Hydrologic Performance Research Articles

Experimental and numerical research on the hydrological characteristics of sunken green space with a new type of composite structure.

Based on the characteristics of concentrated rainwater runoff in the mountainous areas of southwestern China and the low rates of rainwater infiltration into low-permeability soils. We have built a new type of sunken green space structure with a combination of a "overflow port and rainwater storage layer" and carried out model tests of storage and drainage performance under heavy rain conditions. The hydrological response of the new composite structure parameters to the sunken green space was analyzed using the HYDRUS-2D program. The results show that the new composite structure has a significant impact on runoff reduction, drainage, and rainwater storage. For the 100a return period, compared with RSL-0 (0cm rainwater storage layer), the initial and peak drainage times of RSL-25 were delayed by 30min and 38min, respectively, and the rainwater storage rate increased by 13.5%. Compared with no overflow port, the peak drainage increased by 78%, the initial drainage time advanced by 73min, and the cumulative drainage volume increased by 186%. In addition, as the height of the overflow increased, the surface rainwater absorbed by the sunken green space gradually decreased. The sunken green space with OPH-5 (overflow port height of 5cm) could absorb more than 75% of the rainwater in the rainwater overflow layer, while the absorption capacities of OPH-7.5 and OPH-10 (overflow port height of 7.5cm and 10cm) were basically below 75%. In this case, the OPH-5 and the depth of the storage layer not being less than 250cm provide the best setting for the new combined structure of the sunken green space. In conclusion, the new composite structure designed in this experiment effectively increased the hydrological performance of the layered sunken green space.

Mitigation of nutrient leaching from bioretention systems using amendments

Bioretention systems have been showcased to be effective in reducing stormwater quantity and improving stormwater quality. However, the systems can also leach nutrients especially during their initial operation, which needs to be mitigated to optimize their benefits. To examine the efficiency of six amendments selected primarily for reducing phosphorus (P) leaching, six amended and two control cells were constructed and monitored soon after their construction in the field of the 2020 growing season. The effects of the amendments on both the hydrological performance (in terms of water retention rate (WRR)) and water quality performance (in terms of the event mean concentration and pollutant removal rate) were investigated. The results showed that all amendments had the capability of preventing or mitigating P leaching from bioretention systems to varying degrees, with the water treatment residual (WTR) outperforming all other amendments, followed by the activated aluminum (AA) and sorptiveMEDIA (SM) amendments. In addition, some of the amendments (i.e., drywall (DRY), WTR, and SM) were also found to be beneficial in reducing the nitrogen (N) leaching to a slight degree, whereas eggshell (EGG) introduced an extra source of N leached. Furthermore, the temporal evolution of the P leaching of the amendment cells was found to be different from that of the control cells. The same result was not observed for the temporal evolution of the N leaching, implying that the amendments (except EGG) did not largely affect the N leaching. Among the amendments’ effect on WRR, there was no obvious difference. Whereas the observed differences between the control cells and some amendment cells in vegetation growth and antecedent media moisture condition might imply their potential impacts on the hydrologic performance. Overall, other than P leaching, the use of amendments affected other functions of bioretention systems, which should be taken into consideration when selecting an amendment for practice.

Hydrologic performance assessment of nature-based solutions: a case study in North-eastern Italy

The consequences of climate change are exacerbated by land-use changes, which influence the rainfall-runoff relations and consequently the flood risk. Effectively, urbanization is steadily contributing to the increase of impervious areas and reducing the time-to-peak. The effect of Nature Based Solutions (NBSs) on the mitigation of these phenomena is recognized. Nevertheless, these kinds of sustainable infrastructures are still barely known and scarcely adopted in many parts of the European Countries. The LIFE BEWARE project aims to enhance hydraulic safety and spread good practices in rainwater management by promoting and facilitating the adoption of NBSs in the Altovicentino area (Northern Vicenza Province, Veneto Region, Italy). To support the dissemination activities, some full-scale NBSs have been created within the municipality areas involved in the project. The hydrological impact of the structures is continuously monitored thanks to the installation of devices measuring inlet and outlet runoff, and rainfall pattern. This study aims to analyse the monitoring data of the first two years of the built NBSs. Results show that the structures managed almost all the water runoff through processes of infiltration and retention, providing additional insights into understanding the real behaviour of NBSs exposed to the specific environmental conditions of a very rainy foothills area. In particular, mean rain intensity and rainfall duration are the variables that mostly affected the structure performance, especially for events prolonged over time (2-3 days) with mean rainfall intensity in the range of 2-3 mm/h. Therefore, the overall outcomes from this analysis resulted as being useful to improve the design of NBSs and further promote their installation in urban areas.

