Low Impact Development Techniques Research Articles

Runoff Impacts and LID Techniques for Mansionization-Based Stormwater Effects in Fairfax County, Virginia

AbstractThis case study uses the Natural Resources Conservation Service (NRCS) curve number method to quantify the increase in stormwater runoff volume from infill residential redevelopment, or mansionization, in a 0.13-km2 residential subwatershed of Fairfax County, Virginia. Analysis of 10 redeveloped lots in the subwatershed showed an average increase in impervious cover from 8 to 28% per parcel after redevelopment, resulting in an average increase in runoff volume of 18% per parcel for the 10-year, 24-h storm. From 1997 to 2009, the total impervious cover in the subwatershed increased from 18 to 25%, resulting in a calculated 5.6% total increase in runoff volume. Low-impact development (LID) techniques were modeled as retrofits in the subwatershed to mitigate the increase in runoff volume. Measures modeled include bioretention basins, infiltration trenches, amended soils, permeable pavement, and cisterns. Results indicate that placing bioretention basins or infiltration trenches on 0.5% of the subwate...

그린인프라 및 저영향개발 기술의 검증 및 인증 기법 개발

본 연구는 최근 많은 관심을 받고 있는 그린인프라 및 저영향개발 (GI & LID) 기술에 대한 물순환 및 물환경 효율성 측정을 위한 실내 외 검증, 인증 시스템을 개발하였다. 기술의 검증 및 인증을 위한 실외시험시설은 건축형, 도로형, 주차장형, 빗물정원형, 생태공원형 등 크게 5구역으로 나누어 기술종류에 따라 시험이 가능하도록 시스템을 개발하였다. 또한, 실내실험으로는 수리/수문분야, 토질/지반분야, 환경분야 등 다양한 시험이 가능하도록 시험장비의 개발 및 구축을 하였다. 본 연구에서 개발한 GI & LID 검 인증시스템 구축을 위한 실내 및 실외 시험시설의 개발은 GI & LID 기술의 적용을 위한 객관적이고 신뢰성 있는 데이터 제공에 대한 기반을 마련함과 동시에 관련 사업의 활성화에 기여할 것으로 판단된다. This study developed a verification and certification method of technologies of green infrastructure (GI) and low impact development (LID) that gained interest recently. The outdoor testbed used in this study consisted of a building type, a road type, a parking lot type, a rain garden type and a bioretention type. Indoor test facilities were ready for testing using hydrology efficient analysis, pavement and soil analysis and water environment analysis. The development of outdoor and indoor test facilities were used to certify the efficiency of GI & LID technologies, and this was expected to contribute to the activation of the related projects by providing reliable data for the application of GI & LID techniques.

Stormwater Low-Impact Development: A Call to Arms for Hydraulic Engineers

Conventional stormwater management teaches that the primary concern is to remove the water from the site being developed (Ahiablame et al. 2012). Therefore, in order to reduce the risk of flooding, impervious surfaces such as parking lots and buildings are fitted with drainage structures made of impervious materials (pipes or concrete). After the water is collected, it is discharged to the nearest stream or lake. This method prevents local flooding, but it can cause problems downstream such as increased erosion and flooding. Since the conventional stormwater facility on developed property is concerned with removing water as quickly as possible, it changes the hydrology of the site being developed (HolmanDodds et al. 2003). The increase in impervious surfaces reduces infiltration that would have occurred at a site, increasing the peak runoff that the receiving waters must handle, sometimes by multiple times as much over the natural runoff (Hood et al. 2007). Also, the stormwater runoff will carry suspended solids and pollutants from the site into the receiving water (Davis et al. 2009). For this reason, in recent years there has been significant study on establishing Low-Impact Development (LID) (Ahiablame et al. 2012; Davis and McCuen 2005), the goal of which is to mimic the natural hydrology of a site postdevelopment (Davis 2005) or to reduce pollutants entering waterbodies by altering the land use (Barfield et al. 2008). This is accomplished by promoting infiltration and detention, as well as removing pollutants when possible (Garrett 2007). Engineers and scientists are now collaborating to produce more-sustainable LID techniques such that the developed site will not affect runoff (Bedan and Clausen 2009) and watersheds are being restored using LID techniques (Guo 2010; Chang 2010). The purpose of the current work is to (1) briefly review issues involved in LID, (2) illuminate hydraulic issues that may lead to future modeling advances, and (3) encourage hydraulic engineers to lead in this rapidly developing field. Several LID techniques along with hydraulic issues that need addressed will be discussed next in an effort to encourage hydraulic engineers to participate in this rapidly-expanding field.

