| Description |
As one of the most important earth systems, the water cycle is significantly disrupted by changes to land cover and water management accompanying urbanization. Recently, researchers have developed a concept of near-natural hydrology to guide ecological engineering of urban systems to mitigate the impacts of development on the water cycle. Stormwater green infrastructure (GI) is one of the practices that has been used to restore the urban hydrology. The goal of this research is to answer the overarching question: Can GI implemented in a semiarid watershed restore the water budget to its predevelopment condition? Field experiments and hydrologic modeling were conducted in a semiarid city, Salt Lake City, Utah, U.S to answer this question. This work created, for the first time, an ET observation dataset for the semiarid intermountain west of the U.S. Based on the new dataset, empirical parameters for Penman-Monteith ET methods, including crop coefficients and surface resistances for green roofs, were identified and calibrated for this region, also for the first time. Their values can be directly used for ET modeling of green roofs in similar climates. An urban stormwater model, EPA SWMM, was modified to be able to represent spatially heterogeneous ET rates in one catchment for up to six types of land covers, including GI (bioretention, green roof), landscapes (turf, deciduous trees, coniferous trees), and water surface. This creates an improved platform to study the hydrologic response of urban watersheds by addressing the limitation of hydrologic models, not including GI and stormwater models with poor representation of ET. Also, the EPA SWMM was modified to be able to operate using subdaily ET time series input for the first time. With the updated model, the final part of this work studies the potential of restoring the predevelopment urban water budget by adopting GI strategies in a semiarid watershed. Based on the proposed water budget restoration coefficient, the water budgets have been restored due to GI applications 94%, 94%, and 82% of the predevelopment state in the dry, average, and wet years, respectively. |
