Rain Gardens Research Articles

Nematode Community Response to Green Infrastructure Design in a Semiarid City.

Urbanization affects ecosystem function and environmental quality through shifts in ecosystem fluxes that are brought on by features of the built environment. Green infrastructure (GI) has been suggested as a best management practice (BMP) to address urban hydrologic and ecological impacts of the built environment, but GI practice has only been studied from a limited set of climatic conditions and disciplinary approaches. Here, we evaluate GI features in a semiarid city from the perspective of soil ecology through the application of soil nematode community analysis. This study was conducted to investigate soil ecological interactions in small-scale GI as a means of assessing curb-cut rain garden basin design in a semiarid city. We looked at the choice of mulching approaches (organic vs. rock) and how this design choice affects the soil ecology of rain basins in Tucson, AZ. We sampled soils during the monsoon rain season and assessed the soil nematode community as a bioindicator of soil quality and biogeochemical processes. We found that the use of organic mulch in GI basins promotes enhanced soil organic matter contents and larger nematode populations. Nematode community indices point to enhanced food web structure in streetscape rain garden basins that are mulched with organic material. Results from this study suggest that soil management practices for GI can help promote ecological interactions and ecosystem services in urban ecosystems.

A modified eco-efficiency framework and methodology for advancing the state of practice of sustainability analysis as applied to green infrastructure.

We propose a modified eco-efficiency (EE) framework and novel sustainability analysis methodology for green infrastructure (GI) practices used in water resource management. Green infrastructure practices such as rainwater harvesting (RWH), rain gardens, porous pavements, and green roofs are emerging as viable strategies for climate change adaptation. The modified framework includes 4 economic, 11 environmental, and 3 social indicators. Using 6 indicators from the framework, at least 1 from each dimension of sustainability, we demonstrate the methodology to analyze RWH designs. We use life cycle assessment and life cycle cost assessment to calculate the sustainability indicators of 20 design configurations as Decision Management Objectives (DMOs). Five DMOs emerged as relatively more sustainable along the EE analysis Tradeoff Line, and we used Data Envelopment Analysis (DEA), a widely applied statistical approach, to quantify the modified EE measures as DMO sustainability scores. We also addressed the subjectivity and sensitivity analysis requirements of sustainability analysis, and we evaluated the performance of 10 weighting schemes that included classical DEA, equal weights, National Institute of Standards and Technology’s stakeholder panel, Eco-Indicator 99, Sustainable Society Foundation’s Sustainable Society Index, and 5 derived schemes. We improved upon classical DEA by applying the weighting schemes to identify sustainability scores that ranged from 0.18 to 1.0, avoiding the nonuniqueness problem and revealing the least to most sustainable DMOs. Our methodology provides a more comprehensive view of water resource management and is generally applicable to GI and industrial, environmental, and engineered systems to explore the sustainability space of alternative design configurations.

Selection of cost-effective Green Stormwater Infrastructure (GSI) applicable in highly impervious urban catchments

Urban areas such as roads, and parking lots, present different sets of problem, vehicular Nonpoint source (NPS) loadings derived from vehicular use are very high, while the roof have low NPS pollutant loadings. Therefore, this study was conducted to monitor the actual stormwater runoff characteristics of various landuse types and the treatment efficiency of the constructed GSI systems applied. The data used to calculate the pollutant concentrations were gathered from a total of 172 storm events during the five year monitoring period on a paved road, parking lot and roof landuse site. Based on the results, the road and parking lot landuses have characteristics of large amount of stormwater runoff, high peak flow and runoff of high pollutant concentration due to the vehicular activities. Applicable facilities include pretreatment facilities, such as infiltration trench, subsurface flow (SSF) and hybrid constructed wetland and tree box filter which have SA/CA ratios within 1∼2% were appropriate for facilities effective for reducing pollutants including infiltration and filtration functions. Meanwhile, the roof landuse contains low pollutants in comparison to other land uses, so, bioretention, rain garden, and free water surface (FWS) constructed wetland which have SA/CA ratio within 5% were appropriate to enable processing and recycling of large amount of stormwater runoff that have infiltration and retention function. Therefore, costeffective GSI design must not only depend on treated runoff quantity but also quality of the treated runoff for landuse.

