Global lead on urban resilience / urban water management expert / hydrologist
+31613181630Hans.Gehrels@deltares.nl LinkedIn profile
Hans Gehrels holds a PhD in hydrology and is a thought leader on sustainable water management and urban resilience. His main fields of expertise include urban water management, flood risk, climate adaptation and water sensitive urban design. Within Deltares, he is manager of the corporate team on Urban Resilience.
In the Netherlands, Gehrels’ work focuses on initiating and developing research programs addressing water and climate adaptation challenges for the Dutch Ministry of Infrastructure and Water Management (Delta Program on Spatial Adaptation). He is program director of the Climate Resilient Cities Research Track within the Dutch National Water and Climate Knowledge and Innovation Program. Gehrels is a member of several research program commissions to coordinate research funding. Gehrels is part of the Water&Urban program team of the Global Center on Adaptation.
Abroad, Dr. Gehrels has work experience in The Netherlands, Botswana, Canada, Costa Rica, India, Lao PDR, Mexico, Philippines, Puerto Rico, Singapore, South Africa, Sri Lanka, USA, Uzbekistan and Viet Nam. Gehrels is Deltares’ project director of a framework agreement partnership with the World Bank on urban flood risk assessments in the World Bank’s City Resilience Program. He has recently worked as a team leader in projects on urban resilience in New York, Chennai and Mexico City, and in World Bank projects on flood risk management in Vientiane, Colombo, Manila and Ho Chi Minh City. Gehrels is member of the Board of Directors of the EU branch of the Resilient Cities Network. Together with this global network of cities, Deltares has been involved in building resilience in Bangkok, Cape Town, Chennai, Christchurch, Mexico City, Milan, Montevideo, New Orleans, Rotterdam, San Juan, Semarang, Surat, The Hague, Toronto, Vancouver and Washington DC.
Gehrels has experience as a researcher, as a manager and as a strategic advisor for multiple stakeholders. He worked as a researcher at TNO Institute of Applied Geosciences and held the position of assistant professor at Delft University of Technology, focusing on stochastic hydrology and geohydrology. Gehrels has been the general manager of several urban water management departments at TNO and Deltares, being responsible for project management, financial results and human resources. As a strategic advisor, he supports both the Dutch Government in water and climate adaptation knowledge program development and cities in complex projects aiming at improving urban water and climate resilience. Gehrels (co-)authored several publications for international peer-reviewed journals, dealing with flood risk management, surface water and groundwater modelling, time series analysis, unsaturated zone hydrology and aquifer heterogeneity.
|2012- present||Deltares||Corporate team manager Urban Resilience / urban water management expert / hydrologist|
|2009 – 2012||Deltares||Head of the department of Urban Water and Subsurface and member of the Soil and Groundwater Systems management team|
|2008 – 2009||Deltares||Head of the department of Geo-infrastructure and member of the Soil and Groundwater Systems management team|
|2006 – 2007||TNO||Head of the department of Geo-infrastructure and Observation and member of Soil and Groundwater management team|
|1996 – 2005||TNO||Researcher/consultant - National Geological Survey, Groundwater Department|
|2000 – 2004||Delft University of Technology, Faculty of Civil Engineering and Geosciences, Department of Water Management||Assistant professor|
|1994 – 1996||Delft University of Technology, Faculty of Civil Engineering and Geosciences, Department of Water Management||Research fellow|
|1990 – 1994||The Vrije Universiteit Amsterdam, Faculty of Earth Sciences, Department of Hydrology and Quaternary Geology||Ph.D. student|
Climate Resilient Cities - National Water and Climate Knowledge and Innovation Programme
Netherlands, 2017 - present
Ministry of Infrastructure and Water Management; STOWA; RIONED; Municipalities, Program Director
Climate Resilient Cities is the national research track supporting the Dutch Delta Program on Spatial Adaptation. The programme addresses the consequences of pluvial flooding, heat stress, drought and water scarcity in Dutch cities, as part of the National Water and Climate Knowledge and Innovation Programme (NKWK). This research program is executed by a consortium of 20+ Dutch research institutes and engineering consultants with several new work packages being initiated each year. The central research question is how to accomplish that cities become climate-proof and water-robust. The emphasis is on developing, sharing and disseminating knowledge in several work packages addressing specific topics and challenges, such as assessing climate damage and risks; selecting and implementing nature-based (blue-green-grey) interventions and quantifying their impact and co-benefits; guidelines on climate proofing critical infrastructure; building regulations that connect climate adaptation and the energy transition; recommendations for connecting climate adaptation and social resilience.
Overall management of the consortium, project coordination, scientific program development, institutional stakeholder engagement and client consultation, development of work packages, initiating workshops and events.
Framework Agreement for Urban Flood Risk Assessments
Africa, Asia, Latin America, Europe, 2021 - present
World Bank Group, Project Director
Burundi, Mozambique, Niger, Senegal, Serbia
Deltares and the World Bank Group started a partnership called the Framework Agreement for Urban Flood Risk Assessments, to support the World Bank's City Resilience Program. In this partnership Deltares is conducting flood risk management studies around the world to support cities in becoming flood resilient. Activities range from data services and spatial analysis, hydrological and hydraulic modeling, hazards and risks assessment, cost-benefit analysis, future scenarios and mitigation strategies, stakeholder engagement, to knowledge transfer and dissemination.
