Formulation of a Policy to Implement the Water Sensitive Cities Approach
Urban Stormwater Runoff – Converting a Nuisance into a Resource
Formulation of a Policy to Implement the Water Sensitive Cities Approach
Urban Stormwater Runoff – Converting a Nuisance into a Resource
In Israel, urban stormwater runoff affects a wide range of stakeholders. In an era of accelerated urbanization in Israel, and in light of the climate changes that our region has experienced, urban runoff has become a great nuisance that causes frequent flooding, damage to property and people, and pollution of bodies of water downstream of the urban area.
Cities are expanding outwards to their limits, and are also building upwards, and a significant percentage of the city’s area is covered by impervious surfaces (roads, roofs, paving). In a typical city, about 55% of the precipitation will become stormwater runoff which carries with it whatever is in its path, including oil and fuel, a spectrum of heavy metals, nutrients (phosphates and nitrates) and pathogens. The stormwater that flows to the drainage system is directed to giant pipes that release the polluted water into streams or the sea.
The urban runoff problem is interdisciplinary, and as such is relevant to the many stakeholders, including the following:
1. Local authorities
The local authorities are responsible for: management of extreme weather events; construction and maintenance of expensive drainage infrastructure; dealing with flooding; aid and compensation to citizens after flooding events. Improvement stormwater management will affect all of these.
2. Water Authority
The management of stormwater runoff on the catchment level will create a new, readily available water source in the city. In addition, the aquifer will be enriched by the treatment of polluted groundwater during the dry season, which will in turn reduce the need for expensive water transport of stormwater of out the city while at the same time help prevent saltwater intrusion. There will be increased diversity of water sources within the city and the pollution of urban s prevention of pollution of urban streams.
Flooding causes harm to people and property; loss of work days; the need to deal with insurance claims insurance; increases in insurance premiums; other personal costs.
4. Drainage Authorities:
Increased runoff results in increased volume of water to transport out of the city; soil erosion requires expensive maintenance and can be a fatal blow to the ecology of the streams and rivers.
5. Ministry of Environmental Protection
Urban water runoff does not comply with any Israeli water quality standard. As a result, the runoff that flows into bodies of water harms the aquatic ecosystems and causes eutrophication. (For example, the fish of the Lake of Galilee (Kinneret) have been severely affected.)
6. Netivei Yisrael – National Transport Infrastructure Company
This company is responsible for the construction, upgrade, operation and maintenance of 7,000 kilometers of intercity roads in Israel. Netivei Yisrael produces over 130 million cubic meters of runoff, the second largest producer of stormwater (after the local municipalities)
7. Ministry of Health
As was mentioned, untreated urban runoff does not comply with any recognized water quality standards, and as such, is a health risk to those people who come in contact with the water, such as surfers and swimmers. In addition, the creation of an urban microclimate will reduce the health risks of extreme heat waves.
8. Jewish National Fund (JNF-KKL)
The JNF supports research that analyzes the feasibility of water sensitive technologies and created the Center for Water Sensitive Cities in Israel. In addition: implementation of water sensitive criteria in every project it initiates; development of the city-forest interface.
9. Insurance Companies
They deal with claims related to harm to people and property due to flooding.
10. Police and Fire Departments
Storms require expensive preparations; increased call volume and workload during flooding events; increased manpower needed to deal with the increased frequency of these types of events
11. Ministry of Construction and Housing
Responsible for creating both indoor and outdoor spaces that are more energy and water efficient, while improving the thermal comfort and hence quality of life.
12. Ministry of Defense
The coastal aquifer must be rehabilitated and protected, since it is a strategic reservoir in case of emergency, in light of Israel’s high dependence on desalination. Desalination plants are exposed and vulnerable and may be damaged by missiles or natural disasters such as earthquakes. This would affect urban water supply for an extended period.
13. Ministry of the Interior
This ministry if responsible for planning on the drainage basin level, outside the municipal borders; defining zoning plans (tab”a) that are water sensitive; creating tools to examine various scenarios that might affect the plans.
14. The Israeli Green Building Council
Creating awareness of the need to design green building by offering training, informational tours, professional workshops. The goal of the council, in its own words, is to “advance the development of standards and regulations for green building and urban sustainable planning in Israel”.
15. The Standards Institution of Israel
Creating green building standards for public and private spaces, including water sensitive/water conserving standards.
It is enough to observe the flooding that occur during rainstorms in order to understand the magnitude of the problem. This is a problem that will only get worse as weather patterns change and the winters have fewer rainy days but more intense storms. This is a trend that is predicted to intensify in the coming years, due to climate changes that our region is experiencing, as well as the expansion of our cities and reduction of open spaces in favor of surfaces paved with cement and asphalt.
