{"id":10468,"date":"2026-04-13T18:17:23","date_gmt":"2026-04-13T16:17:23","guid":{"rendered":"https:\/\/ingenius.ecoledesponts.fr\/?p=10468"},"modified":"2026-04-13T18:17:23","modified_gmt":"2026-04-13T16:17:23","slug":"rain-gardens-for-managing-urban-runoff-a-study-of-a-parisian-case","status":"publish","type":"post","link":"https:\/\/ingenius.ecoledesponts.fr\/en\/articles\/rain-gardens-for-managing-urban-runoff-a-study-of-a-parisian-case\/","title":{"rendered":"“Rain gardens” for managing urban runoff? A study of a Parisian case"},"content":{"rendered":"\n\n\n
\"\"
Saint-Job rain garden retention basin. Credit : Wikimedia Commons<\/figcaption><\/figure>\n\n\n\n

What is a rain garden and how does it work?<\/h2>\n\n\n\n

Rain gardens are a type of nature-based solution widely used to manage urban stormwater in a more sustainable way. They are typically shallow, vegetated depressions that collect and temporarily store runoff. Beneath the surface, they include one or more layers of soil or engineered media, and sometimes a drainage layer or a gravel storage zone. During rainfall events, rain gardens collect runoff from nearby impervious surfaces. Water is temporarily stored at the surface before infiltrating into the underlying layers. Part of this water is retained within the soil, where it can later be returned to the atmosphere through evaporation and plant transpiration, while the excess leaves the system either through drainage or exfiltration into the surrounding soil.<\/p>\n\n\n\n

By slowing down and storing water, these systems can reduce runoff, promote vegetation development, contribute to urban cooling through evapotranspiration, and in some cases recharge groundwater. They also play an important role in improving water quality and reducing diffuse pollution in receiving aquatic environments.<\/p>\n\n\n\n

\"\"
The schematic of a rain garden and its hydrological processes (By Tinghao Huang & Ruiying Xu. CC BY-SA 4.0).<\/figcaption><\/figure>\n\n\n\n

Why Paris presents the challenge of complex urban underground conditions<\/h2>\n\n\n\n

Paris, a highly urbanised large city, has complex underground conditions: the native gypsum-rich soil in the Parisian basin has dissolution risk; the presence of gypsum in the Paris Basin can locally lead to dissolution hazards; the prevalence of clay at shallow depth leads to low permeability and may also cause swelling and shrinkage phenomena that can damage buildings; many underground infrastructures (e.g., metro lines) and old quarries prohibit deep infiltration; some locations with polluted soil are also not recommended for applying extra infiltration.These numerous subsurface constraints reduce the range of feasible rain garden designs and require careful and site-specific adaptation to local conditions.<\/p>\n\n\n\n

What field observations show?<\/h2>\n\n\n\n
\"\"
Photo and sensors setup of the three experimental rain gardens in Jardin du Breuil (JdB) and Sense-City (SC). By Tinghao Huang. Source : Journal of Hydrology: Regional Studies 64 (2026) 103124. <\/strong><\/a><\/figcaption><\/figure>\n\n\n\n

Three rain garden prototypes were monitored as part of this research in the Paris region. Two of them (JdB1 and JdB2) are located at \u00c9cole Du Breuil, near the Bois de Vincennes. Both were designed as lined systems, meaning that infiltration into the underlying subsoil is prevented. Each garden collects runoff from a roof area about three times larger than the garden itself. As a rain garden, such ratio of catchment over garden surface is relatively low (normally > 10). To cope with that, a loamy silt soil (commonly used in Paris for planting) was selected as the filter media for its water retention capacity, although it has relatively low permeability. The two systems differ by one key feature. In JdB2, the drainage pipe is elevated to create a permanent water storage zone beneath the soil layer. This internal storage helps retain water and support vegetation during dry periods.<\/p>\n\n\n\n

The third rain garden (SC) is located at the Cit\u00e9 Descartes campus within the Sense-City research facility. It collects runoff from an impervious area about twelve times larger than the garden itself. In this garden, a gravel storage layer at the bottom is directly connected to the clayey subsoil. This configuration allows the system to test how much water can infiltrate into low-permeability ground, optimize runoff volume reduction, and contribute to groundwater recharge.<\/p>\n\n\n\n

Long-term monitoring highlighted both expected behaviors and site-specific issues. In the case of the SC garden, interactions with the surrounding soil led to unexpected phenomena, such as water inflows caused by the formation of a temporary perched water table (i.e., saturation of subsurface soil layers) during periods of high cumulative rainfall over several weeks. Despite these incidents, all three rain gardens achieved significant runoff reduction, even when exfiltration to the subsoil was limited or prevented.<\/p>\n\n\n\n

In a system such as the campus garden (SC), the gravel layer promotes substantial exfiltration, even in low-permeability subsoil conditions. For JdB1 and JdB2, evapotranspiration is the key driver of runoff reduction. The presence of an internal water storage zone (in JdB2) helps maintain soil moisture and sustain evapotranspiration throughout the year.<\/p>\n\n\n\n

Overall, according to the observation from field experiments, the functioning of rain gardens results from a combination of infiltration, storage, and evapotranspiration processes, rather than a single dominant mechanism.<\/p>\n\n\n\n