Evaluating Various Low-Impact Development Scenarios for Optimal Design Criteria Development

Low-impact development (LID) practices as a new approach to urban stormwater management have demonstrated their positive effects through the reduction of surface runoff volumes and pollutant loadings in a substantial amount of research. The effectiveness of LID practices can be affected by various LID conditions such as type, location, and area. Cost is also an important factor to be considered in the evaluation of LID effects. This study presented the optimal LID conditions that can achieve targeted reduction goals with minimal cost, and analyzed the effectiveness of LID practices under optimal LID conditions and the consequential cost on a watershed scale. To determine cost-effective LID conditions, three types of LID practices (rain gardens, rainwater harvesting tanks, and permeable pavements), two locations (residential and commercial areas), and percent allocation of LID practices were considered. Manual optimization was conducted under those LID conditions for five targeted reduction goals which were set for surface runoff and nutrient loadings. The results provided various configurations of cost-effective conditions in treating the targeted goals, and represented the impacts of the optimized LID conditions on the effectiveness of LID practices and the consequential cost. The present study could ultimately assist regulators in establishing proper watershed-scale strategies of LID conditions for effectively managing watersheds.

Simulation of the cumulative hydrological response to green infrastructure

AbstractIn this study, we evaluated the cumulative hydrologic performance of green infrastructure in a residential area of the city of Parma, Ohio, draining to a tributary of the Cuyahoga River. Green infrastructure included the following spatially distributed devices: 16 street‐side bioretention cells, 7 rain gardens, and 37 rain barrels. Data consisted of rainfall and outfall flow records for a wide range of storm events, including pretreatment and treatment periods. The Stormwater Management Model was calibrated and validated to predict the hydrologic response of green infrastructure. The calibrated model was used to quantify annual water budget alterations and discharge frequency over a 6 year simulation period. For the study catchment, we observed a treatment effect with increases of 1.4% in evaporation, 7.6% in infiltration, and a 9.0% reduction in surface runoff. The hydrologic performance of green infrastructure was evaluated by comparing the flow duration curve for pretreatment and treatment outfall flow scenarios. The flow duration curve shifted downward for the green infrastructure scenario. Discharges with a 0.5, 1, 2, and 5 year return period were reduced by an average of 29%. Parameter and predictive uncertainties were inspected by implementing a Bayesian statistical approach.

Evaluating the Impact of Low Impact Development (LID) Practices on Water Quantity and Quality under Different Development Designs Using SWAT

The effects of Low Impact Development (LID) practices on urban runoff and pollutants have proven to be positive in many studies. However, the effectiveness of LID practices can vary depending on different urban patterns. In the present study, the performance of LID practices was explored under three land uses with different urban forms: (1) a compact high-density urban form; (2) a conventional medium-density urban form; and (3) a conservational medium-density urban form. The Soil and Water Assessment Tool (SWAT) was used and model development was performed to reflect hydrologic behavior by the application of LID practices. Rain gardens, permeable pavements, and rainwater harvesting tanks were considered for simulations, and a modeling procedure for the representation of LID practices in SWAT was specifically illustrated in this context. Simulations were done for each land use, and the results were compared and evaluated. The application of LID practices demonstrated a decrease in surface runoff and pollutant loadings for all land uses, and different reductions were represented in response to the land uses with different urban forms on a watershed scale. In addition, the results among post-LIDs scenarios generally showed lower values for surface runoff and nitrate in the compact high-density urban land use and for total phosphorus in the conventional medium-density urban land use compared to the other land uses. We suggest effective strategies for implementing LID practices.

