Development And Its Impact On The Water Balance Of An Urban Watershed

Author : Carolyn Breden Voter
Publisher :
ISBN 13 :
Total Pages : 141 pages
Book Rating : 4.:/5 (122 download)

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Download or read book Hydroecologic Effects of Urban Development Decisions in Residential Areas written by Carolyn Breden Voter and published by . This book was released on 2019 with total page 141 pages. Available in PDF, EPUB and Kindle. Book excerpt: As our urban areas grow, so too do these unintended hydrologic consequences of both urban development and traditional stormwater management systems. To combat these issues, cities are increasingly turning to stormwater management practices that better mimic natural hydrology by capturing, infiltrating, or evapotranspiring water in a distributed fashion throughout the watershed. These low impact development (LID) practices have proven effective at locally altering the water balance, but quantitative performance can vary widely across studies and it can be difficult to untangle which site-specific characteristics (e.g., climate, soil, vegetation, microtopography, impervious connectivity) are the most important drivers of observed differences in hydrologic behavior. In order to increase the adoption and reliability of LID, there is a continued need to improve our scientific understanding of how site-specific characteristics affect urban hydrologic processes and the performance of LID practices. In this dissertation, I use a physically-based hydrologic model, ParFlow.CLM, to simulate surface and subsurface hydrology at a high (0.5m) spatial resolution on single-family parcels and explore the effects of LID practices on parcel-scale runoff, deep drainage, and evapotranspiration. First, I examine how three "impervious-centric" practices (disconnecting downspouts, disconnecting sidewalks, and adding a transverse slope to the driveway and front walk), two "pervious-centric" practices (decompacting soil and adding microtopography), and all possible "holistic" combinations affect parcel-scale hydrology. Second, I systematically explore how climate moderates the effects of these LID practices on the water balance by forcing a baseline parcel with no LID practices and a parcel with all five LID practices with one year of hourly meteorological records from the 50 largest U.S. cities plus Madison, WI. Third, I more closely examine the potential of soil amendment as a LID practice by comparing targeting soil amendment a) disconnected impervious features, b) by drainage area, c) by topographic wetness index (TWI), and d) randomly. Lastly, I determine which attributes of residential single-family parcels best predict changes in hydrologic fluxes due to infiltration-based LID practices by 1) developing a suite of typical single-family lot layouts based on property assessor data for tax parcels in Madison, WI, 2) simulating baseline and low impact versions of these lots using ParFlow.CLM, and 3) building statistical models that relate single-family lot attributes to changes in runoff and deep drainage. This research demonstrates the crucial role of impervious-pervious interfaces on urban hydrology. While these sub-parcel features are rarely captured in urban hydrologic models, they have the potential to substantially alter the urban hydrologic water balance. LID interventions which both disconnect impervious surfaces and increase the infiltration capacity of soil adjacent to these features can efficiently and effectively alter the water balance at the parcel scale. The degree of hydrologic change possible from these LID practices is largely driven by the size of all impervious surfaces, the size of the house, and the size of the street plus alley; lot attributes which can be easily identified by water resources managers as a "first-cut" for determining where to encourage LID practices on private property. When evaluating which types of LID practices to promote, it is critical to consider climate characteristics like the aridity index and, to a lesser extent, rainfall intensity and the relative timing of energy and water availability. Overall, this research offers new insights into how site-specific, subparcel characteristics interact to affect larger-scale urban hydrologic processes.