Stormwater Management Facilities Research Articles

The Value of Traditional Ecological Knowledge in Stormwater Management: A Case Study of a Traditional Village

In recent years, floods have occurred frequently in urban and rural areas around the world, causing heavy casualties and property damage. In contrast, some traditional Chinese villages have never flooded. It is hypothesized that these villages, because of their long-term adaptations to their environment, hold necessary ecological knowledge regarding stormwater management so that damaging flooding can be avoided. Previous studies on the traditional ecological knowledge regarding stormwater management in traditional Chinese villages are mostly qualitative studies, and these fail in their evaluation of the functional performance of stormwater management facilities and measures. Therefore, we use the Storm Water Management Model (SWMM) in our quantitative evaluation of stormwater management in Zhuge, a traditional Chinese village, so as to rationally analyze the traditional ecological knowledge regarding stormwater management in traditional Chinese villages. In order to analyze the functions and efficiency of stormwater management facilities such as ponds, canals, and permeable pavement in Zhuge Village, this study sets out four scenarios: the No Pond Scenario (NO-PO), the No Canal Scenario (NO-CO), the No Permeable Pavement Scenario (NO-PP), and the actual Current Scenario (CS). The SWMM is used to simulate and quantitatively analyze the stormwater hydrological processes of the four scenarios in different rainfall return periods. The following conclusions emerged from our evaluation of the approaches used in Zhuge Village: (1) The rainwater regulation system composed of ponds, canals, and permeable pavement can play a dual role in alleviating rainstorm disasters and fully storing rainwater, achieving the flexible allocation of rainwater resources. It can effectively alleviate the problem of uneven time and space of local rainfall in shallow, hilly areas, reflecting the traditional ecological wisdom of residents in adapting to the local natural environment. (2) As a rainwater regulation device, ponds are very effective in storing water and mitigating periods of intense runoff. (3) The main function of canals is to rapidly drain water and balance rainwater resources. (4) The main function of permeable pavement is to increase rainwater infiltration and reduce the peak runoff and runoff. (5) The use of the SWMM proved effective in both quantifying the results as well as elucidating stormwater management strategies.

A multi-objective spatial optimization of wetland for Sponge City in the plain, China

Climate change exacerbates various environmental problems in cities, such as flooding, droughts, and water pollution. As a result of these urban environmental problems, China vigorously promotes the construction of Sponge City. Wetlands are an effective stormwater management facility of Sponge City which can regulate urban stormwater runoff and remove non-point source pollution from stormwater runoff. Wetlands, as sensitive ecosystems in cities, require additional consideration and rational planning in the construction of Sponge City. Wetlands constructed in suitable locations can improve constructed wetland potential, improve wetland benefits, and reduce cost. However, the multi-objective spatial optimization of wetlands in Sponge City is insufficient. To fulfill wetlands planning and construction for Sponge City, a multi-objective optimization method that maximizes constructed wetland potential and pollutant removal and minimizes input costs is proposed by genetic algorithm (NSGA-II, Non-dominated Sorting Genetic Algorithm-II). The wetland space was optimized for the study area, and the Pareto optimal solution of the wetland layout was obtained. The values of the three objectives of wetlands spatial optimization schemes (Pareto optimal solutions) identified is compared with the values of the three objectives of the planned wetlands, which verifies the effectiveness of the wetland spatial optimization method. On the basis of the Pareto optimal solutions, we propose four schemes with the highest economic benefit scheme for constructed wetland potential (constructed wetland potential/input costs), highest economic benefit scheme for pollutant removal efficiency (pollutant removal/input costs), the best compromise scheme between three objectives, and highest constructed wetland potential scheme. Compared with the planned wetlands scheme, these four schemes can increase the constructed wetland potential by 2.2% ∼ 25.1%; increase the TN mass removal by −8.8% ∼28.0%; reduce the input costs by 8.9% ∼ 37.1%.