Evapotranspiration in Rain Gardens Using Weighing Lysimeters

Quantification of evapotranspiration (ET) and infiltration from vegetated stormwater control measures (SCMs), such as rain gardens, is necessary to properly assess their volume reduction potential. Weighing lysimeters at Villanova University mimic three rain garden designs and measure water budget parameters to determine how design elements impact ET. The designs compare two soil media with the same unconstricted drainage systems: a sandy loam and sand and two drainage systems with the same media (sand): an unconstricted valve (UV) outflow and internal water storage (IWS) outflow. A custom system distributed water over the lysimeters to mimic the runoff typically delivered to a rain garden during natural storm events. Runoff simulation trials were performed in summer and fall and compared to direct rainfall to the lysimeters during those seasons. Evapotranspiration rates were unaffected in the sandy loam lysimeter and increased in the sand lysimeters by the simulated rainfall in each system. Average ET over the entire study period was 2.9, 2.7, and 4.3 mm/d for the sandy loam, sand, and sand internal water storage, respectively. Evapotranspiration made up 47, 43, and 70% of the water budget for the sandy loam, sand, and sand IWS systems, respectively. The native soil (sandy loam) did not negatively affect the rate of ET. The IWS drainage system enhanced ET over the unconstricted valve drainage system. In an effort to promote inclusion of ET into rain garden design, seasonal and monthly ET rates are provided as baseline values. The ASCE Penman-Monteith ET and Hargreaves ET equations adequately represent the unconstricted valve lysimeter systems and underrepresent the IWS lysimeter system.

ANALISIS KESESUAIAN LAHAN UNTUK RUANG TERBUKA HIJAU DAN RUANG TERBUKA BIRU DI SENTUL CITY, BOGOR

Sentul City as a new city must be able to meet the water needs of its residents. Sentul City has annual rainfall up to 4 000 mm/year but most are rare groundwater areas. With the topography, its annual rainfall, and proximity to the river, Sentul City is a good potential to make lake and rain garden as retention pond and for replenish groundwater. An analysis of land suitability of green and blue open spaces is needed to optimizing the land use of Sentul City, especially as green and open spaces. This study was aimed to do land evaluation of green and blue open spaces in Sentul City. The research is conducted by land evaluation method using Geographic Information System (GIS). The analysis result shows that the suitable land for park was 24% of the area that moderately suitable and was 54% that marginally suitable. Land that are moderately suitable for urban forest are 25% and 75% are marginally suitable. Land that are moderately suitable for golf are 77% of the area, and 23% are marginally suitable. Land that are suitable for lake as retention pond are 11% of the area, and land that are suitable for rain garden are 22% of the area.

The Jaguaré Creek Revitalization Project: Transforming São Paulo through a Green Stormwater Infrastructure

The surrender of environment and landscape to the pressure of fast rural-urban transition has labelled São Paulo as the ‘Metropolis of Polluted Waters’ worldwide. How can the largest city in Latin America consider this issue of metropolitan dimensions: recover its large sewage rivers and reframe for resilience? The Jaguaré Creek Revitalization Project understands that this recovery depends on a fractionated, but integrated performance over all territories that generate pollution to water resources. Jaguaré Creek watershed corresponds to only 1/10 of the total 270km2 drainage area of Pinheiros River, one of the two main watercourses crossing Greater São Paulo and that is channeled in all its 25Km length. Its waters carry significant load of domestic and industrial sewage and other non-point sources as well. Regarding the failure of all previous public efforts, reversing this scenario requires innovation and an integrated system made of coordinated actions and based on technology, urban planning and advocacy. In order to restore this pilot watershed, the Jaguaré Project is coordinated by Águas Claras do Rio Pinheiros Organization and developed by a multidisciplinary team of researchers including engineers, landscape architects, urban planners, managers, among others, acting in two complementary fronts: 1. Interception and combined treatment of stormwater and sewage illegally discharged into underground drainage system; 2. Non-source point pollution control and runoff management through a Green Stormwater Infrastructure. For this second front, pollutant loads will be measured by runoff samples collected in predefined catchment areas. By associating the sample analysis results with the land use typologies within these areas, surface pollution loads may be quantified for the whole Jaguaré watershed. The sizing of the problem will lead to an optimized distribution of stormwater management LID structures. Rain gardens, bioswales, retention ponds, green roofs and pervious pavements will convey, filter, retain and infiltrate stormwater, respecting the most suitable drainage function to physical and environmental conditions. They will form a green network for urban drainage with greater bond with nature processes, landscape and people. By restoring creeks, São Paulo reclaims its rivers. By saving the rivers, the city will move towards transformation.

