As the 2007 Atlantic hurricane season gets under way, a team of engineers has released a sobering assessment of the technical failures that were largely responsible for turning the worst storm of 2005 into the worst peacetime disaster to strike the United States.

Issued June 1, the official start of hurricane season for the eastern and gulf coasts, the report from the American Society of Civil Engineers is a readable and definitive analysis of the factors responsible for the near-obliteration of New Orleans by Hurricane Katrina in August 2005. Although there has been no shortage of theorizing about the causes of the flooding that inundated so much of the city, the ASCE report summarizes the findings of several technical investigations conducted in the wake of the disaster and provides the clearest summary to date of what went wrong.

In a nutshell: Ignore the allegations that shoddy construction, cronyism and corruption played critical roles in the failure of the flood system.

Political constraints contributed, but the primary cause of the New Orleans disaster was flawed design of its protective structures. And that makes the report much more than a post-mortem of a single disaster. Its conclusions have troubling implications for any community that relies on large-scale and complex systems to protect it from fires, floods, earthquakes or other natural forces.

The paper is titled "The New Orleans Hurricane Protection System: What Went Wrong And Why," and its contents are as admirably clear and straightforward as the title. The report draws on numerous technical investigations conducted in the wake of Katrina, including the 7,000-page report issued by an interagency task force convened by the U.S. Army Corps of Engineers.

The report dismisses as "misperceptions" several common assertions about Katrina-related flooding in New Orleans, among them the unsupported claims that the city would have survived had the levees not been breached, and that malfeasance during construction played a role in the system's collapse.

In reality, the levee breaches were significant but much of the city would have been flooded in any event, the report concludes. In many places, floodwaters flowed over the tops of the levees and flood walls, and, in some cases, this was because engineers used the wrong elevation data to calculate the walls' height, resulting in barriers that were, in some cases, 3 feet lower than designed.

As for malfeasance, there's no evidence of it. What caused the levees and flood walls to fail there were about 50 ruptures, which damaged or destroyed 169 miles of the 284 miles of federal structures protecting the city was improper design and engineering.

The report says engineers relied on flawed calculations of the strength of the underlying soil; employed outdated assumptions about the likely forces produced by a strong storm; failed to take into account the continual sinking of the New Orleans area, which each year reduces the effective height of the protective structures; and made overly simplistic assumptions about the behavior of water as it seeps through sand and marshland.

Some of these errors were inexplicable. Others were products of the political system responsible for financing flood-control projects, the report's authors note. Episodic and unpredictable appropriations from Congress force engineers to develop such systems in a piecemeal fashion, hampering their overall effectiveness. And the language of the appropriation bills often prevents the Corps of Engineers from designing levees and flood walls to provide more than the minimally acceptable level of protection, thus discouraging a built-in safety margin to compensate for possible flaws in design criteria.

The report (available online at http://www.asce.org) offers 10 recommendations for action to reduce the likelihood that a similar constellation of technical miscalculations and flawed policy will doom other American communities, or even assure a repeat disaster in New Orleans. Many are familiar to students of emergency planning: improve interagency coordination, make someone or some agency responsible and accountable, find a way to incorporate new information into the management process.

The report also says, "Prudent land-use decisions (for example, limiting development in the most flood-prone areas, or establishing minimum first-floor elevations) can put fewer people and less property at risk."

That's not exactly a novel notion. Yet, of all the group's recommendations, it would have the greatest effect and likely will prove the most difficult to implement.

John Krist is a senior editor and Opinion page columnist for the Star. To read previous columns, visit http://www.johnkrist.com. His e-mail address is jkrist@VenturaCountyStar.com.