Understanding the factors influencing the removal of heavy metals in urban stormwater runoff

In this research, an infiltration trench equipped with an extensive pretreatment and filter bed consisting of woodchip, sand and gravel was utilized as a low impact development technique to manage stormwater runoff from a highly impervious road with particular emphasis on heavy metal removal. Findings revealed that the major factors influencing the removal of heavy metals were the concentration of the particulate matters and heavy metals in runoff, runoff volume and flow rates. The reduction of heavy metals was enhanced by sedimentation of particulates through pretreatment. Fine particles (<2 mm) had the most significant amount of heavy metals, thus, enhanced adsorption and filtration using various filter media were important design considerations. Sediment was most highly attached on the surface area of woodchip than to other filter media like sand, gravel and geotextile. It is suggested that maintenance must be performed after the end of the winter season wherein high sediment rate was observed to maintain the efficiency of the treatment system.

침투실험을 통한 투수성 포장재의 흙-수분특성곡선 역해석

Permeable pavement systems, an Low Impact Development technique, are widely used for pedestrian and bicycle roads, and parking lots, to relieve the flooding and enhance water cycle, which arises due to climate change and urbanization. However, due to lack of analytical means, permeable pavements are constructed most of time without knowing their performance in reducing runoff. In this paper, saturated permeability and porosity of a pervious concrete sample were experimentally estimated, and a set of infiltration model test was conducted; then, finally, the soil-water characteristics curve of the sample was back-calculated. In inverse analysis, van Genuchten model was selected, and Levenberg-Marquardt method was used for parameter searching algorithm. The results of soil-water characteristics curve presents the air-entry suction pressure is little below 1 kPa, and all the water expels at a suction pressure of 10 kPa. When compared to typical sands, the volumetric water content of pervious concrete drops more steeply with increasing suction pressure.

Developing a stochastic conflict resolution model for urban runoff quality management: Application of info-gap and bargaining theories

Summary In this paper, two deterministic and stochastic multilateral, multi-issue, non-cooperative bargaining methodologies are proposed for urban runoff quality management. In the proposed methodologies, a calibrated Storm Water Management Model (SWMM) is used to simulate stormwater runoff quantity and quality for different urban stormwater runoff management scenarios, which have been defined considering several Low Impact Development (LID) techniques. In the deterministic methodology, the best management scenario, representing location and area of LID controls, is identified using the bargaining model. In the stochastic methodology, uncertainties of some key parameters of SWMM are analyzed using the info-gap theory. For each water quality management scenario, robustness and opportuneness criteria are determined based on utility functions of different stakeholders. Then, to find the best solution, the bargaining model is performed considering a combination of robustness and opportuneness criteria for each scenario based on utility function of each stakeholder. The results of applying the proposed methodology in the Velenjak urban watershed located in the northeastern part of Tehran, the capital city of Iran, illustrate its practical utility for conflict resolution in urban water quantity and quality management. It is shown that the solution obtained using the deterministic model cannot outperform the result of the stochastic model considering the robustness and opportuneness criteria. Therefore, it can be concluded that the stochastic model, which incorporates the main uncertainties, could provide more reliable results.

