CZ
C. Zevenbergen
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50 records found
1
Urban pluvial flooding is influenced by rainfall intensity, drainage capacity, and urban infrastructure. While prior studies mapped flood extents, the spatiotemporal dynamics of drainage saturation and overflow remain underexplored. This study introduces the percentage of node in flood assessment (PNFA) and flood expansion rate (FER) to quantify flood spread within drainage networks. Using EPA SWMM, three historical storms (2008, 2019, and 2020) and seven return-period scenarios were simulated in Do Lo, Hanoi, Vietnam. The results show that despite rainfall variability, spatiotemporal flood patterns remain stable, indicating predictable propagation pathways. FER values ranged from 0.17 (slow) to 0.902 (rapid), reflecting flood expansion speed under light to heavy rainfall. Spatiotemporal analysis produced hazard maps, capturing both spatial and temporal dimensions, revealing not only a persistent critical hotspot near AH13 but also consistent flood evolution patterns across various scenarios. These findings shift perspectives on flood preparedness by emphasizing timing, sequence, and hotspot stability. This study advances urban flood risk assessment through spatiotemporal hazard mapping, offering insights essential for mitigation, urban planning, and drainage resilience. Incorporating time-sensitive models is crucial for managing flood risks amid increasing extreme weather events.
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Urban pluvial flooding is influenced by rainfall intensity, drainage capacity, and urban infrastructure. While prior studies mapped flood extents, the spatiotemporal dynamics of drainage saturation and overflow remain underexplored. This study introduces the percentage of node in flood assessment (PNFA) and flood expansion rate (FER) to quantify flood spread within drainage networks. Using EPA SWMM, three historical storms (2008, 2019, and 2020) and seven return-period scenarios were simulated in Do Lo, Hanoi, Vietnam. The results show that despite rainfall variability, spatiotemporal flood patterns remain stable, indicating predictable propagation pathways. FER values ranged from 0.17 (slow) to 0.902 (rapid), reflecting flood expansion speed under light to heavy rainfall. Spatiotemporal analysis produced hazard maps, capturing both spatial and temporal dimensions, revealing not only a persistent critical hotspot near AH13 but also consistent flood evolution patterns across various scenarios. These findings shift perspectives on flood preparedness by emphasizing timing, sequence, and hotspot stability. This study advances urban flood risk assessment through spatiotemporal hazard mapping, offering insights essential for mitigation, urban planning, and drainage resilience. Incorporating time-sensitive models is crucial for managing flood risks amid increasing extreme weather events.
The governance paradox
Why polycentric systems fail to mitigate urban vulnerability in the global south
Journal article
(2026)
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Syarifah Aini Dalimunthe, Budi Heru Santosa, Gusti Ayu Ketut Surtiari, Andi Muhammad Yasser Hakim, Abdul Fikri Angga Reksa, C. Zevenbergen, Sepanie Putiamini, Agustan Agustan, Lamijo Lamijo, Rachmadi Purwana
The global reliance on Polycentric Governance (PCG) for climate adaptation in rapidly urbanizing coastal cities frequently fails to achieve transformative outcomes, a paradox this research addresses by identifying institutional friction as the core impediment. Using a mixed-methods approach in Semarang, Indonesia, we combined Q-methodology with Cellular Automata–Markov chain (CA-Markov) LULC modeling to relate institutional dynamics to physical land-use outcomes. The Q-methodology analysis of 58 key stakeholders revealed a deep institutional rift characterized by an Adaptation Tempo Dilemma and Trust Deficit, with stakeholders divided between advocates of transformative change and a prevailing preference for incremental adaptation. In parallel, the CA-Markov modeling documented the physical trajectory associated with this governance context: impervious surface areas are projected to increase dramatically from 39% in 2009 to over 51% by 2039, substantially accelerating the city’s vulnerability to flooding in high-risk zones. We conclude that, in the context of the Urban Global South, institutional trust-building and policy coherence are not merely desirable but necessary pre-emptive conditions for PCG to catalyze transformative climate adaptation successfully.
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The global reliance on Polycentric Governance (PCG) for climate adaptation in rapidly urbanizing coastal cities frequently fails to achieve transformative outcomes, a paradox this research addresses by identifying institutional friction as the core impediment. Using a mixed-methods approach in Semarang, Indonesia, we combined Q-methodology with Cellular Automata–Markov chain (CA-Markov) LULC modeling to relate institutional dynamics to physical land-use outcomes. The Q-methodology analysis of 58 key stakeholders revealed a deep institutional rift characterized by an Adaptation Tempo Dilemma and Trust Deficit, with stakeholders divided between advocates of transformative change and a prevailing preference for incremental adaptation. In parallel, the CA-Markov modeling documented the physical trajectory associated with this governance context: impervious surface areas are projected to increase dramatically from 39% in 2009 to over 51% by 2039, substantially accelerating the city’s vulnerability to flooding in high-risk zones. We conclude that, in the context of the Urban Global South, institutional trust-building and policy coherence are not merely desirable but necessary pre-emptive conditions for PCG to catalyze transformative climate adaptation successfully.
Journal article
(2026)
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Feikai Yang, Dafang Fu, Chris Zevenbergen, Floris C. Boogaard, Rajendra Prasad Singh
Evaluation of the hydrological performance of grassed swales usually needs long-term monitoring data. At present, suitable techniques for simulating the hydrological performance using limited monitoring data are not available. Therefore, current study aims to investigate the relationship between saturated hydraulic conductivity (Ks) fitting results and rainfall characteristics of various events series length. Data from a full-scale grassed swale (Enschede, the Netherlands) were utilized as long-term rainfall event series length (95 rainfall events) on the fitting outcomes. Short-term rainfall event series were extracted from these long-term series and used as input in fitting into a multivariate nonlinear model between Ks and its influencing rainfall indicators (antecedent dry days, temperature, rainfall, rainfall duration, total rainfall, and seasonal factor (spring, summer, autumn, and winter, herein refer as 1, 2, 3, and 4). Comparison of short-term and long-term rainfall event series fitting results allowed to obtain a representative short-term series that leads to similar results with those using long-term series. A cluster analysis was conducted based on the fitting results of the representative rainfall event series with their rainfall event characteristics using average values of influencing rainfall indicators. The seasonal index (average value of seasonal factors) was found to be the most representative short rainfall event series indicator. Furthermore, a Bayesian network was proposed in the current study to predict if a given short-term rainfall event series is representative. It was validated by a data series (58 rainfall events) from another full-scale grassed swale located in Utrecht, the Netherlands. Results revealed that it is quite promising and useful to evaluate the representativeness of short-term rainfall event series used for long-term hydrological performance evaluation of grassed swales. Graphical Abstract: (Figure presented.).
