Low Impact Development Technologies Research Articles

Research on water ecological transformation technology of residential district in Lanzhou New Area

Water ecological construction is imminent in Lanzhou because it is an arid region with little precipitation. Through the investigation of the natural conditions and construction status of Lanzhou New Area, furthermore analyze the basic condition of water ecological construction in the residential area of Lanzhou new district and explore the application effect of relevant low-impact development technology. This research tried to summarize the “open source” mode suitable for low impact development of water ecological transformation in residential districts of Lanzhou New Area, improve the regional water environment, promote efficiency of utilization of rain to retain the water resource and form a benign circulation system.

Nutrient concentration in sediments accumulated in pre-treatment basins of urban LID technologies.

In this study, the contribution of pre-treatment basins of low impact development (LID) technologies to nutrient reduction performance was evaluated by understanding the distribution of nutrient in sediments accumulated in each system. The captured sediments were mostly silt to medium sand ranging from 9% to 92% of the sediments collected. Greater average N and P concentrations were found in silt particles amounting to 345 mg/kg and 696 mg/kg, respectively compared to sand and gravel. Although, N concentrations in accumulated sediments were found to be highly variable at different particle sizes (CV: 0.24 to 0.77) compared to P concentration (CV: 0.08 to 0.36) attributed to effective P treatment mechanism through deposition compared to complex nitrogen removal mechanisms. In addition, the difference between N and P concentrations of sediments collected in the pre-treatment basins of LID technologies and in-situ soil was attributed to the continuous pollutant input to the LID technologies during storm events. The study proved that pre-treatment basins of stormwater LID technologies reinforced the nutrient removal performances through sediment retention. The findings of this research may be used to design pre-treatment basins of LID technologies considering nutrients as a limiting factor.

Assessment of cockle shells, walnut shells, and gingko shells as filter media for low impact development technologies

Assessment of cockle shells, walnut shells, and gingko shells as filter media for low impact development technologies

Improving Restorative Maintenance Practices for Mature Permeable Interlocking Concrete Pavements

Permeable Interlocking Concrete Pavements (PICP) are a Low Impact Development (LID) technology that reduce the total volume of stormwater discharge and peak flows from urban hardscapes. Over time, particulates accumulate in the PICP joints, decreasing the pavement’s surface infiltration capacity and negatively affecting its overall functionality. Maintenance with two surface treatment technologies, a hand-held power brush and pressure washer-used in combination with vacuum street sweepers were compared to maintenance with vacuum street sweepers alone at four PICP parking lots. Both surface treatments along with vacuum street sweeping significantly improved the restoration of infiltration capacity for the young (i.e., <4 years) PICP section. Pressure washing in combination with vacuum sweeping was effective for PICP sections with larger (13–14 mm) joint openings. Power brushing, however, provided inconsistent results between the PICP sections. The effect of surface treatments was not significant for older (i.e., >6 years) installations with small (3–4 mm) joint openings. Though surface treatment resulted in significant improvement with a pressure washer and vacuum street sweeper combination, usage intensity of the parking lot was deemed as an important factor in restoring infiltration capacity. These findings re-emphasize that regular maintenance is essential to ensure long-term hydraulic functionality of PICP.

Composite geotextile made with a reinforcing method using friction to unwind filament tows: Manufacturing techniques and property evaluations

Engineering design and academic research have been paying more attention to low impact development (LID), one prime development of which is geotextiles. This study uses friction to unwind filament tows for the production of composite geotextiles, meeting the demands of engineering and strengthened geotextiles. The mechanical and physical properties of the composite geotextiles are evaluated in terms of the filament content and needle punching depth. The test results prove that filament-reinforcement can significantly improve mechanical properties: tensile strength and tearing strength of the composite geotextiles are 2.3 and 7 times, respectively, those of commercially available geotextiles. The physical properties of the geotextiles also meet the standards, suggesting that the reinforcing method, which requires simple equipment to unwind the filament tows, can mechanically improve geotextiles and is suitable for mass production. The method creates multi-functional composite geotextiles and embodies the principles of LID technology. The composite geotextiles with a diversity of applications are helpful with environmental protection and sustainable development.