Strategic advice, program management and coordination with the World Bank and stakeholders, formulation of terms of reference for and supervision of climate risk studies.
Baseline Study on Integrated Urban Flood Risk Management for Vientiane and Pakxan Cities, Lao PDR
Lao People's Democratic Republic, 2021 – present
World Bank Group, Team Leader
The main objective of this Consulting Assignment is to develop a baseline overview of existing data and information on urban flood risk management at city level for the cities Vientiane and Pakxan. The assignment collects all relevant data and information from local sources and complement it with global data where necessary. Based on the available data, a preliminary Flood Risk Analysis is conducted to identify Areas of Potential Significant Flood Risk in the two cities. Through this analysis, critical data and knowledge gaps are identified. All obtained data and information is consolidated for future use.
Development of a methodological framework for flood risk assessment, hydrological and hydrodynamic modelling, capacity building, project management
Global Commission on Adaptation (GCA) - Cities Action Track Support
Netherlands, 2020 – present
Global Center on Adaptation, Strategic Advisor
Gehrels works with GCA's Water&Urban Program Team in the framework of the strategic partnership between GCA and Deltares. The goal of this program is: to support national governments and urban authorities to accelerate and scale urban climate adaptation plans. The Water&Urban team works on the '1000 Cities Adapt Now' program to support cities in including climate resilience as an integral part of their urban planning. The activities focus on ‘knowledge in implementation’ through the development of scalable methods and tools, using knowledge and data from the public domain.
Strategic advice, mapping of climate risks of African cities, development of a methodological framework for climate resilience assessment, formulation of Terms of Reference for and supervision of climate risk studies.
Developing the World Water Atlas
Netherlands, 2020 – present
Ministry of Infrastructure and Water Management, Team Leader
The World Water Atlas (WWA) (www.worldwateratlas.org) is a platform where countries exchange practical examples and lessons learned for dealing with water-related disasters and translating them into solutions. The WWA provides local and international decision-makers, governments, companies and citizens worldwide with tools to tackle water issues. The atlas collects, links, discloses and disseminates knowledge, data, best practices and inspiring local initiatives. Founding Partners: Netherlands Ministry of Infrastructure and Water Management, Deltares, International Architecture Biennale Rotterdam, Netherlands Environmental Assessment Agency.
Overall project coordination, expert advice, vision on development and use, review of content.
A Water as Leverage approach for the Namami Clean Ganga project
Netherlands, 2021 - 2021
Partners for Water Program, Netherlands Enterprise Agency (RVO), Expert advisor
The Joint Working Group between India and the Netherlands requested to conduct a study investigating the possibilities of implementing the Water as Leverage (WaL) approach in 100 cities in the Ganga Basin, India. This study aimed at understanding the risks, vulnerabilities, interdependencies of the urban areas along the basin under climate change. The study also investigated existing capacities for implementing the NMCG in the Ganga Basin and identified urban typologies to select cities suitable for a WaL approach along the Ganga River.
Provinding advice on system analysis, hydrology, risk assessment; developing an approach for investigating large numbers of cities; engaging with counterparts and stakeholders.
NYC Manhattan Financial District and Seaport Climate Resilience Master Plan
USA, 2019 – 2020
New York City Economic Development Corporation (NYCEDC), Project Manager and Flood Risk Expert
The Financial District and Seaport Climate Resilience Master Plan is a shared vision responding to the increasing hazards posed by climate change, while transforming the waterfront to better serve all New Yorkers for generations to come. Objective of the assignment for the Arcadis US-led consortium was to develop the design of a shoreline extension and the integration of transportation and interior drainage infrastructure to support the shoreline extension. This included a preliminary design, detailed implementation plans and a pathway to implementation. Deltares' role was to review the first conceptual designs of the envisioned redevelopment of the Manhattan south side. The purpose of the redevelopment is to minimize flood risk to the Financial District and South Street Seaport neighborhoods resulting from daily tidal flooding, coastal storms, and changing precipitation under current and future conditions due to sea level rise. The review focused on affirming or questioning the selection of alignment for the flood protection in the project area from the perspectives of: flood risk, hydrodynamics, scour, ecology, water quality, climate adaptation planning, green infra alternatives.
My role as a team leader focused on strategic advice, critical review of general practice in Manhattan and abroad, formulating recommendations.
NYC East Side Coastal Resiliency Project Review
USA, 2019 – 2019
New York City Manhattan Borough President’s Office, Independent Advisor
The East Side Coastal Resiliency (ESCR) Project is a $1.4 billion coastal protection initiative, jointly funded by the City of New York and the federal government, aimed at reducing flood risk due to coastal storms and sea level rise on Manhattan's East Side from East 25th Street to Montgomery Street. The project design integrates flood protection into the community fabric, improving waterfront open spaces and access. At the request of the NYC Manhattan Burrough President, Gehrels was requested as an external expert to conduct a review of the concerns surrounding the ESCR project. The New York City Council Newsletter reported on November 12, 2019, that the review report has been critical in reaching agreement between Council Members Chin, Powers and Rivera with Mayor Bill de Blasio on a wide range of community investments and commitmments tied to the construction of the East Side Coastal Resiliency Project .
