Project: Khulna as a Water Inclusive Enclave

The Khulna as a Water Inclusive Enclave team is led by CDR International. Their team works with water infrastructure contractors in Bangladesh and focuses on feasibility and bankable projects.

Defacto is the design lead and a strategic partner in the complex urban planning context of Khulna. Members bring experience and ideas from their input to the Delta Plan 2100 for Bangladesh.

DevConsultant is a partner from Bangladesh that focuses on the social and environmental effects of the conceptual designs. Their team provides support in translating Dutch expertise to the context of Bangladesh.

Nelen & Schuurmans focuses on flood modelling and interactive visualisation tools which are key in the regional workshops.

RoyalHaskoningDHV contributes flood resilience experience from working on comparable challenges elsewhere on the planet and their strong record of urban flood resilience projects.

Through Khulna University the team has a permanent presence on the ground in the city that helps to pass on the team's philosophy to a younger generation of scholars and scientists.

Wageningen University and Research (WUR) adds knowledge of the complex planning context in Bangladesh by means of delta planning and management, including at the nexus of agriculture and food supplies.

As sea level rises and saltwater intrusion increases, Khulna is fast becoming a vulnerable and exposed city.

The Khulna as a Water Inclusive City project addresses water resilience concerns on both the regional and local scales in the area between the Gorai River offtake and the Sundarbans mangrove forest. The multifaceted proposal includes sustainable polders, nature-based coastal protection and three projects for water storage within Khulna City.

Rather than increasing the height of river embankments, which can be unsustainable over time, strategic enhancements are proposed to restore the balance of the southwest tidal floodplain and reduce salinity intrusion using Nature-based Solutions. Tidal River Management is a Building with Nature strategy that is applied here to decrease waterlogging of low-lying polder areas. This will benefit agriculture, ecology and climate resilience in the Khulna District. In the Sundarbans region, the design capitalizes on local hydraulic conditions and natural siltation processes, using poles and brushwood to dampen waves and capture sediment between these barriers and the land. Once the nearshore bed level rises enough, mangroves regenerate naturally, creating a natural defense that protects the hinterland from further erosion and storm damage.

Within Khulna City, the plan is based on storing, retaining and reusing rainwater to the maximum extent and implementing new regulations for future development in the area west of the Moyur River. Low-lying areas currently used for agriculture are transformed into temporary (or permanent) water storage basins to reduce pluvial flooding in the city center. Several interacting component projects are proposed across the city, which augment the storage capacity of existing ponds, design multi-purpose green parks, and establish a blue-green zone for additional water storage.

Fresh water supplies from the Gorai River are reduced as a result of continuous siltation at the off-take area where the Gorai meets the Ganges River.

Many studies have already been conducted to find actionable solutions to this challenge and increase water supplies to Khulna. An updated study is required to serve as the basis for sustainable solutions that can effectively safeguard sufficient fresh water supplies for the floodplain in which Khulna is located.

In the team's proposal, interventions upstream of Khulna are aimed at ensuring adequate water flow in the Rupsha River during the dry season. This will not only help to reduce tidal influence but also prevent further increase of salinity intrusion in soil and groundwater. Increase of fresh water intake via the Gorai river will help to meet the demand in the the south west tidal floodplain and reduce the salinity to the goal limit of 2 pppt by 2050.

The Sustainable Polders proposal recognizes that agricultural production methods must adapt to the effects of climate change, waterlogging and salinization.

Without effective mitigation of these threats, dire consequences may be felt in the food supply from a potential decrease in crop yields, fewer crop types that can withstand the new conditions, and loss of ecological functions. Additionally, mounting flood risk poses serious threats to the health, safety and livelihoods of farmers and residents in water-proximate areas.

There is an urgent need for measures that address all of these issues to safeguard food security. The team proposes using a strategy of Tidal River Management (TRM) to decrease waterlogging in low-lying polder areas which will benefit agriculture, ecosystems and climate resilience in the Khulna District. TRM has major social, ecological and economic potential if it is executed at the right place and time, involves key stakeholders, and can be managed and monitored appropriately.

The team identified three key projects for water inclusivity in Khulna City:

1. 100 Ponds project This project is focussing on protecting 100 ponds within the existing build area of the city in order to preserve (and further increase) there water storage capacity and function. The proposal envisions to go back to the future and again make the ponds a characteristic of the Khulna city.

2. Moyur River The aim for this concept is to protect the capacity of the Moyur River to act as water storage. Khals are used to direct rainwater toward the Moyur River so it can function as a water reservoir. Encroachment on the river is prevented by the design and construction of a linear park on both sides. This adds ecological, recreational and social value to the city.

3. Multi-level city As urban expansion progresses, the agricultural land in the western part of Khulna is increasingly being developed. In order to provide sufficient water storage capacity during extreme events and work toward an inclusive city, different types of building regulations are proposed. Similar to existing regulations in the old town, roof water storage and a standard water-plot size ratio should apply for individual developments. New projects should be designed and developed so that each property can effectively manage its own water on site, by having: – 25% storage space for frequent events (stored in gardens and public spaces) – 40% storage space for extreme events (stored in parking garages, agricultural lands and gardens)

By implementing such building regulations, runoff is mitigated on the property scale, thus reducing the likelihood that large investments will be needed in the future for drainage infrastructure. The team envisions an important role for businesses, citizens & project developers in and around Khulna; and they are developing a public-private partnership (ppp) pilot study.