Exploring community perceptions and engagement of nature-based solutions: The case of Ningbo, a Chinese coastal sponge city

Sustainable stormwater management facilities such as strip bioretention, effectively improve the urban landscape's urban stormwater quality and aesthetics. The progress of Nature-Based Solutions (NBS) and Blue-Green Developments such as the Sponge City Program (SCP) in Chinese cities, is significantly delivering multiple benefits to address urban water, climate and ecosystem services. These practices are transforming the urban environmental context and enhancing the wider aspects of social-environmental interactions and participation. This study will particularly focus on investigating the SCP practices implemented for several years in Ningbo, a selected Sponge pilot city on the east coast of China. There is currently a lack of substantial findings from the perspective of communities towards NBS in China or an understanding of the importance of participation and engagement processes in Sponge or NBS infrastructure in Chinese cities. Through an in-depth semi-structured interview (n = 34), this study will elucidate the previous developments, current challenges and future delivery of constructed NBS infrastructure (e.g. artificial wetland). This article will undertake a detailed investigation of public perceptions, channels of learning, and opportunities for further participation and engagement in the case of Ningbo. In this study, we found that the perception and participation are likely to improve significantly in the future and that public education about SCP practices would foster closer human-nature stormwater connections and co-production to deliver better NBS practices.

How to simulate future scenarios of urban stormwater management? A novel framework coupling climate change, urbanization, and green stormwater infrastructure development

Climate change, urbanization, and green stormwater infrastructure (GSI) planning policies lead to uncertainties in future urban sustainability. Coupling multiple influencing factors such as climate change, urbanization, and GSI development, this study proposes a novel framework for simulating future scenarios of urban stormwater. Subsequently, the changes in annual surface runoff and runoff pollutants in Shanghai's new and old urban areas were compared and analyzed based on 35 typical future and seven baseline scenarios. The following results were obtained: 1) The runoff control rate of the new urban area was significantly higher than that of the old urban area before GSI construction. After GSI construction, both areas could control stormwater runoff and pollutants, while the decline in efficiency in GSI facilities enormously impacted the old area. 2) Surface runoff in the new urban area was mainly affected by urbanization, while climate change was a major factor in the old urban area; runoff pollutants in new and old urban areas were mainly affected by urbanization, and the change in pollutants in new areas was more pronounced. 3) GSI facilities were unlikely to guarantee the quantity and quality of water resources, especially in scenarios where the efficiency of GSI facilities decreases. In old urban areas, the more extreme climate change and urbanization were, the more significant the effect of improving stormwater management facilities. Our findings showed that future studies on stormwater management should specifically consider the different characteristics of new and old urban regions, pay attention to the maintenance and management of GSI facilities, and build adaptive strategies to cope with climate change, urbanization, and GSI facility destruction.

Nitrogen loads in urban surface runoff from a major, cold-region North American city in 1991–2021

Long-term monitoring of pollutant loads in urban surface runoff is important but uncommon. In this study, we examined nitrogen loads in stormwater and snowmelt runoff from four urban catchments of a major, cold-region North American city over the past 31 years (1991–2021). Temporal variability of total organic nitrogen (TON), nitrate and nitrite nitrogen (NOx-N), total ammonia nitrogen (TAN), and total nitrogen (TN) were similar in the four catchments, which had an increasing trend from 1992 (TN: 1.3–3.4 kg/ha/year) to 2006–2011 (TN: 5.5–19.3 kg/ha/year) and a decreasing trend afterward. Trends and change points in the four urban catchments were influenced by storm/snowmelt events, land use, urban drainage infrastructure issues, and stormwater management facilities. The maximum monthly fluctuation occurred in March/April and July due to high variations of snowmelt and storm events. The ratios of monthly loads during the storm season (April to October) to the snow season (November to March) for TON, NOx-N, and TN were 1.31, 1.12, and 1.15, respectively; whereas it was 0.95 for TAN. TKN, TAN, and TN event mean concentrations (EMCs) in snowmelt were higher (18.0%, 94.0%, and 10.8%, respectively) than those in stormwater. However, the NOx-N EMC in snowmelt was lower (9.3%) than in stormwater.