Landscape ecological planning of coastal industrial park based on low impact development concept: A case of the second coastal industrial base in Yingkou City, Liaoning Province, China.

Low impact development (LID) of industrial parks is an important component in the construction of China's sponge cities. We compared the methods of optimizing ecological spatial structure for rain and flood control in industrial parks, via analyzing the influence of landscape pattern on hydrological process. Firstly, according to the hydrological and geological conditions of the coastal area, the landscape pattern of the industrial park was optimized, with the water corridor system being structured and green patches being integrated. Then, the reasonable spatial allocation for the ecological infrastructure of the industrial park was realized, with the rain and flood control areas being divided based on the characteristics of the underlying surface. The runoff control indices of different control areas were determined, and the LID technical measures of different landscape nodes were selected. The results showed that the landscape pattern optimization strengthened landscape connectivity by constructing the ecological network within the industrial park. The runoff control rate of the park increased from 45% to 70% through the combination of various LID technologies, with the pervious pavement, submerged green space, rainwater garden, wet pond and grass ditch accounting for 1.3%, 1.9%, 0.2%, 0.2% and 0.1% of the total area, respectively. This study could provide new ideas and methods for the low impact development and construction of coastal industrial parks.

Evaluation of Effect of Urban Non-point Source Pollution Control on Porous Asphalt-Bio-retention Combined Roads

Different combinations of low impact development (LID) technologies can be applied for control of urban non-point source pollution. There are currently few evaluations of urban non-point source pollution and pollution load reduction based on a combination of porous asphalt and bio-retention. Taking Shenzhen International Low Carbon City as an example, road-deposited sediments were collected prior to and after rainfall events. Runoff was monitored under six typical rainfall events, from porous asphalt and the inlet/outlet of bio-retention. Through analysis of changes in the process of "build-up-wash-off-transport" of pollutant loads, the average build-up of road-deposited sediments in the study area was found to be (15.80±3.79) g·m-2; the mass percentage of road-deposited sediments (size>250 μm) was approximately 65.14%. The average wash-off percentage of six different intensity rainfall events was 17.15%, and road-deposited sediments (size<105 μm) were carried by 62.71%-74.94%. The average pollution loads of surface runoff pollutants SS, TN, and TP were 2.02, 0.025, and 0.0013 g·m-2, respectively. The removal rates of SS, TN, and TP through porous asphalt under infiltration and filtration were 70.26%, 46.29%, and 19.27%, respectively. The secondary purification removal rates of runoff water in bio-retention were 85.25%, 20.22%, and 70.27%, respectively. Pollutant loads into Dingshan River totaled 0.08, 0.011, and 0.0003 g·m-2, representing 4.05%, 43.47%, and 24.39% of runoff. The combination thus had a significant effect on runoff purification. Through quantitative research on the formation of non-point source pollution, this paper provides a scientific basis for estimating pollution loads of urban non-point source pollution and evaluating the performance of LID projects. It makes suggestions for the popularization and application of LID and sponge city design in China.

A Review of Green Roof Applications for Managing Urban Stormwater in Different Climatic Zones

Many regions have turned to low impact development technologies (LIDs), which are implemented to restore the changes in stormwater runoff that have resulted from urbanization. Green roofs are one typical type of LID. Until now, many studies have validated their roles in managing urban stormwater runoff. However, they have also revealed that the performance of green roofs largely varies with their design configuration, as well as their hydro-climatic exposure. The objectives of this review paper are to statistically synthesize the effects of the influential factors, including design and hydrologic variables, on green roof performance and to explore their effects in different climatic zones. The review’s results confirm the differences in the influential variables and, thus, the performance of green roofs in different climatic zones. These are the barriers to knowledge translation among engineering designers, stormwater managers, and policymakers in different climatic zones when implementing green roofs. Consequently, region- or site-specific studies are necessary to implement green roofs with confidence.

