CARE2022 Hong Kong Conference

24 3 Government Panel on Adaptation and Resilience difference becomes increasing large towards the end of this century (by 2100), demonstrating the increasing uncertainties further out in time. This is the same challenge faced by other jurisdictions. While there is consensus in using IPCC AR6 as the base for projections, government engineers must decide when to build what types of coastal protection infrastructure to defend against sea level rise. CEDD uses IPCC AR6’s intermediate emissions scenarios that goes out to mid-century as the starting point to consider near-term infrastructure needs (up until 2050) because the science is more certain (see Figure 3.4). As such, CEDD’s current thinking is that, for enhancement of existing structures, measures like wave walls with adequate reserve for future upgrade would be sufficient for Hong Kong in the near-to-medium term (i.e. up to midcentury). Nevertheless, for the design of new structures considering their end-of-design life need beyond mid-century (i.e., final design for end-century), CEDD would include “design allowance” to cater for possible higher emissions scenarios further out in time under the “progressive adaptive approach” in planning coastal infrastructures. In other words, for new coastal infrastructure, CEDD would take into account the design allowance needed for climate change effect endcentury. For new infrastructure, the infrastructure design could either adopt the design allowance in one-go or in stages. This approach has the advantage of reducing capital, maintenance, and operating costs in the near-term but has the design flexibility to enable additional infrastructure works that could deal with a higher risk in the future (see debate in Workshop A below). CEDD also showed different types of adaptation measures that could be used along coastlines, including wave walls and flood barriers, and demountable flood barriers at the frontages of buildings as the last line of defence. FIGURE 3.6 Types of adaptation measures Ma Wan Tsuen, Lei Yue Mun Water-filled Tube Barrier Demountable Flood Barrier Tseung Kwan O Waterfront Park Flood Wall Demountable Flood Barrier