Long-Term Monitoring of an Urban Stormwater Infiltration Trench in South Korea with Assessment Using the Analytic Hierarchy Process

Evaluating the functionality of small and decentralized low-impact development (LID) technologies often requires extensive labor, time, and costs for water quality analysis. In order to reduce these in an infiltration trench in South Korea, monitoring data gathered over a period of 8 years were used to determine its long-term performance, establish a stormwater quality estimation model, and develop a comprehensive evaluation tool. Our findings show that the infiltration trench can treat up to 90% of the stormwater runoff from a paved road but would require annual maintenance to minimize the reduction in infiltration capacity. The facility was able to remove an average of 83% of total suspended solids (TSS), 75% of biochemical oxygen demand (BOD), 80% of chemical oxygen demand (COD), 76% of total nitrogen (TN), and 79% of total phosphorus (TP), with the highest removal efficiencies observed after maintenance was conducted. Rainfall depth and air quality parameters (i.e., PM2.5 and PM10) were found to be positively correlated with TSS, COD, TN, and TP. These parameters were then used to develop a model for the estimation of influent stormwater quality, which can help in estimating the effluent water quality based on the average removal efficiencies. Furthermore, a comprehensive evaluation tool considering indicators such as treatment efficiency, cultural benefits, and facility and operating conditions was established through the analytic hierarchy process (AHP). Aside from determining the facility’s overall efficiency, this can also serve as a diagnostic tool to identify whether maintenance is needed or not. While atmospheric and hydrological characteristics differ in different regions, and the results may vary if applied in other facilities, this study can serve as a guide to the effective and efficient evaluation of similar stormwater management facilities in South Korea.

Tracking geomorphic changes after suburban development with a high density of green stormwater infrastructure practices in Montgomery County, Maryland

Stream morphology is affected by changes on the surrounding landscape. Understanding the effects of urbanization on stream morphology is a critical factor for land managers to maintain and improve vulnerable stream corridors in urbanizing landscapes. Stormwater practices are used in urban landscapes to manage runoff volumes and peak flows, potentially mitigating alterations to the flow regime that drive changes in channel morphology. However, there remains a paucity of long-term studies assessing watershed-scale relationships between urbanization and effects on stream morphology where green stormwater infrastructure exists in high densities. This paper evaluates the geomorphic changes across four headwater catchments in the Chesapeake Bay Watershed over the course of >10 yr and relates these changes to urban development. Annual cross-sectional surveys conducted from 2002 to 2019 in one forested catchment, one agricultural catchment, and two treatment catchments were used to understand the relationship between urbanization and changes in stream morphology. Six cross-sectional geomorphic metrics were calculated and compared with development timelines and high flow events. A channel evolution model was then used to understand the status of morphologic stability at sites within the study. Results suggest downstream environments in developing areas are more impacted during early phases of suburban construction. Channel change during construction could be a result of sediment and erosion control efforts' limitations on preventing and controlling overland sediment mobilization or of increased discharge causing widening and thus bank-derived sediment to move to the streambed. Results demonstrate that geomorphic metrics are highly variable within a small area and are not always accurate representations of broader landscape changes but rather of the more localized environment at a specific stream segment. Despite a high density of stormwater management facilities in urban catchments, substantial alterations to cross sections were found at multiple locations in each catchment including the controls.