Impacts of nonpoint source pollutants on microbial community in rain gardens

Low-impact development (LID) techniques are being applied to reduce non-point source (NPS) pollution which are generated from various land uses. Cost-effective LID design requires consideration of influent runoff properties as well as physical and ecological pollutant-removing mechanisms. However, current LID technology design has failed to reflect the different properties of influent water from various land uses, and the biological design factors in LID facilities causing low efficiency and difficulties in maintenance. This study was conducted to identify biological design factors by analyzing the impact of the pollutants included in influent runoff and physical environment on microbial growth in rain garden facilities applied to different land uses. The results showed that the non-point source pollutant loadings were about 1.5–3 times higher in the runoff from parking lots, which are frequently visited by automobiles than in roof runoff. Type of soil, chemical species, and chemical composition were assessed as internal environmental factors having significant impact on the phylum and the count of microorganisms in the facilities. The growth of Cyanobacteria, Streptophyta, Chlorophyta, Bacillariophyta, and Xanthophyceae was good when there was appropriate water content in the soil, light, and sandy soil. Based on these results, the future design of rain garden facilities should be performed by considering a microorganism appropriate to the properties of the influent pollutants, determining appropriate water content, nutrient content and soil type, and choosing plants that contribute to microbial growth.

Application of indices to evaluate LID facilities for sediment and heavy metal removal

Heavy metal and sediments transported from the urban catchment are the prime interest among researchers these days due to its toxic behaviour and hazardous effect on the animals, plants and human. The inflow from urban catchments and outflow from the Low impact development technologies (LID) were evaluated using different types of indices. Indices like fd, fp and Kd showed that heavy metals like Pb, Cd and Ni were dominantly observed in the dissolved form. These metals possess higher threat to the water bodies receiving urban runoff without any treatments. The state of heavy metal was highly dependent on the particle size which was directly affected by the TSS EMC in urban area. The indices like fd, fp and Kd were good enough to understand the behaviour, nature and state of metal in urban inflow and outflow from the system. On the other hand, calculated MPI and PERI indices showed that runoff from urban areas without any treatment bare very strong risk to the environment. LID technologies were found to be the better option in reducing the risk of urban areas to the receiving water bodies. These indices could be valuable for the decision making before the selection of applicable LID types, plants and filter media. Furthermore, indices like these can be devised to measure the impact of LID system to the environment as well as the decision making tool before discharge of outflow to the nearby streams.

Impact of Low-Impact Development Technologies from an Ecological Perspective in Different Residential Zones of the City of Atlanta, Georgia

Abstract Low-impact development (LID) technologies have a great potential to reduce water usage and stormwater runoff and are therefore seen as sustainable improvements that can be made to traditional water infrastructure. These technologies include bioretention areas, rainwater capturing, and xeriscaping, all of which can be used in residential zones. Within the City of Atlanta, residential water usage accounts for 53% of the total water consumption; therefore, residential zones offer significant impact potential for the implementation of LID. This study analyzes the use of LID strategies within the different residential zones of the City of Atlanta from an ecological perspective by drawing analogies to natural ecosystems. The analysis shows that these technologies, especially with the addition of a graywater system, work to improve the conventional residential water network based upon these ecological metrics. The higher metric values suggest greater parity with healthy, natural ecosystems.

