Green infrastructure solutions for solving Beira's Stormwater problems

The nearly finalized “Masterplan Beira 2035” – as developed in the AgentschapNL funded project with the same name and managed by Deltares – sets the strategy and direction towards sustainable development of the lowland, delta town Beira in Mozambique. The plan amongst others addresses urban stormwater as an urgent problem to tackle as it causes serious urban flooding and soil erosion and poses a serious threat to infrastructure and human health and well-being. It is also anticipated in the plan that existing urban infrastructure will have to be improved and new infrastructure to be integrated in town expansions (needed to provide housing to the increasing population). Beira is located in the Delta of the Pungue River, where the Pungue River meets the Indian Ocean. The city is facing several challenges. First, economic growth and population growth have a direct impact on the city. The city is growing fast, resulting in substantial demand for (newly reclaimed) land. However, urban development is poorly regulated and settlements in flood prone areas and without basic infrastructure are common. More suitable land is needed for industrial purposes, for new and improved housing and public facilities. Large-scale coal mining has started in Tete province, north of Beira, and is an important driver of economic change. Coal is transported along the Sena railway to the port of Beira from where it will be exported. A terminal in the existing port is fully equipped for the export of coal and an increase in throughput and export capacity to about twenty million tons per year is already in preparation. The increase in the transport and export of coal will have an impact on the infrastructure and the city. Second, the city is facing serious threats of climate change. A clear adaptation strategy is of major importance for coastal protection because the city is located just a few meters above sea level. In addition, Beira is confronted with other water-related challenges such as the provision of safe (drinking) water and the improvement of flood protection through appropriate stormwater and sewer systems. Developments in the agricultural sector, such as the Beira Agricultural Growth Corridor (BAGC), will increase water demand and will affect the quality of the Pungue River and Delta. Central Beira can be characterized as a flat plain bordered by a coastal ridge. There is limited natural drainage of the area to Rio Macuti in the East and to Rio Chiveve in the West. The majority of the city is built on naturally marshy land. This natural drainage has been augmented by the construction of storm water channels and pipes. These systems make up approximately 81 km of pipes and 33 km of channels. Piped storm water infrastructure only exists in the formal areas of Beira. The piped and open channels systems collect storm water to a primary drainage system that isdischarge directly to the sea. The drainage of swamps in the northern part is connected to the primary channels as well. Between the neighborhoods of the urban areas, there are unsettled areas subject to flooding (see Fig. 4). All these systems have serious problems. Some of the causes are: -    Natural causes including high rainfall intensity (stormwater), flat topography in some areas, and poor infiltration; -    Man-made causes, such as undersized culverts; poor maintenance operations; -    Underdevelopment of tertiary drainage facilities; and encroachment on the right-of-way of primary and secondary channels; -    Developments taking place in low-lying areas prone to flooding which are not suitable for development. It has been analyzed by the Masterplan study Beira 2035 that to prevent flooding additional storage capacity needs to be created for the alleviation of the primary drainage infrastructure during high tides and intensive rainfall. Two retention basins of 50 ha each would be sufficient but it turned out that there is no space left for these retention basins. Therefore there is the need to develop other solutions through green infrastructure planning. Het Masterplan Beira 2035 moet helpen om van Beira een veilige, welvarende en mooie stad te maken. Met ons project beogen we om die ambitie concreet te maken in een van de woonwijken van Beira. Ons project wil de regelmatige overstroming van die woonwijk tegengaan – en zo dus de veiligheid vergroten – door gebruik te maken van groene infrastructuur. Groene infrastructuur maakt wijken ook welvarender en mooier. De burgemeester van Beira geeft in een brief aan ons aan dat ons project dan ook juist een van de projecten is die zij voor ogen hebben voor het operationaliseren van de Masterplan ambitie.

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