Modeling Post‐Wildfire Hydrologic Response: Review and Future Directions for Applications of Physically Based Distributed Simulation

AbstractWildfire is a growing concern as climate shifts. The hydrologic effects of wildfire, which include elevated hazards and changes in water quantity and quality, are increasingly assessed using numerical models. Post‐wildfire application of physically based distributed models provides unique insight into the underlying processes that affect water resources after wildfire. This work reviews and synthesizes post‐wildfire applications of physically based distributed models by examining the scales and geographic/ecohydrologic distribution of model applications, hydrologic response process representation, model parameterization, and model performance metrics. Highlighted gaps and opportunities for advancing physically based distributed hydrologic response modeling after wildfire include the following: (a) applying models in under‐represented geographic (S. America, Africa, Asia) and ecohydrologic regions (arid or dry subhumid climates), (b) incorporating all four major streamflow generation mechanisms (infiltration excess, saturation excess, subsurface storm flow, and groundwater flow), (c) representing integrated vadose zone and saturated zone processes to better capture subsurface streamflow generation, (d) building new remotely sensed model parameterization methods for precipitation interception, infiltration, and overland flow that account for burn severity and recovery, (e) incorporating distributed state variables (e.g., soil moisture, groundwater levels) in model performance assessment, (f) designing model intercomparison studies, including field datasets specifically for post‐wildfire model development and validation, (g) linking mechanistic vegetation regrowth models with hydrologic models to improve simulation of process shifts as ecosystems recover, and (h) creating a new community modeling framework to integrate modeling advances across the wildfire science community.

Assessing hydrological performance for optimized integrated grey-green infrastructure in response to climate change based on shared socio-economic pathways

Integrated grey-green infrastructure (IGGI) is considered as a promising facility for mitigating urban flooding during extreme rainfall events. However, most IGGI strategies rely heavily on historical precipitation data, while ignoring the long-term effects of dynamic and non-stationary climate change. This study explored a novel approach to assess the hydrological performance under Shared Socio-economic Pathways (SSPs) based on long-term rainfall time series, facilitating the exploration of the optimal solution to urban runoff alleviation in response to climate change. A case study of Guangzhou, China, was applied for model validation. The results indicated that through non-stationarity analysis and stage division, the future time series of the three SSPs were identified with an abrupt point and divided into two stages. By assessing the hydrological performance of the optimal solutions at various historical and future stages, both fully centralized IGGI and decentralized IGGI are found vulnerable to long-term climate change. Based on a certain extent of trade-off between centralization and decentralization, an appropriate degree of decentralization was observed to significantly enhance the hydrological performance of the whole IGGI system, particularly for reducing peak flow following extreme rainfall events. The authors believe that the findings could provide a novel perspective on hydrological performance assessment for IGGI in response to non-stationary and multi-scenario climate change in urban catchments with high built-up density.

Evaluation of distributed process-based hydrologic model performance using only a priori information to define model inputs

Fully distributed, integrated surface–subsurface hydrological models (ISSHMs) have seen renewed interest due to availability of better software, high performance computing facilities, and high-resolution, spatially extensive data products. ISSHMs are valuable as tools for advancing system understanding as they can resolve multiple processes defined on the plot scale including three-dimensional interaction of surface water and groundwater. Here, we evaluated the performance of an ISSHM, the Advanced Terrestrial Simulator (ATS), on seven diverse catchments across the continental US using widely available data products to define model inputs without calibration. We compare the ATS-simulated streamflow and evapotranspiration with gauge observations and MODIS-derived evapotranspiration, respectively. Using the Kling-Gupta Efficiency (KGE) as metric, ATS with default data products performed reasonably well at 6 of 7 catchments for streamflow. However, in one of those 6 catchments ATS had poor performance on baseflow and ATS’s overall performance was thus judged to be inadequate despite the acceptable KGE. ATS performance for evapotranspiration was good in all 7 catchments using default data products. In the two catchments where ATS streamflow performance using default data products was not acceptable, the performance was significantly improved by using local information on subsurface properties below the soil. We also compare the model-simulated streamflow and evapotranspiration with the Sacramento soil moisture accounting (SAC-SMA) model, a semi-distributed model that was calibrated on a catchment-by-catchment basis. Uncalibrated ATS performance is comparable to the calibrated SAC-SMA model in terms of streamflow while ATS performance is similar to or better (much better in certain catchments) in reproducing MODIS-derived evapotranspiration. Reasonably good performance of ATS without catchment-specific calibration provides new confidence in the ISSHM class of models and community data products as tools for advancing understanding of watershed function in a changing environment.

