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Reducing risk from natural hazard, pollution and climate change in megacities and associated networks
Published in Mark Pelling, Sophie Blackburn, Megacities and the Coast, 2014
Hard engineering approaches include sea walls, breakwaters, revetments, groynes, gabions, offshore breakwaters and armourstones. These act to stabilize the shoreline position and are commonly applied to protect high-value or densely populated urban coasts. However, a static coastline can be problematic because of its inability to respond to sea-level changes in the medium-and long-term (coastal squeeze) and its cessation of interactions and of sediment inputs to the natural sediment budget (Doody, 2004; Wolters et al., 2005). Thinking long-term and beyond the city has led to the growing appeal of working with nature and utilizing soft engineering approaches (Coy, 2000; Hartig et al., 2011), which include beach nourishment feeding, dune building, increasing natural sedimentation and managed realignment. In a similar mode land-use up-river of urban centres is increasingly seen as playing a water retention role so that it is designed to provide space for river floodwaters to flow and slow, dissipating energy and smoothing flood peaks so to reduce damage in the city.
Sustainable hard and soft measures for coastal protection – Case studies along the Indian Coast
Published in Marine Georesources & Geotechnology, 2022
Vallam Sundar, Sannasi Annamalaisamy Sannasiraj, Sukanya Ramesh Babu
The hard engineering options typically implies the construction of a gravity structure comprising of rubble mound or concrete units, conventionally their cross-section is trapezoidal in shape and is designed to endure the critical wave characteristics incident on the designated shoreline. A series of well-established handbooks, design manuals and plentiful literature are available for reference on implementation of hard measures/hard structures for coastal protection. Implementing/Commissioning such structures along the coast often bring about irreversible adverse effects on the coasts. These are most often sought after to bring about an immediate solution to erosion problems, such projects are extremely successful when diligently engineered with a thorough knowledge of the wave climate, local bathymetry and sediment characteristics. The standard hard engineered structures along the coasts are groins, seawalls, breakwaters, and offshore breakwaters (submerged and emerged).
Sticky stuff: biological cohesion for scour and erosion prevention
Published in Environmental Technology, 2022
Rob Schindler, Richard Whitehouse, John Harris
Scour can be reduced by modifying the structure to reduce the strength of turbulent vortices that result in increased erosive force. Even with these improvements, some degree of scour is inevitable, and reinforcement of the substrate in which the structure is placed is required. Typically, methods of protecting against scour erosion rely on ‘hard engineering’ approaches to armor sediments, including the positioning of concrete, large rocks, gabion baskets, plastic matting and rock mattresses on the affected site. Consequently, the environmental ‘footprint’ of a structure includes the materials used to protect it. ‘Hard engineering’ methods of scour mitigation have shortcomings for: (1) Economic reasons: cost of material and transport to site, cost of specialist vessels; (2) Practical reasons: distance to offshore sites, uncertainty of sea operations, need for precise sub-sea assembly; (3) Environmental reasons: disruption of geomorphological processes, damage to ecological communities, reliance of carbon-intensive methods [5,6].
Evaluation of performance of Active, Beautiful and Clean (ABC) on stormwater runoff management using MIKE URBAN: a case study in a residential estate in Singapore
Published in Urban Water Journal, 2019
Kok Meng Tan, Wei Kiong Seow, Chien Looi Wang, Huiling Jernice Kew, Suresh Babu Parasuraman
Urban stormwater management philosophy has evolved from the traditional hard-engineering approach of building more and enlarging concrete drains to a more soft-engineering approach that leverages on decentralised control features known as Active, Beautiful and Clean (ABC) in Singapore or other common names such as low impact development (LID), best management practices (BMP) or green infrastructure (GI) amongst others. The overall idea of ABC and the like is to ‘maintain’ the hydrology of the pre-development condition of the catchment that will be developed. This switch in approach is mainly driven and necessitated by climate change and rapid urbanisation that existing infrastructure upgrading is unable to keep up and it is also not sustainable in terms of costs and available space. The adoption of this new management philosophy has been picking up pace in recent years and is evident in the availabilities of guidelines published by various countries under their national programs such as the ABC program in Singapore, LID in USA, water sensitive urban design (WSUD) in Australia, sustainable urban design system (SUDS) in UK and Sponge City in China (Fletcher et al. 2015). The adoption of this new storm-water management philosophy will lead to a more sustainable development (Lloyd, Wong, and Chesterfield 2002) and resilience to climate change impacts, a healthy and vibrant urban ecology (Chang et al. 2018) on top of an aesthetically pleasing landscape.