Evaluating Capability of Green Stormwater Infrastructure on Large Properties toward Adaptive Flood Mitigation: The HLCA+C Methodology

Abstract

Current flood protection capacities will become inadequate to protect many low-lying coastal cities from climate change-induced flooding in the future. Under climate change uncertainty, an adaptive strategy is required to provide supplemental flood mitigation. Green Stormwater Infrastructure (GSI) in developed areas has the potential to provide substantial catchment runoff reduction. However, individual properties vary in their Flood Mitigation Capability (FMC) depending on their land characteristics. An effective methodology is needed to evaluate the FMC of properties to help urban planners determine which to target for GSI and when to implement GSI in light of increased climate change impacts. We advance the Hydrology-based Land Capability Assessment and Classification (HLCA+C) methodology for evaluating the FMC of large properties over the long term (80 to 100-year). It builds on the strengths of existing methodologies and uses a land unit analysis approach for assessing FMC, considering interdependent hydrological and geographical variables. The FMC classification system groups properties with similar flood mitigation characteristics, helping urban planners to understand their potentials and limitations for flood mitigation toward the development of adaptive strategies through time. Step-by-step instructions demonstrate how to apply the methodology to any low-lying coastal city.

Effectiveness of Strategically Located Green Stormwater Infrastructure Networks for Adaptive Flood Mitigation in a Context of Climate Change

“…The Hydrology-based Land Capability Assessment and Classification (HLCA+C) methodology [21] was used to evaluate the Flood Mitigation Capability (FMC) of different industrial Storm Water Management (SWM) zones within the catchment based on their hydrological and geographical characteristics. SWM zones are defined as industrial properties located in the same drainage area sharing a common drainage outlet.…”

“…The methodology is described in detail in Muangsri, et al [21]. The methodology is specially designed to provide planners with an initial assessment of properties for their flood mitigation capabilities, and to understand their flood mitigation characteristics.…”

“…Nor is much known about how GSI on individual industrial properties, having different flood mitigation characteristics, can be orchestrated through time to form effective networks. Using a catchment in Christchurch, New Zealand, as a case study, the Hydrology-based Land Capability Assessment and Classification (HLCA+C) methodology [21] was applied to evaluate the Flood Mitigation Capability (FMC) of GSI on industrial properties that have different biophysical and built-environmental characteristics in support of flood mitigation, through time under climate change. Based on this evaluation, implementation approaches are suggested to maximise their FMCs individually and as networks through time.…”