Hydrological Analysis of Green Roofs Performance under a Mediterranean Climate: A Case Study in Lisbon, Portugal

In this paper, the hydrological performance of eight pilot green roofs (GR) installed in Lisbon, Portugal, under a Mediterranean climate is analyzed. The pilot units were installed at Instituto Superior Técnico campus of Lisbon University. The pilots present different plant species and different substrate types, with some of the units incorporating recycled construction and demolition waste (RCW). The green roofs pilots’ hydrologic performance was evaluated through the simulation of artificial precipitation events between March 2021 and July 2021. Considering the results obtained, it can be concluded that the inclusion of RCW in the substrate composition did not hinder the development of vegetation or the hydrological performance of GR. The results showed a rainfall water retention per event ranging from 37% to 100%, with an average rainfall retention of about 81%. The runoff delay ranged from 2 to 18 min, and the peak attenuation ranged from 30 to 100%. The results indicated that previous substrate moisture strongly influences the hydrological performance of GR. As the inclusion of RCW in the substrate composition promotes a more effective drainage of the substrate during dry conditions, it is considered that RCW may have positive impacts on GR’s hydrological performance.

Channel Water Storage Anomaly: A New Remotely Sensed Quantity for Global River Analysis

AbstractRiver channels store large volumes of water globally, critically impacting ecological and biogeochemical processes. Despite the importance of river channel storage, there is not yet an observational constraint on this quantity. We introduce a 26‐year record of entirely remotely sensed volumetric channel water storage (CWS) change on 26 major world rivers. We find mainstem volumetric CWS climatology amplitude (CA) represents an appreciable amount of basin‐wide terrestrial water storage variability (median 2.78%, range 0.04%–12.54% across world rivers), despite mainstem rivers themselves represent an average of just 0.2% of basin area. We find that two global river routing schemes coupled with land surface models reasonably approximate CA (within ±50%) in only 11.5% (CaMa‐Flood) and 30.7% (HyMap) of rivers considered. These findings demonstrate volumetric CWS is a useful quantity for assessing global hydrological model performance, and for advancing understanding of spatial patterns in global hydrology.

Stormwater quantity and quality control performance of bioretention systems: A literature review.

Bioretention systems, as one of the most widely used modern stormwater management tools, have outstanding performance in capturing runoff, mitigating peak flow, delaying outflow occur time, and improving effluent quality. We reviewed the research of hydrologic and water quality performance of bioretention systems around the world from different perspectives, including the structure and classification of bioretention systems, the mechanisms of runoff and pollutants regulation of bioretention systems, the hydrologic and water quality performances of bioretention systems, the runoff control and water purification evaluation models of bioretention systems, as well as the influencing factors of runoff control and water purification efficiency. We proposed that future research should focus on hydrologic and water quality of bioretention systems, e.g., optimization of design configurations, revealing the mechanisms of plant action, revealing the mechanisms of microbial action, the effects of climate change on hydrologic and water quality performance, watershed/regional scale hydrologic and water quality performance, purification effect and mechanisms of emerging pollutants, maintenance methods, as well as life-cycle assessment and cost analysis. This review would provide theoretical and technical supports for research, design, construction, and maintenance of bioretention systems.

Hydrological model performances in small and mid-size Brazilian semi-arid ungauged watersheds under agricultural use

Hydrological model performances in small and mid-size Brazilian semi-arid ungauged watersheds under agricultural use

Hydrological model performances in small and mid-size Brazilian semi-arid ungagged watersheds under agricultural use

Hydrological model performances in small and mid-size Brazilian semi-arid ungagged watersheds under agricultural use

Statistical evaluation on hydrologic performance of bioretention design parameters under different rainfall conditions