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Evaluation of the hydrological performance of grassed swales usually needs long-term monitoring data. At present, suitable techniques for simulating the hydrological performance using limited monitoring data are not available. Therefore, current study aims to investigate the relationship between saturated hydraulic conductivity (Ks) fitting results and rainfall characteristics of various events series length. Data from a full-scale grassed swale (Enschede, the Netherlands) were utilized as long-term rainfall event series length (95 rainfall events) on the fitting outcomes. Short-term rainfall event series were extracted from these long-term series and used as input in fitting into a multivariate nonlinear model between Ks and its influencing rainfall indicators (antecedent dry days, temperature, rainfall, rainfall duration, total rainfall, and seasonal factor (spring, summer, autumn, and winter, herein refer as 1, 2, 3, and 4). Comparison of short-term and long-term rainfall event series fitting results allowed to obtain a representative short-term series that leads to similar results with those using long-term series. A cluster analysis was conducted based on the fitting results of the representative rainfall event series with their rainfall event characteristics using average values of influencing rainfall indicators. The seasonal index (average value of seasonal factors) was found to be the most representative short rainfall event series indicator. Furthermore, a Bayesian network was proposed in the current study to predict if a given short-term rainfall event series is representative. It was validated by a data series (58 rainfall events) from another full-scale grassed swale located in Utrecht, the Netherlands. Results revealed that it is quite promising and useful to evaluate the representativeness of short-term rainfall event series used for long-term hydrological performance evaluation of grassed swales. Graphical Abstract: (Figure presented.).
Journal article
(2026)
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Junling Liu, Chris Zevenbergen, Jingyi Lu, Qi Qi, William Veerbeek, Sami W. Chowdhury, Liyuan Qian
In biodiversity-rich borderlands, some humanitarian settlements are rapidly expanding. This creates a profound conflict: refugees need a place to live, and ecosystems need protection. However, how settlement growth spatially affects the ecology surrounding protected areas remains understudied. This study takes as an example the city of Teknaf in Bangladesh, one of the world’s largest refugee gathering areas, to explore how settlement expansion changes the ecological structure and function of protected area boundaries, with a focus on two questions: Are there critical spatial thresholds? What is the role of climate feedback mechanisms? We build an analysis framework that integrates several types of data: multitemporal remote sensing images, land-use changes, ecological indicators (NDVI, LST, HQ), landscape pattern indices, gradient analysis, and 2036 simulations based on the business-as-usual scenario. Through this framework, we identify the ecological threshold at the junction of settlements and forests within the Teknaf Wildlife Sanctuary. The expansion of settlements has turned the landscape, which was originally dominated by vegetation, into fragmented hard patches. At the same time, the habitat is severely degraded, and heat stress intensifies. Notably, a critical transition zone emerges at approximately 300–500 m from the protected area boundary, where landscape fragmentation intensifies, habitat quality declines, and heat stress reaches its peak, highlighting a spatial hotspot of ecological vulnerability. If there are no intervention measures, future scenario simulations show that the continued expansion of settlements will only isolate protected areas and accelerate ecological degradation. On the basis of gradient analysis for spatial diagnosis, we propose a zoning management framework and regeneration landscape strategy with the direct goal of coordinating ecological protection and humanitarian needs in crisis-prone border areas.
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In biodiversity-rich borderlands, some humanitarian settlements are rapidly expanding. This creates a profound conflict: refugees need a place to live, and ecosystems need protection. However, how settlement growth spatially affects the ecology surrounding protected areas remains understudied. This study takes as an example the city of Teknaf in Bangladesh, one of the world’s largest refugee gathering areas, to explore how settlement expansion changes the ecological structure and function of protected area boundaries, with a focus on two questions: Are there critical spatial thresholds? What is the role of climate feedback mechanisms? We build an analysis framework that integrates several types of data: multitemporal remote sensing images, land-use changes, ecological indicators (NDVI, LST, HQ), landscape pattern indices, gradient analysis, and 2036 simulations based on the business-as-usual scenario. Through this framework, we identify the ecological threshold at the junction of settlements and forests within the Teknaf Wildlife Sanctuary. The expansion of settlements has turned the landscape, which was originally dominated by vegetation, into fragmented hard patches. At the same time, the habitat is severely degraded, and heat stress intensifies. Notably, a critical transition zone emerges at approximately 300–500 m from the protected area boundary, where landscape fragmentation intensifies, habitat quality declines, and heat stress reaches its peak, highlighting a spatial hotspot of ecological vulnerability. If there are no intervention measures, future scenario simulations show that the continued expansion of settlements will only isolate protected areas and accelerate ecological degradation. On the basis of gradient analysis for spatial diagnosis, we propose a zoning management framework and regeneration landscape strategy with the direct goal of coordinating ecological protection and humanitarian needs in crisis-prone border areas.
The three-point sponge policy approach for integrating blue-green-grey infrastructure by design
Lessons from the 2021 extreme flood in Zhengzhou, China
Journal article
(2026)
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Mila Avellar Montezuma, Chris Zevenbergen, Frans van de Ven, Zihang Ding, William Veerbeek, Gerald Corzo Perez, Junguo Liu
The increasing frequency and intensity of extreme weather events, coupled with rapid urbanization, are placing unprecedented pressure on urban environments. The Three-Point Sponge Policy Approach (3PSPa) integrates the Three-Point Approach (3PA) with Sponge City principles to enhance urban flood resilience through design-driven, adaptive, and multifunctional solutions. This paper applies the 3PSPa framework to Zhengzhou, China, which experienced devastating flooding in 2021, to assess its current flood resilience measures and explore pathways for improvement. Two contrasting urban districts in Zhengzhou were analysed: B1, a newly developed, low-density district offering high potential for implementing large-scale blue-green-grey infrastructure (BGGI); and B2, a dense, older district where interventions are limited, typically emerging incrementally through targeted retrofitting associated with urban renewal activities. By applying the 3PSPa’s five-step design process, this study identifies resilience gaps and proposes tailored interventions, balancing short-term, localized strategies with long-term, catchment-wide transformations. It emphasizes the importance of shifting from a conveyance-based water management approach to a diversified strategy that integrates infrastructure with natural hydrological processes.
