Comptroller Warned of Tel Aviv Flooding Years Ago

This week’s extensive flooding of the Ayalon River canal, which repeatedly shut down Tel Aviv’s main traffic artery, might have been averted, had the municipality taken more prompt action on recommendations made by the State Comptroller eight years ago, The Jerusalem Post reported on Thursday.

A 2004 State Comptroller’s report warned that due to inadequate drainage, if the canal was not diverted, overflows would result. Since prevention of flooding is dependent on the capacity of the drainage system relative to water flow, a lack of investment in drainage facilities would likely result in much higher future costs, the report said.

The 2004 assessment was not the first. Severe flooding in the winter of 1991-1992 led to a State Comptroller’s Office audit in 1993, which catalogued various deficiencies in these areas, and the problems were reviewed in 2003.

One issue that the State Comptroller’s Office focused on was the drainage of the Ayalon Highways project. While traversing the Ayalon riverbed with a highway and railway, it became necessary to built a concrete canal to channel the river’s floodwaters in the 1970s – a canal that would be under the auspices of the Yarkon River Drainage Authority, the report said.

While the flow capacity of the canal – both in 2003 and today – allows for floodwaters coming through at up to 400 cubic meters per second, experts have long agreed that the accepted standard for major drainage routes requires that the canal be upgraded to  handle a flow of 600 cubic meters per second.

“In this situation, widespread urban areas are exposed along the Ayalon canal to flooding and to severe damage in a recurrence interval of 15 years or less,” the State Comptroller’s Office wrote.

For technical and bureaucratic reasons, diversion of the canal was delayed for several years. However, plans for adding a fourth railway track forced some progress. In 2002, a the Transportation Ministry and the Yarkon River Drainage Authority endorsed a diversion plan.

But the high cost of the project—an estimated 800 million to 1 billion shekels — necessitated cost-benefit analyses by a series of committees, a drawn-out process.

The State Comptroller’s Report of 2004 noted that a decade had already passed without a plan for the canal being finalized, and that in the meantime the volume of upstream construction grew — increasing the risk of flooding in built-up areas.

In January 2013, the floods came.

This article appeared in print on page 7 of the January 11th, 2013 edition of Hamodia.