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Timeline of Wonmin Sohn

Published new article


The influence of climate on the effectiveness of low impact development: A systematic review

Published: 01 April 2019 by Elsevier BV in Journal of Environmental Management

doi: 10.1016/j.jenvman.2018.11.041

Low impact development (LID) has been increasingly practiced since its emergence in the 1990s. Although the hydrological benefits of LIDs have been extensively documented, the climate impact on LID performance remains unclear with increasing variations in spatial and temporal climate patterns. This systematic review contributes to providing a structured summary of research on how LID systems are sensitive to climate variability by empirical and hypothetical research approaches. The selected 46 peer-reviewed journal articles published between 2003 and 2017 were analyzed by key variables, including climatic factors, LID types, and hydrologic measures used to quantify LID performance. A conceptual framework formulated in this study synthesizes the relationship between climate and LID effectiveness. The results of weighted meta-analysis reveal a greater sensitivity of runoff volume to changing storm frequency than peak discharge rates, while the capacity of LID systems to reduce both volume and peak discharge rates diminishes with increasing storm intensity. Future explorations of the sensitivity of LIDs to climate fluctuations will help strategize LID installation for targeted storm patterns and flood mitigation goals. To enhance existing methods and make a balance between empirical and hypothetical knowledge, this study suggests future directions of research and encourages development of effective stormwater management policy.

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Published new article


Low-impact development for impervious surface connectivity mitigation: assessment of directly connected impervious areas...

Published: 23 March 2017 by Informa UK Limited in Journal of Environmental Planning and Management

doi: 10.1080/09640568.2016.1264929

Urbanization increases directly connected impervious area (DCIA), the impervious area that is hydraulically connected to downstream drainage by closed pipelines. Although the benefits of low-impact development (LID) have been examined in other studies, its effect on alleviating DCIA levels has seldom been assessed. This study measured the DCIA of urban watersheds in Houston, TX, USA. Five land-use types were categorized and the contribution of LID facilities to reducing DCIA in each type was estimated by using Sutherland's equations. The results showed (1) DCIA in commercial areas was greater than that in residential areas, especially for big-box retailers; (2) the percentage of DCIA reduction by LID varied by land-use type; and (3) optimal combinations of LID application could maximize the effectiveness of DCIA reduction. The results contribute to prioritizing land-use type for implementing LID practices and providing local governments with a useful measure to estimate runoff volume.

2 Reads | 0 Citations
Published new article


Neighborhood Landscape Spatial Patterns and Land Surface Temperature: An Empirical Study on Single-Family Residential Ar...

Published: 02 September 2016 by MDPI in International Journal of Environmental Research and Public Health

doi: 10.3390/ijerph13090880

Rapid urbanization has accelerated land use and land cover changes, and generated the urban heat island effect (UHI). Previous studies have reported positive effects of neighborhood landscapes on mitigating urban surface temperatures. However, the influence of neighborhood landscape spatial patterns on enhancing cooling effects has not yet been fully investigated. The main objective of this study was to assess the relationships between neighborhood landscape spatial patterns and land surface temperatures (LST) by using multi-regression models considering spatial autocorrelation issues. To measure the influence of neighborhood landscape spatial patterns on LST, this study analyzed neighborhood environments of 15,862 single-family houses in Austin, Texas, USA. Using aerial photos, geographic information systems (GIS), and remote sensing, FRAGSTATS was employed to calculate values of several landscape indices used to measure neighborhood landscape spatial patterns. After controlling for the spatial autocorrelation effect, results showed that larger and better-connected landscape spatial patterns were positively correlated with lower LST values in neighborhoods, while more fragmented and isolated neighborhood landscape patterns were negatively related to the reduction of LST.

5 Reads | 10 Citations
Published new article


Urban Natural Environments, Obesity, and Health-Related Quality of Life among Hispanic Children Living in Inner-City Nei...

Published: 12 January 2016 by MDPI in International Journal of Environmental Research and Public Health

doi: 10.3390/ijerph13010121

Although a substantial body of literature has provided evidence supporting the positive effects of natural environments on well-being, little has been known about the specific spatial patterns of urban nature in promoting health-related quality of life (HRQOL) among children. This study assessed the association that the urban natural environment measured by landscape spatial patterns may have with obesity and HRQOL among Hispanic children. Ninety-two 4th and 5th grade students were recruited from Houston, Texas, and the Pediatric Quality of Life Inventory (PedsQL) was used to capture the children’s HRQOL. The quality of urban natural environments was assessed by quantifying the landscape spatial patterns, using landscape indices generated by Geographic Information Systems and remote sensing. From the bivariate analyses, children’s body mass index showed a significantly negative association with their HRQOL. After controlling for socio-demographic factors, the results revealed that larger and more tree areas were positively correlated with children’s HRQOL. In addition, those children living in areas with tree patches further apart from each other showed higher HRQOL. This research adds to the current multi-disciplinary area of research on environment-health relationships by investigating the roles of urban greeneries and linking their spatial structures with children’s HRQOL.

5 Reads | 10 Citations
Published new article

Low Impact Development Applications in Urban Watersheds: Efficacy Evaluation by Imperviousness Connctivity Estimations

Published: 08 June 2015 by MDPI AG in Proceedings of 8th Conference of the International Forum on Urbanism (IFoU)

doi: 10.3390/ifou-D003

Although recent studies have emphasized the benefits of Low Impact Development (LID), the influence of LID on impervious surface connectivity to downstream drainage has not yet been fully investigated by using quantitative measurements. Some previous studies have attempted to measure correlates between discharged stormwater volume and the directly connected impervious areas (DCIA), a fraction of the impervious area that is hydraulically connected to downstream drainage by a piped route. They found that DCIA could be a more accurate predictor of urban development impacts on stream ecosystems than is the total impervious area. This study measured the DCIA of urban watersheds in the Energy Corridor District, Houston, Texas, where rapid urbanization and increasing impervious surfaces have caused urban stream degradation during the past decades. This study primarily prioritized land use into four types based on the contribution of hypothetically implemented LID facilities to DCIA reduction for each land use. Stormwater infrastructure and impervious cover data were analyzed using Geographic Information Systems. Sutherland's equations taken from Sutherland, R.C. (1995) were utilized to compute DCIA at the parcel level. The results were 1) a greater value of current DCIA in commercial areas than in residential areas (single family houses 40%, multi-family houses 64%, big box retails 77%, scattered small-scale retails 71%); 2) a significant reduction of DCIA for all land uses after hypothetically implementing LID applications (reduction rates ranged from 6.4% to 52.2%); and 3) the greatest change of DCIA in big box retail areas with pervious pavement and vegetated swale installation. The results will contribute to determining which land use type is of higher priority in implementing source-control stormwater infrastructure and providing local governments with a better index to calculate drainage fees, which are currently imposed on property owners based on total impervious area.

8 Reads | 0 Citations
Conference participation

Wonmin Sohn participated at conference 8th Conference of the International Forum on Urbanism (IFoU).