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The increasing frequency and intensity of extreme weather events, coupled with rapid urbanization, are placing unprecedented pressure on urban environments. The Three-Point Sponge Policy Approach (3PSPa) integrates the Three-Point Approach (3PA) with Sponge City principles to enhance urban flood resilience through design-driven, adaptive, and multifunctional solutions. This paper applies the 3PSPa framework to Zhengzhou, China, which experienced devastating flooding in 2021, to assess its current flood resilience measures and explore pathways for improvement. Two contrasting urban districts in Zhengzhou were analysed: B1, a newly developed, low-density district offering high potential for implementing large-scale blue-green-grey infrastructure (BGGI); and B2, a dense, older district where interventions are limited, typically emerging incrementally through targeted retrofitting associated with urban renewal activities. By applying the 3PSPa’s five-step design process, this study identifies resilience gaps and proposes tailored interventions, balancing short-term, localized strategies with long-term, catchment-wide transformations. It emphasizes the importance of shifting from a conveyance-based water management approach to a diversified strategy that integrates infrastructure with natural hydrological processes.
From silos to synergies
Comparing traditional and integrated approaches in urban water management
Journal article
(2026)
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Taiane Regina Hoepers, Michel Marques Monteiro, Juliana Leithold, Gerald A.Corzo Perez, Cristovão V. Scapulatempo Fernandes, Chris Zevenbergen, Daniel Costa dos Santos
As urban areas expand, the need for sustainable water management becomes increasingly urgent. Traditional approaches treat water supply, wastewater and stormwater systems separately, whereas integrated approaches consider the urban water cycle as a whole. Although integrated management is widely advocated, direct quantitative comparisons across different integration perspectives remain limited. This study addresses this gap by applying the urban water use (UWU) decision-support tool to compare three integration levels: Limited, Partial, and Broad, reflecting different managerial perspectives during planning. Results show that Broad Integration outperformed the other approaches, increasing the Effectiveness Index by up to 81% compared to Limited Integration and by up to 21% compared to Partial Integration, depending on the group of measures. By revealing synergies and trade-offs that remain hidden under lower integration levels, the findings support more informed decision-making and reinforce the need to shift from fragmented toward integrated urban water management, particularly in complex urban contexts.
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As urban areas expand, the need for sustainable water management becomes increasingly urgent. Traditional approaches treat water supply, wastewater and stormwater systems separately, whereas integrated approaches consider the urban water cycle as a whole. Although integrated management is widely advocated, direct quantitative comparisons across different integration perspectives remain limited. This study addresses this gap by applying the urban water use (UWU) decision-support tool to compare three integration levels: Limited, Partial, and Broad, reflecting different managerial perspectives during planning. Results show that Broad Integration outperformed the other approaches, increasing the Effectiveness Index by up to 81% compared to Limited Integration and by up to 21% compared to Partial Integration, depending on the group of measures. By revealing synergies and trade-offs that remain hidden under lower integration levels, the findings support more informed decision-making and reinforce the need to shift from fragmented toward integrated urban water management, particularly in complex urban contexts.
Journal article
(2026)
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Jiaxuan Qin, Chris Zevenbergen, Liyuan Qian, Yihua Zhong, Sixiang Zhou, Saeid Pirasteh
Extreme rainfall events intensify flood-related hazards in mountainous national parks and their surrounding communities, where complex terrain and coupled hazard processes create major challenges for spatial risk management. This study focuses on the Tangjiahe district of the Giant Panda National Park and develops an integrated framework for flood-related multi-hazard identification and zoning. The 100-year flood process was simulated using Hydrologic Engineering Center’s River Analysis System (HEC-RAS), runoff retention was assessed using the Integrated Valuation of Ecosystem Services and Tradeoffs (InVEST) model, and slope stability risk zoning was conducted using the Analytic Hierarchy Process (AHP). Based on multi-source spatial overlay, Integrated Flood-Related Multi-Hazard Risk Zoning was generated. Spatial statistical analyses, including Global Moran’s I, Local Indicators of Spatial Association (LISA), and Getis-Ord Gi*, supported the identification of clustered high-risk areas and hotspot zones. In parallel, Disaster Prevention and Control Zoning was established, classifying the study area into multiple management-oriented zones to support differentiated spatial governance and targeted management. The proposed framework provides a practical approach for integrating multi-hazard processes into spatial planning and disaster risk management in mountainous protected areas.
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Extreme rainfall events intensify flood-related hazards in mountainous national parks and their surrounding communities, where complex terrain and coupled hazard processes create major challenges for spatial risk management. This study focuses on the Tangjiahe district of the Giant Panda National Park and develops an integrated framework for flood-related multi-hazard identification and zoning. The 100-year flood process was simulated using Hydrologic Engineering Center’s River Analysis System (HEC-RAS), runoff retention was assessed using the Integrated Valuation of Ecosystem Services and Tradeoffs (InVEST) model, and slope stability risk zoning was conducted using the Analytic Hierarchy Process (AHP). Based on multi-source spatial overlay, Integrated Flood-Related Multi-Hazard Risk Zoning was generated. Spatial statistical analyses, including Global Moran’s I, Local Indicators of Spatial Association (LISA), and Getis-Ord Gi*, supported the identification of clustered high-risk areas and hotspot zones. In parallel, Disaster Prevention and Control Zoning was established, classifying the study area into multiple management-oriented zones to support differentiated spatial governance and targeted management. The proposed framework provides a practical approach for integrating multi-hazard processes into spatial planning and disaster risk management in mountainous protected areas.
Journal article
(2025)
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M. Randall, M. B. Jensen, F. van de Ven, C. Zevenbergen, J. H. Körber, Z. Sun, S. Chen, S. Zhang
Urban stormwater is sometimes a risk, sometimes a resource. To address both aspects, the Three Points Approach (3PA) is advocated. This research applied the 3PA to map stormwater approaches in two Chinese and four European cities. While all cities have targets for the Technical Design Domain, none have targets for all domains; and thereby lack interventions to maximize benefits of frequent small events in the Day-to-Day Domain or minimize flood risks of rare large events in the Extreme Domain. Using open global precipitation data cities’ stormwater targets were expressed as more comparable rain depths, demonstrating that event depths within the Day-to-Day Domain in Chinese cities, cover much of the same range as those within the Technical Design Domain in the European cities. Expressing targets as depths in the context of the 3PA framework may facilitate transdisciplinary and transnational knowledge sharing, paving the way for management strategies covering all three domains.
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Urban stormwater is sometimes a risk, sometimes a resource. To address both aspects, the Three Points Approach (3PA) is advocated. This research applied the 3PA to map stormwater approaches in two Chinese and four European cities. While all cities have targets for the Technical Design Domain, none have targets for all domains; and thereby lack interventions to maximize benefits of frequent small events in the Day-to-Day Domain or minimize flood risks of rare large events in the Extreme Domain. Using open global precipitation data cities’ stormwater targets were expressed as more comparable rain depths, demonstrating that event depths within the Day-to-Day Domain in Chinese cities, cover much of the same range as those within the Technical Design Domain in the European cities. Expressing targets as depths in the context of the 3PA framework may facilitate transdisciplinary and transnational knowledge sharing, paving the way for management strategies covering all three domains.