The role of models<\/h2>\n\n\n\n

Models are useful tools for exploring design options and predicting overall system performance. In this study, a physically based model was developed using one of the monitored rain gardens (SC) as a reference case. In order to assess the predictive power of this model under operational conditions, it was necessary to examine how the quality of the input data used to parameterize it affects its results. Compared with field observations, the model showed robust performance in predicting water fluxes, even when input data were limited. However, it was less reliable in describing internal processes such as soil moisture dynamics. Overall, the model provides reliable estimates of water balance indicators, such as runoff reduction and exfiltration, but still has limitations in representing moisture variations within the soil.<\/p>\n\n\n\n

Rethinking how we design rain gardens<\/h2>\n\n\n\n

Designing effective systems requires a clear understanding of how water moves through the rain garden and interacts with the surrounding environment. In practice, this means that pre-design site investigations are essential to account for soil properties, groundwater conditions, and underground constraints. When such constraints apply, specific design adaptations can be used: internal water storage can improve drought resilience and reduce runoff through evapotranspiration, while a thin bottom gravel storage layer can promote exfiltration even in low-permeability subsoils. These storage is actually quite lower than the one implemented on JdB2 and SC.<\/p>\n\n\n\n

In addition, the choice of soil media also involves a trade-off between hydraulic conductivity (capacity of the soil media to allow water to flow through) and water retention, requiring careful balance to avoid issues such as clogging or prolonged ponding brought associated with the fine media. The ratio between the catchment area and the rain garden surface is critical for water balance: evapotranspiration alone cannot reduce the runoff water for high inflow conditions, while very low inflow may lead to uneven wetting and reduced effectiveness across the system.<\/p>\n\n\n\n

Proofreaders :Marie-Christine Gromaire and Hayath Zime Yerima<\/em><\/p>\n\n\n\n

\n

This research was conducted as part of the OPUR research program<\/a>. The author extends his sincere thanks to OPUR\u2019s partners for their financial support, particularly the City of Paris. The City of Paris also contributed to the experimental setup and data collection at the Jardin du Breuil. Thanks are also extended to the Sense-City<\/a> partners and to CEREMA for their technical support and data management.<\/p>\n<\/div>\n\n\n\n

<\/p>\n","protected":false},"excerpt":{"rendered":"

What is a rain garden and how does it work? Rain gardens are a type of nature-based solution widely used […]<\/p>\n","protected":false},"author":9,"featured_media":10460,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_related_content_post":[],"_related_content_subject":[937,936],"_related_content_author":[10480],"_related_content_category":[1720],"_related_content_folder":[10530],"_excerpt":"Can \"rain gardens\" still work when the ground beneath them barely lets water through? In cities like Paris, complex underground conditions challenge the way these systems are usually expected to function. Yet, field observations show that rain gardens can still achieve notable runoff reduction, even when deeper infiltration is limited. A key question thus raises: how do rain gardens actually work under such constraints?","_duration":5,"_manual_duration":false,"footnotes":""},"article-types":[13],"class_list":["post-10468","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","article-types-article"],"has_blocks":true,"block_data":[{"blockName":"enpc\/excerpt","attrs":{"lock":[],"metadata":[],"className":"","style":""},"innerBlocks":[],"innerHTML":"","innerContent":[],"rendered":""},{"blockName":"core\/image","attrs":{"id":10459,"sizeSlug":"large","linkDestination":"none","align":"wide","blob":"","url":"https:\/\/ingenius.ecoledesponts.fr\/wp-content\/uploads\/2026\/04\/Image_Wikimedia-CommonsJardin_de_pluie_de_Saint-Job._Le_bassin_de_retention-1024x607.jpg","alt":"","caption":null,"lightbox":[],"title":"","href":"","rel":"","linkClass":"","width":"","height":"","aspectRatio":"","scale":"","linkTarget":"","lock":[],"metadata":[],"className":"wp-block-image alignwide size-large","style":"","borderColor":"","anchor":""},"innerBlocks":[],"innerHTML":"\n

\"\"
Saint-Job rain garden retention basin. Credit : Wikimedia Commons<\/figcaption><\/figure>\n","innerContent":["\n
\"\"
Saint-Job rain garden retention basin. Credit : Wikimedia Commons<\/figcaption><\/figure>\n"],"rendered":"\n
\"\"
Saint-Job rain garden retention basin. Credit : Wikimedia Commons<\/figcaption><\/figure>\n"},{"blockName":"core\/heading","attrs":{"style":{"elements":{"link":{"color":{"text":"var:preset|color|red"}}}},"textColor":"red","textAlign":"","content":null,"level":2,"levelOptions":[],"placeholder":"","lock":[],"metadata":[],"align":"","className":"wp-block-heading has-red-color has-text-color has-link-color","backgroundColor":"","gradient":"","fontSize":"","fontFamily":"","borderColor":"","anchor":""},"innerBlocks":[],"innerHTML":"\n

What is a rain garden and how does it work?<\/h2>\n","innerContent":["\n

What is a rain garden and how does it work?<\/h2>\n"],"rendered":"\n

What is a rain garden and how does it work?<\/h2>\n"},{"blockName":"core\/paragraph","attrs":{"align":"","content":null,"dropCap":false,"placeholder":"","direction":"","lock":[],"metadata":[],"className":"","style":"","backgroundColor":"","textColor":"","gradient":"","fontSize":"","fontFamily":"","borderColor":"","anchor":""},"innerBlocks":[],"innerHTML":"\n