Interviews were held with representatives of residents, interest groups, community boards, and government officials from the City, State and Federal level. The project proposal was discussed with representatives from the Mayor’s Office, the NYC Department of Design and Construction, NYC Parks, Manhattan Borough President’s Office, and several third-party entities. The input from the stakeholder interviews, the perspective of the City and the project documentation were combined in an analysis of the concerns surrounding this project relative to the principal objectives stated for the ESCR Project’s design. Recommendations were formulated for improvement of the ESCR project implementation.
A Resilience Plan for Xochimilco, Mexico City
Mexico, 2018 - 2020
The Rockefeller Foundation Philanthropy Advisors, Project Director
Xochimilco is part of the UNESCO World Heritage Zone in Mexico City. The area suffers from environmental deterioration caused by uncontrolled growth of urban settlements, water pollution and the disappearance of traditional agricultural practice. The general objective of the project was to contribute to the recovery of the hydrological system and the restoration of the Heritage Zone, in order to become resilient to climate change, geological (earthquake and subsidence) risks, socio-economic and environmental issues. A vision for the Heritage Zone was developed integrating resilience, taking water as a main axis to develop the area. A hydrological analysis was undertaken based on groundwater modelling of Mexico Valley and hydraulic modelling of the Xochimilco area. A Water Resilience Plan was developed defining the strategic actions to protect and restore the Heritage Zone’s hydrological system, as part of Mexico City’s Resilience Strategy.
Overall project coordination, hydrological analysis, vision development, stakeholder engagement, leading and presentation in participatory workshops, formulation of conceptual project proposals.
2D Urban Flood Modelling for Washington D.C.
United States, 2018 - 2019
City of Washington D.C., Flood Risk Expert
In order to become more water resilient, Washington D.C. needs to assess and mitigate the risks of periodic flooding from rainfall. In this project a 2D urban model was developed capturing flooding from rainfall and identifying high-risk areas within the District. In addition, a roadmap was formulated for the future development of an integrated model suite to determine the integrated risks from rainfall, river and coastal hazards. The developed 2D model forms the start of this integrated approach.
Risk assessment, stakeholder consultation, drafting of a roadmap, strategic advice on the future development of an integrated modelling framework.
Livable Urban Waterways for Cape Town
South Africa, 2018 - 2020
City of Cape Town, Urban Resilience Expert
This project initiative was developed by Deltares, University of Cape Town, Umvoto, FABRICations and the City of Cape Town during the 100 Resilient Cities CoLab “Building a Water Resilient City” in Cape Town (September 2018). The LUW-concept aims to integrate technical and community knowledge for the co-design of blue-green infrastructure and urban river rehabilitation projects in Cape Town. The team developed the concept further during the ‘CoCreateMyCity’ event organized by the Dutch Consulate in Cape Town (November 2019). The concept has been implemented in the Resilience Strategy and Water Strategy of Cape Town.
Engagement with institutional stakeholders, co-development of the conceptual idea, advice on implementation.
Water as Leverage: Rise Chennai | Rising Waters, Raising Futures
India, 2018 - present
Netherlands Enterprise Agency (RVO), Project Director
Chennai is a modern metropolis facing enormous environmental and social challenges related to urban growth, water management and climate change. In this project, a process of design and engineering was developed with active citizen engagement in order to improve the resilience of the water system, the city and the citizens. We created a chain of proposals for implementable projects needed for transformative change of the city. In this process the water system was taken as the vehicle to improve social welfare and the environment. The project resulted in a comprehensive vision on urban resilience for Chennai, and a set of scalable, replicable and bankable project proposals in line with this vision.
Overall project coordination, vision development, stakeholder engagement, leading and presentation in participatory workshops, hydrological analysis.
Urban Resilience Strategy for Tashkent City, Uzbekistan
Uzbekistan, 2018 - present
The World Bank Group, Flood Risk Expert
Tashkent is prone to natural hazards and associated shocks and stresses, for which there is currently no comprehensive management strategy in place. Flooding poses a significant risk to the city due to regular compounding disruption to the functioning of the city. In this project ARUP and Deltares provide integrated technical support in strengthening urban resilience by assessing multi-hazards; working with authorities to integrate climate and disaster risk information in planning and city development; designing resilient infrastructure and services; and delivering technical advice across the entire range of the built environment.
Hydrological analysis, assessment of flood risk, stakeholder engagement, participation and presentation in workshops.
Toronto Roadmap for Urban Flood Resilience
Canada, 2018 - 2018
City of Toronto, Flood Risk Expert
This engagement has resulted in the collaborative production of a Roadmap for Urban Flood Resilience, offering the framework for a detailed set of actions for the city of Toronto. The Roadmap for Urban Flood Resilience is an instrumental part of Toronto’s Resilience Strategy, aiming to lay out the necessary steps to be taken to address and increase urban flood resilience.
Engagement with institutional stakeholders, drafting of a roadmap, participation and presentation in workshops, strategic advice on flood risk-informed governance and implementation.