Quantitative evaluation about rainwater-runoff characteristics of rain garden

本研究は，京都学園大学太秦キャンパスに導入された雨庭の効果を定量的に評価し日本における導入可能性を示すため，降雨量・流出量・地下水位の実測を行った。その結果，降雨強度が 30 mm/hを超える降雨に対しては急激な流出水位勾配の変化が見られたことから，この値が雨庭の浸透能の上限値であることが示唆された。また降雨流出特性の評価指標として，降雨流出の発生した 5つの降雨イベントの流出率を計算したところ，その最大値は 29.6 ％であった。

Design, calculations and performance evaluation of rain gardens in an urban neighborhood of Thessaloniki, Greece

Design, calculations and performance evaluation of rain gardens in an urban neighborhood of Thessaloniki, Greece

A sustainability comparison of green infrastructure interventions using emergy evaluation

Green infrastructure (GI) has been touted as a more economically, socially, and environmentally sustainable option for urban stormwater management than more traditional gray infrastructure solutions. There are many types of GI, however, and there has been limited comparison of sustainability between types. This study examines the benefits and detriments of current GI designs (rain gardens, green roofs, porous pavements, and tree plantings) using emergy analysis, an environmental accounting system that evaluates the direct and indirect energy inputs used in the production of goods or services. Results of the analysis revealed inherent differences between the four GI typologies examined and identified system inputs that dominate emergy flows, and thus sustainability outcomes. Porous pavements performed the worst when evaluated using standard emergy-based environmental sustainability indices and the best when using economic indices. Indices calculated for green roofs and tree plantings indicated that these types of green infrastructure might inherently be more environmentally sustainable. Emergy inputs of stone and soil were dominant inputs for all systems, as was the emergy cost of disposal of excavated materials. Porous asphalt was a high emergy input for the porous pavement projects examined. Labor and equipment inputs were high for most projects, but were overshadowed by stone and soil inputs. These dominant emergy inputs show areas where efficiency of designs could be improved by practices such as recycling excavated sediments or utilizing construction materials that are less emergy intensive. In addition, the results of this study show that not all GI projects are created equally. Urban planners and other decision makers can use this information to improve standard design and implementation practices for GI projects.

Indicator and Pathogen Removal by Low Impact Development Best Management Practices

Microbial contamination in urban stormwater is one of the most widespread and challenging water quality issues in developed countries. Low impact development (LID) best management practices (BMPs) restore pre-urban hydrology by treating and/or harvesting urban runoff and stormwater, and can be designed to remove many contaminants including pathogens. One particular type of LID BMP, stormwater biofilters (i.e., vegetated media filters, also known as bioinfiltration, bioretention, or rain gardens), is becoming increasingly popular in urban environments due to its multiple co-benefits (e.g., improved hydrology, water quality, local climate and aesthetics). However, increased understanding of the factors influencing microbial removal in biofilters is needed to effectively design and implement biofilters for microbial water quality improvement. This paper aims to provide a holistic view of microbial removal in biofilter systems, and reviews the effects of various design choices such as filter media, vegetation, infauna, submerged zones, and hydraulic retention time on microbial removal. Limitations in current knowledge and recommendations for future research are also discussed.