Rain gardens are a type of nature-based solution widely used to manage urban stormwater in a more sustainable way. They are typically shallow, vegetated depressions that collect and temporarily store runoff. Beneath the surface, they include one or more layers of soil or engineered media, and sometimes a drainage layer or a gravel storage zone. During rainfall events, rain gardens collect runoff from nearby impervious surfaces. Water is temporarily stored at the surface before infiltrating into the underlying layers. Part of this water is retained within the soil, where it can later be returned to the atmosphere through evaporation and plant transpiration, while the excess leaves the system either through drainage or exfiltration into the surrounding soil.<\/p>\n","innerContent":["\n

Rain gardens are a type of nature-based solution widely used to manage urban stormwater in a more sustainable way. They are typically shallow, vegetated depressions that collect and temporarily store runoff. Beneath the surface, they include one or more layers of soil or engineered media, and sometimes a drainage layer or a gravel storage zone. During rainfall events, rain gardens collect runoff from nearby impervious surfaces. Water is temporarily stored at the surface before infiltrating into the underlying layers. Part of this water is retained within the soil, where it can later be returned to the atmosphere through evaporation and plant transpiration, while the excess leaves the system either through drainage or exfiltration into the surrounding soil.<\/p>\n"],"rendered":"\n

Rain gardens are a type of nature-based solution widely used to manage urban stormwater in a more sustainable way. They are typically shallow, vegetated depressions that collect and temporarily store runoff. Beneath the surface, they include one or more layers of soil or engineered media, and sometimes a drainage layer or a gravel storage zone. During rainfall events, rain gardens collect runoff from nearby impervious surfaces. Water is temporarily stored at the surface before infiltrating into the underlying layers. Part of this water is retained within the soil, where it can later be returned to the atmosphere through evaporation and plant transpiration, while the excess leaves the system either through drainage or exfiltration into the surrounding soil.<\/p>\n"},{"blockName":"core\/paragraph","attrs":{"align":"","content":null,"dropCap":false,"placeholder":"","direction":"","lock":[],"metadata":[],"className":"","style":"","backgroundColor":"","textColor":"","gradient":"","fontSize":"","fontFamily":"","borderColor":"","anchor":""},"innerBlocks":[],"innerHTML":"\n

By slowing down and storing water, these systems can reduce runoff, promote vegetation development, contribute to urban cooling through evapotranspiration, and in some cases recharge groundwater. They also play an important role in improving water quality and reducing diffuse pollution in receiving aquatic environments.<\/p>\n","innerContent":["\n

By slowing down and storing water, these systems can reduce runoff, promote vegetation development, contribute to urban cooling through evapotranspiration, and in some cases recharge groundwater. They also play an important role in improving water quality and reducing diffuse pollution in receiving aquatic environments.<\/p>\n"],"rendered":"\n

By slowing down and storing water, these systems can reduce runoff, promote vegetation development, contribute to urban cooling through evapotranspiration, and in some cases recharge groundwater. They also play an important role in improving water quality and reducing diffuse pollution in receiving aquatic environments.<\/p>\n"},{"blockName":"core\/image","attrs":{"id":10469,"width":"721px","height":"auto","aspectRatio":"1.0764071772183013","sizeSlug":"full","linkDestination":"none","blob":"","url":"https:\/\/ingenius.ecoledesponts.fr\/wp-content\/uploads\/2026\/04\/image.png","alt":"","caption":null,"lightbox":[],"title":"","href":"","rel":"","linkClass":"","scale":"","linkTarget":"","lock":[],"metadata":[],"align":"","className":"wp-block-image size-full is-resized","style":"","borderColor":"","anchor":""},"innerBlocks":[],"innerHTML":"\n

\"\"
The schematic of a rain garden and its hydrological processes (By Tinghao Huang & Ruiying Xu. CC BY-SA 4.0).<\/figcaption><\/figure>\n","innerContent":["\n
\"\"
The schematic of a rain garden and its hydrological processes (By Tinghao Huang & Ruiying Xu. CC BY-SA 4.0).<\/figcaption><\/figure>\n"],"rendered":"\n
\"\"
The schematic of a rain garden and its hydrological processes (By Tinghao Huang & Ruiying Xu. CC BY-SA 4.0).<\/figcaption><\/figure>\n"},{"blockName":"core\/heading","attrs":{"style":{"elements":{"link":{"color":{"text":"var:preset|color|red"}}}},"textColor":"red","textAlign":"","content":null,"level":2,"levelOptions":[],"placeholder":"","lock":[],"metadata":[],"align":"","className":"wp-block-heading has-red-color has-text-color has-link-color","backgroundColor":"","gradient":"","fontSize":"","fontFamily":"","borderColor":"","anchor":""},"innerBlocks":[],"innerHTML":"\n

Why Paris presents the challenge of complex urban underground conditions<\/h2>\n","innerContent":["\n

Why Paris presents the challenge of complex urban underground conditions<\/h2>\n"],"rendered":"\n

Why Paris presents the challenge of complex urban underground conditions<\/h2>\n"},{"blockName":"core\/paragraph","attrs":{"align":"","content":null,"dropCap":false,"placeholder":"","direction":"","lock":[],"metadata":[],"className":"","style":"","backgroundColor":"","textColor":"","gradient":"","fontSize":"","fontFamily":"","borderColor":"","anchor":""},"innerBlocks":[],"innerHTML":"\n