Master Plan for a water-sensitive Curridabat, Costa Rica
Costa Rica, 2017 - 2020
Municipalidad de Curridabat; Tropcial Science Center, Team leader and Expert Advisor
Curridabat, a suburb of Costa Rica's capital San José, is a city with an abundant system of natural rivers tightly squeezed within the urban fabric - making the city susceptible to flooding. The city aims to introduce river management in public policy as part of biodiversity restoration and urban nature development. Objective of the project was to contribute to the development of a master plan on urban water management. Elements of particular importance were the river that connects the city with other cities in the same river basin, the biodiversity, a sustainable water infrastructure, and social cohesion. Hydrological and hydraulic models were deployed to model flooding from rainfall and river discharge. The most acute problems were then identified and recommendations were formulated for the city’s master plan. The outcomes of the model calculations were validated during field trips. As a result, urban water management is tailored more closely to the city’s biodiversity ambitions.
Project management, hydrological analysis, leading and presentation in participatory workshops, identification and evaluation of interventions.
Strengthening Disaster Risk Management and Urban Flood Resilience in Lao PDR
Lao People's Democratic Republic, 2017 - 2018
The World Bank Group, Team Leader and Expert Advisor
Lao PDR is regularly impacted by flooding which causes widespread damage to infrastructure and impacts livelihoods. The current project provided technical support on flood risk management and water sensitive urban design in Muang Xay City in the Oudomxay Province. Investments proposed by the government were critically assessed, looking at disaster risk, benefit-cost analysis, social and environmental impact, and urban planning and design. Recommendations were formulated for the development of a strategic integrated urban design and flood risk management plan, and on the prioritization of anticipated investments to reduce flood risk and improve urban planning. The results showed that flood risk in Muang Xay can almost completely be reduced to zero.
Overall project coordination, flood risk assessment, leading and presentation in participatory workshops, identification and evaluation of interventions.
San Juan Resiliente - Shoreline Communities Resilience Program
Puerto Rico, 2017 - 2017
City of San Juan, Urban Resilience Expert
This engagement with the City of San Juan and the 100 Resilient Cities Network supported measurable improvements on coastal communities in San Juan, by addressing three main resilience needs: (1) flood risk exposure, (2) vulnerabilities related to blight and underutilized community spaces and (3) limitations in autonomous adaptive capacity through access to resources and decision-making tools. Exposure to flooding was analysed with a 2D flood model for the neighbourhoods in the city where communities are vulnerable to inundations caused by extreme storm events and high-water levels in the lagoon. Results were presented in a workshop attended by members of the community, water agencies, people from the municipality of San Juan, professors and students of the University of Puerto Rico.
Flood risk assessment, community and institutional engagement, leading and presentation in participatory workshops, identification and evaluation of interventions.
A Resilient Water System for Xochimilco, Mexico City
Mexico, 2016 - 2017
SEDEMA - Secretaría del Medio Ambiente de la CDMX, Team Leader and Expert advisor
Xochimilco is a UNESCO World Cultural and Environmental Heritage Site in Mexico City suffering from high environmental degradation and increasing urban expansion with informal settlements.
Objective of the project was to support the City in protecting and restoring the water system of Xochimilco in such a way that it can cope with environmental, climatic and socio-economic changes. The project focused on analysis and modelling of the water system of Xochimilco and resulted in a Water Resilience Strategy for the water system of Xochimilco as part of Mexico City.
Project coordination, hydrological analysis, formulation of urban water management strategies, leading and presentation in participatory workshops.
Detailed Flood Risk Assessment for the Colombo Metropolitan Region
Sri Lanka, 2016 - 2017
Metro Colombo Urban Development Project; Ministry of Megapolis and Western Development, Team leader and Expert Advisor
Metro Colombo is highly vulnerable to flooding and has experienced regular floods over the past 30 years, affecting a large number of people annually. The overall objective of the project was to carry out an assessment of the flood risk in the Colombo metropolitan region and to formulate a strategy to mitigate the flood risk. The results were input for the long-term flood mitigation strategy and action plan for Metro Colombo which is implemented by the government to minimize the impacts of future flooding.
Overall project coordination, hydrological and flood risk analysis, leading and presentation in participatory workshops.
Towards a Water Sensitive Public Space in Mexico City
Mexico, 2016 - 2016
Public Space Authority of Mexico City (Autoridad del Espacio Público; AEP), Urban Resilience Expert
The Public Space Authority of Mexico City recognizes periodic pluvial flooding and water scarcity as the most pressing urban vulnerabilities in Mexico City. The goal of the project was to investigate how to tackle this paradox through the use and design of vibrant public space. The project developed generic proposals for implementing blue and green infrastructure in various districts of the city, by combining quality of public space, problem solving water management strategies and creating socially sustainable places in the urban public realm. The project resulted in a strategy for a water sensitive public space in Mexico City.
Hydrological analysis, formulation of urban water management strategies, co-design of blue and green interventions, leading and presentation in participatory workshops.
Strengthening infrastructural and non-structural investments for flood risk management in Ho Chi Minh City (Viet Nam)
Viet Nam, 2014 - 2015
The World Bank Group, Team Leader and Expert Advisor
At the request of the World Bank a review was conducted of a series existing feasibility studies for structural investments in waterworks (canals, sluices, ship locks, urban drainage systems) to protect Ho Chi Minh City against flooding. Proposals for strengthening the investments were made. A roadmap was formulated for non-structural investments and institutional arrangements for further developing integrated flood risk management. The roadmap for institutional strengthening focused on organizational, legal, technical and financial topics. The roadmap for non-structural investments addressed the hydromet observation networks and forecasting; flood risk information management system; early warning and flood emergency response; and risk sensitive spatial planning.