Integrating Sponge City Requirements into the Management of Urban Development Land: An Improved Methodology for Sponge City Implementation

Sponge city planning aims to manage urban development land to prevent flooding and to support the achievement of water resource protection objectives. In this study, from the perspective of rainfall management demand and ability, we present an improved planning method, including two calculation models, aimed at determining the VCRAR (volume capture ratio of annual rainfall) and then integrating VCRAR requirements into the management of urban development land more accurately and objectively, while simultaneously considering the rainfall condition and urban planning attributes to support the implementation of sponge city planning. Compared to the current method, the VCRAR calculation model greatly improves the accuracy of the VCRAR for various space scales, and the conversion model solves the fundamental problem that urban land indicators corresponding to the VCRAR are difficult to calculate objectively and accurately. Moreover, this methodology can achieve a reasonable tradeoff between the development of individual districts and the environmental protection of the whole urban watershed, which allows a poetic vision to be turned into executable planning and design. The results of the application of this methodology in a case study in Jizhou, China, show that the improved method can make land utilization, development period and natural conditions more integrated and scientifically involved in the indicator calculation. The results also quantitatively show that the capacity of volume capture inside the site for one district increases as its green space ratio increases, and it decreases with an increase in the transformation difficulty for stormwater management facilities, when restricted by the investment and available space.

Stormwater management in urban areas using dry gallery infiltration systems

The increase in the frequency of extreme precipitation events due to climate change, together with the continuous development of cities and surface sealing that hinder water infiltration into the subsoil, is accelerating the search for new facilities to manage stormwater. The Canary Islands (Spain) are taking advantage of the knowledge acquired in the construction of water mines to exploit a novel stormwater management facility, which we have defined as a dry gallery. Dry galleries are constituted by a vertical well connected to a horizontal gallery dug into highly permeable volcanic layers of the vadose zone, from where infiltration takes place. However, the lack of scientific knowledge about these facilities prevents them from being properly dimensioned and managed. In this work, we simulate for the first time the infiltration process and the wetting front propagation from dry galleries based on a 3D unsaturated flow model and provide some recommendations for the installation and sizing of these facilities. The fastest advance of the wetting front takes place during the earliest times of infiltration (<2 h), with plausible propagation velocities and infiltration rates higher than 1000 m∙d−1 and 2 m3∙s−1. As time progresses, the propagation velocity and infiltration rate decrease as a consequence of the hydraulic gradient attenuation between the gallery and the aquifer. Therefore, stormwater infiltration is a highly transient process in which a sizing underestimation of 100% may be committed if unsaturated conditions or geological configuration are neglected.

Evaluation of Alnus subcordata for urban environments through assessment of drought and flooding tolerance

The urban environment is stressful and trees experience multiple stresses, including drought, flooding, and extreme heat, all of which are likely to increase under future climate warming and increasing urbanisation. In the selection of tree species to maximise ecosystem services, tolerance to site characteristics such as flooding and severe drought is of critical importance. This study evaluated the suitability of a rare species, Alnus subcordata C.A. Mey (Caucasian alder) from the Hyrcanian forests of southern Azerbaijan,for its functionality as an urban tree. A total of 48 pot-grown, two-year-old saplings of A. subcordata were tested in a greenhouse experiment using a complete randomised block design. Each block contained four replicates of three treatments (waterlogging, drought, control), with 16 plants per treatment. Height differences between treatments were measured, and water status was estimated by determination of midday leaf water potential (ΨL) and stomatal conductance (gs). To estimate drought tolerance reaction in the treatments, leaf water potential at turgor loss (ΨP0) was used together with broken-stick modelling of water status over time. There was a significant difference in tree height between the different treatments. In the drought treatment, A. subcordata plants showed no height increase, while plants in both the waterlogged and control treatments increased in height during the nine-week experiment. Over 63 days of flooding, plant water status was slightly more negative in the waterlogging treatment, but did not deviate essentially from the control. In the drought treatment, plant water status rapidly deviated from the control. There was a significant differencein ΨP0 between treatments, with drought-treated plants showing the lowest value (−2.31 MPa).This study demonstrated that A. subcordata has limited tolerance to drought and seems to rely more on waterloss-avoiding strategies. However, the species may be usable at periodically waterlogged sites, due to its high tolerance to flooding. It could therefore be recommended for wet urban environments and stormwater management facilities, for which reliable guidance on suitable trees is currently lacking.

