Integrated Stormwater Management Research Articles

China's Sponge City Development: Global Position, Governance, and Potential Enhancement with Ecosystem Services

ABSTRACT China has been implementing a policy initiative termed sponge city development (SCD) since 2014 to address complex, interlinked water challenges, particularly flooding and runoff pollution, faced by urban development under climate change. Pilot implementation of the initiative in 30 selected cities provides an opportunity for learning and enhancement relevant to global practice in general and SCD expansion in particular. This article reviews China’s SCD, synthesizing: (1) SCD position in global practices for urban stormwater management; (2) governance and implementation; (3) challenges and issues in planning and management; and 4) potential enhancement with ecosystem service (ES). The article shares that: (1) China’s SCD differs from, while sharing some similarity with, global practices for urban stormwater management, particularly marked by engineering dominated implementation; (2) the policy implementation exhibits sophisticated governance in supporting the initiative; (3) there are challenges and issues concerning particularly planning and management, characterized by a lack of a systematic approach linking physical projects, ecosystem functions, societal impact, and urban development goals; and (4) an ES-based framework can deliver a systematic approach enhancing SCD beyond water resilience toward urban green transition and sustainability. This article contributes to learning about ecosystem-based integrated stormwater management during urbanization and climate change.

Hydrological Performance Assessment of Low-Impact Development Practices: A Vegetated Swale Case Study

The increase in rainfall intensity caused by climate change, combined with high levels of urban soil sealing and the limited capacity of drainage systems, is significantly increasing flooding risk. Integrated stormwater management is a key factor in dealing with the consequences of climate change by mitigating flood risk based on nature-based solutions. An experimental site was designed to assess the hydrological response of vegetated swales depending on different catchment surfaces, and to evaluate the impact of spatial variability of the hydraulic conductivity (K). A hydrological model was developed on EPA SWMM and calibrated based on measured data in two experimental swales with different active surfaces (N6—50 m2 and N11—100 m2). The model validation was assessed with NSE scores higher than 0.7. The simulations considered various factors, such as the water level in the swales, the actual rainfall, the evapotranspiration, the swale geometry, the catchment area (Sa), and the hydraulic conductivities of the natural silty soil, to assess, for the heaviest rainfall event, the best swale morphological characteristics. The study examined the combined impact of K (8) and Sa (6) on swale storage capacity, designed with a 250 mm depth. The simulations showed that the 250 mm overflow limit was exceeded for N10 (90 m2) when K ≤ 2 × 10−6 m/s, and for N11 (100 m2) when K ≤ 4 × 10−6 m/s. These results provide valuable information on the optimal storage capacity based on the swales’ geometrical and physical properties.

DYNAMIQUE DES RISQUES D’ÉROSION RAVINANTE DES TERRES MARGINALES DE LA COMMUNE RURALE D’IDIOFA (KWILU/R.D. CONGO)

The erosion of marginal lands in the Idiofa Rural Commune is a major problem for urban authorities and the local population. This Commune has no integrated stormwater management plan, which has a detrimental impact on its site and its overall socio-economic and cultural development. The main objective of this study is to: (i) Identify the various gullies and their morphometric characteristics, (ii) Map the marginal areas in Idiofa, (iii) Identify the causes of the accelerated gully erosion observed in Idiofa, (iv) Assess the resulting socio-environmental consequences, (v) Understand, discuss and assess the risks, and (vi) Propose strategies to respond to these risks. The method used consisted of two stages: (i) a survey carried out among a sample of 200 people to obtain a population view of the degradation of its environment, (ii) field observations on the inventory of gullies and their dimensions, to complement and validate the data from radar interpretation. EpiData 3.0, Microsoft Excel 2016 and SPSS 22 were used to process the data collected. Thematic maps of the studied phenomenon were designed using ArcMap 10.8, QGIS Desktop 3.36 and Google Earth Pro. According to the results obtained, all the 133 identified ravines left a void volume of approximately 2,530,246 m3. This represents a loss of land of more than 2,000,000 tonnes, with considerable collateral damage.