Project coordination, hydrological analysis, review of feasibility studies, formulation of a roadmap.
Adaptive Circular Cities
Netherlands, 2014 - 2015
Ministry of Economic Affairs, Research Program Leader
The objective of this research program funded by the Dutch Ministry of Economic Affairs was to contribute to a breakthrough in cross-sectoral decisions on investing in concepts that lead to both climate adaptation, climate mitigation and resource efficiency in urban regions. The focus was on case studies in the cities of Utrecht, Amsterdam, Almere and Rotterdam. In Utrecht, design principles were defined for the planning of blue and green infrastructure in the city to ensure that water and green areas make the maximum contribution to environmental factors such as air quality, water and temperature regulation, and water quality. The consortium consisted of Deltares, Wageningen UR, TNO and ECN.
Overall program coordination, institutional stakeholder engagement, formulation of design principles.
Urban flood modelling for the Metro Manila region, the Philippines
Philippines, 2014 - 2015
The World Bank Group, Team Leader and Expert Advisor
In the Metro Manila region, the Philippines, flooding is a recurring problem. Objective of this World Bank funded project was to strengthen the capabilities of the Department of Public Works and Highways (DPWH) in analysing, modelling and visualising flood events in the Lower Marikina and Pasig River Basins and to support its decision-making capacities in urban flood prevention with the use of new tools. To this end, a flood simulation model was developed with the software code 3Di for the Lower Marikina-Pasig basin to demonstrate the use of flood modelling technologies in supporting flood risk management. Professionals from Manila government agencies were trained in a workshop that focused on using the model for assessing flood hazard and identifying mitigating measures.
Project coordination, institutional stakeholder engagement, hydrological analysis, leading and presentation in training workshops.
Southeast Florida Resilient Redesign
United States, 2014 - 2014
Southeast Florida Regional Compact on Climate Change, Urban Resilience Expert
The objective of this engagement with the Southeast Florida Regional Compact on Climate Change was to develop resilient design strategies for the urban environment of southeast Florida with emphasis on adaptation to sea level rise, integration of natural infrastructure, and the development of transferable models relevant to development and redevelopment opportunities throughout the region. This resulted in preliminary water resilient designs for specific locations in Miami Beach, Miami Dade and Miami.
Co-design of blue and green interventions in participatory workshops.
Preliminary flood modelling of Fort Lauderdale with 3Di water management
United States, 2013 - 2013
City of Fort Lauderdale, Flood Risk Expert
The objective of the project was to demonstrate the capabilities of the software code 3Di and to simulate urban flooding as a result of tidal inundation and excess precipitation. Results were presented at the South East Florida Climate Leadership Summit. Partners: Deltares, Nelen & Schuurmans.
Project management, institutional stakeholder engagement, hydrological analysis, conference presentation.
Exploring groundwater resources on Jurong Island, Singapore
Singapore, 2012 - 2012
Public Utilities Board, Expert Advisor
The objective of the project was to assess the groundwater resources of Jurong Island as a first step towards utilizing Singapore’s full groundwater potential. Partners: National University of Singapore, Deltares, TriTech.
Project management, hydrological analysis, pumping test analyses, groundwater resources assessment.
How to keep the NYC Jamaica Bay area safe and resilient
United States, 2012 - 2012
Henry Hudson 500 Foundation, Urban Resilience Expert
The objective of the project was to develop approaches and methodologies that help formulate a vision and strategy for Jamaica Bay that connect to the goals of PlaNYC 'A Stronger, More Resilient New York'. Partners in the NYC Jamaica Bay Strategy Team were: Waggonner & Ball, Fugro, RPA, Deltares, Nelen & Schuurmans, Pratt Institute, Arcadis USA, Rebel Group, Perkins Eastman, Provincie Noord Holland.
Co-design of blue and green interventions in a participatory workshop, hydrological analysis, conference presentation.
EU INTERREG IVB North-West Europe project ‘CityChlor’
Netherlands, 2011 - 2013
City of Utrecht, Think Tank Member
The objective of the research program was to develop an integrated approach to tackle the threats caused by contamination with chlorinated solvents in urban areas. One of the European case studies was conducted in the city centre of Utrecht, where Aquifer Thermal energy storage (ATES) is employed as a decontamination technique (i.e. a "Bio-washing Machine"). The study resulted in a better understanding and quantification of the effectiveness of the technology. Partners: Deltares, Wageningen UR, Bioclear.
Review of technical reports, providing expert advice, formulation of recommendations.
Strategic research program on Urban flooding and Water supply
Netherlands, 2010 - 2013
Ministry of Economic Affairs, Knowledge for Climate Programme, Rioned, STOWA, Project Leader and Expert Advisor
Objectives of the research program were to develop (i) a research portfolio of multiple projects focusing on the impact of climate change on urban water systems and water management, and (ii) tools and measures to counteract urban flooding and to improve water supply.
Program coordination, stakeholder engagement, review of technical reports, providing expert advice, formulation of recommendations.