Paris, a highly urbanised large city, has complex underground conditions: the native gypsum-rich soil in the Parisian basin has dissolution risk; the presence of gypsum in the Paris Basin can locally lead to dissolution hazards; the prevalence of clay at shallow depth leads to low permeability and may also cause swelling and shrinkage phenomena that can damage buildings; many underground infrastructures (e.g., metro lines) and old quarries prohibit deep infiltration; some locations with polluted soil are also not recommended for applying extra infiltration.These numerous subsurface constraints reduce the range of feasible rain garden designs and require careful and site-specific adaptation to local conditions.<\/p>\n","innerContent":["\n

Paris, a highly urbanised large city, has complex underground conditions: the native gypsum-rich soil in the Parisian basin has dissolution risk; the presence of gypsum in the Paris Basin can locally lead to dissolution hazards; the prevalence of clay at shallow depth leads to low permeability and may also cause swelling and shrinkage phenomena that can damage buildings; many underground infrastructures (e.g., metro lines) and old quarries prohibit deep infiltration; some locations with polluted soil are also not recommended for applying extra infiltration.These numerous subsurface constraints reduce the range of feasible rain garden designs and require careful and site-specific adaptation to local conditions.<\/p>\n"],"rendered":"\n

Paris, a highly urbanised large city, has complex underground conditions: the native gypsum-rich soil in the Parisian basin has dissolution risk; the presence of gypsum in the Paris Basin can locally lead to dissolution hazards; the prevalence of clay at shallow depth leads to low permeability and may also cause swelling and shrinkage phenomena that can damage buildings; many underground infrastructures (e.g., metro lines) and old quarries prohibit deep infiltration; some locations with polluted soil are also not recommended for applying extra infiltration.These numerous subsurface constraints reduce the range of feasible rain garden designs and require careful and site-specific adaptation to local conditions.<\/p>\n"},{"blockName":"core\/heading","attrs":{"style":{"elements":{"link":{"color":{"text":"var:preset|color|red"}}}},"textColor":"red","textAlign":"","content":null,"level":2,"levelOptions":[],"placeholder":"","lock":[],"metadata":[],"align":"","className":"wp-block-heading has-red-color has-text-color has-link-color","backgroundColor":"","gradient":"","fontSize":"","fontFamily":"","borderColor":"","anchor":""},"innerBlocks":[],"innerHTML":"\n

What field observations show?<\/h2>\n","innerContent":["\n

What field observations show?<\/h2>\n"],"rendered":"\n

What field observations show?<\/h2>\n"},{"blockName":"core\/image","attrs":{"id":10471,"sizeSlug":"full","linkDestination":"none","blob":"","url":"https:\/\/ingenius.ecoledesponts.fr\/wp-content\/uploads\/2026\/04\/image-1.png","alt":"","caption":null,"lightbox":[],"title":"","href":"","rel":"","linkClass":"","width":"","height":"","aspectRatio":"","scale":"","linkTarget":"","lock":[],"metadata":[],"align":"","className":"wp-block-image size-full","style":"","borderColor":"","anchor":""},"innerBlocks":[],"innerHTML":"\n
\"\"
Photo and sensors setup of the three experimental rain gardens in Jardin du Breuil (JdB) and Sense-City (SC). By Tinghao Huang. Source : Journal of Hydrology: Regional Studies 64 (2026) 103124. <\/strong><\/a><\/figcaption><\/figure>\n","innerContent":["\n
\"\"
Photo and sensors setup of the three experimental rain gardens in Jardin du Breuil (JdB) and Sense-City (SC). By Tinghao Huang. Source : Journal of Hydrology: Regional Studies 64 (2026) 103124. <\/strong><\/a><\/figcaption><\/figure>\n"],"rendered":"\n
\"\"
Photo and sensors setup of the three experimental rain gardens in Jardin du Breuil (JdB) and Sense-City (SC). By Tinghao Huang. Source : Journal of Hydrology: Regional Studies 64 (2026) 103124. <\/strong><\/a><\/figcaption><\/figure>\n"},{"blockName":"core\/paragraph","attrs":{"align":"","content":null,"dropCap":false,"placeholder":"","direction":"","lock":[],"metadata":[],"className":"","style":"","backgroundColor":"","textColor":"","gradient":"","fontSize":"","fontFamily":"","borderColor":"","anchor":""},"innerBlocks":[],"innerHTML":"\n

Three rain garden prototypes were monitored as part of this research in the Paris region. Two of them (JdB1 and JdB2) are located at \u00c9cole Du Breuil, near the Bois de Vincennes. Both were designed as lined systems, meaning that infiltration into the underlying subsoil is prevented. Each garden collects runoff from a roof area about three times larger than the garden itself. As a rain garden, such ratio of catchment over garden surface is relatively low (normally > 10). To cope with that, a loamy silt soil (commonly used in Paris for planting) was selected as the filter media for its water retention capacity, although it has relatively low permeability. The two systems differ by one key feature. In JdB2, the drainage pipe is elevated to create a permanent water storage zone beneath the soil layer. This internal storage helps retain water and support vegetation during dry periods.<\/p>\n","innerContent":["\n