Assessing the Potential of Low-Impact Development Techniques on Runoff and Streamflow in the Templeton Gap Watershed, Colorado

This study examines how the impact of impervious surface in the Templeton Gap watershed (Colorado) could be reduced through the use of low-impact development (LID) strategies. LID is a sustainable stormwater approach to land management that retains runoff close to the source by preserving natural landscape features and limiting imperviousness. Our research indicates that LID techniques could reduce peak flows generated by stormwater runoff, allow city engineers to restore the stream channel to a more natural state, and improve the safety of residents and the security of property below the levee. This study developed a model of the Templeton Gap watershed and its associated stormwater infrastructure using the Stormwater Management Model (SWMM) developed by the U.S. Environmental Protection Agency (EPA). Specifically designed for small urban watersheds, SWMM allows users to accurately represent stormwater runoff dynamics and project the impact of hypothetical LID features such as porous pavement, rain gardens, and infiltration trenches on runoff and streamflow.

하이브리드 빗물정원 시스템에서의 비점오염물질 및 강우유출수 이송 특성

본 연구는 도시 강우유출수 처리를 위한 하이브리드 빗물정원 시스템을 개발하고자 수행되었으며, Pilot scale 모니터링을 통하여 시스템 내의 서로 다른 구성요소간의 효율을 검증하였다. 유입수는 국내 외 도로강우유출수의 농도를 고려한 인공강우유출수를 이용하여 수행하였다. 모니터링 결과 하이브리드 빗물정원은 시설 내 저류 80%, 지하수의 침투 15%로 유입수의 약 95% 저감되는 것으로 나타났다. 이는 ST의 저류 및 PB와 IT의 침투 기작이 물순환 효과에 기여한 것으로 판단된다. 또한 오염물질 저감효율을 산정한 결과, TSS의 경우 평균 87%으로 나타났으며, 유기물은76%, 영양염류는 46%, 중금속은 56%으로 나타났다. 이는 PB와 IT에 포함된 여재의 여과, 침투 및 식생과 토양의 생물학적 흡수 기작 영향에 의해 나타난 결과로 판단된다. 이러한 연구 결과는 향후 빗물정원의 효율을 향상시키기 위한 시설의 개선 및 설계방안으로 활용 가능할 것으로 평가된다. In this research, a pilot scale hybrid rain garden system was developed in order to investigate the efficiency in the different components of the hybrid rain garden system and at the same time evaluate the initial efficiency of the system in treating urban stormwater runoff prior to its actual use in the field. Experimental runs were conducted using synthetic runoff having target concentrations similar to that of the typical runoff characteristics found in different countries and in Korea. With the employment of the hybrid rain garden system, hydrologic improvement was observed as the system demonstrates an approximately 95% reduction in the influent runoff volume with 80% retained in the system, and 15% recharged to groundwater. The reduction was contributed by the retention capabilities of ST and infiltration capabilities in PB and IT. With the combined mechanisms such as filtration-infiltration, biological uptake from plants and soil and phytoremediation that are incorporated in PB and IT, the system effectively reduces the amount of pollutant concentration wherein the initial mean removal efficiency for TSS is 87%, while an approximate mean removal efficiency of 76%, 46% and 56% was observed in terms of organics, nutrients and heavy metal, respectively. With these findings, the research helps in the further improvement, innovation and optimization of rain garden systems and other facilities as well.

The Value of Integrating Water Management and Urban Infrastructure

Water management in cities is changing as a result of climate change and increasing urbanisation. Instead of a “big pipes in, big pipes out” approach which imports water from the river basin into the city and discharges sewage water downstream, more and more the city itself is seen as a catchment and urban runoff as a resource. This requires a different approach to urban water management, which integrates water in urban infrastructure and planning. In addition to purely managing stormwater and urban water resources the water sensitive design approaches that have emerged increasingly have recreational and social goals. Urban infrastructure such as rain gardens, green roofs and retention ponds have an aesthetic and recreational function and can help making people aware of the preciousness of water. Yet, new approaches are often more complex and expensive than conventional urban water infrastructure and with long time horizons make a good trade-off between costs and benefits is difficult. Although the environmental, social and engineering benefits seem obvious, expressing it in monetary terms is challenging with standard economic methods. Based on the ABC Waters Programme in Singapore, several alternative methods for valuing new types of infrastructure are explored and methodological challenges identified.