Effectiveness of a bioretention cell (BC) in mitigating stormwater peak flow load to an urban drainage system is highly dependent on the design configuration and retrofitting scale. The selection of appropriate BC design parameters has always been critical to achieving its maximum benefits. The BC modeling in the stormwater management model (SWMM) relies on numerous design parameters (in total of 18) with wide selection ranges, making parameter selection challenging. This study investigated the effect of hydrologic dynamics of BC design parameters under different rainfall conditions (i.e., intensity, duration, time-to-peak) on surface infiltration, surface outflow, and storage. Firstly, the seven influential BC design parameters (i.e., conductivity, berm height, vegetation volume, suction head, porosity, wilting point, and soil thickness) were selected based on one-factor-at-a-time (OAT) method, and 1000 random samples of each parameter were generated across the factor space by following respective uniform distributions. The simulations were performed with a python wrapper of SWMM (PySWMM) that used random samples for one parameter while leaving the others constant each time. In general, the statistical results of each parameter represent a significant variation in the volume distribution under various design rainfall conditions. Comparatively, the parameters of conductivity, berm height, and vegetation volume are categorized as the most influential compared to other BC design parameters for surface infiltration, storage, and surface outflow, respectively.

Optimization and trade-off framework for coupled green-grey infrastructure considering environmental performance

Implementing runoff control infrastructure has been regarded as an efficacious measure in stormwater management. The issue of its cost-effectiveness is a primary concern for decision makers since it is an exorbitant investment. However, most of existed studies only concentrated on the cost-effectiveness optimization of runoff control infrastructure, especially green infrastructure, between hydrological and economic aspects, and therefore, the potential layout scenarios with high extra environmental benefits could be neglected in the traditional two-dimensional frameworks. In this study, a novel carbon dioxide equivalent-based index was quantified to represent the extra environmental benefits of runoff control infrastructure besides stormwater management and was further integrated into the assessment framework. The effectiveness of green and grey infrastructure was comprehensively evaluated and traded off between hydrological, environmental and economic aspects. The results demonstrated that grey infrastructure is a better measure than green infrastructure when only hydrological (HF index) and economic (CI index) performances were considered. Nevertheless, the environmental performance (EROI index) of green infrastructure prevails over grey infrastructure, and when optimizing green and grey infrastructure simultaneously in the three-dimensional framework considering environmental effectiveness, green infrastructure is comparable with grey infrastructure. Furthermore, an appropriate composition of coupled green-grey infrastructure is requisite, which could achieve an optimal trade-off between hydrological and environmental effectiveness. The sources of environmental benefits were also identified and analyzed from three representative preference scenarios. The findings of the study could serve as a trade-off basis between green and grey infrastructure, as well as between EROI and HF.

Vegetated roofs rainwater management experimental research in Brazil: A georeferenced exhaustive review of a continental-size country

Flood risk is an increasing concern in densely populated cities as urban drainage systems are demanded progressively more. The need for decentralising water management becomes relevant, and vegetated roofs are internationally known to be able to assist in locally retaining and detaining stormwater. For these Nature-based Solutions to be effective, there must be science-based standardisation, supporting decision-makers towards effective public policy-making based on hydrological performance. However, this performance should be associated with local environmental conditions, and continental-size countries such as Brazil can have a large variety of climates. At the same time, Brazil lacks a comprehensive review associating experimental results with climatic classifications. In this sense, the present work aims at reviewing the experimental research undertaken in Brazil and synthesising its rainwater retention outcomes associating it to the Köppen-Geiger climate classification. To accomplish this task, the Rational Method is used to extract and conform data from 34 records involving internationally and nationally published works as well as grey literature. Results of this work present to national researchers not only gaps but important trends, generating further innovative opportunities for work, and present to international researchers an accessible and georeferenced bulk of data on vegetated roofs' hydrological performance in Brazil with the highest possible resolution. It was found that semi-arid climates had the best average rainwater retention rates (0.79), followed by subtropical (0.54–0.72), and the tropical climates had the lowest (0.55–0.69). The work concludes that vegetated roofs have a positive hydrological performance throughout Brazil. However, further work is needed to quantify the hydrological influence of a range of different structural and environmental factors that modify the roofs' performance. It is also shown that climates, particularly outside the financial centres of Brazil, lack data and hence need further investigation and experimental research. • Vegetated roof hydrology is still an unexplored subject in many climates of Brazil. • Challenges in real-time sensing flow rate difficult detention quantification. • Average green roof retention rates for each climate with available data are presented. • Blank spots and further innovative research suggestions for green roofs are presented. • Rational method is used for extracting standard data from indexed and grey literature.