Three rain garden prototypes were monitored as part of this research in the Paris region. Two of them (JdB1 and JdB2) are located at \u00c9cole Du Breuil, near the Bois de Vincennes. Both were designed as lined systems, meaning that infiltration into the underlying subsoil is prevented. Each garden collects runoff from a roof area about three times larger than the garden itself. As a rain garden, such ratio of catchment over garden surface is relatively low (normally > 10). To cope with that, a loamy silt soil (commonly used in Paris for planting) was selected as the filter media for its water retention capacity, although it has relatively low permeability. The two systems differ by one key feature. In JdB2, the drainage pipe is elevated to create a permanent water storage zone beneath the soil layer. This internal storage helps retain water and support vegetation during dry periods.<\/p>\n"],"rendered":"\n

Three rain garden prototypes were monitored as part of this research in the Paris region. Two of them (JdB1 and JdB2) are located at \u00c9cole Du Breuil, near the Bois de Vincennes. Both were designed as lined systems, meaning that infiltration into the underlying subsoil is prevented. Each garden collects runoff from a roof area about three times larger than the garden itself. As a rain garden, such ratio of catchment over garden surface is relatively low (normally > 10). To cope with that, a loamy silt soil (commonly used in Paris for planting) was selected as the filter media for its water retention capacity, although it has relatively low permeability. The two systems differ by one key feature. In JdB2, the drainage pipe is elevated to create a permanent water storage zone beneath the soil layer. This internal storage helps retain water and support vegetation during dry periods.<\/p>\n"},{"blockName":"core\/paragraph","attrs":{"align":"","content":null,"dropCap":false,"placeholder":"","direction":"","lock":[],"metadata":[],"className":"","style":"","backgroundColor":"","textColor":"","gradient":"","fontSize":"","fontFamily":"","borderColor":"","anchor":""},"innerBlocks":[],"innerHTML":"\n

The third rain garden (SC) is located at the Cit\u00e9 Descartes campus within the Sense-City research facility. It collects runoff from an impervious area about twelve times larger than the garden itself. In this garden, a gravel storage layer at the bottom is directly connected to the clayey subsoil. This configuration allows the system to test how much water can infiltrate into low-permeability ground, optimize runoff volume reduction, and contribute to groundwater recharge.<\/p>\n","innerContent":["\n

The third rain garden (SC) is located at the Cit\u00e9 Descartes campus within the Sense-City research facility. It collects runoff from an impervious area about twelve times larger than the garden itself. In this garden, a gravel storage layer at the bottom is directly connected to the clayey subsoil. This configuration allows the system to test how much water can infiltrate into low-permeability ground, optimize runoff volume reduction, and contribute to groundwater recharge.<\/p>\n"],"rendered":"\n

The third rain garden (SC) is located at the Cit\u00e9 Descartes campus within the Sense-City research facility. It collects runoff from an impervious area about twelve times larger than the garden itself. In this garden, a gravel storage layer at the bottom is directly connected to the clayey subsoil. This configuration allows the system to test how much water can infiltrate into low-permeability ground, optimize runoff volume reduction, and contribute to groundwater recharge.<\/p>\n"},{"blockName":"core\/paragraph","attrs":{"align":"","content":null,"dropCap":false,"placeholder":"","direction":"","lock":[],"metadata":[],"className":"","style":"","backgroundColor":"","textColor":"","gradient":"","fontSize":"","fontFamily":"","borderColor":"","anchor":""},"innerBlocks":[],"innerHTML":"\n

Long-term monitoring highlighted both expected behaviors and site-specific issues. In the case of the SC garden, interactions with the surrounding soil led to unexpected phenomena, such as water inflows caused by the formation of a temporary perched water table (i.e., saturation of subsurface soil layers) during periods of high cumulative rainfall over several weeks. Despite these incidents, all three rain gardens achieved significant runoff reduction, even when exfiltration to the subsoil was limited or prevented.<\/p>\n","innerContent":["\n

Long-term monitoring highlighted both expected behaviors and site-specific issues. In the case of the SC garden, interactions with the surrounding soil led to unexpected phenomena, such as water inflows caused by the formation of a temporary perched water table (i.e., saturation of subsurface soil layers) during periods of high cumulative rainfall over several weeks. Despite these incidents, all three rain gardens achieved significant runoff reduction, even when exfiltration to the subsoil was limited or prevented.<\/p>\n"],"rendered":"\n

Long-term monitoring highlighted both expected behaviors and site-specific issues. In the case of the SC garden, interactions with the surrounding soil led to unexpected phenomena, such as water inflows caused by the formation of a temporary perched water table (i.e., saturation of subsurface soil layers) during periods of high cumulative rainfall over several weeks. Despite these incidents, all three rain gardens achieved significant runoff reduction, even when exfiltration to the subsoil was limited or prevented.<\/p>\n"},{"blockName":"core\/paragraph","attrs":{"align":"","content":null,"dropCap":false,"placeholder":"","direction":"","lock":[],"metadata":[],"className":"","style":"","backgroundColor":"","textColor":"","gradient":"","fontSize":"","fontFamily":"","borderColor":"","anchor":""},"innerBlocks":[],"innerHTML":"\n

