Msimbazi River Basin City Park Project

Introduction

Dar es Salaam is one of the fastest urbanising cities on the continent. With an influx of approximately 1000 residents per day in Dar es Salaam and about 80% unplanned housing, the daily reality is that the government is playing catch-up (Worldbank Blogs, 2019; Kombe et al., 2015). The unplanned nature of the city affects the availability of infrastructure and services. For example, residents of Dar es Salaam spend an average of 170 minutes commuting per day (mostly by bus, so-called Dalladalla) (PO-RALG, 2023).  Another shocking fact is that only 2% of respondents in Tanzania feels at home (sense of belonging) in the city compared to where they come from (FES, 2022).

Rapid and unregulated urbanisation is swiftly diminishing green spaces in the city crucial for water infiltration within and around the city (Figures 2 and 3). Moreover, settlements and infrastructure are moving into floodplains due to a lack of space and housing options. As a result, large areas of urbanised land are flooded during the rainy seasons, including the Msimbazi basin (Figure 1). Other factors contributing to flooding include climate change, narrow bridge underpasses and increased erosion and sediment influx due to deforestation upstream.

Objectives of the study

The primary objective of this study was to mitigate the impact of flooding on settlements and critical infrastructure and promote resilient urban development in targeted communities within the Dar es Salaam Metropolitan Area. The study employs  globally recognised best practice on integrated (storm) water management and flood resiliency using nature-based solutions in a low-income country context.

The approach: design charrettes

Responding to the flood risk in Dar es Salaam, the Msimbazi Opportunity Plan was developed through a participatory design process, known as a ‘Charrette’ (Figure 4).

PO-RALG and the World Bank jointly coordinated the Charrettes, undertaken from January to August 2018. Through the Charrette process, the Msimbazi Strategy and Management Framework (MSMF) and the Detailed Plan for the Msimbazi Lower Basin were designed by a group of main stakeholders over a six month period. The Charrette was tailor-made and developed by Ecorys, DASUDA, CDR and Wema.

The Design Charettes took place in 30 work sessions, with more than 200 people from 59 institutions, such as community representatives, NGO’s, municipal councils, ministries, TANROADS, DAWASCO, Tanzanian Forest Service, National Land Use Planning Commision and others. Through the collective contributions of such a wide and diverse set of stakeholders, a unique opportunity was created to transform the Msimbazi Basin into a beacon of urban resilience.

The stakeholder Charrettes were based on the ACCA approach (Figure 5), the content of the different sessions being built around the following topics:

1) Understanding the challenges, complexity and its relevance for the Msimbazi;

2) Making an inventory of ideas from the stakeholders for possible interventions;

3) Envisioning Msimbazi futures

4) Designing the Msimbazi Strategy and Management Framework MSMF

5) Designing the Detailed Plan of the Msimbazi Valley

The Charrette stakeholders engaged not only in formulating strategies for the entire basin but also dedicated significant attention to designing the Lower Basin. Central to the design process for the Lower Basin was the flood modeling, presenting outcomes reflective of heavy flood events. Additionally, the most efficacious interventions were identified in mitigating such events. This analysis served as a crucial foundation for the designs.

Further emphasis was placed on delineating desired functions for the City Park. Through collaborative design sessions, stakeholders mapped out the spatial positioning of these functions. This information was then organised into three distinct spatial approaches, yielding a range of alternative models for the Lower Basin: the Asset Islands, the River Front, and the Wetland Park (Figure 6).

Subsequently, these alternatives underwent comprehensive evaluation utilising multi-criteria analysis techniques. The culmination of this evaluative process led to the conceptualisation of the Detailed Plan (Figure 7).

The Msimbazi Opportunity Plan represents a new paradigm in urban open space design, which recognizes that rivers are dynamic systems and emphasises the importance of adopting a holistic approach that involves collaboration between different stakeholders and sectors. The approach embraces natural processes to combat flood risk, recognises multisectoral needs, such as infrastructure development, and has been tailored to the local context. Additionally, the study is bankable, driven by enabling revenues from urban development, ensuring that the proposed solutions are economically feasible and sustainable.

The Msimbazi Opportunity Plan was followed by the Feasibility Study and the hydraulic model by the consortium of CDR, Norplan and DASUDA, which served as the starting point for the subsequent design works. During this phase a deep multidisciplinary approach was applied, collaborating in a team of technical, economic, social and environmental experts. To ensure seamless integration between the different design packages, an integrated spatial framework was developed.

This spatial framework (Figure 8) was designed to facilitate collaboration and communication between specialists from all relevant disciplines, and weekly design meetings with the international and local experts and staff were held to secure correlation between design tasks. Specific topics were addressed in separate design meetings.

Results and findings

The study has led to several key results and findings.

First, the study has demonstrated that an integrative and multi-sectoral approach to flood management in a low-income country context leads to a comprehensive flood management strategy that creates an enabling environment for resilient urban development. The participatory design process, crucial for commitment and a shared vision for the project, was tailor-made, and it was based on the ”Design Charrette” methodology.

Second, the study showed that the Dutch ‘Room for the river’ approach can be adapted to the context of an emerging African city like Dar es Salaam. It has led to innovative results including the reuse of excessive sediments in the basin to restore the riverbed, floodplains and to build terraces (Figures 9 and 10). The flood-safe raised terraces will be used for a 200 ha public city park, urban agriculture, and urban development, creating much-needed housing stock in all income fields (ca. 80 ha of developable area).

Third, the study demonstrates nature-based solutions such as vegetated erosion protections for the terrace banks (ca. 35km), ecological rehabilitation of the floodplains, planting native trees and mangrove restoration. Additionally, the City Park features mostly unpaved surfaces, with 4,000 predominantly native trees and 80,000 square metres of forested areas to minimise the heat island effect and improve air quality and micro-climate on a regional level (Figure 11).

Fourth, the design by DASUDA’s landscape architects of VE-R resulted in the continent’s largest city park, which integrates many functions to foster ownership and sense of belonging, such as sports- and playfields, regulated urban farming, and a festival terrain for social and cultural events, located at the old Simba and Yanga sports fields. It also provides 15,000 new homes in the flood resilient urban areas and a network of safe cycling and pedestrian paths with five bridges and boulevards connecting surrounding neighbourhoods (Figure 13). With a total area of 400 hectares, the park not only enhances the city’s resilience to extreme weather events but also provides a crucial green public space for its 6 million inhabitants. The project also addresses critical infrastructure needs, such as the New Jangwani Bridge (Figure 12).

Fifth, the study shows that a collaborative vision and well researched and designed feasibility study can lead to funding for implementation. Having been endorsed by the Tanzanian government, the World Bank (International Development Association), Dutch Government (Invest International) and Spanish government provided a loan of $260 million budget for implementation.

Significance

Overall, the study’s innovative and integrative approach has led to the creation of a sustainable and resilient flood management system that also promotes economic development and social welfare. The project is expected to bring numerous benefits to the city of Dar es Salaam, including improved flood protection, ecological preservation, green spaces, and opportunities for recreation, urban agriculture and housing development (Figure 14). The project is set to be the first river rehabilitation initiative of its kind on the African continent. The project will be followed up by supervision and design services this year in different packages, including earthworks and redevelopment of urban and landscape (park) design.

‍

‍

‍