Waterways transformation and green stormwater infrastructure: enabling governance for Adelaide’s River Torrens Catchment, Australia

ABSTRACT This paper explores the enabling governance conditions for implementing green stormwater infrastructure to transform waterways. Using Australia’s largest integrated stormwater management project in Adelaide’s River Torrens Catchment as a case study, we explore four key governance dimensions and their shifts over time: actors, rules of the game, discourse, and resources and power. Overall, 11 enablers emerged from these dimensions. These include collaboration and coordination, bipartisan support, regulation enforcement, knowledge and beliefs, leadership and expertise, and incremental funding. The paper reflects on the prevalence of these factors and provides recommendations to revitalize polluted waterways and address riverine flood risk.

Combining Stormwater Management and Park Services to Mitigate Climate Change and Improve Human Well-Being: A Case Study of Sponge City Parks in Shanghai

Due to climate change and rapid urbanization, contemporary cities face the dual challenges of providing sufficient stormwater management and adequate park services, which potentially conflict over limited space and resources. To solve these problems, cities are increasingly combining stormwater infrastructure with park space in ways that create new efficiencies. To date, most research has focused on the stormwater management performance aspect of these combinations and not the techniques employed to achieve the combined goals. To fill this gap, 23 sponge city parks in Shanghai were investigated to examine the combination of stormwater and park services. Our findings show that stormwater techniques were primarily combined with the park facilities of water areas, paved open spaces, and pathways. Additionally, we found that larger parks employed a wider range of techniques for managing stormwater runoff and supported broader sets of park activities, while those at smaller scales prioritized infiltration, detention, and purification measures, as well as concentrated on social and economic activities. This study is the first to explore SPC parks that integrate stormwater management and park services, thereby providing implications for SPC development in China and insights into the ways that the two properties can be combined in other cities.

Green Infrastructure and Urban-Renewal Simulation for Street Tree Design Decision-Making: Moderating Demands of Stormwater Management, Sunlight and Visual Aesthetics.

The design of green infrastructure in urban renewal sites is complex, requiring engagement with existing communities and future sustainable development goals, consideration of existing and future urban forms, changing climatic conditions, and the sites often being in low-lying and flood-prone areas. Traditional street tree decision-making approaches are inadequate for addressing the scale, environmental complexity, and mutability of decisions involved in urban renewal projects—new tree selection approaches that consider complex competing criteria for tree selections addressing stormwater management systems, visual assessment and solar amenity are needed. This paper describes a new method of multi-criteria street design decision modelling that combines outputs from hydrology modelling, digital procedural tree modelling and urban form analysis, with animation and gaming technologies. We evaluate our approach through application to the design of a large-scale, urban renewal project underway in Melbourne, Australia. The results of the study demonstrate the functionality of our model, which allowed the simultaneous output of streetscape visualisation, with tree selection responding to integrated stormwater management infrastructure and flooding, along with the likely overshadowing conditions of urban renewal built-form. Our multi-criteria approach makes a significant contribution to the tools available to urban designers, planners and landscape architects in their pursuit of smarter streetscape design decisions that respond to complex spatial, cultural and climatic urban challenges.

A Review of Pollutant Concentrations in Urban Stormwater Across Eastern Australia, After 20 Years

Concerns about pollutants in urban stormwater were initially raised in the early 1970s. Australian investigations decades later, also found urban stormwater runoff contained elevated levels of sediment and nutrients, as well as heavy metals, that brought stormwater management to the forefront for regulators. Planning policies were implemented to integrate stormwater management into development in the form of water sensitive urban design (WSUD), also known internationally as low-impact design (LID) and Sustainable Urban Design solutions (SUDs). Since their introduction, comprehensive broad scale field research to verify their success in achieving load reduction targets (LRTs), has been limited. Paucity of field data on the performance of WSUD has prompted organisations to initiate their own locally-specific studies. Limited regulatory guidance on design of monitoring programs has resulted in various methodologies and meta-data recording. This research review collates urban stormwater data from 77 Australian studies, from geographic regions of east coast Australia. The raw dataset in this review included 2,836 events and 4,536 individual results, collected between 1993 and 2021 from local councils, research organisations and water authorities. The review examined total suspended solids (TSS), total phosphorus (TP) and total nitrogen (TN) concentrations, prior to any form of treatment measures as they are the focus of current guidelines and standards for stormwater management. Seminal research, used to inform stormwater guidelines and water quality modelling across Australia, is significantly different (p < 0.001), in this case approximately double the reviewed concentrations. International data is also >20% higher, on average. Geographic location of catchments had the greatest influence on pollutant concentrations, after accounting for the effects of land use and catchment urbanisation date (p < 0.001). Based on the findings of this review, generic load reduction targets (expressed as a percentage of annual inputs, e.g. 80% TSS reduction, 45% TN, 45% TP) typical in current Australian planning regulations, may be sub-optimal in achieving receiving water quality goals, particularly given the difficulty of removing pollutants when present in low concentrations. Alternately, place-based discharge targets which meet, or exceed, background water quality, or ecological and hydrological benchmarks may be a more appropriate tool to achieve environmental objectives.