Flood Risk Mitigation and Valve Control in Stormwater Systems: State-Space Modeling, Control Algorithms, and Case Studies

The increasing access to inexpensive sensors, computing power, and more accurate forecasting of storm events provides unique opportunities to shift flood management practices from static approaches to an optimization-based real-time control (RTC) of urban drainage systems. Recent studies have addressed a plethora of strategies for flood control in stormwater reservoirs; however, advanced control theoretic techniques are not yet fully investigated and applied to these systems. In addition, there is an absence of a coupled integrated control model for systems composed of watersheds, reservoirs, and channels for flood mitigation. To this end, we developed a novel nonlinear state-space model of hydrologic and hydrodynamic processes in watersheds, reservoirs, and one-dimensional channels. The model was tested under different types of reservoir control strategies based on real-time measurements (reactive control) and predictions of the future behavior of the system (predictive control) using rainfall forecastings. We applied the modeling approach in a system composed of a single watershed, reservoir, and channel connected in series for the observed rainfall data in San Antonio. Results indicate that for flood mitigation, the predictive control strategy outperforms the reactive controls not only when applied for synthetic design storm events, but also for a continuous simulation. Moreover, the predictive control strategy requires smaller valve operations while still guaranteeing efficient hydrological performance. From the results, we recommend the use of the nonlinear model predictive control strategy to control stormwater systems because of the ability to handle different objective functions, which can be altered according to rainfall forecasting and shift the reservoir operation from flood-based control to strategies focused on increasing detention times, depending on the forecasting.

Constructing an inventory for fast screening of hydraulic and hydrologic performance of stormwater control measures

Abstract Stormwater control measures (SCMs) are effective and sustainable complementary means of managing stormwater in cities. Unlike underground drainage systems, they require space on the city surface, and therefore must be included in initial sketches of urban planning and design. These initial sketches are often made by architects and urban planners, who are usually not trained in hydrology, and therefore require simple and robust tools to inform their initial plans with respect to stormwater management. There may be local guidelines for dimensioning SCMs, but their applicability is often limited with regard to the range of SCMs, and the methodology behind them may be oversimplified, including a lack of assessment of benefits on the urban hydrological cycle. We developed a methodology for estimating multiple performance indicators of a wide range of SCMs and applied it to Danish meteorological conditions. The methodology includes consulting expected end users, configuring an SWMM model for each SCM type and choosing applicable parameter ranges, running multiple simulations for each type covering the parameter space, and post-processing the results using python and PySWMM. The outputs can be used to draw general recommendations regarding effective application ranges for different SCMs, and to quickly assess the performance of case-specific configurations.

Evaluating the impact of climate change on future bioretention performance across the contiguous United States

In light of shifting precipitation patterns induced by climate change, communities are seeking to build resiliency in urban drainage systems through interventions such as green stormwater infrastructure (GSI). Bioretention cells are one of the most commonly implemented forms of GSI for their ability to reduce peak discharge, retain runoff, and filter pollutants. However, they may be at risk of reduced function in the future due to deviations from historic precipitation frequency and intensity patterns which are essential to their design. Further, changes in future function are likely to vary regionally as the magnitude of future climate changes will differ across the globe. To explore the range of impacts to future bioretention function, an ensemble of 10 regional climate models at 17 locations across the contiguous United States were evaluated to provide the widest range of potential future outcomes using a probabilistic approach to capture the uncertain nature of climate change. Bioretention cells were modeled using USEPA’s Storm Water Management Model (SWMM) to compare existing and future performance under a range of climate change projections. Median annual rainfall and 99th percentile rainfall event depths and intensities were projected to increase across all 17 locations while antecedent dry period (i.e., the time between consecutive rain events) was projected to increase for 11 locations. Correspondingly, bioretention cell hydrologic performance decreased across all 17 locations under future scenarios: relative to performance under current climate conditions, annual volumes of infiltration decreased between 4.0 and 24.0% across all 17 locations while overflow increased between 0.4 and 19.6% for 15 locations. Results suggest that bioretention cells in the southern United States are at significant risk of reduced function in the future while those in the Midwest and Northeast are at moderate risk. Bioretention cells in the Northwest/West performed the best under future climate scenarios; that is, they showed similar function in the future to that of the present. Findings demonstrate that most, if not all, bioretention cells across the contiguous United States will require some degree of modification to maintain existing function under future conditions.