신도시 LID 기법 적용방안 및 효과분석 모니터링에 관한 연구 (I) LID 기법 선정 및 적정규모 산정

신도시 건설로 인한 도시화로 불투수 면적이 크게 증가하면서, 증발산량과 지하침투는 감소하고 지표유출 및 비점오염부하는 증가하고 있는 실정이다. 이러한 도시화로 인한 개발의 악영향에 대한 대안으로 최근 저영향개발(Low Impact Development; LID) 기법이 적용되고 있다. 본 연구에서는 연구대상 신도시 유역에 대한 최적 LID 기법의 선정과 적정규모를 산정하였다. 강우유출관리, 오염물질제거 능력, 토양조건 등을 검토하여 침투도랑, 식생체류지, 나무여과상자, 인공습지 및 투수성 포장 등의 기법을 선정하였다. 본 연구에서 검토한 적정규모는 각각의 기법에 맞는 산정식(WQV, WQF)을 이용하였으며, 총 LID 면적은 <TEX>$80,300m^2$</TEX>으로 산정되었다. 본 연구에서 제시하는 LID 기법의 선정과 규모산정의 방법론은 최근 자연재해와 기후변화에 대응하여 효율적으로 미래의 토지이용 및 빗물관리계획을 수립하는데 일조할 것이다. With an increase in the impermeable areas being used for the construction of new town cities and urbanization, evapotranspiration and infiltration have decreased, while surface flow and non-point pollution loads have increased. As a solution to the adverse effects of development resulting from rapid urbanization, Low Impact Development(LID) techniques are being applied recently. In this study, the most suitable LID techniques were selected and an optimum area for their application was estimated in a new town city basin. The techniques such as the Infiltration Trench, Bio-retention, Tree box Filter, Artificial Wetland, and Porous Pavement were selected after reviewing the rainfall runoff management, LID techniques ability is to eliminate pollutants, and the condition of the soil in the study area. The optimum size was calculated using formulas(WQV, WQF) from various techniques, and the total LID area was calculated to be <TEX>$80,300m^2$</TEX>. The methodologies used in this study for selecting the optimum LID techniques and calculating the optimum size are expected to present effective solutions in response to the recent natural disasters and climate changes, and contribute toward establishing future land use and rainfall management plans.

The Management of Nonpoint Source and Storm Water Reduction with LID Techniques in Inchon City, South Korea

Impervious areas have been expanded by urbanization and the natural structure of water circulation has been destroyed. The limits of centralized management for controlling storm water runoff in urban areas have been suggested. Low impact development (LID) technologies have been promoted as a crucial alternative, establishing a connection with city development plans to build green infrastructures in environmentally friendly cities. Thus, the improvement of water circulation and the control of nonpoint source were simulated through XP-SWMM (storm water and wastewater management model for experts) in this study. The application of multiple LID combination practices with permeable pavements, bioretention cells, and gutter filters were observed as reducing the highest runoff volume by up to 70%. The results from four different LID installation scenarios indicated that permeable paving is the most effective method for reducing storm water runoff. The rate of storm water runoff volume reduced as the rainfall duration extended. Based on the simulation results, each LID facility was designed and constructed in the target area. The LID practices in an urban area enable future studies of the analysis of the criteria, suitable capacity, and cost-efficiency, and proper management methods of various LID techniques.

Study on the Reduction Assessment of Pollutant Loads by Low Impact Development Technique for Total Maximum Loads Management with Modified SWAT Model

Study on the Reduction Assessment of Pollutant Loads by Low Impact Development Technique for Total Maximum Loads Management with Modified SWAT Model

비점오염 저감시설에 적용되는 여재의 흡착 및 탈착 능력 평가

Urbanization causes many environmental, hydrological and ecological problems such as distortion of the natural water circulation system, increase in nonpoint source pollutants in stormwater runoff, degradation of surface water quality, and damage to the ecosystem. Due to the increase in impervious surface by urbanization, developed countries apply low impact development (LID) techniques as important alternatives to reduce the impacts of urbanization. In Korea, LID techniques were employed since 2012 in order to manage nonpoint source pollutants. LID technology is a technique for removing pollutants using a variety of physical, chemical and biological mechanisms in plants, microorganisms and filter media with the reduced effluence of stormwater runoff by mimicking natural water circulation system. These LID facilities are used in a variety of filter media, but an assessment has not been carried out for the comprehensive comparison evaluation of adsorption and desorption characteristics for the pollutant removal capacity. Therefore, this study was conducted to analyze the adsorption and desorption characteristics of various filter media used in the LID facilities such as sand, gravel, bioceramic, wood chips and bottom ash etc. in reducing heavy metals(Pb, Cu). In this study, the adsorption affinity for Pb in all filter media was higher than Cu. Pseudo second order equation and Langmuir-3 isotherm are more applicable in the adsorption kinetic model and adsorption isotherm model, respectively. As a result of the desorption experiment, the filter media does not exceed KSLT which is the hazardous substance leaching limit, showing the capability of the filter media in LID. The bioceramic and woodchip as filter medias were evaluated and exhibited excellent adsorption capacity for Pb.