Assessment of Factors Affecting the Removal Efficiency of Suspended Solids and Particulate Matters for Pretreatment Units in a Stormwater Management Facility

Non-point source (NPS) pollution is one of the primary sources of contamination in aquatic systems, such as rivers and lakes. Various techniques and devices, including low impact development (LID) and best management practice (BMP) devices, can reduce NPS pollution. These devices are installed with pretreatment units to remove NPS pollutants more efficiently and to facilitate maintenance. In this study, suspended solids (SS) and particle size distributions (PSD) were investigated in a pilot-scale facility to determine the effect of various pretreatment unit types and inflows on SS removal. We found that the efficiency of SS concentration and particulate matter removal changed significantly (p &lt; 0.05) based on the aspect ratio of the pretreatment unit. Three flow conditions were also tested (10, 15, and 20 m3/h); SS removal was most efficient at 15 m3/h. These findings can be applied to the design of NPS management facilities, which is expected to help increase the efficiency of new NPS facilities while reducing operating costs.

The capitalized amenity of green infrastructure in single-family housing values: An application of the spatial hedonic pricing method

The environmental benefits of having retention/detention ponds as major stormwater management facilities in a neighborhood have been well documented since the adoption of green infrastructure strategies in early 1990s. However, the capitalization effect of stormwater treatment ponds in real estate values still remains unclear. This study developed classic hedonic pricing and spatial econometric models to examine the capitalization effects of neighborhood-level detention and retention ponds using both cross-sectional and longitudinal housing prices. The housing market value from 2007 to 2016 was assessed in four subdivisions in Houston, Texas. A subdivision, located in the upper neighborhood, had retention ponds which were converted from detention ponds in 2011, while three subdivisions in the lower neighborhood had detention ponds over the same study period. The study results show that living near retention ponds has positive capitalization impacts on single-family housing prices, not only cross-sectionally but also longitudinally. In contrast, maintaining detention ponds depreciates housing values, and living nearby lowers the price increase over a decade. The findings in this study imply the importance of converting stormwater facilities into a park-like amenity to enhance aesthetic value and generate long-term economic benefits to a neighborhood.

Real-Time Control Algorithm for Enhancing Operation of Network of Stormwater Management Facilities

AbstractThe deployment of real-time control (RTC) technology has improved the performance of stormwater management facilities. However, most of the current research focuses on individual pilot site...

High-resolution modelling of the grass swale response to runoff inflows with Mike SHE

The feasibility of simulating the hydrological response of a grass swale to runoff inflows was examined using the hydrological model Mike SHE and the available input data from 12 irrigation events mimicking runoff from block rainfalls. The test swale channel had a trapezoidal cross-section, bottom slope of 1.5%, length of 30 m, and was built in loamy fine sand. The irrigation events consisted in releasing two equal constant inflows to the swale: a concentrated longitudinal flow at the upstream end and a distributed lateral inflow along the swale side slope adjacent to the contributing drainage area. The total inflows approximated runoff from two events with return periods of 2 months and 3 years, respectively, for durations of 30 min. Irrigation experiments were done for two states of the initial soil moisture, dry or wet antecedent moisture conditions (AMC). Mike SHE has been extensively used on catchments of various sizes, but rarely for small stormwater management facilities and their detailed topography investigated in this study. The latter application required high spatial and temporal resolutions, with computational cells of 0.2 × 0.2 m and time steps as short as 0.6 s to avoid computational instabilities. For dominant hydrological processes, the following computational options in Mike SHE were chosen: Soil infiltration – the van Genuchten equation, unsaturated zone flow – the one-dimensional Richards equation, and overland flow – the diffusive wave approximation of the St. Venant equations. For study purposes, the model was calibrated for single events representing one of four combinations of low and high inflows, and dry and wet AMC, and then applied to the remaining 11 events. This was complemented by calibration for two events, representing high inflow on wet AMC and low inflow in dry AMC. The goodness of fit was statistically assessed for observed and simulated peak flows, hydrograph volumes, Nash-Sutcliffe model efficiencies (NSE), and soil water content (SWC) in swale soil layers. The best fit (NSE > 0.8) was obtained for high inflows and wet AMC (i.e., when the primary swale function is flow conveyance); the least fit was noted for low inflows and dry AMC, when the primary swale function is flow attenuation. Furthermore, this observation indicates the overall importance of correct modelling of the soil infiltration. The effects of spatial variation of SWC on the swale discharge hydrograph could not be confirmed from simulation results, but high topographical accuracy was beneficial for reproducing well the locations of the observed water ponding. No significant increases in simulated SWC at 0.3 m or greater depths were noted, which agreed with field observations. Overall, the results indicated that Mike SHE was effective in process-oriented small-scale modelling of grass swale flow hydrographs.

