During the past few years, cities, town, and open spaces in Israel have been suffering frequently from increasing damages caused by floods. Regional drainage limitations combine to form significant hurdles in development of high-demand areas, as well as urban renewal areas.
Previously, adjusted infrastructure conduits were essentially the drainage sole solution for management; however, they can no longer provide this solution on their own. The limited attention to soil's natural function of percolation and drainage, during the planning phases, in addition to the ever-growing density, construction and the reduction in open spaces in cities, has taken a significant toll. These circumstances result in a deterioration of the urban landscape, which gets flooded often, along with a limited quality of open areas. In addition, the aquifers are being hurt, seawater and rivers are being polluted, and overflow and sediment damages are taking place in the law areas.
Climate Changes in Israel, manifested in changes of rainfall patterns among other things, point to a move towards short and intensive rain events. In combination with the population growth and urbanization, which means more impervious areas and less percolation due to construction, the amount of runoff is set to grow in the future. The anticipated effects are estimated to include rising frequency and intensity of flooding events, following the damages mentioned above. Furthermore, the potential use of runoff water, for decent planned landscape, urban naturalization, irrigation, and ground water enriching, will be lost.
Due to these reasons, the Planning Administration has led a wide reform regarding runoff management within planning procedures. In conjunction with this document, Amendment number 8 of the Water section in the National Outline Plan 1 (TAMA 1) and Runoff Management Appendix (B-4) are moving forward in which the main objectives are: requiring a runoff management document and to make any plan responsible for the additional runoff it generates.
This document was created in order to provide a wide, professional framework for the implementation of the reform among the workflow of professionals involved in the planning process, included planners, architects and landscape architects, hydrologists, drainage engineers, ecologists and more. The policy provided in this document calls for the implementation of runoff management aspects in the initial phases of the planning process. This will be accomplished by providing and involving local hydro-geological information, thus allowing smart implementation of a range of natural and technical runoff management solutions. This policy document is meant to provide a general overview about the water management status in Israel, and proposed policy, including implementation instructions for professionals during the entire planning phase.
The document begins with two introductory chapters, followed by chapter three which includes an overview of the status of water management in Israel, regarding drainage and runoff management and an introduction to the key players in regulation and national and regional planning. The overview describes the overlap and gaps in the field. For example, the region-based separation of responsibility for flood management, which places responsibility on local authorities for regions beyond their defined area. In addition, the overview shows a separation of responsibilities of different aspects regarding drainage and runoff management. For example, while the drainage authorities are responsible for drainage outside urban areas, The Ministry of Environmental Protection is in charge of the environmental aspects of rivers and water quality, in which they share the latter responsibility with The Ministry of Health and the Water Authority. This review shows the need of creating an overall, up-to-date policy regarding drainage management and runoff management.
In chapter four the comprehensive policy is presented, including its implications in different plans and in specific plans for drainage and runoff management (basin and local Master plans), and tools for implementing the new policy are being suggested. The chapter introduces the various plans for runoff management, their purpose, content, and their interconnectedness as one coherent complex from the basin level, through localities, all the way to the neighborhood or even the single lot.
In addition, the fourth chapter discusses policy implementation in comprehensive and master plans, and emphasizes the importance of integrating runoff aspects from the very beginning of the planning process, in order to provide an appropriate infrastructure of water runoff management. There is also a suggested list of optional instructions for Plan Regulations, and expanding on the statutory changes, including suggestions to the method of policy implementation in the planning process and the plan documents. To further assist planning teams and institutions, there is also a suggestion with regards to the decision-making method for choosing runoff management components for the plan.
Chapter five analyzes the economic impact of the new policy, using Preferred Housing Areas Plan 1001 (TAMAL1001): Tel Hashomer Center, as a test case. As part of the economic overview, the plan examined four different alternatives for drainage systems: a default alternative which includes a conduit system alone, and three runoff management alternatives (a combination of a smaller conduit system with various runoff management solutions) that meet the runoff management calculated target for the plan. The four alternatives were built in two geographically different areas – coastline and mountain. Altogether, eight different alternatives were examined. The differences between the alternatives were the variety of runoff management solutions fitted to each geographic area, as well as the distribution of said solutions between developed and open lots and private and public areas. The review concluded that the relative additional investment to a housing unit among the different runoff management alternatives was less than 1% of the building cost.