Watershed Plan Implementation Challenges for SMS4s in Murrells Inlet

This case study describes the plan development process, implementation strategies and initial and future challenges to implementation for the Murrells Inlet Watershed Plan (WRCOG, 2014). The Plan was crafted by a group of key stakeholders with community support and guidance to address fecal coliform bacteria loading in shellfish harvesting waters in the Murrells Inlet Estuary along the northeastern South Carolina coast. Stakeholders debated the interpretation of the data analysis and ultimately concluded that the primary pollutant sources were non-human, namely wildlife and domestic animals. Stakeholders also concluded that the loads from these sources were being delivered to the estuary via a landscape that includes a network of surface drainage ditches and subsurface pipes so that water retention on the landscape has been largely short-circuited. Armed with this information, plan participants devised management measures that encompass several strategies, including: (1) utilize an end-of-pipe/ditch solution that addresses pollution nearest the discharge point; (2) generally reduce volume and flow and/or increase retention/detention across the landscape to reduce the pollutant load; and (3) use education and outreach to achieve behavior change. During both plan development and the implementation of management measures, the plan steering committee faced significant challenges. Initial challenges include: geographic and space limitations that make the use of large retention or detention devices impractical; lack of state or local requirements to use low impact development techniques to increase retention; and mounting outreach campaigns that cannot guarantee significant pollution reductions. Additional complications include mechanisms to sustain community support and involvement. As implementation progresses, the steering committee must track plan implementation and determine creative ways to evaluate the effectiveness of management measures. Local funding allocations must also be sought to leverage against potential grant funds to enable implementation.

The use of WorldView-2 satellite imagery to model urban drainage system with low impact development (LID) Techniques

Within a wide range of best management practices for stormwater management in urban areas, there has been an increasing interest in source control measures. Source controls such as low-impact development (LID) techniques are potentially attractive as retrofit options for older developed areas that lack available land to implement conventional measures such as stormwater management ponds. Hence, distributed urban drainage models requiring detailed representation of developed drainage areas should be developed to accurately estimate the benefits that LIDs may provide. This study (1) presents a two-stage classification process on a high-resolution WorldView-2 image, and (2) demonstrates how to use the extracted land cover information in the subsequent hydrologic modelling and assessment of different LIDs’ performance. The proposed two-stage classification method achieved an overall accuracy of 80.6%, whereas a traditional pixel-based achieved 68.4% in classifying the same urban area into six land cover classes. From the classification results, the hydrologic properties of micro-subcatchments were imported in the United States Environmental Protection Agency Storm Water Management Model to assess the performance of LIDs. A reduction of run-off volume 18.2% and 37.1% was found with the implementation of porous pavement and bioretention, respectively, in a typical low-rise residential area located in the city of San Clemente, California, US. The study demonstrates the use of high-resolution remote sensing image to aid in evaluating LID retrofit options, and thus benefits in situations where detailed drainage area information is not available.

Experimental Testing for Evaluating the Influence of Substrate Thickness on the Sub-Surface Runoff of a Green Roof

Green roofs (GRs) represent one of the most widespread Low Impact Development (LID) techniques, although the lack of adequate modeling tools is a limiting factor in the diffusion of such practices. GRs may represent a solution for minimizing the impact of urbanization on the hydrological cycle and for sustainably managing water resources in urban environment. Several studies have shown that GRs effectively control surface runoff in urban drainage system reducing overall volumes and peak flow rates. The performance of a GR is strongly dependent upon substrate soil depth. The understanding of infiltration phenomena in soil medium is one of the most important factors in the LID’s hydrological behavior analysis. In this study the hydrologic/hydraulic behavior of a GR for varying substrate thicknesses and constant rainfall intensities, ranging from 45 to 130 mm/h is tested. The results show that sub-surface runoff is linearly influenced by substrate thickness.