Strategic Insights on the Role of Farm Ponds as Nonconventional Stormwater Management Facilities

AbstractFarm ponds are constructed for different purposes in many parts of the world, including irrigation, livestock water, and so forth; however, their impacts are not fully captured in stormwate...

The influence of vegetation on rain garden hydrological performance

Rain gardens are increasingly adopted in urban areas to mitigate urban stormwater impacts. They provide an opportunity to adopt taxonomically diverse plantings to enhance habitat and aesthetic value. However, few studies to date have quantified how rain garden hydrological performance is affected by vegetation type. In the present study, two vegetation types were considered: taxonomically diverse communities composed of forb-rich perennials; and mown grasses, as well as a bare soil control group. Detention effects were measured independently from retention. The forb-rich perennial mixes consistently provided the best hydrologic performance in terms of both stormwater retention and detention. The diverse perennial community showed up to 1.2 mm higher initial losses over the experimental catchment compared with mown grasses, and also offered 54% and 32% longer detention compared with bare soils and mown grasses, respectively. We therefore recommend prioritising taxonomically and structurally diverse planting for vegetated stormwater management facilities wherever possible.

Bivariate frequency analysis of rainfall intensity and duration for urban stormwater infrastructure design

This study presents a storm-event based bivariate frequency analysis approach to determine design rainfalls in which, the number, intensity and duration of actual rainstorm events were considered. To derive more realistic design storms, the occurrence probability of an individual rainstorm event was determined from the joint distribution of storm intensity and duration through a copula model. Hourly rainfall data were used at three climate stations respectively located in Singapore, South Korea and Canada. It was found that the proposed approach could give a more realistic description of rainfall characteristics of rainstorm events and design rainfalls. As results, the design rainfall quantities from actual rainstorm events at the three studied sites are consistently lower than those obtained from the conventional rainfall depth-duration-frequency (DDF) method, especially for short-duration storms (such as 1-h). It results from occurrence probabilities of each rainstorm event and a different angle for rainfall frequency analysis, and could offer an alternative way of describing extreme rainfall properties and potentially help improve the hydrologic design of stormwater management facilities in urban areas.

Exploring the effects of green infrastructure placement on neighborhood-level flooding via spatially explicit simulations

State and local governments are increasingly considering the adoption of legislation to promote green infrastructure (e.g., bioswales, green roofs) for stormwater management. This interest emerges from higher frequencies of combined sewer outflows, floods and exposure of residents and habitat to polluted water resulting from growing urbanization and related pressure on stormwater management facilities. While this approach is promising, there are many unknowns about the effects of specific implementation aspects (e.g., scale, layout), particularly as urban settlements and climate conditions change over time. If green infrastructure is to be required by law, these aspects need to be better understood. We developed a spatially-explicit process-based model (the Landscape Green Infrastructure Design model, L-GriD) developed to understand how the design of green infrastructure may affect performance at a neighborhood scale, taking into consideration the magnitude of stormevents, and the spatial layout of different kinds of land cover. We inform the mechanisms in our model with established hydrological models. In contrast with watershed data-intensive models in one extreme and site level cost-savings calculators in the other, our model allows us to generalize principles for green infrastructure design and implementation at a neighborhood scale, to inform policy-making. Simulation results show that with as little as 10% surface coverage, green infrastructure can greatly contribute to runoff capture in small storms, but that the amount would need to be doubled or tripled to deal with larger storms in a similar way. When placement options are limited, layouts in which green infrastructure is dispersed across the landscape—particularly vegetated curb cuts—are more effective in reducing flooding in all storm types than clustered arrangements. As opportunities for green infrastructure placement increase and as precipitation increases, however, patterns that follow the flow-path and accumulation of water become more effective, which can be built on an underlying curb-cut layout. If space constraints prevented any of these layouts, random placement would still provide benefits over clustered layouts.

