«

»

Aug 26 2011

The Next New Orleans? (Part 3)

Afterwards, if one were to take statistical probability as a guide, there was every reason to believe we would not see another flood of that magnitude [the 1986 flood] for many years… – David Kennedy, former Director of California Department of Water Resources, from his forward to Battling the Inland Sea

Does Sacramento have the potential for the disaster that hit New Orleans? It’s the question we’ve been examining. In Part 1, we looked at the Central Valley and Sacramento’s history up to the late 1860s. In Part 2, we looked at everything leading up to major flood event of 1986. Now we’ll see that the flooding of 1986 was just a precursor to what would happen in 1997.

1997 Flooding

image_thumb[5]

In the storms and flooding of 1997, there were dozens of breaks in the levee system on the San Joaquin River and roughly half a dozen in the Sacramento basin (above: levee near Arboga on the Sacramento River). Over 300 square miles were flooded. This storm system, which occurred around New Year’s Day, also caused flooding on the Truckee River through the Reno-Sparks area, where I’m from. The Truckee flooding put 3 feet of water on the Reno-Tahoe Airport runway and flooded the downtown part of Reno.

image_thumb[7]

Over 23,000 homes, businesses, bridges, roads, and flood management infrastructure facilities were damaged. Nine more people were killed and over 120,000 people were evacuated.

And yet, only eleven years later, the January 1997 flood produced flows on several major streams , such as the Feather and Yuba rivers, some 20 percent greater than 1986.  – David Kennedy, former Director of California Department of Water Resources, from his forward to Battling the Inland Sea

Impact of 1997 Flooding

The flooding of 1997 was a wake up call that was not fully heeded in 1986. It triggered 4 specific actions:

  1. Annual river erosion inventory (USACE Sacramento District): The levees are inspected by the waterside. It has gone on for 13 years now and covers 300 miles of river and an additional 300 miles of bypasses. The bypasses are only visited when flow dictates.
  2. Hydrographic Survey of the Sacramento and San Joaquin Systems and Hydraulic Modeling: This data set is still their standard bathymetric data in use to this day.
  3. Emergency fixes and maintenance efforts: This is basically dumping rock off the side of the levee where holes are noticed.
  4. Repair work: This is actual bank protection that was limited to only 5 sites prior to 2006.

image_thumb[9]

We’ve been involved in some form with each of these actions and I’ll explore them in more detail in future posts, but the key thing to note here is that only 5 levee locations (besides the levee breaks) were repaired between 1997 and 2006. These were locations that were actively eroding and considered weak points in the levee. Why were only 5 sites repaired? As we’ve seen in the history of this system, the events of 1986 and 1997 were not unusual. There are other events that I haven’t even mentioned. These 2 more recent events were just floods that happened in the modern era. There were a number of reasons, though, that more sites were not repaired, not the least of which was funding.

However, there is one more event that would be the trigger for closer scrutiny and an unleashing of repairs throughout the entire levee system… to be continued!

3 pings

  1. » The Next New Orleans (Part 4) Hydraulically Inclined

    […] for the Central Valley levees. What this did was finally kick emergency repairs in gear. The annual levee inventory/inspection was utilized and work began immediately on sites that were deemed “critical.” By […]

  2. » The Next New Orleans? (Part 5) Hydraulically Inclined

    […] Part 3: The 1997 Flood and its impact […]

  3. The Next New Orleans? (Part 1) » Hydraulically Inclined

    […] Part 3: The 1997 Flood and its impact […]

Leave a Reply

Your email address will not be published. Required fields are marked *

You may use these HTML tags and attributes: <a href="" title=""> <abbr title=""> <acronym title=""> <b> <blockquote cite=""> <cite> <code> <del datetime=""> <em> <i> <q cite=""> <s> <strike> <strong>