Aquifer Thermal Energy Storage Opportunities in the Netherlands
Netherlands, 2008 - 2012
35 organizations from government and industry, Program Director and Technical Steering Committee Board member
Aquifer Thermal Energy Storage (ATES) is a technology that is widely used for the sustainable heating and cooling of buildings in the Netherlands. Its application is actively encouraged by the Dutch government to achieve CO2 emission targets, but there are still several uncertainties related to the effects of the technology on the subsurface. This four-year research program ("Meer Met Bodemenergie") has been a unique cooperation of public and private parties, assessing the impact of ATES on soil and groundwater quality (hydrological, thermal, microbiological and chemical effects) and addressing questions such as whether or not the subsurface is capable of coping with the increasing pressure of the growing numbers of ATES systems. Partners: Deltares, IF Technology, Bioclear, Wageningen University.
Overall project coordination, strategic discussion with Steering Committee, initiation of work packages, review of technical reports, providing expert advice, formulation of recommendations.
Emergency water management and crisis consulting services
Netherlands, 2008 - 2017
Ministry of Infrastructure and Water Management (Rijkswaterstaat), Core Team Member
In the event of a major emergency or incident in the Netherlands, Deltares must be able to provide expert advisory services to Rijkswaterstaat Crisis Teams as and when required. A Core team member is on line available and, in the occasion of an emergency, responsible for setting up a project team and managing the process leading to an expert advice within the smallest amount of time (hours to days). Typical emergencies that may arise, for which trainings were repeatedly held, are massive flooding along main rivers, coastal storm surges leading to dike breaches, pollutant spills in critical waterways, infrastructure failure and all combinations of these.
Support to emergency procedures at Deltares, participation in regular training sessions and leading of at least one major exercise per year, execution of several real-world emergency expert advisory projects.
Impact assessment of cessation of the DSM groundwater abstraction in the city of Delft
Netherlands, 2005 - 2008
Delft Cluster Research Program, City of Delft Water Board of Delfland, Province of Zuid-Holland, Project Director
The city of Delft and surrounding municipalities need to anticipate to the planned reduction of the extremely large, century-old, DSM groundwater abstraction and the planned construction of the deep railway tunnel passing under Delft. The objective of this research project was to identify solution pathways for future water management. First, an overview was compiled of the effects and the possible solutions of the combination of interventions by focusing at: groundwater rise, geomechanics and water quality. Next, an integrated modelling framework was developed to quantify impacts and predict effectiveness of measures simulating groundwater flow, surface water flow, groundwater quality and geomechanical behaviour. The modelling framework was used to simulate the impact of gradual cessation scenarios and to evaluate solutions.
Overall project coordination, review of technical reports, providing expert advice, formulation of recommendations.
Research Agenda for Knowledge development on Urban water management
Netherlands, 2005 - 2006
Research Program Living with Water and STOWA, Project manager and Expert Advisor
The project resulted in a research agenda for the research funding program Living with Water. This agenda resulted in about 20 research projects in the area of urban water. Partners: TNO, TU Delft, DHV, Arcadis.
Project management, taking interviews, structuring knowledge gaps and identifying research questions, drafting a research agenda.
Water as a Guiding Principle in Spatial Planning
Netherlands, 2004 – 2009
Research Program Delft Cluster, Waterboards, Provinces, Vitens, Mekong River Commission, Project Director
Research Program Delft Cluster, Waterboards, Provinces, Vitens, Mekong River Commission
Purpose of this research project was developing a method to base spatial planning on the water system. This was approached along three main lines: (1) developing a set of instruments with which spatial planning can be tailored to the water system and to the interests of stakeholders; (2) formulating criteria to evaluate water management based on these instruments; (3) conducting case studies for gaining experience and building capacity in successful coordination of spatial planning and water management in practice (Twente, Bergen aan de Bron, Low Netherlands and Mekong river basin). Partners: WL | Delft Hydraulics, UNESCO-IHE, TNO, Accanto, Wageningen University, University of Utrecht, Delft University of Technology, Hanoi Water Resources University, Royal University of Phnom Penh, World Wildlife Fund, Kiwa Water Cycle Research and Rijkswaterstaat.
Overall project coordination, review of technical reports, providing expert advice, formulation of recommendations.
EU FP5 Research Project ‘Stochastic analysis of well head protection and risk assessment (W-SAHARA)’
European Union, 2002 - 2005
EU DG Research, Work Package Leader
The objectives of this EU FP5 research project were : (a) develop and apply a quantitative risk-based methodology for the protection of groundwater drinking well fields; and (b) produce guidelines for drinking water companies and Environmental Agencies on how to reduce uncertainty on heads/fluxes prediction by geological field investigations and monitoring of groundwater heads/concentrations. Partners: Polytechnic of Milan, Delft Univ. of Techn., Imperial College, ETH Zurich, Univ. Tuebingen, Univ. Louis Pasteur.
Overall work package coordination, review of technical reports, providing expert advice, formulation of recommendations.
Rapid Assessment of Comparative Climate Risk in Cities. Panel Discussion
2021 Gehrels, Hans, Guy van Hemel, Leon Kapetas., Understanding Risk Asia 2021, Singapore.
A Water Sensitive Strategy for the Sweet City of Curridabat; Reconnecting the Rivers to the Urban Landscape.