Inexact fuzzy chance-constrained programming for community-scale urban stormwater management

Abstract Due to frequent and serious waterlog and environmental pollution in cities in recent years, urban stormwater management (USM) has become an essential issue of urban sustainable development in China. Low Impact Development (LID) technologies are effective and popular measures of USM, and can be used to reduce urban waterlog and the associated environmental pollution. In this paper, in order to identify an optimal strategy of LID technologies based on economic efficiencies and environmental performances, the construction costs and environmental benefits of the four LID technologies (including grass swales, bioretention cells, green roofs, and permeable pavement) were analyzed. Then, due to the uncertain feature of rainfall, concentration of pollutants and many social-economic factors, an inexact fuzzy chance-constrained programming (IFCCP) model was developed. Multiple uncertainties that can be expressed as interval parameters, fuzzy sets, and stochastic distribution can be addressed effectively and incorporated directly into the modeling process. Based on the analysis of the precipitation probability distribution and land use data, the developed model was applied to a university campus with relatively high building density and plot ratio in Beijing. Then, optimal solutions of multiple precipitation probabilities ( p m ) under varying USM goals were obtained. The four LID technologies were chosen to meet multiple USM goals based on multiple p m values. When p m = 0.1 , 0.05 , 0.02 and 0.015 , the total construction investments would be 1.46 to 4.66, 1.46 to 5.25, 2.31 to 8.54 and 3.95 to 12.7 million yuan, respectively. The relationship between construction costs and p m represented the relationship between economic benefit and system risk. The results indicated that USM was influenced by the rainfall capacity, construction costs would increase with the increase of precipitation, and the risks of constraint violation would decrease as the construction costs increase. When considering the four LID technologies during the planning stage of USM, the preferred selection order would be bioretention cells, permeable pavements, grass swales and green roofs. Therefore, the solutions under each p m level could provide the references for desired USM plans.

Application of low impact development technology in rainwater drainage system reconstruction project

Urban roadway contributing much to the runoff and non-point source pollution in modern cities is one of the key objectives when conducting stormwater management in Sponge City construction, which was recently launched by Chinese government. In the present case study, Qinhuang Avenue (hbox {length}times hbox {width}=2.4,hbox {km}times 80~hbox {m}) from Xixian New Area in northwest China was chosen as the research objective. The current limitations within the rainwater drainage system of Qinhuang Avenue were analyzed as well as its environmental background (such as the structure and permeability of the wet-sunk loess). Under the premise of maintaining roadway safety and taking the horizontal and vertical line into consideration, low impact development (LID) technology was applied for the design and planning of the reconstruction project according to the principle and requirement of LID technology. The implementation results of the project indicated that waterlogging and flooding issues in the object region were obviously resolved and environmental capacity was improved as evidenced by the reduced volume, peak value and contaminants concentration of total runoff.

Global policy analysis of low impact development for stormwater management in urban regions

Population increase and migration from rural areas to urbanized regions have resulted in the formation of gray cities mainly comprised of impervious surfaces. High quantities of stormwater runoff containing pollutants from gray cities cause problems including inland flooding and water pollution. An innovative and evolving response to this global issue is the development of green cities that utilize low impact development (LID) and analogous initiatives. This paper aims to assess LID efforts and relevant governmental policies from a global perspective. It provides a vantage on major evolving LID technologies, where the best policies regarding planning, design, construction, and management are still not well known. The case studies of LID and relevant governmental policies around the world are presented to facilitate future quantitative and qualitative stormwater management in urban regions. This study found that the western and eastern regions around the globe have different driving forces and attitudes regarding implementing LID. These differences are reflected in the name of their LID-like initiatives with varying ramifications. The western regions, such as the United States, pay more attention to restoring water quality, whereas the eastern regions, such as China, prioritize flood prevention and rainwater harvesting. Levying stormwater fees and indirect subsidies by offering a discount are effective for promoting LID to some extent. This paper also provides an in-depth discussion in regard to the latest essence of LID technologies, which magnify their ability to manage stormwater while also providing societal, environmental, hydrological, and aesthetic benefits. Governments should encourage and support the development of green cities by using LID and analogous initiatives.