In recent years, a number of principles, approaches and technologies have been successfully tested, with the goal of transform urban stormwater from a nuisance into a resource:
a. Harvesting, detention, and purification of rainwater, primarily using biofiltration technology, both with and without vegetation
This is a technology that has been widely adopted on a national and state level in Australia. Beginning in 2010 three biofilter pilot projects have been built in Israel, in Kfar-Saba, Bat-Yam and Ramla, and have been successfully tested. The water at the outlet of the biofilters comply with existing water quality standards, such as the Inbar Committee standards for unrestricted irrigation, stream discharge, groundwater recharge, and even drinking water standards.
b. End solution for reclaimed water
The aquifer is replenished by infiltrating purified stormwater via designated wells. Alternatively, the reclaimed water can be collected into winter pools, reservoirs or constructed wetlands.
c. Hybrid use
In the winter, the biofilter purifies urban runoff. During the dry season, the same biofilter system can be used to rehabilitate the polluted groundwater (removing nitrates, heavy metals, organic matter and more), and also has the ability to reclaim air conditioner condensate, recycle grey water.
d. Flood prevention
Water sensitive urban planning makes use of the biofilter to harvest stormwater at its source (i.e. where the rain falls) and detains the water for treatment and infiltration. This decreases the peak discharge rates and stormwater volume, and reduces the chance of flooding in the city.
e. Infrastructure savings
Management of urban runoff at its source, according to the Australian experience, allows for a reduction of 50% in the diameters of the city’s drainage pipes, and in addition reduces the wear and tear of the roads, as a result of reduced stormwater flow.
Water sensitive technology can be put to use even with a relatively low budget (reclaimed stormwater is 20% cheaper to produce than desalinated water), with marginal operating costs that are lower than conventional urban gardening costs. At the same time, the technology creates an available water resource for a variety of uses, and reduces drainage costs.
The range of benefits mentioned above incorporates the idea of an urban “green lung” that enhances the urban landscape. In effect, the biofilter integrates a (green) drainage system, a water treatment system and an infiltration system and converts open spaces in the city into functional spaces. At the same time, it creates a new water source that is both abundant and readily available. This same water was once considered a nuisance that was sent out of the city to streams and the ocean, contaminating these bodies of water with a range of pollutants.
With the experience we have accumulated from constructing, operating and monitoring the three biofilters in Kfar-Saba, Bat-Yam and Ramla, and with the close cooperation of the Water Authority, the Hydrological Service, local authorities, Mekorot, the Ministry of Health, the Ministry of Environmental protection and others, an interdisciplinary picture of a wide range of benefits emerges. In effect, the end users of urban water sensitive development (such as the biofilter) are the local authorities that are upgrading existing development and/or are developing new neighborhoods and public parks. The municipalities are building smart “green” infrastructure that help enrich the groundwater (in our existing case studies, specifically the coastal aquifer). Therefore, these cities need to be compensated by the state for their investment, since water sensitive urban development is more expensive than conventional development. An economic assessment conducted with the help of the “Kivvun” organization, headed by Gadi Rosenthal, pointed to the economic benefits of water sensitive urban design.
The management and reclamation of urban stormwater in Israel and in the world is a topic that affects many different stakeholders and local authorities, as listed above, is not quite perfect, since it lacks an interdisciplinary perspective that would improve the benefits to those stakeholders, including the public
In order to perform a multidisciplinary assessment of urban planning in general, and specifically management of urban stormwater, in 2016 we launched a new, multidisciplinary, applied research program with the support of JNF-KKL. Three leading Israeli universities participate in this four-year research program, called “Creating Water Sensitive Cities in Israel,” which involves a diverse group of scientists, architects and engineers. The main goal is to provide a comprehensive response to various aspects of the topic, in order to create a reliable database, along with a set of recommendations to implement and adopt in accordance with the unique needs of Israeli cities.
1. Methodological analysis
To comprehensively examine, in a holistic, multidisciplinary way, the reclamation (collection, purification, and use) of runoff, with emphasis on the advantages and public benefits relevant to the various stakeholders mentioned above. In order to develop a sustainable mechanism that allows for the development of industry related to the topic (entrepreneurs, planners, contractors), we suggest that the Ministry of National Infrastructure, Energy and Water and/or the Ministry of the Interior take the lead in round table discussions, in cooperation with the Ministry of Agriculture, the Federation of Local Authorities in Israel and KKL-JNF, to help develop effective and sustainable regulation. In order to accomplish this, we are available to assist and to provide the knowledge, information and data that has accumulated in Israel and in Australia.
At the bottom line, the reclamation of urban runoff can definitely be an economically successful enterprise, but currently, local municipalities avoid it, missing out the chance to increase the range of water sources in the cities, although the state would benefit from the improvement in the quality of the groundwater. Since this is the case, a mechanism of reimbursement is required that would encourage and enable the municipalities to build water sensitive infrastructure. This would allow for the consolidation and adaptation of an industry around investments in smart municipal infrastructure that will conserve water, improve the quality and quantity of water sources inside and outside cities and create public spaces that contend with climate changes improve quality of life.
2. Compensation/incentives for the local authorities and entrepreneurs
a. “Net meter mechanism”
Offset each cubic meter of water consumed by a municipality with a cubic meter of purified runoff that is recharged into the groundwater, similar to the net metering used in the solar energy field. The city will pay the difference between consumption and production. The state simply offsets the volume of water that that is recharged into the groundwater within the municipality’s jurisdiction, on the condition that it complies with the required water quality standards.
b. “Sustainable water supply mechanism”
Enable the local authorities to extract at least 60% of the water that was recharged to the aquifer. This pumping will primarily take place during the dry season and will provide numerous benefits:
Dr. Yaron Zinger
Director, The Center for Water Sensitive Cities in Israel
Research Associate, Ben-Gurion University and Hebrew University
Dr. Haim Messing
Head of the Central Region, Keren Kayemet LeYisrael