The results also found that the various runoff management mix solutions suggested for the developed lots (residential, commerce, public buildings) were more expensive than the ones suggested for large scale open public spaces. This means that there are financial advantages to the implementation of runoff management solutions in large scale open public areas. The advantages are derived from Economies of scale as well as from the wide variety of nature-based solutions (not artificial / technological). That is in addition to other benefits, such as improving the quality of the planned areas and utilizing the runoff water. The annual costs (capital recovery and maintenance) of runoff management tools in public spaces are less expensive for the local authorities in comparison to the default alternative, yet they are more expensive for private properties, compared to the current situation. The main reason is that these tools require refurbishment more often than traditional drainage systems. That being said, with adequate annual maintenance the costs may go down significantly.
TAMAL 1001 is a plan designed with runoff management in mind. Open areas in the plan were located where runoff management potential was high, giving it an advantage in implementing efficient and cost-effective runoff management components. A sensitivity test was conducted, measuring the cost of runoff management systems considering fewer implementation in Public open spaces, and more tools in the development lots. The sensitivity test found that even managing only 40% of the runoff around public open spaces and the rest is in the developed lots, the relative cost per housing unit was approximately 1% of building costs. This test is also an indicator for new urban renewal plans, which usually have less open public spaces possibilities.
The various economic benefits of runoff management solutions were reviewed, from both the local and national points of view. Based on a literature review it was estimated that these benefits can reach hundreds of millions of ILS annually, depending on the local authority characteristics.
Chapter six reviews hydrological tools and databases for planning, which were used by the planning teams in the preparation of the runoff management document. This chapter aims to assist professionals in optimizing compliance with the Appendix instructions and the new policy, as well as creating a new professional, high standard in using calculation modules in their workflow. The chapter includes explanations and references to relevant methods of calculating like Time of Concentration, Peak Discharge Runoff, Runoff volumes, Floodplain, etc. Furthermore, the chapter introduces new databases created during the working process, their methodology and the way they were created, pointing to additional sources and databases where relevant.
Chapter seven introduces various tools for runoff management, presented in a broad datasheet of available tools for use in different scales – starting from the single lot, through the block and the neighborhood, and ending with urban open spaces.
The chapter starts with concept and principals for runoff management applicable in the beginning of the planning process, in order to promote plans that utilize the potential for runoff management in the plans’ scope, allowing an efficient implementation of runoff management tools. The chapter offers a wide variety of runoff management tools divided into the different operation type of each method: Flow Control, Detention and Retention, Percolation and Penetration to the saturated and unsaturated medium, betterment the water quality. For each method, information is provided about its implementation in plans, its advantages and disadvantages, examples, typical details and demonstrations. The purpose of this chapter is to introduce the variety of accessible possibilities at hand, and to encourage the exploration of new tools. It is also intended to help professionals in translation of policy and concepts into practice, and serve as an index for planning teams and institutions, in both planning and statutory phases.
Chapter eight offers a set of complementary tools for efficient implementation of the regulatory changes and new policy. Among others, this chapter offers steps for completing the phase of basin and localities planning for drainage and runoff management, and for their adoption in the planning institutions; promote the supplemental National outline Plan for flood risk management in open areas; and promote updating current regulations in relevant subjects.
The policy implementation is dependent on the commitment of all actors taking part in the planning and construction fields. Especially notable is the commitment required from the local authorities, which are in charge of the urban landscape, after the approval and implementation of the plan, since constant maintenance is critical to the function of the runoff management tools.
Currently, the responsibility for regional drainage infrastructure lies within the local authorities and is executed mainly through the construction of drainage conduits or other public drainage infrastructure. The eighth amendment of TAMA 1 requires every plan to achieve quantitative runoff destinations. This can be practically done using a combination of drainage and runoff management solutions. Which means that for the first time, private properties will also be held accountable for their region's drainage.
This policy document is part of a comprehensive planning document. Its wide scope determines goals for the improvement of the planning quality of urban areas and preparations towards climate change, and it is part of a breakthrough reform in the field of runoff management in planning processes. We hope that we were successful in meeting our goals in this document, and that it will indeed support implementing the changes required to TAMA 1 water section, as well as to the overall policy, and will be in frequent use by the planning institutions and teams in their daily workflow.