High-resolution rainfall forecasts are essential for forecasting urban pluvial floods and providing local decision support before an event when using rainfall or model-based approaches. Regional Numerical Weather Prediction (NWP) models increase the resolution and extend forecasts by several days when initialised with global models. These models produce forecasts at higher spatial and temporal resolutions but are computationally demanding and do not necessarily result in more accurate forecasts especially in data-scarce cities. This research evaluated how rainfall forecasting model scale dependencies satisfy high-resolution hazard forecasting requirements with two different flood forecasting approaches. Rainfall forecasts of different spatial resolutions, cumulus schemes and lead times from a high-resolution Weather Research and Forecasting (WRF) model were first evaluated and then used as input in a rainfall threshold and 1D MIKE urban drainage model for flood forecasting in the data-scarce city of Alexandria City, Egypt. Results indicate the flood forecast severity class and flood model simulation results vary with the neighbourhood size, forecast horizon, and chosen cumulus configuration but in general the smallest resolutions evaluated did not improve the hazard estimation for both flood forecasting approaches. Therefore, trade-offs must be made regarding model configurations, resolution, lead times and how the forecast output will be used. This study demonstrates the opportunities and limitations for better integrating high-resolution meteorological for the development of a rainfall threshold-based and model-based flood forecasting in cities with similar conditions. It also highlights the need to align the selected model configuration with the goals of the flood forecasting application which is critical for effective early warning systems and anticipatory flood management.
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High-resolution rainfall forecasts are essential for forecasting urban pluvial floods and providing local decision support before an event when using rainfall or model-based approaches. Regional Numerical Weather Prediction (NWP) models increase the resolution and extend forecasts by several days when initialised with global models. These models produce forecasts at higher spatial and temporal resolutions but are computationally demanding and do not necessarily result in more accurate forecasts especially in data-scarce cities. This research evaluated how rainfall forecasting model scale dependencies satisfy high-resolution hazard forecasting requirements with two different flood forecasting approaches. Rainfall forecasts of different spatial resolutions, cumulus schemes and lead times from a high-resolution Weather Research and Forecasting (WRF) model were first evaluated and then used as input in a rainfall threshold and 1D MIKE urban drainage model for flood forecasting in the data-scarce city of Alexandria City, Egypt. Results indicate the flood forecast severity class and flood model simulation results vary with the neighbourhood size, forecast horizon, and chosen cumulus configuration but in general the smallest resolutions evaluated did not improve the hazard estimation for both flood forecasting approaches. Therefore, trade-offs must be made regarding model configurations, resolution, lead times and how the forecast output will be used. This study demonstrates the opportunities and limitations for better integrating high-resolution meteorological for the development of a rainfall threshold-based and model-based flood forecasting in cities with similar conditions. It also highlights the need to align the selected model configuration with the goals of the flood forecasting application which is critical for effective early warning systems and anticipatory flood management.
This paper presents the intermediate results of the Redesigning Deltas – Rivers Atelier in which a transition design approach is applied to develop scenarios for sustainable future river development. As a first step, a set of exploratory scenarios is derived from extrapolations of historic drivers for the development of the river Rhine: Water Way, Water Machine, Free Flow and Sponge Scape. Instead of addressing a predefined problem and valuating alternative futures, these scenarios were instrumental in gaining a better understanding of the river system at hand, and more specifically the effects of drivers on the physical river system. We conclude that explicit deliberation thereof is needed to break through the vicious intervention-response relationships that have characterized river management practices of the last centuries.
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This paper presents the intermediate results of the Redesigning Deltas – Rivers Atelier in which a transition design approach is applied to develop scenarios for sustainable future river development. As a first step, a set of exploratory scenarios is derived from extrapolations of historic drivers for the development of the river Rhine: Water Way, Water Machine, Free Flow and Sponge Scape. Instead of addressing a predefined problem and valuating alternative futures, these scenarios were instrumental in gaining a better understanding of the river system at hand, and more specifically the effects of drivers on the physical river system. We conclude that explicit deliberation thereof is needed to break through the vicious intervention-response relationships that have characterized river management practices of the last centuries.
Journal article
(2024)
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Chris Zevenbergen, Maurice G. Harteveld, Pieter Bloemen, Maarten van Ham, Wim van den Doel, Marcel Hertogh, Fransje Hooimeijer, Taneha Bacchin, Eddy Moors, More Authors...
Urbanizing river deltas are highly susceptible to sea level rise and extreme weather events such as floods and droughts. Water-related disasters are already happening more often due to climate change, rapid urbanization, unsustainable land use and aging infrastructure threatening a large fraction of human and natural environments in these low lying and sinking areas around the globe. As stress levels of climate change are accelerating, societal and physical transformations are essential for adapting our deltas to climate change. In the Netherlands, imagination and evidence by design in the form of a long-term spatial vision, played a pivotal role in the past century to set, share and accomplish a new direction to overcome flood disasters by altering the coastlines and riverbeds of the Rhine–Meuse–Scheldt delta. The unprecedented rainfall in July 2021 and the storm in December 2021 which hit Western Europe revealed the effectiveness of this new direction. We therefore plea for a prominent role of design in climate science and delta management to imagine, analyse and communicate future perspectives for climate adaptation in urbanizing deltas.
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Urbanizing river deltas are highly susceptible to sea level rise and extreme weather events such as floods and droughts. Water-related disasters are already happening more often due to climate change, rapid urbanization, unsustainable land use and aging infrastructure threatening a large fraction of human and natural environments in these low lying and sinking areas around the globe. As stress levels of climate change are accelerating, societal and physical transformations are essential for adapting our deltas to climate change. In the Netherlands, imagination and evidence by design in the form of a long-term spatial vision, played a pivotal role in the past century to set, share and accomplish a new direction to overcome flood disasters by altering the coastlines and riverbeds of the Rhine–Meuse–Scheldt delta. The unprecedented rainfall in July 2021 and the storm in December 2021 which hit Western Europe revealed the effectiveness of this new direction. We therefore plea for a prominent role of design in climate science and delta management to imagine, analyse and communicate future perspectives for climate adaptation in urbanizing deltas.