2020 Gehrels, Hans, Eskedar Gebremedhin, Laurene Bouaziz, Begoña Arellano Jaimerena. Deltares report, 60 pp.
Evaluating adaptation measures for reducing flood risk: A case study in the city of Colombo, Sri Lanka.
2019 Wagenaar, D.J., R.J. Dahm, F.L.M. Diermanse, W.P.S. Dias, D.M.S.S. Dissanayake, H.P. Vajja, J.C. Gehrels, L.M. Bouwer. Int. J. Disaster Risk Reduction 37: 101162.
Resilient cities according to Michael Berkowitz (100 Resilient Cities) and Hans Gehrels (Deltares)
2019 Berkovitz, Michael and Hans Gehrels. Urban judo: . Deltalife March 2019.
East Side Coastal Resiliency Project Review
2019 Gehrels, Hans. NYC. Deltares report, 68 pp.
A Water Resilience Plan for the Heritage Zone of Xochimilco, Tlahuac and Milpa Alta.
2019 Gehrels, Hans, Corine ten Velden, Eugenio Gómez Reyes, Roberto Constantino Toto, César Arredondo Vélez, Marco Antonio Torres Pérez, Negrón, Arturo Farias, Juan Pablo Rico, Cecilia Barraza, Nora A. Morales.Deltares report, 353 pp.
Livable Urban Waterways in Cape Town
2019 Gehrels, Hans, Olv Klijn, Tyrel Flugel, Tamsin Faragher, Kevin Winter. . FABRICations report, 44 pp.
Qualitative Flood Risk assessment for the Western Province of Sri Lanka
2018 Weerasinghe, Kumari M., Hans Gehrels, N.M.S.I. Arambepola, Hari Prasad Vajja, J.M.K. Herath, K. B. Atapattu., Procedia Engineering 212: 503–510.
Development of damage functions for flood risk assessment in the city of Colombo (Sri Lanka)
2018 Dias, Priyan, N.M.S.I. Arambepola, Kumari Weerasinghe, K.D.N. Weerasinghe, Dennis Wagenaar, Laurens M. Bouwer, Hans Gehrels. . Procedia Engineering 212 (2018) 332–339.
Towards Urban Flood Resilience in Muang Xay: Flood risk management and investment priorities for urban planning and design.
2017 Gehrels, Hans, Chris Smithies, Govert Verhoeven, John Ward, Anisur Rahman, Ruben Dahm, David Dettrick, Paul Simcock, Ferdinand Diermanse, Thanongdeth Insixiengmay, Dennis Wagenaar, Didrik Meijer, Nigel Murphy, Stefania Valenzuela Velazquez, The World Bank Group, Washington, 71 pp.
Towards a Water Sensitive Mexico City: public space as a rain management strategy,
2016 Salinas, Eduardo Marín, Florian Boer, Bas van de Pas, Victor Rico Espínola, Hans Gehrels, , De Urbanisten, Rotterdam, 152 pp.
Designing green and blue infrastructure to support healthy urban living
2016 Gehrels, Hans, Suzanne van der Meulen, Femke Schasfoort (eds.) and Peter Bosch, Reinder Brolsma, Daniëlle van Dinther, Gertjan Geerling, Martin Goossen, Cor Jacobs, Merijn de Jong, Sien Kok, Harry Massop, Leonard Osté, Marta Pérez-Soba, Vera Rovers, Annemieke Smit, Peter Verweij, Barry de Vries, Ernie Weijers, , TO2 Federatie Report, 109 pp.
Recent Advances in Flood Modeling: 3Di water management
2013 Arthur van Dam, Elgard van Leeuwen, Hans Gehrels, Guus Stelling, Wytze Schuurmans, , Invited key note lecture at 5th Annual Southeast Florida Regional Climate Leadership Summit, Fort Lauderdale
A Hidden Treasure
2012 Tom McNeilan, Sally McNeilan, Rob Daoust, Hans Gehrels, Elgard van Leeuwen, Mark Ekerm, Wytze Schuurmans, Irene Pohl, Stefan Nijwening, Carl Paauwe, Kyle Kozar, Eric Fang, Elisabetta Distefano, Key note lecture at Henry Hudson H2O9 Forum – Water challenges for Coastal Cities; Strategy-session 2: how to keep the Jamaica Bay area safe and resilient
Land & Water Management in the Urban Environment,
2009 Van de Ven, F.H.M., H. Gehrels, H. van Meerten, B. van de Pas, E. Ruijgh, D., Vatvani, N. van Oostrom and Th van der Linden, Deltares, Utrecht/Delft. 68 pp.
How water can support the city
2009 Van de Ven, F.H.M., Gehrels, J.C., Van der Linden, T., & Van Oostrom, N.G.C., , H2O 42(45).
Coupled Surface and groundwater flow modelling; a case study of a Dutch polder
2008 Bakr, M.I., N. Goorden, R.J. Stuurman, J.C. Gehrels, A. Lourens & G. Verhoeven, , IAHR international Groundwater Symposium, Istanbul.
