- 20th July 2018
- Posted by: Sophie Smith
- Category: Blog
Our geomorphology team are working with the World Bank to investigate how erosion and sedimentation problems in Dar es Salaam, Tanzania are influencing river processes and flood risk within Tanzania’s largest city. Matt Hemsworth, Lead Geomorphologist, and Becca Thrower, Geomorphologist, travelled to Dar es Salaam at the start of this month to carry out site work and meet with stakeholders involved in the project.
Four days were spent visiting several key areas within Dar es Salaam and the outlying more rural headwaters areas. The team were aided by members of the local World Bank team who were able to provide valuable insight into catchment-related issues and transport the team around the city on some of Dar es Salaam’s more challenging unpaved roads.
An insight into the city
As well as making for interesting driving, the unpaved roads expose vast expanses of readily erodible bare earth. The city is underlain by loose, sandy and loamey soils, which are very susceptible to erosion.
Slope failures were frequently observed, as were gullies which have formed at the roadside where vegetation has been stripped away and the bare soil is made vulnerable to erosion from runoff and wind. Urbanisation and deforestation are key drivers behind the sediment erosion issues in the city.
As well as a chance to see key areas and gain an impression of the main geomorphological processes taking place within the rivers at different stages of their development, the World Bank Mission provided an opportunity to meet key stakeholders including:
- Members of local authorities
- Students from the universities
- World Bank staff
- Local engineers
- City planners.
This provided a valuable insight into local management practises and information on recent flood events and changes within the rivers and their floodplains.
Supporting future development within the city
Whilst in Tanzania the team attended the 6th Msimbazi Charrette, a multi-stakeholder workshop coordinated by the World Bank and PO-RALG to develop a detailed plan for flood mitigation in the Msimbazi valley, in Dar es Salaam. This was a valuable experience, allowing geomorphology to be considered at the catchment scale along with providing an insight into other city wider projects, including the development of a new city masterplan.
The aim of this first World Bank Mission was to observe first-hand the rivers and their catchments in Dar es Salaam, collecting information on morphological processes and the pressures impacting river behaviour. It was clear after only a short period of time in the city that the rapid rate of urbanisation is impacting rivers on a large scale.
We will now continue working with the World Bank over the coming months to identify short and longer-term solutions and
strategies to combat erosion and sedimentation problems.
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