With rapid urbanization, the types of land in China’s cities are continuously evolving, irreversibly impacting the habitat patches within urban areas. However, the development of park cities has reversed this trend to some extent, particularly in Chengdu, China. To investigate the influence of land use type changes on habitat quality in Chengdu Tianfu New District, the research team selected remote sensing imagery data from the Landsat satellite for three distinct periods: 2014, 2019, and 2024. By employing a comprehensive approach that includes land cover trajectory analysis, land transfer matrices, FRAG-STATS landscape pattern indices, and the habitat quality module within the In-VEST model, this study analyzes the spatial and temporal evolution of land use patterns and the dynamics of habitat quality categories. The findings reveal: (1) the coverage of trees and shrubs in the study area initially declined but later increased, primarily driven by anthropogenic construction activities. Specifically, the land use types in the built-up areas on the northern side of Tianfu New District underwent notable fluctuations, whereas those on the southern side, adjacent to the Longquan Mountain Range, remained relatively stable. (2) From 2014 to 2019, high-quality habitats were predominantly distributed in the southeast of Tianfu New District, characterized by a robust ecological foundation, high landscape integrity, and strong connectivity of ecological land. In contrast, the areas with the poorest habitat quality were situated in the northern built-up areas of Tianfu New District, exhibiting highly fragmented habitat patches, simple edge shapes, and low connectivity. However, between 2019 and 2024, the overall habitat quality within the study area improved, characterized by an increase in the number of high-quality habitats and continuous expansion of habitat areas. The research findings offer valuable insights into future urban planning, ecological restoration, and conservation efforts in Chengdu Tianfu New District, providing critical guidance for the implementation and strategic development of the park city policy.
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With rapid urbanization, the types of land in China’s cities are continuously evolving, irreversibly impacting the habitat patches within urban areas. However, the development of park cities has reversed this trend to some extent, particularly in Chengdu, China. To investigate the influence of land use type changes on habitat quality in Chengdu Tianfu New District, the research team selected remote sensing imagery data from the Landsat satellite for three distinct periods: 2014, 2019, and 2024. By employing a comprehensive approach that includes land cover trajectory analysis, land transfer matrices, FRAG-STATS landscape pattern indices, and the habitat quality module within the In-VEST model, this study analyzes the spatial and temporal evolution of land use patterns and the dynamics of habitat quality categories. The findings reveal: (1) the coverage of trees and shrubs in the study area initially declined but later increased, primarily driven by anthropogenic construction activities. Specifically, the land use types in the built-up areas on the northern side of Tianfu New District underwent notable fluctuations, whereas those on the southern side, adjacent to the Longquan Mountain Range, remained relatively stable. (2) From 2014 to 2019, high-quality habitats were predominantly distributed in the southeast of Tianfu New District, characterized by a robust ecological foundation, high landscape integrity, and strong connectivity of ecological land. In contrast, the areas with the poorest habitat quality were situated in the northern built-up areas of Tianfu New District, exhibiting highly fragmented habitat patches, simple edge shapes, and low connectivity. However, between 2019 and 2024, the overall habitat quality within the study area improved, characterized by an increase in the number of high-quality habitats and continuous expansion of habitat areas. The research findings offer valuable insights into future urban planning, ecological restoration, and conservation efforts in Chengdu Tianfu New District, providing critical guidance for the implementation and strategic development of the park city policy.
Impact of land use land cover changes on urban temperature in Jakarta
Insights from an urban boundary layer climate model
Journal article
(2024)
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Dikman Maheng, Assela Pathirana, Biswa Bhattacharya, Chris Zevenbergen, Dirk Lauwaet, Siswanto Siswanto, Aries Suwondo
Urbanization is one of the important drivers of increasing local temperatures. As cities and urban areas evolve, extensive land use and land cover (LULC) changes alter the physical characteristics of surface materials. This modification results in reduced evapotranspiration rates, ultimately contributing to higher surface and air temperatures. This study investigated the impact of urbanization on urban temperature in Jakarta. Urban temperature was simulated for a 20-year time period (1995–2014) by the urban boundary layer climate model UrbClim, using LULC data for both 1995 and 2014. Temperature changes were analysed by assessing the temperature anomaly across different LULC change classes divided into four main classes namely no built-up changes (BB), no green spaces changes (GG), built-up to green spaces (BG), and green spaces to built-up (GB). The study revealed that the conversion of green spaces to built-up areas (GB) had the most significant impact on the increase in air temperature. This was indicated by the mean values of the temperature anomaly of GB of about 0.24°C followed by GG, BB, and BG with the mean values of the temperature anomaly of about 0.20°C, 0.19°C, 0.17°C, respectively. The different temperature anomalies of the LULC change classes indicate that green spaces have an important role in maintaining local climate. Hence, it is important for local government to effectively manage the composition, the quantity, as well as the distribution of green spaces within a city. By looking at temperature anomalies of LULC change classes, the present study provides an alternative approach to many existing methods that provide general information about temperature changes, without specifically analyzing the effects of LULC transformations.
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Urbanization is one of the important drivers of increasing local temperatures. As cities and urban areas evolve, extensive land use and land cover (LULC) changes alter the physical characteristics of surface materials. This modification results in reduced evapotranspiration rates, ultimately contributing to higher surface and air temperatures. This study investigated the impact of urbanization on urban temperature in Jakarta. Urban temperature was simulated for a 20-year time period (1995–2014) by the urban boundary layer climate model UrbClim, using LULC data for both 1995 and 2014. Temperature changes were analysed by assessing the temperature anomaly across different LULC change classes divided into four main classes namely no built-up changes (BB), no green spaces changes (GG), built-up to green spaces (BG), and green spaces to built-up (GB). The study revealed that the conversion of green spaces to built-up areas (GB) had the most significant impact on the increase in air temperature. This was indicated by the mean values of the temperature anomaly of GB of about 0.24°C followed by GG, BB, and BG with the mean values of the temperature anomaly of about 0.20°C, 0.19°C, 0.17°C, respectively. The different temperature anomalies of the LULC change classes indicate that green spaces have an important role in maintaining local climate. Hence, it is important for local government to effectively manage the composition, the quantity, as well as the distribution of green spaces within a city. By looking at temperature anomalies of LULC change classes, the present study provides an alternative approach to many existing methods that provide general information about temperature changes, without specifically analyzing the effects of LULC transformations.
