Resilient planning optimization through spatially explicit, Bi-directional sociohydrological modeling

Stormwater runoff is one critical urban issue that exemplifies the complexity in coupling human and natural systems. Innumerable studies have described and assessed the hydrological responses that result from land-use changes through a 'post land use change' hydrological analysis. Complex systems theory, however, suggests that the urban and ecological systems operate as an intertwined whole. This means that typical one-directional analysis can miss critical components of a bi-directional sociohydrological process. In addition, there is a difference in physical scales between hydrological analysis and policymaking that is often left unresolved. Typical hydrological models are limited to a watershed and are not easily applied to policymaking that is generally demarcated by a political boundary. These types of models also lack the spatial explicitness needed for physical design responses. To address these issues, we develop an integrated, finely scaled, spatially explicit sociohydrological modeling system. The coupled land use/stormwater model projects and assesses bi-directional sociohydrological impacts to changing land uses. We apply and test the system in McHenry County, Illinois, by modeling three scenarios to the year 2045. The results show that residential and commercial developments exhibit different responses to hydrological variables, resulting in varying patterns of land use locational choices. We also find that there is a conflict between developmental preferences that prefer to be located near water (housing) and those that prefer to be located away from runoff-prone water areas (commercial land uses). Our bi-directional modeling system simulates cell-to-cell interactions to produce quantifiable and practically useful outputs. The output for McHenry County, Illinois, includes specific, locational information on how to optimize developmental regulations in response to the contradictory developmental preferences and, more importantly, how to live with runoff in the context of resilience. This research supports the need for cell-based forward-looking modeling to better understand complex urban systems and strategically establish a resilient built environment.