Influence of Rainfall and Tree Traits on Stem Flow Production of Selected Urban Tropical Trees

Stem flow is small but important fraction of intercepted precipitation channeled through a tree canopy to the base of the trunk. Given increased impervious covers in cities, quantification of stem flow is necessary for a holistic understanding of hydrology in urban ecosystems. The values of urban treesare increasingly being recognized over the decades and authorities have invested in urban green infrastructure including urban forestry. However, knowledge related to rainfall redistribution by urban trees and reduce storm water are yet to be discovered for topical tree species. Therefore, this study aimed study the effect of canopy traits on stem flow percent and funneling ratios for isolated urban trees in a tropical wet climate. The stem flow of 21 individual trees (7 species with 3 replicates) located in University of Sri Jayewardenepura, Sri Lanka were measured from August 2019 to November 2019 by installing SF collars at diameter at breast height (dbh). The stem flow was measured for 20 individual storm events started with dry canopy condition. Gross precipitation was recorded using an automated weather station located in an open area in University premises. All trees produced stemflow for storm events larger than 4 mm. Felicium decipiens generated the highest stem flow and Pterocarpus marsupium Roxburgh generated the lowest among studied species. While F. decipiens showing negative correlation between rainfall and stem flow others showed positive correlation. In all species, crown volume, dbh and bark thickness showed negative relationship with stem flow. However, individual-tree stem flow percent and funneling ratio values were variable, even for similar rain depths, suggesting that meteorological factors play a role. Our findings highlight the need of careful species selection for urban forestry and importance of infiltration capacity at the base of urban trees when integrating storm water management with vegetation and soils in cities.
 Keywords: Stem flow percent, Funneling ratio, Urban hydrology, Urban forestry, Storm water management

The material politics of integrated urban stormwater management in Los Angeles, California

ABSTRACT Cities worldwide have embraced the idea of integrated stormwater management using more decentralised and green infrastructures to enhance urban sustainability. Los Angeles County has recently introduced a new stormwater tax that envisions achieving sustainable stormwater futures through far-reaching infrastructural change. While embracing such visions, however, different actors seek to use tax revenues for diverging infrastructure designs. Our paper therefore explores shifting stormwater politics in Los Angeles by highlighting the social relations underlying technology. Technical disputes that we frame as combinations of material artefacts, discourses, expertise and institutions provoke the specific “material politics” behind the emergence of a hybrid stormwater system in which centralised stormwater practices of incumbent public utilities predominate but increasingly co-exist with more decentralised landscape-centred practices and become interdependent on them. We argue that technical disputes reflect ambiguities about a future stormwater system and engender the renegotiation of responsibility, knowledge orders and the overall rationale of stormwater management. An inherited focus on controlling stormwater volumes thwarts attempts to couple stormwater and urban greening improvements more tightly. We conclude by emphasising that infrastructures are relational systems that carry many potential stormwater futures and by outlining ways to better align stormwater management with wider urban sustainability objectives.

MSMA Implementation Factors in Integrated Stormwater Management

The Department of Irrigation and Drainage Malaysia (DID) released the Urban Stormwater Management Manual for Malaysia (MSMA) in 2000 as a guideline to address longterm national goals and priorities in ensuring that sustainable urban drainage systems are properly used. MSMA’s emphasis on control at source approaches may be divided into three categories: water quantity control, erosion and sediment control, and water quality control. As highlighted in the manual, a successful implementation of its principles and techniques though calls for involvement of various professionals including engineers, urban planners, environmental scientists, landscape architects and other professionals. Apart from civil engineers, not much known about the other professional’s involvement in the execution of MSMA. The development of comprehensive and adaptable techniques requires increased collaboration among a varied group of individuals engaged. However, progress toward more inclusive planning has been gradual, with technological and institutional lock-ins. Taking this into consideration, this paper discusses the findings of a survey carried out to assess the levels of understanding and involvement of urban planning professionals in the implementation of MSMA. The study was conducted using a questionnaire form approach in obtaining feedback from the respondents involved. Questionnaires designed to assess the levels of understanding and involvement of the urban planning professionals in MSMA were distributed to randomly selected urban planning professionals from government agencies and private firms. The responses were then tabulated and analysed using the Statistical Package for Social Sciences (SPSS) software. The findings of the study are based on the highest mean values for each category in order of priority: policy management and action (3.800), education and marketing (3.732), cost and maintenance (3.646), and technological design (3.817). Based on this order of priorities can indicate the main factors that are obstacles to the effectiveness of the implementation of MSMA.