The Performance of Natural Flood Management at the Large Catchment-Scale: A Case Study in the Warwickshire Stour Valley

The limited understanding of Natural Flood Management (NFM) performance, especially at large hydrological scales, is considered a critical barrier for the further funding and implementation of these nature-based solutions to the increasing international problem of flooding. The publications of the Intergovernmental Panel on Climate Change (IPCC) Sixth Assessment Report and Environment Agency’s National Flood and Coastal Erosion Risk Management Strategy (NFCERMS) for England have shown that extreme weather, including increased likelihood of high magnitude flood events, will occur and will require more novel management methods. This study focused on the ability of co-designed NFM measures to ameliorate downstream fluvial flooding by attenuating catchment response through a highly spatially distributed network of attenuating and roughening measures. Performance was characterised by the ability of NFM to attenuate flood peaks at different spatial scales across a large (187 km2) dendritic catchment, including the lowering of flood peaks and delaying the time-to-peak. Using a coupled modelling methodology and applying it to the upper Stour Valley, Warwickshire-Avon, UK, a rural response to the application of a set of NFM interventions was developed using the hydrodynamic model Flood Modeller Pro and XPSWMM ©. The method demonstrated a means of incorporating local knowledge in a realistic set of NFM schemes, tested to multiple flood risk scenarios (including climate change). Under frequent, smaller design storm events (e.g., Index Flood (QMED) and 3.3% AEP), flood peaks were lowered across all hydrological scales tested (5.8 km2 to 187 km2). As the design flood event severity increases, impact from upstream NFM attenuation on downstream peak response diminished significantly, especially at the largest hydrological scales. However, even at the largest hydrological scale, delays in time-to-peak were noted, increasing the ability of downstream communities to respond and enact flood preparation activities, thus increasing resilience to potential flooding events. While the benefits were limited to large flood events, the modelling indicated that NFM has the potential to reduce downstream flood risk. However, greater integration of observed data to improve model confidence and reduce uncertainty in modelled events is needed, especially the uncertainty associated with using single peaked design storm events from the Flood Estimation Handbook (FEH). This paper proposes a future Before–After Control–Impact (BACI) monitoring programme that could be integrated with models and applied across non-tidally influenced catchments seeking to empirically test the hydrological performance of in-situ NFM.

Variability of green infrastructure performance due to climatic regimes across Sweden

In the context of increasing urbanization and global warming, there is a growing interest in the implementation of green infrastructure (GI) across different climates and regions. Identifying an appropriate GI design criteria is essential to ensure that the design is tailored to satisfy local environmental requirements. This article aims to compare the hydrological performance of GI facilities in eleven Swedish cities by isolating the effect of climatic conditions using an identical GI design configuration. Long-term simulations based on 23-years of meteorological time-series were used as inputs for the Storm Water Management Model (SWMM) with Low Impact Development (LID) controls representing two types of facilities: a biofilter cell (BC) and a green roof. (GR). Large differences in potential annual and seasonal runoff retention were found between locations, driven mainly by the extent of winter/spring season, and the distribution of precipitation patterns (for BCs) and the sequence of rainy days-dry periods and evapotranspiration rates (for GRs). Winter/spring and summer demonstrated the highest/lowest differences between the seasons, results that suggest that implications for design might be aligned to the spatio-temporal distribution of precipitation patterns, and runoff regimes generated by snowmelt and rain-on-snow events, in locations where snowmelt represent high portion of runoff generation.

Green infrastructure drainage of a commercial plaza without directly connected impervious areas: a case study.

A paired-catchment study of two adjacent commercial areas in northern Sweden, one with Green Infrastructure (GI) storm drainage and the other with a conventional storm sewer system, served to evaluate the hydrological performance of both drainage systems and demonstrate advantages of GI. The GI catchment avoided directly connected impervious areas by diverting runoff from a parking lot to a cascade of three infiltration features, a fractured rock strip draining onto a sloping infiltration area, followed by a collector swale. Both catchments were monitored over 4 years by measuring rainfall, runoff and, in the vicinity of the swale, soil water content and groundwater levels. For frequent storms, the median GI efficiencies in reducing runoff volumes and peak flows, and extending peak flow lags, were 96, 99 and 60%, respectively, compared to conventional drainage. The storm rainfall depth, initial soil water content, increases in intra-event soil water storage and groundwater levels had statistically significant effects on either runoff volume or peak flow reductions. No effects were found for storm rainfall intensity and duration, antecedent dry days, and initial groundwater levels. The study demonstrated that GI drainage can be successfully applied even in the challenging environment of a subarctic climate.