Rehabilitation of concrete canals in urban catchments using low impact development techniques

Urbanization generally increases surface runoff and pollutant loading and decreases infiltration and dry weather flow in canals. Efforts to handle the increased surface runoff, such as widening and deepening canals, further degrade the landscape and riverine habitats. To avert the negative effects of such changes, low-impact development (LID) has been adopted to restore natural flow processes and enhance nutrient removal from urban runoff in recent years. However, the installation of LID techniques often requires space, which can be very limited in intensely developing catchments. This study proposes to install a LID structure, referred to as the Green Channel Cover (GCC), in the space available on top of an open concrete canal to retain stormwater at the receiving end of the water body. The bioretention LID module of the Environmental Protection Agency’s Storm Water Management Model 5 was used to simulate flow through the proposed GCC. The peak canal flow depth in a heavily urbanized, tropical catchment was reduced by up to 14% in the presence of the GCC, which occupied only 0.07% of the catchment area. The proposed GCC also retained up to 36 mm of the storm water runoff during peak flows, which resulted in peak flow reduction, especially during high intensity rainfall events with precipitation rates greater than 25 mm h−1. A sensitivity analysis showed that the hydraulic conductivity and depths of the soil and storage layers of the GCC did not influence the peak flow reduction as much as the percent impervious area of the catchment. A partial GCC, with an opening that allows direct sunlight and rainfall into canal, was also successfully tested for efficiency in reducing canal peak flows. Overall, the GCC was found to be a good augmentation to existing rehabilitation measures in urban catchments.

Stormwater management the American way: why no policy transfer?

From the 1940s until the 1980s the federal government gradually extended its authority over the structure of the American stormwater management system. The goal was to improve the water quality of the nation’s waterways by regulating the pollution loads entering the system, primarily through the use of gray infrastructure. However during the1980s the Environmental Protection Agency (EPA) began to explore new approaches toward the regulation of stormwater pollution. Instead of focusing only on gray mechanisms, the EPA began developing and promoting the use of low impact development (LID) techniques as an element municipal governments could use to achieve their total maxim daily load of pollutants allowable under the National Pollutant Discharge Elimination System permit system. In light of the incentive offered by the EPA for the use of LID in the management of stormwater, it should be expected to provide a perfect area to observe policy transfer between federal, state and local governments; but it does not. This article will establish why the EPA began promoting a green approach to stormwater management and why this has not led to a widespread transfer of best management practices in the ways the literatures associated with federalism and policy transfer would suggest.

Cost Efficiency of Low Impact Development (LID) Stormwater Management Practices

Stormwater management has focused increasingly on Low Impact Development (LID) techniques in recent years. Although their effectiveness has been demonstrated in a number of cases, methodologies for the selection of most appropriate solutions for individual sites are still evolving. The cost efficiency of implementing a wide range of LID techniques in a proposed land development in the City of London, Ontario, Canada was investigated using continuous hydrologic simulation and a recently developed LID costing tool. The results indicate that infiltration trench and infiltration trench in combination with green roof were the most cost efficient solutions for runoff reduction.

LID 기술 적용을 통한 공동주택단지 물순환 개선 연구 - 침투시설 적용을 중심으로 -

Change in the Global Climate causes flood, drought, heavy snow, and rainfall patterns in the Korean Peninsula. A variety of alternatives related to climate change are considered. The foreign researchers are interested in Low Impact Development(LID); the utilization of water resources and eco friendly development, over 10 years ago. The research and development of related technology has been advanced to apply LID techniques in order to develop several projects in the country. However, sharing of technology or system that can be used easily in the private sector is insufficient. The performance of the elements of LID Technology has not been fully agreed. LID elements of this technology are easy to apply to Apartment complex. The elements are classified technology. The infiltration of elements performs the functions of apartment complex landscaping space technology applied to the target. The water cycle simulation(SWMM 5.0) and technology the implementation of the effectiveness is also verified. For this purpose, three different places in apartment complex to target by SWMM5.0 U.S. EPA conducted utilizing simulated rainfall and applying LID techniques before and after the simulated water cycle (infiltration, surface evaporation, and surface runoff) were conducted. The importance of green space in the LID techniques of quantitative and qualitative storm water control as well as the role of Apartment Housing is to promote Amenity. Remember that the physical limitations of apartment complex and smooth water circulation system for the application of LID integrated management techniques should be applied. To this end, landscapes, architecture, civil engineering, environmental experts for technical consilience between the Low Impact Development efforts are required.

