Abstract
In a warming world, urban environmental stresses are exacerbated by population-increase-induced development of grey infrastructure that usually leaves minimal scope for blue (and green) elements and processes, potentially resulting in mismanagement of stormwater and flooding issues. This paper explores how urban growth planning in the megacity of Dhaka, Bangladesh can be guided by a blue-green infrastructure (BGI) network that combines blue, green, and grey elements together to provide a multifunctional urban form. We take a three-step approach: First, we analyze the existing spatial morphology to understand potential locations of development and challenges, as well as the types of solutions necessary for water management in different typologies of urban densities. Next, we analyze existing and potential blue and green network locations. Finally, we propose the structural framework for a BGI network at both macro and micro scales. The proposed network takes different forms at different scales and locations and offers different types of flood control and stormwater management options. These can provide directions on Dhaka’s future urban consolidation and expansion with a balance of man-made and natural elements and enable environmental, social, spatial, financial, and governance benefits. The paper concludes with some practical implications and challenges for implementing BGI in Dhaka.
Highlights
The city is a dynamic landscape characterized by natural and man-made elements
Step 1—Spatial Morphology: Figure 4 shows the result of space syntax analysis; the color range from blue to red indicates the level of street integration from lower to higher values
floor space intensity (FSI) on the Y axis gives an impression of the intensity of the built environment of a particular area and shows the results of the Spacematrix analysis for an areaOSR
Summary
The city is a dynamic landscape characterized by natural (blue and green) and man-made (grey) elements. Over densification and unplanned urbanization leave little room for interaction among blue, green, and grey elements, and as a result, the natural elements (e.g., water, green space) and natural characteristics (e.g., topography) are deprioritized in many cities. One manifestation of this is that water—a vital structuring element—can become a challenge for the urban environment during extreme weather events such as heavy rainfall. Despite guaranteeing the protection of water bodies and actively managing water resources, many cities across the world are encountering complicated issues related to population growth, water shortage, and climate change [1] This is more common in megacities that often confront water-related challenges [2,3]. Megacities are frequently considered as enlarged forms of cities, Land 2019, 8, 138; doi:10.3390/land8090138 www.mdpi.com/journal/land
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