In a system such as the campus garden (SC), the gravel layer promotes substantial exfiltration, even in low-permeability subsoil conditions. For JdB1 and JdB2, evapotranspiration is the key driver of runoff reduction. The presence of an internal water storage zone (in JdB2) helps maintain soil moisture and sustain evapotranspiration throughout the year.<\/p>\n","innerContent":["\n

In a system such as the campus garden (SC), the gravel layer promotes substantial exfiltration, even in low-permeability subsoil conditions. For JdB1 and JdB2, evapotranspiration is the key driver of runoff reduction. The presence of an internal water storage zone (in JdB2) helps maintain soil moisture and sustain evapotranspiration throughout the year.<\/p>\n"],"rendered":"\n

In a system such as the campus garden (SC), the gravel layer promotes substantial exfiltration, even in low-permeability subsoil conditions. For JdB1 and JdB2, evapotranspiration is the key driver of runoff reduction. The presence of an internal water storage zone (in JdB2) helps maintain soil moisture and sustain evapotranspiration throughout the year.<\/p>\n"},{"blockName":"core\/paragraph","attrs":{"align":"","content":null,"dropCap":false,"placeholder":"","direction":"","lock":[],"metadata":[],"className":"","style":"","backgroundColor":"","textColor":"","gradient":"","fontSize":"","fontFamily":"","borderColor":"","anchor":""},"innerBlocks":[],"innerHTML":"\n

Overall, according to the observation from field experiments, the functioning of rain gardens results from a combination of infiltration, storage, and evapotranspiration processes, rather than a single dominant mechanism.<\/p>\n","innerContent":["\n

Overall, according to the observation from field experiments, the functioning of rain gardens results from a combination of infiltration, storage, and evapotranspiration processes, rather than a single dominant mechanism.<\/p>\n"],"rendered":"\n

Overall, according to the observation from field experiments, the functioning of rain gardens results from a combination of infiltration, storage, and evapotranspiration processes, rather than a single dominant mechanism.<\/p>\n"},{"blockName":"core\/heading","attrs":{"style":{"elements":{"link":{"color":{"text":"var:preset|color|red"}}}},"textColor":"red","textAlign":"","content":null,"level":2,"levelOptions":[],"placeholder":"","lock":[],"metadata":[],"align":"","className":"wp-block-heading has-red-color has-text-color has-link-color","backgroundColor":"","gradient":"","fontSize":"","fontFamily":"","borderColor":"","anchor":""},"innerBlocks":[],"innerHTML":"\n

The role of models<\/h2>\n","innerContent":["\n

The role of models<\/h2>\n"],"rendered":"\n

The role of models<\/h2>\n"},{"blockName":"core\/paragraph","attrs":{"align":"","content":null,"dropCap":false,"placeholder":"","direction":"","lock":[],"metadata":[],"className":"","style":"","backgroundColor":"","textColor":"","gradient":"","fontSize":"","fontFamily":"","borderColor":"","anchor":""},"innerBlocks":[],"innerHTML":"\n

Models are useful tools for exploring design options and predicting overall system performance. In this study, a physically based model was developed using one of the monitored rain gardens (SC) as a reference case. In order to assess the predictive power of this model under operational conditions, it was necessary to examine how the quality of the input data used to parameterize it affects its results. Compared with field observations, the model showed robust performance in predicting water fluxes, even when input data were limited. However, it was less reliable in describing internal processes such as soil moisture dynamics. Overall, the model provides reliable estimates of water balance indicators, such as runoff reduction and exfiltration, but still has limitations in representing moisture variations within the soil.<\/p>\n","innerContent":["\n

Models are useful tools for exploring design options and predicting overall system performance. In this study, a physically based model was developed using one of the monitored rain gardens (SC) as a reference case. In order to assess the predictive power of this model under operational conditions, it was necessary to examine how the quality of the input data used to parameterize it affects its results. Compared with field observations, the model showed robust performance in predicting water fluxes, even when input data were limited. However, it was less reliable in describing internal processes such as soil moisture dynamics. Overall, the model provides reliable estimates of water balance indicators, such as runoff reduction and exfiltration, but still has limitations in representing moisture variations within the soil.<\/p>\n"],"rendered":"\n

Models are useful tools for exploring design options and predicting overall system performance. In this study, a physically based model was developed using one of the monitored rain gardens (SC) as a reference case. In order to assess the predictive power of this model under operational conditions, it was necessary to examine how the quality of the input data used to parameterize it affects its results. Compared with field observations, the model showed robust performance in predicting water fluxes, even when input data were limited. However, it was less reliable in describing internal processes such as soil moisture dynamics. Overall, the model provides reliable estimates of water balance indicators, such as runoff reduction and exfiltration, but still has limitations in representing moisture variations within the soil.<\/p>\n"},{"blockName":"core\/heading","attrs":{"style":{"elements":{"link":{"color":{"text":"var:preset|color|red"}}}},"textColor":"red","textAlign":"","content":null,"level":2,"levelOptions":[],"placeholder":"","lock":[],"metadata":[],"align":"","className":"wp-block-heading has-red-color has-text-color has-link-color","backgroundColor":"","gradient":"","fontSize":"","fontFamily":"","borderColor":"","anchor":""},"innerBlocks":[],"innerHTML":"\n