Performance of biofilter with a saturated zone for urban stormwater runoff pollution control: Influence of vegetation type and saturation time

Stormwater runoff greatly contributes to surface water pollution and deterioration of aquatic environment in urban areas. Biofilter, as low impact development (LID) technology, has been widely applied in controlling urban runoff pollution in recent years. A multi-layered biofilter with a saturated zone was employed in this study to test its removal efficiency of pollutants and the effect of saturation time on its performance with the real road runoff. Two groups of columns were built with different vegetations (Zoysia matrella, ZM and a combination of Iris pseudacorus and Z. matrella, IZ). During a 2.5-month duration, five times of runoff dosing trials with collected stormwater were conducted at a load of 20–25Lday−1. All filter systems had effective retention of particulate matters, with the turbidity removals of over 95%. The IZ group performed more efficiently than ZM systems in the removal of total phosphorus (TP), ammonia (NH4-N), nitrate (NO3-N) and turbidity. The mean removal of total nitrogen (TN) and TP was 49.8±23.8% and 74.8±9.9% in IZ group, and 42.6±22.0% and 66.4±12.2% in ZM group. Saturation time had significant effect on the removal of TN, TP and turbidity, whose concentrations declined with the saturation duration. The performances of biofilters were dynamic, as a function of media depth and retention time. The configuration of saturated zone and optimized depth of media layers (at least 0.75m) can provide a favorable condition for nitrogen removal under random inflow condition.

Modelling and optimization of land use/land cover change in a developing urban catchment.

The impacts of land use/cover change (LUCC) on hydrological processes and water resources are mainly reflected in changes in runoff and pollutant variations. Low impact development (LID) technology is utilized as an effective strategy to control urban stormwater runoff and pollution in the urban catchment. In this study, the impact of LUCC on runoff and pollutants in an urbanizing catchment of Guang-Ming New District in Shenzhen, China, were quantified using a dynamic rainfall-runoff model with the EPA Storm Water Management Model (SWMM). Based on the simulations and observations, the main objectives of this study were: (1) to evaluate the catchment runoff and pollutant variations with LUCC, (2) to select and optimize the appropriate layout of LID in a planning scenario for reducing the growth of runoff and pollutants under LUCC, (3) to assess the optimal planning schemes for land use/cover. The results showed that compared to 2013, the runoff volume, peak flow and pollution load of suspended solids (SS), and chemical oxygen demand increased by 35.1%, 33.6% and 248.5%, and 54.5% respectively in a traditional planning scenario. The assessment result of optimal planning of land use showed that annual rainfall control of land use for an optimal planning scenario with LID technology was 65%, and SS pollutant load reduction efficiency 65.6%.

A new methodology for surcharge risk management in urban areas (case study: Gonbad-e-Kavus city).

This research presents a simulation-optimization model for urban flood mitigation integrating Non-dominated Sorting Genetic Algorithm (NSGA-II) with Storm Water Management Model (SWMM) hydraulic model under a curve number-based hydrologic model of low impact development technologies in Gonbad-e-Kavus, a small city in the north of Iran. In the developed model, the best performance of the system relies on the optimal layout and capacity of retention ponds over the study area in order to reduce surcharge from the manholes underlying a set of storm event loads, while the available investment plays a restricting role. Thus, there is a multi-objective optimization problem with two conflicting objectives solved successfully by NSGA-II to find a set of optimal solutions known as the Pareto front. In order to analyze the results, a new factor, investment priority index (IPI), is defined which shows the risk of surcharging over the network and priority of the mitigation actions. The IPI is calculated using the probability of pond selection for candidate locations and average depth of the ponds in all Pareto front solutions. The IPI can help the decision makers to arrange a long-term progressive plan with the priority of high-risk areas when an optimal solution has been selected.