Development of a hazard risk map for assessing pedestrian risk in urban flash floods
A case study in Cúcuta, Colombia
Journal article
(2024)
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Gerald Augusto Corzo Perez, Diego Ivan Sanchez Tapiero, Manuel Antonio Contreras Martínez, Chris Zevenbergen
The rapid growth of impervious areas in urban basins worldwide has increased the number of impermeable surfaces in cities, leading to severe flooding and significant economic losses for civilians. This trend highlights the urgent need for methodologies that assess flood hazards and specifically address the direct impact on pedestrians, which is often overlooked in traditional flood hazard analyses. This study aims to evaluate a methodology for assessing the risk to pedestrians from hydrodynamic forces during urban floods, with a specific focus on Cúcuta, Colombia. The methodology couples research outcomes from other studies on the impact of floodwaters on individuals of different ages and sizes with 1D/2D hydrological modeling. Advanced computational algorithms for image recognition were used to measure water levels at 5-s intervals on November 6, 2020, using drones for digital elevation model data collection. In Cúcuta, where flood risk is high and drainage infrastructure is limited, the PCSWMM (Computer-based Urban Stormwater Management Model) was calibrated and validated to simulate extreme flood events. The model incorporated urban infrastructure details and geomorphological parameters of Cúcuta's urban basin. Four return periods (5, 10, 50, 100), with extreme rainfall of 3 h, were used to estimate the variability of the risk map. The output of the model was analyzed, and an integrated and time-varying comparison of the results was done. Results show that the regions of high-water depth and high velocity could vary significantly along the duration of the different extreme events. Also, from 5 to 100 years return period, the percentage of area at risk increased from 9.6% to 16.6%. The pedestrian sensitivity appears much higher than the increase in velocities or water depth individually. This study identified medium to high-risk locations, which are dynamic in time. We can conclude dynamics are spatiotemporal, and the added information layer of pedestrians brings vulnerability information that is also dynamic. Areas of immediate concern in Cúcuta can enhance pedestrian safety during flash flood events. The spatiotemporal variation of patterns requires further studies to map trajectories and sequences that machine learning models could capture.
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The rapid growth of impervious areas in urban basins worldwide has increased the number of impermeable surfaces in cities, leading to severe flooding and significant economic losses for civilians. This trend highlights the urgent need for methodologies that assess flood hazards and specifically address the direct impact on pedestrians, which is often overlooked in traditional flood hazard analyses. This study aims to evaluate a methodology for assessing the risk to pedestrians from hydrodynamic forces during urban floods, with a specific focus on Cúcuta, Colombia. The methodology couples research outcomes from other studies on the impact of floodwaters on individuals of different ages and sizes with 1D/2D hydrological modeling. Advanced computational algorithms for image recognition were used to measure water levels at 5-s intervals on November 6, 2020, using drones for digital elevation model data collection. In Cúcuta, where flood risk is high and drainage infrastructure is limited, the PCSWMM (Computer-based Urban Stormwater Management Model) was calibrated and validated to simulate extreme flood events. The model incorporated urban infrastructure details and geomorphological parameters of Cúcuta's urban basin. Four return periods (5, 10, 50, 100), with extreme rainfall of 3 h, were used to estimate the variability of the risk map. The output of the model was analyzed, and an integrated and time-varying comparison of the results was done. Results show that the regions of high-water depth and high velocity could vary significantly along the duration of the different extreme events. Also, from 5 to 100 years return period, the percentage of area at risk increased from 9.6% to 16.6%. The pedestrian sensitivity appears much higher than the increase in velocities or water depth individually. This study identified medium to high-risk locations, which are dynamic in time. We can conclude dynamics are spatiotemporal, and the added information layer of pedestrians brings vulnerability information that is also dynamic. Areas of immediate concern in Cúcuta can enhance pedestrian safety during flash flood events. The spatiotemporal variation of patterns requires further studies to map trajectories and sequences that machine learning models could capture.
Changing Urban Temperature and Rainfall Patterns in Jakarta
A Comprehensive Historical Analysis
The increasing global population and in-country migration have a significant impact on global land use land cover (LULC) change, which reduces green spaces and increases built-up areas altering the near-surface radiation and energy budgets, as well as the hydrological cycle over an urban area. The LULC change can lead to a combination of hazards such as increasing urban temperatures and intensified rainfall, ultimately resulting in increased flooding. This present study aims to discuss the changing pattern in urban temperature, daily rainfall, and flooding in Jakarta. The daily urban temperature and daily rainfall were based on a 30-year dataset from three meteorological stations of Jakarta in the period between 1987 and 2013. The changing trend was analyzed by using the Mann–Kendall and the Pettitt’s tests. The relation between daily rainfall and flooding was analyzed using a 30-year flooding dataset collected from several sources including the international disaster database, research, and newspaper. The results show that there was an increasing trend in the daily temperature and the daily rainfall in Jakarta. The annual maximum daily temperature showed that an increasing trend started in 2001 at the KMY station, and in 1996 at the SHIA station. In general, the highest annual maximum daily temperature was about 37 °C, while the lowest was about 33 °C. Moreover, the maximum daily rainfall started increasing from 2001. An increase in the maximum daily rainfall was observed mainly in January and February, which coincided with the flood events recorded in these months in Jakarta. This indicates that Jakarta is not only vulnerable to high urban temperature but also to flooding. While these two hazards occur in distinct timeframes, there is potential for their convergence in the same geographical area. This study provides new and essential insights to enhance urban resilience and climate adaptation, advocating a holistic approach required to tackle these combined hazards.
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The increasing global population and in-country migration have a significant impact on global land use land cover (LULC) change, which reduces green spaces and increases built-up areas altering the near-surface radiation and energy budgets, as well as the hydrological cycle over an urban area. The LULC change can lead to a combination of hazards such as increasing urban temperatures and intensified rainfall, ultimately resulting in increased flooding. This present study aims to discuss the changing pattern in urban temperature, daily rainfall, and flooding in Jakarta. The daily urban temperature and daily rainfall were based on a 30-year dataset from three meteorological stations of Jakarta in the period between 1987 and 2013. The changing trend was analyzed by using the Mann–Kendall and the Pettitt’s tests. The relation between daily rainfall and flooding was analyzed using a 30-year flooding dataset collected from several sources including the international disaster database, research, and newspaper. The results show that there was an increasing trend in the daily temperature and the daily rainfall in Jakarta. The annual maximum daily temperature showed that an increasing trend started in 2001 at the KMY station, and in 1996 at the SHIA station. In general, the highest annual maximum daily temperature was about 37 °C, while the lowest was about 33 °C. Moreover, the maximum daily rainfall started increasing from 2001. An increase in the maximum daily rainfall was observed mainly in January and February, which coincided with the flood events recorded in these months in Jakarta. This indicates that Jakarta is not only vulnerable to high urban temperature but also to flooding. While these two hazards occur in distinct timeframes, there is potential for their convergence in the same geographical area. This study provides new and essential insights to enhance urban resilience and climate adaptation, advocating a holistic approach required to tackle these combined hazards.
