Green infrastructure and its catchment‐scale effects: an emerging science

Abstract

Urbanizing environments alter the hydrological cycle by redirecting stream networks for stormwater and wastewater transmission and increasing impermeable surfaces. These changes thereby accelerate the runoff of water and its constituents following precipitation events, alter evapotranspiration processes, and indirectly modify surface precipitation patterns. Green infrastructure, or low-impact development (LID), can be used as a standalone practice or in concert with gray infrastructure (traditional stormwater management approaches) for cost-efficient, decentralized stormwater management. The growth in LID over the past several decades has resulted in a concomitant increase in research evaluating LID efficiency and effectiveness, but mostly at localized scales. There is a clear research need to quantify how LID practices affect water quantity (i.e., runoff and discharge) and quality at the scale of catchments. In this overview, we present the state of the science of LID research at the local scale, considerations for scaling this research to catchments, recent advances and findings in scaling the effects of LID practices on water quality and quantity at catchment scales, and the use of models as novel tools for these scaling efforts.

Biochar-augmented biofilters to improve pollutant removal from stormwater – can they improve receiving water quality?

“…The pollutant removal efficiencies of biofilters at the unit scale are promising, but watershed scale efficacy is less well understood. Watershed-scale implementation of SCMs has been investigated regarding water quantity, but fewer studies have investigated the impacts of watershed-scale installation of SCMs on water quality, 102,103 and only two studies to date have looked at watershed scale effects of biochar-augmented biofilters. 104,105 Studies have generally found that installation of biofilters results in improved water quality at the watershed scale, but these results vary in extent depending on watershed size, climate, impervious area treated, and pollutants of concern.…”

Cumulative Effects of Low Impact Development on Watershed Hydrology in a Mixed Land-Cover System

“…Model selection for assessing the hydrological effects of watershed-scale LID implementation is challenging because it involves trade-offs in achieving the necessary fidelity (i.e., the extent to which the model faithfully represents the modeled system) to hydrological, biological, and biogeochemical processes for prediction accuracy, while minimizing complexity and uncertainty [14]. Careful consideration of these tradeoffs is needed for future work that addresses how LID affects watershed-scale hydrological processes, particularly in mixed land cover systems.…”

“…On the other hand, models that have been explicitly developed to assess the effects of LID practices in mixed land cover watersheds (e.g., VELMA and Regional Hydro-Ecological Simulation System (RHESSys) [66]) may have a strong biogeochemical module (because of their mixed land cover focus) but a more limited hydrological capacity to physically represent LID practices, as compared with a model such as SWMM. Responses to these challenges are evolving by incorporating LID modules within ecohydrological models, such as VELMA, that provide mechanistic representations of LID performance [14] and coupling models to quantify how LID affects the fate and transport of various pollutants, as well as couple SWMM with other watershed models to improve simulations of urban hydrology [67].…”

“…These previous studies provide foundational research for scaling LID approaches to watersheds. However, limited evidence of LID effectiveness at the watershed scale exists [12,13], and research focusing on LID impacts at watershed scales is just beginning to emerge [14]. Therefore, questions remain about how LID practices can individually or cumulatively affect watershed hydrology [14,15].…”

Is there a limit to bioretention effectiveness? Evaluation of stormwater bioretention treatment using a lumped urban ecohydrologic model and ecologically based design criteria

“…Urbanization replaces natural vegetation cover with impervious surfaces and lawns and alters the natural hydrology of watersheds primarily by reducing infiltration rates and the hydraulic resistance to overland flow and by rapidly discharging surface runoff into rivers and lakes through the storm sewer (Fanelli, Prestegaard, & Palmer, ; Golden & Hoghooghi, ). Generation of more frequent and larger volumes of stormwater runoff, increased streamflow variability, and flashiness as well as decreased watershed lag time are among the most commonly reported hydrological consequences of urbanization (e.g., Booth et al, ; Burges, Wigmosta, & Meena, ; Fanelli et al, ; Loperfido, Noe, Jarnagin, & Hogan, ; Paul & Meyer, ; Yao, Chen, & Wei, ).…”