Assessing the potential for rainwater harvesting at Amsterdam Airport Schiphol

February 8th, 2016

M. Kuller, N. Dolman, Dr. J.H.G. Vreeburg & Dr. M. Spiller

The Netherlands qualify as a delta area in a temperate climate and as such are endowed with an abundant and high-quality fresh water supply. However, occasional water shortages occur in summer, resulting in damage to both nature and the economy. Climate change is expected to result in more frequent and prolonged periods of drought combined with an increased water demand. One of the negative side effects will be an increased saline intrusion in the lower parts of The Netherlands1. Thus, both the optimisation of water distribution through the public water supply system and an increased self-sufficiency are required. Rainwater harvesting and storage can contribute to this ambition.

Rainwater can be utilised as a fit-for-purpose alternative to piped drinking water for uses that do not require potable water including toilet flushing, cleaning, irrigation, building cooling and firefighting. Traditionally, the application of rainwater harvesting has focussed on single buildings with the roof as a catchment2,3. However, self-sufficiency in terms of water supply requires rainwater harvesting on a larger, regional scale. This study assesses the feasibility of rainwater harvesting on the scale of Amsterdam Airport Schiphol (Figure 1). Large areas suitable for rainwater harvesting in combination with a mix of household and industrial water demand make the airport area an interesting case study.

The airport’s water demand equals that of a city with 30.000 inhabitants and is distributed in hotels and offices with household type demand, but also in terminals and terminal buildings with a more industrial type of demand. This study assesses the potential water supply (i.e. amount of rainwater that can be harvested) and the economic feasibility of rainwater harvesting in this semi-industrial delta 4.

Amsterdam Airport Schiphol is one of the four largest airports in Europe and it is located in the economic heart of the Netherlands, 5 meters below sea level. The total land area of the case study area is 21 km2. Increasing saline intrusion is a specific water-related challenge in this delta area. This study includes a feasibility analysis of rainwater harvesting for replacing drinking water on site as well as supplying fresh water to its surrounding areas through a system of ditches, canals, and rivers during dry periods to counter further salinization.

Water balance

To assess the potential for rainwater harvesting at Schiphol Airport, a numerical model was developed describing the water balance, using an hourly time-step. The water balance has three components as shown in Figure 2:

Rainwater supply and catchment

Storage and treatment

Fit-for-purpose (non-potable) water demand

Harvest scenarios were developed for different combinations of catchment surfaces and volumes of storage capacity, for a dry-, an average and a wet year (based on historical data of the past 20 years). Three different types of catchment surfaces were assessed in the model: roofs, paved airside and paved landside. The hourly non-potable water demand was determined using bi-monthly demand totals. The data was transformed into weekly and daily water demand patterns based on models provided in the literature2,5. The fraction of drinking water which can be replaced by non-potable rainwater supply was determined for each building type (terminal, hangar, hotel, etc.).

Performance of the rainwater harvesting and supply systems was assessed on an hourly basis using historical rainfall data from the national meteorological institute6. Performance is measured using the parameter RUR: ‘rainwater utilisation rate’ indicating the fraction of the total, non-potable water demand that is covered by rainwater supply7. Costs for infrastructure and operation of all harvest and storage systems were assessed using net present valuation.

Results

All non-potable water demand at Schiphol can be supplied through rainwater harvesting, saving the airport 58% on its water bill. Using only roofs as catchment surfaces to meet all demand requires large storage capacity (Figure 3). Also, less frequent and more intense rainfall patterns associated with climate change will increase the storage capacity required. Adding other catchment surfaces (paved landside and paved airside) decreases the required storage capacity and increases harvesting dramatically. In an average year, potential harvesting from all catchment surfaces amounts to nearly 7 million m3, which is about ten times the total non-potable demand at the airport. The optimal combination of storage capacity and catchment areas is found at the level where marginal costs of adding an extra unit equals 1 for both these factors. Hence, aiming for a RUR of 100% is not optimal.

Because of the low, whole sale based water charges (amounting to 0.80 per m3), the only economically attractive option is a small scale system for the supply of water to firefighting drills. The return period on investment for this small-scale system is the only one under 15 years. However, using Dutch non-industrial water prices (1.40 per m3), or even higher prices found in other European countries8, larger scale systems become feasible as well. Most notably, supply of all installations at Schiphol and the supply of terminal uses with runoff from roofs and paved landside become feasible.