Performance of an Underground Stormwater Detention Chamber and Comparison with Stormwater Management Ponds

The transportation of pollutants from impervious surfaces during runoff events to receiving water bodies is a serious environmental problem. Summer runoff is also heated by impervious surfaces, causing thermal enrichment in receiving water body systems and degradation of coldwater aquatic ecosystems. End-of-pipe stormwater management facilities that are open to the environment can result in further elevated temperatures due to exposure to solar radiation. Receiving water systems that provide coldwater habitat require cool water temperatures to sustain healthy conditions for cold water flora and fauna (e.g., trout, dace). Underground Stormwater Detention Chambers (USDC) are a technology for the detention and treatment of stormwater runoff that can potentially solve the thermal issues associated with sun-exposed detention facilities while still providing an equivalent level of treatment services for stormwater pollutants. A field study of an USDC located in Southern Ontario was undertaken to characterize its treatment performance and effect on water temperature. The results were: the USDC was found to provide similar levels of stormwater treatment as wet detention ponds. On average, outlet maximum temperatures were 5 °C cooler than inlet maximum temperatures, and outlet water temperatures remained within the thermal regime for coldwater fish habitat throughout the evaluation period. There was little to no stratification of temperature, nor dissolved solids, but stratification of dissolved oxygen was observed mid-winter and into the spring.

Replacing natural wetlands with stormwater management facilities: Biophysical and perceived social values

Urban expansion replaces wetlands of natural origin with artificial stormwater management facilities. The literature suggests that efforts to mimic natural wetlands in the design of stormwater facilities can expand the provision of ecosystem services. Policy developments seek to capitalize on these improvements, encouraging developers to build stormwater wetlands in place of stormwater ponds; however, few have compared the biophysical values and social perceptions of these created wetlands to those of the natural wetlands they are replacing. We compared four types of wetlands: natural references sites, natural wetlands impacted by agriculture, created stormwater wetlands, and created stormwater ponds. We anticipated that they would exhibit a gradient in biodiversity, ecological integrity, chemical and hydrologic stress. We further anticipated that perceived values would mirror measured biophysical values. We found higher biophysical values associated with wetlands of natural origin (both reference and agriculturally impacted). The biophysical values of stormwater wetlands and stormwater ponds were lower and indistinguishable from one another. The perceived wetland values assessed by the public differed from the observed biophysical values. This has important policy implications, as the public are not likely to perceive the loss of values associated with the replacement of natural wetlands with created stormwater management facilities. We conclude that 1) agriculturally impacted wetlands provide biophysical values equivalent to those of natural wetlands, meaning that land use alone is not a great predictor of wetland value; 2) stormwater wetlands are not a substantive improvement over stormwater ponds, relative to wetlands of natural origin; 3) stormwater wetlands are poor mimics of natural wetlands, likely due to fundamental distinctions in terms of basin morphology, temporal variation in hydrology, ground water connectivity, and landscape position; 4) these drivers are relatively fixed, thus, once constructed, it may not be possible to modify them to improve provision of biophysical values; 5) these fixed drivers are not well perceived by the public and thus public perception may not capture the true value of natural wetlands, including those impacted by agriculture.