Urban Form and Climate Change: Enhancing the Resilience of Mathare Valley Informal Settlement in Nairobi City, Kenya

Abstract

Informal settlements within cities are often the most vulnerable areas to climate change due to their location in hazard prone areas, high density of population and poorly constructed structures, as well as the poor condition, or inadequacy of infrastructural facilities. Mathare Valley which is one of Nairobi’s largest informal settlements, houses an estimated population of 122,115 people in an area of 1.16 square kilometres. Disasters caused by weather extremes such as flooding have been documented within Mathare Valley, yet a knowledge gap on the interaction between urban form and climate disasters in the settlement exists. This research therefore sought to assess the urban form-climate change link for the urban poor and propose solutions for incorporation of this knowledge into urban planning and infrastructure design for enhanced resilience to climate change. This research was based on critical review of documented literature and detailed field surveys. Data collection involved administration of 100 household questionnaires, 13 commercial enterprise questionnaires, and interviews with three key informants, as well as one focus group discussion. Urban form information was collected from historical documents, field mapping and aerial images. Data analysis involved the use of the Statistical Package for Social Sciences (SPSS) to generate descriptive statistics such as frequencies and cross-tabulations, as well as geo-spatial analysis of urban form and climate risks. Data presentation within this thesis report encompasses the use of narrative writing, maps, charts, tables, graphs and diagrams. This research found that Mathare Valley faces climate change impacts in the form of heat stress, flooding, landslides, aridity and cold stress. This is because of the settlement’s location within a riparian zone with steep cliffs in some areas, high density of structures, location of most residential and commercial activities on ground-level, the non-resilient nature of building materials, and the poor condition of infrastructural services such as roads, water and electricity. Ongoing upgrading initiatives within the slum such as road and culvert construction have led to a decrease in flooding disasters, but the resultant impact of increased settlement closer to Mathare River is mal-adaption. Shifting of building materials from mud to iron sheet to create more flood-resilient structures has created uncomfortable indoor conditions increasing thermal stress for residents. Further, the dense layout of iron sheets building in the slum has created uncomfortable thermal conditions at ground level with little opportunity for air circulation. The most vulnerable sub-sets of the community to thermal stress and flooding within the settlement, are residents living within the immediate vicinity of the river, women, children, the elderly, the sick, the disabled and persons working outdoors. On the other hand, persons residing within structures constructed on top of, or at the bottom of steep cliffs are the most vulnerable to landslide risk in the event of heavy rainfall. In conclusion, this research established a clear link between the urban form of Mathare Valley and the climate change impacts it faces. One fifth of the community proposed hard engineering solutions to flooding while the majority were in support of softer responses to climate risks. However, due to the high risks posed to both property and human life, this study proposes the relocation of structures located within the high-risk flooding and landslide zones, reinforcement of structures within the medium flooding zones and incorporation of cooler building materials such as clay bricks settlement-wide. This plan, however, can only be supported by responsive policy and further detailed research for its success.