Optimizing Green-Gray Infrastructure for Non-Point Source Pollution Control under Future Uncertainties.

Non-Point Source Pollution (NPS) caused by polluted and untreated stormwater runoff discharging into water bodies has become a serious threat to the ecological environment. Green infrastructure and gray infrastructure are considered to be the main stormwater management measures, and the issue of their cost-effectiveness is a widespread concern for decision makers. Multi-objective optimization is one of the most reliable and commonly used approaches in solving cost-effectiveness issues. However, many studies optimized green and gray infrastructure under an invariant condition, and the additional benefits of green infrastructure were neglected. In this study, a simulation-optimization framework was developed by integrated Stormwater Management Model (SWMM) and Non-dominated Sorting Genetic Algorithm (NSGA-II) to optimize green and gray infrastructure for NPS control under future scenarios, and a realistic area of Sponge City in Nanchang, China, was used as a typical case. Different levels of additional benefits of green infrastructure were estimated in the optimizing process. The results demonstrated that green-gray infrastructure can produce a co-benefit if the green infrastructure have appropriate Value of Additional Benefits (VAB), otherwise, gray infrastructure will be a more cost-effectiveness measure. Moreover, gray infrastructure is more sensitive than green infrastructure and green-gray infrastructure under future scenarios. The findings of the study could help decision makers to develop suitable planning for NPS control based on investment cost and water quality objectives.

Intensifying rehabilitation of combined sewer systems using trenchless technology in combination with low impact development and green infrastructure.

Throughout Europe, there is a considerable need for investment in the upgrade of sewer systems - due to three main factors: ageing infrastructure, climate change and urban population growth. The need for investments is expected to grow significantly in the years ahead. Trenchless rehabilitation (no-dig) of sewer pipelines is a cost-efficient and environmental friendly method for upgrading existing pipelines with sufficient capacity. This study examines the possibility of applying no-dig to combined sewer systems (CS) with insufficient capacity. In this study, a concept assessment methodology that combines the analytical approaches from stormwater and sewer system assessments is presented. The methodology was tested on a case area that was part of an environmental project in Oslo, Norway. Three alternative concepts were examined; A0: no-dig and low impact development (LID), A1: no-dig, LID and green infrastructure (GI), and A2: CS up-sizing using open-cut methods. The study concludes that CS with insufficient capacity can be rehabilitated using no-dig if LID and GI. The combination of no-dig and LID reduces costs considerably but does involve the risk of damages from uncontrolled surface runoff. The main risk-reduction measure is the development of GI as an integrated stormwater management system that requires cross-sector collaboration within municipalities.

Investigation of soil permeability and suitable vegetation for rain gardens in Kecskemet

Nowadays, the implementation of integrated stormwater management is an important element of urban climate adaptation. Rain gardens are part of this system, which effectively handles large amounts of sudden precipitation. In this way, they are suitable for preventing the increasing frequency of flash floods. For rain gardens, it is important to collect information about the soil and the vegetation.We examined the permeability of the typical soil types in Kecskemét – humus sandy soil, solonetz meadow soil – and Bácsvíz compost, in order to decide what proportion of soils and compost can be considered ideal for rain gardens. In addition, experiments were performed with three broad-tolerant plants (Inula Britannica, Aster tripolium subsp. pannonicus and Limonium gmelinii) planted in the studied soil types and compost, as well as in a mixture of these. Based on our results, it can be concluded that the solonetz meadow soil practically means a waterproof layer, while a mixture of half of this soil type and compost already has adequate water permeability and water storage properties, which provide the necessary living conditions for plants.

