly demonstrate a need to address these issues, hence, for the first time a framework has been developed focused on informal settlements to set out a process whereby SSWM could be achieved. This framework aims to guide stakeholders in the water management sector to achieve SSWM through the adoption of SuDS. The transition framework has been designed by adapting and building upon 4 existing water management frameworks, but tailored to suit developing countries. It has been evaluated by field experts across four countries: Nigeria, Gambia, Uganda and the UK. The evaluation process indicates that the framework is fit for purpose and can deliver SSWM. The design consisted of 4 iterative phases: Phase 1, knowledge/change; Phase 2, strategy; Phase 3, tactics; and Phase 4, implementation and maintenance. It identifies the implementation of SuDS as an essential tool to ensure SSWM.

This study has collected data on flooding issues and events amongst selected informal settlements that have not been previously investigated or recorded. This data was a prerequisite for the development of a novel framework to guide the transitioning to SSWM by all stakeholders. The use of simple yet effective methods have been investigated and evaluated to sustainably manage runoff in this study. Furthermore, the framework delivers a sense of responsibility to residents as well as officials to effect positive and sustainable change to their water management systems, not just in Nigeria but in other LDCs.

Date of Award	Mar 2019
Original language	English
Awarding Institution	Coventry University
Supervisor	SM Charlesworth (Supervisor) & Frank Warwick (Supervisor)