Consider the Climate: Understanding What to Expect from Urban Hydrology Interventions Depending on Where You Are
Image credit: AGUAbstract
Green infrastructure and other low impact stormwater management practices are more widely encouraged today than ever before, but our understanding of how their performance varies based on geographic location remains largely limited to site-specific case studies and measurements of runoff from discrete events. As we move toward more holistic approaches for addressing urban hazards, we must also move beyond only predicting event-scale runoff reduction to develop generalizable principles for how hydrologic interventions alter long-term (i.e., annual or longer) urban water and energy balances. At these longer time scales, climate is a critical control. Here, we explore how climate alters the effect of two types of urban hydrology interventions - infiltration-based stormwater management practices and planting of street trees - on long-term urban water and energy balances. We use a physically-based hydrologic model (ParFlow) and custom version of a widely-used land surface model (NOAH-MP) to simulate how the same interventions perform under meteorological forcing from major cities across the United States in a range of climatic settings. While within-storm characteristics (e.g., precipitation intensity) are conventionally considered to be the main control on the performance of these types of hydrologic interventions, our findings show that longer-term urban water and energy balances are controlled by the relative balance and timing of water and energy availability (PET:P, 30 d correlation of PET and P) and measures of precipitation intermittency. We close with suggestions for incorporating these ideas and concepts into management practices and future studies.