Agriculture-dependent developing Southeast Asian countries need to assess residual pesticides in receiving water from agricultural runoff as one of the basis for the establishment of baseline data. Monitoring residual pesticides in surface water is challenging due to pesticides’ irregular/intermittent emission and low solubility in water. To address the challenge of pesticide assessment, passive samplers composed of silicon rubber sheets (SR) and speedisk (SD) were used to capture hydrophobic and hydrophilic organic pesticides and other organic pollutants, respectively. Samplers were submerged uninterruptedly for at least 30 days in three selected sites in Can Tho River, Mekong Delta, Vietnam, and Cagayan de Oro River Basin, Philippines, for 2 years. Passive samplers (SR spiked with 232 pesticides) captured 83 and 69 residual pesticides at concentrations of ng/L levels in Vietnam and the Philippines, respectively, which is unattainable through conventional grab sampling methods. Trace concentrations of banned compounds such as OCPs, PCBs, and PAHs were also detected at pg./L levels. The success of this alternative methodology can be attributed to the combination of passive samplers tailored for nonpolar (water-insoluble) and polar (water-soluble) organic contaminants coupled with sensitive analytical instruments, including GCMSMS and LCMSMS.
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Agriculture-dependent developing Southeast Asian countries need to assess residual pesticides in receiving water from agricultural runoff as one of the basis for the establishment of baseline data. Monitoring residual pesticides in surface water is challenging due to pesticides’ irregular/intermittent emission and low solubility in water. To address the challenge of pesticide assessment, passive samplers composed of silicon rubber sheets (SR) and speedisk (SD) were used to capture hydrophobic and hydrophilic organic pesticides and other organic pollutants, respectively. Samplers were submerged uninterruptedly for at least 30 days in three selected sites in Can Tho River, Mekong Delta, Vietnam, and Cagayan de Oro River Basin, Philippines, for 2 years. Passive samplers (SR spiked with 232 pesticides) captured 83 and 69 residual pesticides at concentrations of ng/L levels in Vietnam and the Philippines, respectively, which is unattainable through conventional grab sampling methods. Trace concentrations of banned compounds such as OCPs, PCBs, and PAHs were also detected at pg./L levels. The success of this alternative methodology can be attributed to the combination of passive samplers tailored for nonpolar (water-insoluble) and polar (water-soluble) organic contaminants coupled with sensitive analytical instruments, including GCMSMS and LCMSMS.
Journal article
(2024)
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Frans. H.M. van de Ven, Chris Zevenbergen, Mila Avellar Montezuma, Zihang Ding, William Veerbeek, Shiyang Chen
Urban water management is confronted with more frequent, more extreme weather events. This paper introduces the Three-Points Approach (3PA) into Sponge City concept, to create a novel framework aimed at guiding water management interventions across local, urban, regional, and river basin scales. The 3PA integrates three domains—Day-to-day, Design, and Extreme —offering a nuanced strategy for flood and drought risk mitigation, also for extreme events. Notably, the 3PA emphasizes the fusion of blue-green infrastructure (BGI) with conventional gray approaches to enhance both multifunctionality and resilience in extreme weather conditions. The study identifies critical issues of implementing this Three-Points Sponge Policy (3PSP) approach, including spatial and temporal scales, transitioning from gray to blue-green infrastructure, asset management, data handling, and effective communication. Interventions spanning various spatial scales and addressing flood protection, drought resilience, and water quality are explored in a first and indicative application in Zhengzhou. The case study distills key design principles, highlighting the imperative of never shifting problems, embracing ecosystem-based adaptation, seeking synergy between interventions, and incorporating adaptability into designs. The 3PSP approach emerges as a holistic framework that considers both risks and benefits, contributing valuable insights to the discourse on integrating urban and river basin water management, improving our ways of dealing with extreme weather events while maximizing the day-to-day benefits of our interventions.
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Urban water management is confronted with more frequent, more extreme weather events. This paper introduces the Three-Points Approach (3PA) into Sponge City concept, to create a novel framework aimed at guiding water management interventions across local, urban, regional, and river basin scales. The 3PA integrates three domains—Day-to-day, Design, and Extreme —offering a nuanced strategy for flood and drought risk mitigation, also for extreme events. Notably, the 3PA emphasizes the fusion of blue-green infrastructure (BGI) with conventional gray approaches to enhance both multifunctionality and resilience in extreme weather conditions. The study identifies critical issues of implementing this Three-Points Sponge Policy (3PSP) approach, including spatial and temporal scales, transitioning from gray to blue-green infrastructure, asset management, data handling, and effective communication. Interventions spanning various spatial scales and addressing flood protection, drought resilience, and water quality are explored in a first and indicative application in Zhengzhou. The case study distills key design principles, highlighting the imperative of never shifting problems, embracing ecosystem-based adaptation, seeking synergy between interventions, and incorporating adaptability into designs. The 3PSP approach emerges as a holistic framework that considers both risks and benefits, contributing valuable insights to the discourse on integrating urban and river basin water management, improving our ways of dealing with extreme weather events while maximizing the day-to-day benefits of our interventions.
Journal article
(2024)
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Taiane Regina Hoepers, Juliana Leithold, Michel Marques Monteiro, Gerald A. Corzo Perez, Cristovão V. Scapulatempo Fernandes, Chris Zevenbergen, Daniel Costa dos Santos
In response to pressing global challenges like climate change, rapid population growth, and an urgent need for sustainable infrastructure, cities face an immediate and crucial necessity to transition swiftly toward an integrated approach to managing urban water resources. This shift is not merely an option but an imperative, driven by the rapidly evolving urban landscape. In addressing this imperative, a crucial decision support tool that has emerged as an asset in the domain of urban water planning and management is the Urban Water Use (UWU) tool. This tool offers an integrated approach for strategic planning, promoting urban water conservation and environmental health through the investigation of interventions in urban infrastructure under different scenarios. In this study, the latest version of this UWU tool was deployed in a case study conducted in Almirante Tamandaré, Brazil. The objective was to evaluate how an integrated decision-making approach concerning urban water systems influences the efficiency and effectiveness of interventions, ultimately contributing to achieve widespread adoption, accessibility, and relevance of urban water services. The refined UWU tool evaluates a spectrum of measures across diverse scenarios, incorporating various drivers, focusing on the stakeholders' visions for the locality. These visions are composed of sustainability indicators, specifying different sets of target values and importance weights for each indicator. The approach followed in this study demonstrates how the effectiveness indexes can vary based on stakeholders' perception. Measures under Water Sensitive Urban Design and Water Demand Management strategies were deployed to simulate the response of urban water systems under three distinct scenarios, embracing the complexities of social dynamics and of climate change. The findings of the study emphasize that realizing a desired vision through selected measures relies significantly on the adoption of an integrated approach within the decision-making process. The stakeholders' perception of how indicators should be weighted while defining the vision was found to significantly impact the effectiveness range of these measures.