Calibration and reliability in groundwater modelling: from uncertainty to decision making,
2006 Bierkens, M.F.P., Gehrels, J.C., & Kovar, K., IAHS Proceedings And Reports; No. 304 316.
A non-linear state space approach to model groundwater fluctuations
2006 Berendrecht, W.L., Heemink, A.W., Van Geer, F.C. & Gehrels, J.C., , Advances in Water Resources, Volume 29, Issue 7, July 2006, Pages 959-973
Reliability assessment of groundwater monitoring networks at landfill sites,
2005 Yenigul, N.B., A.M.M. Elfeki, J.C. Gehrels, C. van den Akker, A.T. Hensbergen & F.M. Dekking , Journal of Hydrology, Volume 308, Issues 1–4, 12 July 2005, Pages 1-17
Reliability assessment of groundwater monitoring networks at landfill sites
2005 Yenigül, N. Buket, Amro M.M.Elfeki, Johannes C.Gehrels, Cees van den Akker, André T.Hensbergen, F. Michel Dekking, , Journal of Hydrology, Volume 308, Issues 1–4, 12 July 2005, Pages 1-17
State-space modeling of water table ﬂuctuations in switching regimes
2004 Berendrecht, W.L., Heemink, A.W., Van Geer, F.C. & Gehrels, J.C., , Journal of Hydrology, Volume 292, Issues 1–4, 15 June 2004, Pages 249-261
2003 Gehrels, J.C. & Gieske, A., Chapter 6: , Simmers, I. (ed.), Understanding water in a dry environment (Hydrological processes in arid and semi-arid zones). IAH-IHP V UNESCO publication.
Designing tomorrow’s urban hydrological system
2003 Buma, J.T., Gehrels, J.C.,Stuurman, R.J., , Delft Cluster (ed.): Papers of the 1st International Conference on Sustainable Development & Management of the Subsurface, 5-7.
Impact of human activity on groundwater dynamics.
2001 Gehrels, J.C., Peters, N.E., Hoehn, E., Jensen, K., Leibundgut, C. Griffioen, J., Webb, B. & Zaadnoordijk, W.J. (eds.), Proceedings No. 269, Symposium S3, IAHS Sixth Scientific Assembly, The Netherlands, July 2001, 369 pp., IAHS Publ. 369 pp.
Groundwater level fluctuations; separation of natural from anthropogenic influences and determination of groundwater recharge in the Veluwe area, the Netherlands
1999 Gehrels, J.C.,, Ph.D. thesis, Vrije Universiteit Amsterdam, 269 pp.
The mechanism of soil water movement as inferred from 18O stable isotope studies
1998 Gehrels, J.C, J. E. M. Peeters, J. J. De Vries and & M. Dekkers. , Hydrological Sci. J., 43:4, 579-594,
Ground Penetrating Radar for determining volumetric soil water content; results of comparative measurements at two test sites
1997 Van Overmeeren, R.A., Sariowan, S.V. & Gehrels, J.C., , J. Hydrol. 197 316–338.
Decomposition of groundwater level fluctuations using transfer modelling for a range of shallow to deep unsaturated zones
1994 Gehrels, J.C., Van Geer, F.C. & De Vries, J.J., , J. Hydrol. 157 105–138.
|2022 – present||Board Member||Member of the Board of Directors of the European branch of the Resilient Cities Network|
|2017 – present||Team member||Member of Knowledge Program Team of the Dutch Delta Program on Spatial Adaptation (DPRA; Min. of Infrastructure and Water Management)|
|2020 – present||Commission member||Member of Review Commission of the Knowledge Agenda Agriculture, Water, Food of the Top sectors Agri & Food, Horticulture and Water & Maritime (Min. of Agriculture, Nature and Food Quality)|
|2020 – present||Commission member||Member of ZonMw Commission Cluster Health Prevention (Min. of Health, Welfare and Sport)|
|2015 – 2019||Deltares-representative||Deltares' Point of Contact for 100 Resilient Cities powered by Rockefeller|
|2013 – 2016||Member||the Singapore Thought Leadership Team for High Density Living|
|2012 – 2015||Co-founder||Knowledge Centre for Healthy Urban Living (formed by Utrecht University, RIVM, TNO, Deltares and KNMI)|
|2012 – 2014||Deltares-representative||PIB Orange Goes Green, San Francisco, USA|
|2011 – 2013||Member||EU Interreg IVB ‘CityChlor’ Think Tank on tackling urban soil and groundwater contamination|
|2008 – 2012||Member||of the Program Committee Bodem Breed|
|2010 – 2012||SKB||SKB-Adviserend Bedrijfsleven en DOO-Kennisbasistafel|
|2008 – 2011||Board member||Technical Commission ‘Geothermal energy opportunities (Meer met Bodemenergie)’|
|1999–2005||Member||editorial board of ‘Stromingen’ (Dutch Journal published by NHV)|
|2000 – 2004||Assistant professor||Delft University of Technology, Faculty of Civil Engineering and Geosciences, responsible for 5th year M.Sc courses in Stochastic Hydrology and Geohydrology, and supervision of PhD candidates.|
|1996-2006||Guest lecturer||(groundwater recharge estimation) at UNESCO-IHE in Delft.|
|1994 – 2004||Guest lecturer||(groundwater modeling with MicroFEM) at GEOPLAN|
|1990 – 1996||Assistant researcher||Vrije Universiteit, Amsterdam, Faculty of Earth Sciences, assisting in field courses at BSc level and supervising MSc students with M.Sc thesis.|