Challenges and developments of bioretention facilities in treating urban stormwater runoff; A review

Bioretention or rain garden is a preferable low impact development (LID) approach due to its characteristics which reflect natural water cycle processes. However, this system is still little understood and quite complicated in terms of design and implementation due to many technical considerations. Hence, this paper gives a review of the challenges and developments for the use of bioretention facilities to enhance its capabilities in attenuating peak flow and treating stormwater runoff particularly in urban areas. This paper reviews the main aspects of bioretention which are stormwater hydrologic, hydraulic and treatment performance. Some of the limitations during the implementation of this natural approach are highlighted in design configuration and the public perception towards this new approach. It is concluded that the bioretention approach is one of the sustainable solutions for stormwater management that can be applied either for individual systems or regional systems.

Use of rain gardens for stormwater management in urban design and planning

Ecosystem services in urban areas have deteriorated year on year due to increased urbanization. As a consequence of increased urbanization, floods threaten inhabitants of various cities in Japan. Although a conventional way of treating urban flooding is to construct sewage systems, alternative approaches have to be developed because of their expense in the context of the current financial crisis, especially in local governments. Rain gardens, a type of low-impact development, have recently been recommended as a best management practice for the treatment of stormwater runoff in Northern European countries, the USA, etc. While demand for rain gardens has been increasing in Japan, there is a lack of knowledge about their functions and characteristics. The present study aims to explain the function of rain gardens through a verification experiment and field survey. This study shows that rain gardens are suitable for dealing with low flow volumes of rainwater, although their suitability could be slightly changed by soil properties and catchment area. Our field survey indicated that rain gardens must be connected to a sewage system. In addition, like other green infrastructure, rain gardens require maintenance. The most frequent type of maintenance is the disposal of garbage, as garbage can block channels running between a rain garden and a conventional sewage system. Moreover, garbage build up can lead to the retention of rain water for more than 36 h, and this water can become a habitat for mosquito larvae.

In situ air temperature and humidity measurements over diverse land covers in Greenbelt, Maryland, November 2013–November 2015

Abstract. As our climate changes through time there is an ever-increasing need to quantify how and where it is changing so that mitigation strategies can be implemented. Urban areas have a disproportionate amount of warming due, in part, to the conductive properties of concrete and asphalt surfaces, surface albedo, heat capacity, lack of water, etc. that make up an urban environment. The NASA Climate Adaptation Science Investigation working group at Goddard Space Flight Center in Greenbelt, MD, conducted a study to collect temperature and humidity data at 15 min intervals from 12 sites at the center. These sites represent the major surface types at the center: asphalt, building roof, grass field, forest, and rain garden. The data show a strong distinction in the thermal properties of these surfaces at the center and the difference between the average values for the center compared to a local meteorological station. The data have been submitted to Oak Ridge National Laboratory Distributed Active Archive Center (ORNL-DAAC) for archival in comma separated value (csv) file format (Carroll et al., 2016) and can be found by following this link: http://daac.ornl.gov/cgi-bin/dsviewer.pl?ds_id=1319.

Low impact development and green infrastructure

Water is the main source of life for all living creatures and water resources should be protected from draining away. There are two main sources of water that is used for water supply such as ground water and surface water. Both of them are fed by precipitation water in order to stay stable for providing consumption requirements. Thus, only one drop of precipitation water should not be wasted so storm water management practices come to light. Two of the mostly known storm water management practices are low impact development (LID) which works with nature to manage stormwater at place closer to its source and green infrastructure which uses natural processes to provide infiltration and evapotranspiration or reuses runoff on the generation area. There are many LID practices that have been used to adhere to these principles such as bio retention facilities, rain gardens, vegetated rooftops, rain barrels and permeable pavements. Green infrastructure can be used in wide range of landscapes in addition to more traditional stormwater control systems to support the principles of LID. In this research, definition and main features of LID and green infrastructure was investigated, main practices used for implementation of these methods were reviewed and two methods were compared according to their benefits.