Rethinking how we design rain gardens<\/h2>\n","innerContent":["\n

Rethinking how we design rain gardens<\/h2>\n"],"rendered":"\n

Rethinking how we design rain gardens<\/h2>\n"},{"blockName":"core\/paragraph","attrs":{"align":"","content":null,"dropCap":false,"placeholder":"","direction":"","lock":[],"metadata":[],"className":"","style":"","backgroundColor":"","textColor":"","gradient":"","fontSize":"","fontFamily":"","borderColor":"","anchor":""},"innerBlocks":[],"innerHTML":"\n

Designing effective systems requires a clear understanding of how water moves through the rain garden and interacts with the surrounding environment. In practice, this means that pre-design site investigations are essential to account for soil properties, groundwater conditions, and underground constraints. When such constraints apply, specific design adaptations can be used: internal water storage can improve drought resilience and reduce runoff through evapotranspiration, while a thin bottom gravel storage layer can promote exfiltration even in low-permeability subsoils. These storage is actually quite lower than the one implemented on JdB2 and SC.<\/p>\n","innerContent":["\n

Designing effective systems requires a clear understanding of how water moves through the rain garden and interacts with the surrounding environment. In practice, this means that pre-design site investigations are essential to account for soil properties, groundwater conditions, and underground constraints. When such constraints apply, specific design adaptations can be used: internal water storage can improve drought resilience and reduce runoff through evapotranspiration, while a thin bottom gravel storage layer can promote exfiltration even in low-permeability subsoils. These storage is actually quite lower than the one implemented on JdB2 and SC.<\/p>\n"],"rendered":"\n

Designing effective systems requires a clear understanding of how water moves through the rain garden and interacts with the surrounding environment. In practice, this means that pre-design site investigations are essential to account for soil properties, groundwater conditions, and underground constraints. When such constraints apply, specific design adaptations can be used: internal water storage can improve drought resilience and reduce runoff through evapotranspiration, while a thin bottom gravel storage layer can promote exfiltration even in low-permeability subsoils. These storage is actually quite lower than the one implemented on JdB2 and SC.<\/p>\n"},{"blockName":"core\/paragraph","attrs":{"align":"","content":null,"dropCap":false,"placeholder":"","direction":"","lock":[],"metadata":[],"className":"","style":"","backgroundColor":"","textColor":"","gradient":"","fontSize":"","fontFamily":"","borderColor":"","anchor":""},"innerBlocks":[],"innerHTML":"\n

In addition, the choice of soil media also involves a trade-off between hydraulic conductivity (capacity of the soil media to allow water to flow through) and water retention, requiring careful balance to avoid issues such as clogging or prolonged ponding brought associated with the fine media. The ratio between the catchment area and the rain garden surface is critical for water balance: evapotranspiration alone cannot reduce the runoff water for high inflow conditions, while very low inflow may lead to uneven wetting and reduced effectiveness across the system.<\/p>\n","innerContent":["\n

In addition, the choice of soil media also involves a trade-off between hydraulic conductivity (capacity of the soil media to allow water to flow through) and water retention, requiring careful balance to avoid issues such as clogging or prolonged ponding brought associated with the fine media. The ratio between the catchment area and the rain garden surface is critical for water balance: evapotranspiration alone cannot reduce the runoff water for high inflow conditions, while very low inflow may lead to uneven wetting and reduced effectiveness across the system.<\/p>\n"],"rendered":"\n

In addition, the choice of soil media also involves a trade-off between hydraulic conductivity (capacity of the soil media to allow water to flow through) and water retention, requiring careful balance to avoid issues such as clogging or prolonged ponding brought associated with the fine media. The ratio between the catchment area and the rain garden surface is critical for water balance: evapotranspiration alone cannot reduce the runoff water for high inflow conditions, while very low inflow may lead to uneven wetting and reduced effectiveness across the system.<\/p>\n"},{"blockName":"core\/paragraph","attrs":{"fontSize":"small","align":"","content":null,"dropCap":false,"placeholder":"","direction":"","lock":[],"metadata":[],"className":"has-small-font-size","style":"","backgroundColor":"","textColor":"","gradient":"","fontFamily":"","borderColor":"","anchor":""},"innerBlocks":[],"innerHTML":"\n

Proofreaders :Marie-Christine Gromaire and Hayath Zime Yerima<\/em><\/p>\n","innerContent":["\n

Proofreaders :Marie-Christine Gromaire and Hayath Zime Yerima<\/em><\/p>\n"],"rendered":"\n

Proofreaders :Marie-Christine Gromaire and Hayath Zime Yerima<\/em><\/p>\n"},{"blockName":"enpc\/accordion","attrs":{"title":"ACKNOWLEDGEMENT","lock":[],"metadata":[],"className":"wp-block-enpc-accordion","style":""},"innerBlocks":[{"blockName":"core\/paragraph","attrs":{"align":"","content":null,"dropCap":false,"placeholder":"","direction":"","lock":[],"metadata":[],"className":"","style":"","backgroundColor":"","textColor":"","gradient":"","fontSize":"","fontFamily":"","borderColor":"","anchor":""},"innerBlocks":[],"innerHTML":"\n

This research was conducted as part of the OPUR research program<\/a>. The author extends his sincere thanks to OPUR\u2019s partners for their financial support, particularly the City of Paris. The City of Paris also contributed to the experimental setup and data collection at the Jardin du Breuil. Thanks are also extended to the Sense-City<\/a> partners and to CEREMA for their technical support and data management.<\/p>\n","innerContent":["\n