Modeling low impact development potential with hydrological response units

Evaluations of benefits of implementing low impact development (LID) stormwater management techniques can extend up to a watershed scale. This presents a challenge for representing them in watershed models, since they are typically orders of magnitude smaller in size. This paper presents an approach that is focused on trying to evaluate the benefits of implementing LIDs on a lot level. The methodology uses the concept of urban hydrological response Unit and results in developing and applying performance curves that are a function of lot properties to estimate the potential benefit of large-scale LID implementation. Lot properties are determined using a municipal geographic information system database and processed to determine groups of lots with similar properties. A representative lot from each group is modeled over a typical rainfall year using USEPA Stormwater Management Model to develop performance functions that relate the lot properties and the change in annual runoff volume and corresponding phosphorus loading with different LIDs implemented. The results of applying performance functions on all urban areas provide the potential locations, benefit and cost of implementation of all LID techniques, guiding future decisions for LID implementation by watershed area municipalities.

The effects of low impact development on urban flooding under different rainfall characteristics

Low impact development (LID) is generally regarded as a more sustainable solution for urban stormwater management than conventional urban drainage systems. However, its effects on urban flooding at a scale of urban drainage systems have not been fully understood particularly when different rainfall characteristics are considered. In this paper, using an urbanizing catchment in China as a case study, the effects of three LID techniques (swale, permeable pavement and green roof) on urban flooding are analyzed and compared with the conventional drainage system design. A range of storm events with different rainfall amounts, durations and locations of peak intensity are considered for holistic assessment of the LID techniques. The effects are measured by the total flood volume reduction during a storm event compared to the conventional drainage system design. The results obtained indicate that all three LID scenarios are more effective in flood reduction during heavier and shorter storm events. Their performance, however, varies significantly according to the location of peak intensity. That is, swales perform best during a storm event with an early peak, permeable pavements perform best with a middle peak, and green roofs perform best with a late peak, respectively. The trends of flood reduction can be explained using a newly proposed water balance method, i.e., by comparing the effective storage depth of the LID designs with the accumulative rainfall amounts at the beginning and end of flooding in the conventional drainage system. This paper provides an insight into the performance of LID designs under different rainfall characteristics, which is essential for effective urban flood management.

Analysis of the characteristics of non-point pollutant runoff applied LID techniques in industrial area

Various techniques are being developed and applied for the management of non-point pollutants. Especially, there has been an increasing interest in the techniques which work for both the restoration of hydrologic cycle and management of non-point pollutants. When the need for the management of non-point pollutants first arose, structural concept of BMP was developed. Recent years saw the expansion of management plans including precautionary land use techniques such as low impact development (LID). LID is usually applied to new development areas but lately is in extensive use with existing city areas. To analyze the effect of LID application on an industrial complex by using Strom Water Management Model (SWMM), a point with clear division of the soil pipe and rainwater pipe sections was selected for monitoring non-point pollutant runoff and analyzing the characteristics of the runoff in this study. Furthermore, to construct a SWMM-LID model of a small-scale catchment, RUNOFF blocks were subdivided into sections and six event data with satisfactory flow pattern were selected from 24 monitoring data collected over three years (2009–2011) to be calibrated, two more event data were used for verification to complete the construction of the model. LID key technologies were applied as four CASEs: existing condition of the city (CASE 1), application of rain barrel (CASE 2), rain barrel and tree filter box (CASE 3), rain barrel, tree filter box, and porous pavement (CASE 4) for short-term and long-term (seasonal) simulation analyses.