The Analysis of Stormwater Runoff Quality and Quantity of Water Cycle Sidewalk using Low Impact Development Technologies in Urban Areas

LID facilities on the green area-sidewalk-road in cities can be applied in different types and forms according to the status and characteristics of a space. There are some limitations of using LID facilities with respect to area, these limitations can overcome by using the suitable combination of LID practices in an area. For this purpose, the Water Cycle Sidewalk (WCS) was used through the connections of various LID techniques. The WCS could manage stormwater runoff and water quality in a space adjacent to green area-sidewalk-road as a part of WCS, a permeable block pavement (PBP) was installed on the sidewalk, and a vertical infiltration pipe (VIP) and an infiltration-storage tank were located underneath the PBP. Runoff on the sidewalk was pre-treated by a first flash treatment facility and then stored in a storage tank for watering the green area. The average infiltration capacity of a PBP with a storage tank under the pavement was 0.30 mm/sec, about 6 times higher than that of a general PBP section. From the results, the infiltration capacity of a single VIP was approximately 0.35 mm/sec. The overall efficiency rate of runoff reduction from this facility was between 50% and 70%. In addition, the rainwater in the Storage Tank analyzed to be appropriate to use water for landscaping.

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.

식생이 조성된 LID 시설의 효율 평가

도시 지역의 물순환 구축과 비점오염물질 저감을 위해 구축되는 LID 시설의 지속적 효율은 주요 내부 구성요소(식물, 토양, 여재, 미생물 등)의 최적화된 상호작용에 의하여 나타난다. 본 연구는 식생이 조성된 4가지 LID 기술 (식생체류지, 소규모 인공습지, 빗물정원 및 나무여과상자)의 실제 도시 강우유출수의 유입으로 인한 식물의 성장상태 변화와 물순환 효과 및 비점오염물질 저감능력을 평가하기 위하여 수행되었다. 도시지역의 강우유출수의 약 40% 이상의 유출저감을 위한 적정 SA/CA (facility surface area / catchment area) 비는 시설마다 차이는 있지만 1~5% 범위가 적당한 것으로 평가되었다. 강우시 LID 시설에서의 유출저감은 비점오염물질 저감효율 향상에 중요한 영향을 끼치는 기작으로 나타났으며, SA/CA는 LID 시설의 중요한 설계인자로 도출되었다. 유출저감에 효과적인 시설은 빗물정원 > 나무여과상자 > 식생체류지 > 소규모 인공습지 순으로 나타났으며 입자상 물질 (TSS)의 제거능력은 빗물정원 > 나무여과상자 > 소규모 인공습지 > 식생체류지 순으로 분석되었다. 유기물 (COD, TOC), 영양물질 (TN, TP) 및 중금속 (Cu, Pb, Cd, Zn) 제거에는 빗물정원 > 나무여과상자 > 식생체류지 > 소규모 인공습지 순으로 조사되었으며 이러한 결과들은 향후 도시지역의 물순환 구축 및 비점오염물 제거에 적용되는 LID 시설의 설계에 중요한 자료로 활용 가능할 것으로 판단된다. Low impact development (LID) facilities are established for the purpose of restoring the natural hydrologic cycle as well as the removal of pollutants from stormwater runoff. Improved efficiency of LID facilities can be obtained through the optimized interaction of their major components (i.e., plant, soil, filter media, microorganisms, etc.). Therefore, this study was performed to evaluate the performances of LID facilities in terms of runoff and pollutant reduction and also to provide an optimal maintenance method. The monitoring was conducted on four LID technologies (e.g., bioretention, small wetlands, rain garden and tree box filter). The optimal SA/CA (facility surface area / catchment area) ratio for runoff reduction greater than 40% is determined to be 1 - 5%. Since runoff reduction affects the pollutant removal efficiency in LID facilities, SA/CA ratio is derived as an important factor in designing LID facilities. The LID facilities that are found to be effective in reducing stormwater runoff are in the following order: rain garden > tree box filter > bioretention> small wetland. Meanwhile, in terms of removal of particulate matter (TSS), the effectiveness of the facilities are in the following order: rain garden > tree box filter > small wetland > bioretention; rain gardens > tree box filter > bioretention > small wetland were determined for the removal of organic matter (COD, TOC), nutrients (TN, TP) and heavy metals (Cu, Pb, Cd, Zn). These results can be used as an important material for the design of LID facilities in runoff volume and pollutant reduction.