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In response to pressing global challenges like climate change, rapid population growth, and an urgent need for sustainable infrastructure, cities face an immediate and crucial necessity to transition swiftly toward an integrated approach to managing urban water resources. This shift is not merely an option but an imperative, driven by the rapidly evolving urban landscape. In addressing this imperative, a crucial decision support tool that has emerged as an asset in the domain of urban water planning and management is the Urban Water Use (UWU) tool. This tool offers an integrated approach for strategic planning, promoting urban water conservation and environmental health through the investigation of interventions in urban infrastructure under different scenarios. In this study, the latest version of this UWU tool was deployed in a case study conducted in Almirante Tamandaré, Brazil. The objective was to evaluate how an integrated decision-making approach concerning urban water systems influences the efficiency and effectiveness of interventions, ultimately contributing to achieve widespread adoption, accessibility, and relevance of urban water services. The refined UWU tool evaluates a spectrum of measures across diverse scenarios, incorporating various drivers, focusing on the stakeholders' visions for the locality. These visions are composed of sustainability indicators, specifying different sets of target values and importance weights for each indicator. The approach followed in this study demonstrates how the effectiveness indexes can vary based on stakeholders' perception. Measures under Water Sensitive Urban Design and Water Demand Management strategies were deployed to simulate the response of urban water systems under three distinct scenarios, embracing the complexities of social dynamics and of climate change. The findings of the study emphasize that realizing a desired vision through selected measures relies significantly on the adoption of an integrated approach within the decision-making process. The stakeholders' perception of how indicators should be weighted while defining the vision was found to significantly impact the effectiveness range of these measures.
Book chapter
(2023)
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Trikurnianti Yanti Kusumanto, Gusti Ayu Ketut Surtiari, Chris Zevenbergen, Annisa Triyanti, D. Ary A. Samsura, Tristam Pascal Moeliono, Yus Budiyono
This chapter assesses ACM’s potential as a pathway to address the flooding problem of Greater Jakarta, significantly exacerbated by land subsidence and climate change. It is based on a thought experiment by the authors to envision application of this approach to the problem and is not the result of empirical work. A background of Jakarta’s flooding is first provided and subsequently its framing as a ‘wicked problem’. Results of the thought experiment are then discussed, focusing on three questions: (i) Can ACM be applied, given Jakarta’s flooding governance structure? (ii) Will ACM’s social learning work for the flooding problem? And (iii) if ACM were applicable to Jakarta’s case, what operational indicators would apply? The chapter concludes with recommending a two-step ACM pathway: (1) adjusting the current flooding governance structure, for which leadership is needed with a long-term vision and the application of adaptive governance at the river basin scale; (2) shaping the enabling conditions for learning that stimulate creativity in and discovery of new problem framings and solutions outside the policy system. While the authors recognise the considerable challenges when applying ACM to the flooding of Greater Jakarta, the crisis stage it has reached necessitates adaptation approaches that can break the cycle of narrow, longstanding paradigms, policy beliefs, and maladaptive pathways..
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This chapter assesses ACM’s potential as a pathway to address the flooding problem of Greater Jakarta, significantly exacerbated by land subsidence and climate change. It is based on a thought experiment by the authors to envision application of this approach to the problem and is not the result of empirical work. A background of Jakarta’s flooding is first provided and subsequently its framing as a ‘wicked problem’. Results of the thought experiment are then discussed, focusing on three questions: (i) Can ACM be applied, given Jakarta’s flooding governance structure? (ii) Will ACM’s social learning work for the flooding problem? And (iii) if ACM were applicable to Jakarta’s case, what operational indicators would apply? The chapter concludes with recommending a two-step ACM pathway: (1) adjusting the current flooding governance structure, for which leadership is needed with a long-term vision and the application of adaptive governance at the river basin scale; (2) shaping the enabling conditions for learning that stimulate creativity in and discovery of new problem framings and solutions outside the policy system. While the authors recognise the considerable challenges when applying ACM to the flooding of Greater Jakarta, the crisis stage it has reached necessitates adaptation approaches that can break the cycle of narrow, longstanding paradigms, policy beliefs, and maladaptive pathways..
Time-varying characteristics of saturated hydraulic conductivity in grassed swales based on the ensemble Kalman filter algorithm
A case study of two long-running swales in Netherlands
Journal article
(2023)
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Feikai Yang, Dafang Fu, Chris Zevenbergen, Floris C. Boogaard, Rajendra Prasad Singh
Saturated hydraulic conductivity (Ks) of the filler layer in grassed swales are varying in the changing environment. In most of the hydrological models, Ks is assumed as constant or decrease with a clogging factor. However, the Ks measured on site cannot be the input of the hydrological model directly. Therefore, in this study, an Ensemble Kalman Filter (EnKF) based approach was carried out to estimate the Ks of the whole systems in two monitored grassed swales at Enschede and Utrecht, the Netherlands. The relationship between Ks and possible influencing factors (antecedent dry period, temperature, rainfall, rainfall duration, total rainfall and seasonal factors) were studied and a Multivariate nonlinear function was established to optimize the hydrological model. The results revealed that the EnKF method was satisfying in the Ks estimation, which showed a notable decrease after long-term operation, but revealed a recovery in summer and winter. After the addition of Multivariate nonlinear function of the Ks into hydrological model, 63.8% of the predicted results were optimized among the validation events, and compared with constant Ks. A sensitivity analysis revealed that the effect of each influencing factors on the Ks varies depending on the type of grassed swale. However, these findings require further investigation and data support.
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Saturated hydraulic conductivity (Ks) of the filler layer in grassed swales are varying in the changing environment. In most of the hydrological models, Ks is assumed as constant or decrease with a clogging factor. However, the Ks measured on site cannot be the input of the hydrological model directly. Therefore, in this study, an Ensemble Kalman Filter (EnKF) based approach was carried out to estimate the Ks of the whole systems in two monitored grassed swales at Enschede and Utrecht, the Netherlands. The relationship between Ks and possible influencing factors (antecedent dry period, temperature, rainfall, rainfall duration, total rainfall and seasonal factors) were studied and a Multivariate nonlinear function was established to optimize the hydrological model. The results revealed that the EnKF method was satisfying in the Ks estimation, which showed a notable decrease after long-term operation, but revealed a recovery in summer and winter. After the addition of Multivariate nonlinear function of the Ks into hydrological model, 63.8% of the predicted results were optimized among the validation events, and compared with constant Ks. A sensitivity analysis revealed that the effect of each influencing factors on the Ks varies depending on the type of grassed swale. However, these findings require further investigation and data support.