This research was conducted as part of the OPUR research program<\/a>. The author extends his sincere thanks to OPUR\u2019s partners for their financial support, particularly the City of Paris. The City of Paris also contributed to the experimental setup and data collection at the Jardin du Breuil. Thanks are also extended to the Sense-City<\/a> partners and to CEREMA for their technical support and data management.<\/p>\n"],"rendered":"\n

This research was conducted as part of the OPUR research program<\/a>. The author extends his sincere thanks to OPUR\u2019s partners for their financial support, particularly the City of Paris. The City of Paris also contributed to the experimental setup and data collection at the Jardin du Breuil. Thanks are also extended to the Sense-City<\/a> partners and to CEREMA for their technical support and data management.<\/p>\n"}],"innerHTML":"\n

<\/div>\n","innerContent":["\n
",null,"<\/div>\n"],"rendered":"\n
\n

This research was conducted as part of the OPUR research program<\/a>. The author extends his sincere thanks to OPUR\u2019s partners for their financial support, particularly the City of Paris. The City of Paris also contributed to the experimental setup and data collection at the Jardin du Breuil. Thanks are also extended to the Sense-City<\/a> partners and to CEREMA for their technical support and data management.<\/p>\n<\/div>\n"},{"blockName":"core\/paragraph","attrs":{"align":"","content":null,"dropCap":false,"placeholder":"","direction":"","lock":[],"metadata":[],"className":"","style":"","backgroundColor":"","textColor":"","gradient":"","fontSize":"","fontFamily":"","borderColor":"","anchor":""},"innerBlocks":[],"innerHTML":"\n

<\/p>\n","innerContent":["\n

<\/p>\n"],"rendered":"\n

<\/p>\n"}],"seo":{"title":"\u201cRain gardens\u201d for managing urban runoff? A study of a Parisian case"},"media":{"img":"\"\"","src":"https:\/\/ingenius.ecoledesponts.fr\/wp-content\/uploads\/2026\/04\/Image_Wikimedia-CommonsJardin_de_pluie_de_Saint-Job._Le_bassin_de_retention-scaled.jpg"},"url":"\/en\/articles\/rain-gardens-for-managing-urban-runoff-a-study-of-a-parisian-case\/","related":{"post":[],"author":[{"title":"Tinghao Huang","url":"\/en\/authors\/tinghao-huang\/","id":"10480","media":"\"Tinghao","slug":"tinghao-huang"}],"subject":[{"title":"Energy, Ecology & Climate","url":"\/en\/subjects\/energy-ecology-climate\/","id":"937","media":"\"\"","slug":"energy-ecology-climate"},{"title":"Cities, Urban planning & Construction","url":"\/en\/subjects\/cities-urban-planning-construction\/","id":"936","media":"\"\"","slug":"cities-urban-planning-construction"}],"category":[{"title":"Article collection","url":"\/en\/articles\/category\/dossier\/","id":"1720","media":"","slug":"dossier","_related_post_type":"folder"}],"folder":[{"title":"Better manage urban stormwater through Nature-Based Solutions","url":"\/en\/folders\/better-manage-urban-stormwater-through-nature-based-solutions\/","id":"10530","media":"\"\"","slug":"better-manage-urban-stormwater-through-nature-based-solutions"}]},"translated":"https:\/\/ingenius.ecoledesponts.fr\/articles\/des-jardins-de-pluie-pour-gerer-le-ruissellement-urbain-observations-en-region-parisienne\/","icon":"icon-article","duration":"5","custom_excerpt":"Can \"rain gardens\" still work when the ground beneath them barely lets water through? In cities like Paris, complex underground conditions challenge the way these systems are usually expected to function. Yet, field observations show that rain gardens can still achieve notable runoff reduction, even when deeper infiltration is limited. A key question thus raises: how do rain gardens actually work under such constraints?","duration_type":"","_links":{"self":[{"href":"https:\/\/ingenius.ecoledesponts.fr\/en\/wp-json\/wp\/v2\/posts\/10468","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/ingenius.ecoledesponts.fr\/en\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/ingenius.ecoledesponts.fr\/en\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/ingenius.ecoledesponts.fr\/en\/wp-json\/wp\/v2\/users\/9"}],"replies":[{"embeddable":true,"href":"https:\/\/ingenius.ecoledesponts.fr\/en\/wp-json\/wp\/v2\/comments?post=10468"}],"version-history":[{"count":5,"href":"https:\/\/ingenius.ecoledesponts.fr\/en\/wp-json\/wp\/v2\/posts\/10468\/revisions"}],"predecessor-version":[{"id":10552,"href":"https:\/\/ingenius.ecoledesponts.fr\/en\/wp-json\/wp\/v2\/posts\/10468\/revisions\/10552"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/ingenius.ecoledesponts.fr\/en\/wp-json\/wp\/v2\/media\/10460"}],"wp:attachment":[{"href":"https:\/\/ingenius.ecoledesponts.fr\/en\/wp-json\/wp\/v2\/media?parent=10468"}],"wp:term":[{"taxonomy":"article-types","embeddable":true,"href":"https:\/\/ingenius.ecoledesponts.fr\/en\/wp-json\/wp\/v2\/article-types?post=10468"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}