Conclusion: Rainwater harvesting at the scale of an airport?

Amsterdam Airport Schiphol can harvest enough rainwater to meet all its non-potable demand using roofs as catchment surfaces. When paved landside and paved airside catchment surfaces are added to roof catchments, rainwater harvesting can exceed the non-potable water demand by ten times, allowing Schiphol to function as a water supplier to its surrounding polders to fight saline intrusion.

When considering a rainwater harvesting system that supplies the local demand at the airport, the low industrial water charges make most configurations of the system economically unfeasible. Only a small scale application seems realistic, for example supplying weekly firefighting drills with rainwater. However, when water rates increase due to scarcity both in quantity and quality, results suggest that larger systems or even full scale application of rainwater harvesting may become feasible at the scale of airports or comparable sites with combined household and industrial non-potable water demand.

References:

Oude Essink, G., Van Baaren, E. S., & De Louw, P. G. (2010). Effects of climate change on coastal groundwater systems: A modeling study in the Netherlands. Water Resources Research, 46(10). Blokker, E., Pieterse-Quirijns, E., Vreeburg, J. & Van Dijk, J., 2011. Simulating nonresidential water demand with a stochastic end-use model. Journal of Water Resources Planning and Management, 137 (6), 511-520. Ward, S., Memon, F.A. & Butler, D., 2010. Rainwater harvesting: Model-based design evaluation. Water Science and Technology, 61, 85-96. Kuller, M., Dolman, N., Vreeburg, J., & Spiller, M. (2015). Scenario analysis of rainwater harvesting and use on a large scale-assessment of runoff, storage and economic performance for the case study Amsterdam Airport Schiphol. Urban Water Journal, 1-10. Lazarova, V., Hills, S. & Birks, R., 2003a. Using recycled water for non-potable, urban uses: A review with particular reference to toilet flushing. Water Science and Technology, 3, 69-77. KNMI, 2012. Uurgegevens van het weer in nederland. (Hourly data for the weather in the netherlands.) [online]. Koninklijk Nederlands Meteorologisch Instituut. Available from: http://www.knmi.nl/klimatologie/uurgegevens/#no [Accessed Access Date 2013]. Kim, J. & Furumai, H., 2012. Assessment of rainwater availability by building type and water use through gis-based scenario analysis. Water Resources Management, 26 (6), 1499-1511. GWI, 2008. Global water tariff survey. Paris, France.

Martijn Kuller completed a Bachelor of Science in Environmental Economics in 2010 and a Master of Science in Urban Environmental Management in 2013 at Wageningen University in The Netherlands. His current PhD research at Monash University (Melbourne, Australia) aims to improve the urban planning process for water sensitive urban design (WSUD), taking into account the complete array of technical, biophysical, socio-economic, environmental and planning aspects relevant for its success. Nanco Dolman is leading professional Water Resilience in Urban Areas at Royal HaskoningDHV with a MSc in Civil Engineering from Delft University of Technology (1998) and a BLArch in landscape design from Amsterdam Academy of Architecture (2008). Nanco is also part time lecturer Adaptive Urban Development at Rotterdam University of Applied Sciences. As one of the Dutch front runners in Water Sensitive Urban Design (WSUD) Since 1998, Nanco is the strategic advisor of Amsterdam Airport Schiphol for airport water management, water assessment and other water challenges related to airport planning. Jan Vreeburg is principal researcher at KWR Watercylce Research Institute and associate professor Urban Water Infrastructure at the Wageningen University. He graduated at the University of Technology in Delft and also got his PhD from the same university. A large part of his research is concentrated on the (re)design of drinking water distribution networks and sewer collection systems. Marc Spiller is a researcher and lecturer at sub-department of Environmental Technology of Wageningen University (NL). He obtained his PhD from Cranfield University (UK) where he researched asset management and pollution source control by UK water wastewater service providers. His current research interests focus on the design and assessment of flexible urban water systems and water and nutrient reuse in urban environments.

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