MAKING SMART URBAN DECISIONS: THE NICHE OF A PARAMETRIC SPATIAL MODEL TO BALANCE THE NEEDS OF URBAN STORMWATER MANAGEMENT AND HUMAN WELLBEING

Abstract. Rapid urbanization has resulted in high-density construction, more impervious area and with increasing threats of urban stormwater, drought and negative influences on human wellbeing. Although there has been progress in sustainable stormwater management and the promotion of human wellbeing with green space, the research has been conducted from a mono-disciplinary perspective and has brought potential conflicts in the utilisation of green space in an urban area. Since smart city proposed, researchers are exploring informational and integrated urban management to face this type of development conflicts and achieve a harmonious and sustainable future. This research proposes a parametric spatial model to integrate stormwater management and human recreation needs based on the understanding of the relationship between them on the same urban green space. We expect that this integrated parametric spatial model will help residents to interact with functional green space and provide options to organize the urban green space smarter and more effectively. This paper presents: (1) A review of the main sustainable stormwater management measures with principles, models and facilities to reveal an overlooked but important relationship between space and stormwater management. (2) Investigation of the research on the benefits of green space on human wellbeing. The study argues that the participation of green space cannot be effectively and accurately analysed with the current main analysis measures which relying on satellite-based vegetation indices or land-use database. This research is intended to set smarter decision making on urban green spaces which connects sustainable stormwater management with human wellbeing via visualised parametric spatial model.

Green infrastructure needs green governance: Lessons from Australia’s largest integrated stormwater management project, the River Torrens Linear Park

The River Torrens Catchment in Adelaide has suffered from poor water quality and flooding for decades. To address these challenges, a green infrastructure project, specifically a Linear Park, was created within the catchment. Although the project has functioned reasonably well since its implementation, its complex nature poses several management challenges. Despite the scale of this project, there is little scholarly literature available. Hence, to analyse these management challenges, this paper reviews the original project documentation, as well as regulations and policy documents together with findings from interviews with key project informants. The aim is to investigate the key drivers for implementation; the major stakeholders involved; and the challenges emerging from the multidimensional attributes of the project. The challenges relate to the inconsistent and informal management structure, the involvement of multiple stakeholders, and pressure from surrounding development. The challenges are further grouped under four main themes, including communication and collaboration, project design goals, institutional and political frameworks, and planning and development regulations. This paper argues that green governance is the key to the successful implementation and management of sustainable green infrastructure projects. The findings from this case study can inform policymakers, planners and researchers to propose appropriate scenarios to manage urban stormwater and to reclaim neglected waterways.

Integrated 1D and 2D model for better assessing runoff quantity control of low impact development facilities on community scale

This study proposes a modelling framework of integrated one-dimensional (1D) and two-dimensional (2D) hydrodynamic modelling to evaluate the effectiveness of sponge city construction at community scale. Through a case study in Zhuhai, we integrate Stormwater Management Model (SWMM) and Cellular Automata Dual-DraInagE Simulation (CADDIES) 2D model to analyze the rainfall-runoff process involving green infrastructures. SWMM is applied to analyze the change of surface runoff control effects before and after the implementation of sponge city low impact development (LID) facilities, and CADDIES is adopted to simulate the propagation of excess runoff on the surface. The results show that the LID facilities can effectively reduce the runoff volume of small and medium-sized rainfall events since the maximum runoff reduction rate is 94.4%. For long-term operation, the LID can capture 52.9% of annual rainfall volume and reduce annual runoff by 28.0%. However, the CADDIES 2D model simulations indicate that LID facilities have little effect on flood alleviation in specific regions under extreme rainfall conditions. In addition, we compared the modelling performance using four different terrain Digital Elevation Model (DEM) resolutions and found that 1 m terrain DEM resolution can produce comparable results to 0.25 m DEM with a fraction of computational time. We also find that the MIKE FLOOD model and the integrated model of SWMM and CADDIES 2D can obtain similar simulation results, the p-value = 0.09 which is >0.05, but SWMM-CADDIES integrated model is more suitable for small-scale simulation.

