The Impact of Climate and Land Use on Urban Stormwater Runoff, and Implication for Low Impact Development and Green Infrastructure

Low impact development (LID) and green infrastructure have been increasingly practiced since their emergence in the 1990s. The hydrological benefits of these stormwater management techniques have been extensively studied and documented. However, performance of LID techniques and green infrastructure under increasing climate change and variability with land use conditions of different spatial and temporal scales remains unclear. The major purpose of this study is to expand our current knowledge of the rainfall and runoff process in urban watersheds under varying climate and land use conditions and encourage implementation of sustainable techniques in an effective manner. This study has two major components: (1) a systematic summary of how performance of site-scale LID techniques responds to climate variability, and (2) an exploration of how land use composition and configuration of green infrastructure contributes to moderating conveyance of stormwater runoff at a regional level. Statistical approaches such as meta-analysis and ordinal logit regression were employed. The results of weighted meta-analysis revealed a greater sensitivity of runoff volume to changing storm frequency than peak discharge rate, while the retention capacity of LID systems to reduce both volume and peak discharge rate diminished with increasing storm intensity. In addition, the results of an ordinal logit regression showed that the connected pattern of green infrastructure significantly reduced the probability of high-level runoff depth while different spatial forms of urban development expedited runoff conveyance depending on development intensity. Sprawling patterns of medium- and low-intensity development as well as a connected form of high-intensity development should be avoided to reduce flood risks. Future explorations of how various LID techniques are sensitive to climate fluctuations will help strategize LID installation for targeted storm patterns and flood mitigation goals at a site scale. In addition, more studies on spatial arrangement of green infrastructure will help develop effective stormwater management policies at a regional level in accordance with land use plan