Blue-Green Infrastructure for Sustainable Urban Stormwater Management—Lessons from Six Municipality-Led Pilot Projects in Beijing and Copenhagen

Managing stormwater on urban surfaces with blue-green infrastructure (BGI) is being increasingly adopted as an alternative to conventional pipe-based stormwater management in cities. BGI combats water problems and provides multiple benefits for cities, including improved livability and enhanced biodiversity. The paper examines six municipality-led pilot projects from Beijing and Copenhagen, through a review of documents, site observations and interviews with project managers. Beijing’s projects attempt to divert from a pipe-based approach but are dominated by less BGI-based solutions; they could benefit from more integration of multiple benefits with stormwater management. Copenhagen’s projects combine stormwater management with amenity improvement, but lack focus on stormwater utilization. Reviewed municipality-led pilot projects are shown to play an important role in both testing new solutions and upscaling them in the process of developing more sustainable cities. Key lessons are extracted and a simple guideline synthesized. This guideline suggests necessary considerations for a holistic solution that combines stormwater management and urban space improvements. Key lessons for sustainable solutions include defining a clear water technique priority, targeting both small and big rain events, strengthening ‘vertical design’ and providing multiple benefits. An integrated stormwater management and landscape design process is a prerequisite to the meaningful implementation of these solutions. Research and documentation integrated with pilot projects will help upscale the practice at city scale.

Climate change will both exacerbate and attenuate urbanization impacts on streamflow regimes in southern Willamette Valley, Oregon

AbstractInteractions between climate change and urbanization may affect stream ecosystems in unexpected ways. With an integrated modelling framework, we assessed the combined hydrological impacts of climate change and urbanization under historical and future climate regimes across varied development scenarios in three watersheds in the Willamette Valley, Oregon. First, through an agent‐based land use change model Envision, we created four development scenarios that consisted of 2 × 2 combinations of regional growth (compact population growth in urban cores vs. dispersed growth into rural areas) and stormwater management scenarios (with vs. without integrated stormwater management, ISM). ISM was defined as the integration of strategic organization of land uses with site‐scale stormwater best management practices. Next, two future climate regimes were developed by statistically downscaling projections from two general circulation models (CanESM2 and CNRM‐CM5) that performed well in replicating historical climate. The hydrological assessment of these scenarios was then conducted with the Soil and Water Assessment Tool. Using 10 ecologically significant flow metrics, we evaluated each scenario based on the magnitude of change in each metric and the degree to which such changes could be mitigated. Climate change alone led to a drying trend in flow regimes under both future climates. Combined with urbanization, it magnified changes in six of 10 metrics but attenuated impacts for three other measures of flashiness in at least one basin. The combination of compact growth and ISM effectively mitigated alterations for seven (out of nine) metrics sensitive to the combined impacts in at least one basin, with ISM being more effective than compact growth. The modelling framework teased out both nuanced differences and generalizable trends in hydrological impacts of urbanization and climate change and offers key methodological innovations towards an integrated framework capable of linking landscape planning mechanisms with the goal of sustaining stream ecosystem health.

The influence of heavy metals in road dust on the surface runoff quality: Kinetic, isotherm, and sequential extraction investigations

This study examines the adsorption and desorption characteristics of heavy metals in road dust (RD) for the aspect of integrated stormwater management. The chemical fractionations of Cu, Zn, Ni, and Cd were determined by a three-step sequential extraction protocol. Pseudo-first-order and Pseudo-second-order kinetic models, along with Langmuir, Freundlich, and Temkin isotherms were adopted to simulate the batch experimental data. The proportional shift of metals' chemical fractionations in original RD, adsorption equilibrium, and desorption equilibrium were determined. Results show that RD has a remarkable affinity to adsorb heavy metal within a short time. The adsorption processes were well described by the Pseudo-second-order kinetic model (R2 = 0.98–0.99) and Freundlich isotherm (R2 = 0.89–0.98) for most of the given metals indicating that the chemical adsorption was probably the rate-controlling step and the binding energy for each site was not identical. The maximum adsorption capacities for Cu, Cd, Zn, and Ni were 6300 mg kg−1, 5800 mg kg−1, 4000 mg kg−1, and 3200 mg kg−1, respectively. A linear fit to the equilibrium pH and the total amounts of the adsorbed metals indicates a strong pH-dependent adsorption. According to the proportional shift of metals’ chemical fractionations during the adsorption and desorption processes, the exchangeable fractions of heavy metals in RD were irreversible. It suggests that a portion of the surface sites of RD would be not exchangeable once it was occupied.

Integrating Stormwater Management and Stream Restoration Strategies for Greater Water Quality Benefits

Integrating Stormwater Management and Stream Restoration Strategies for Greater Water Quality Benefits