The Army Corps of Engineers and city officials of Dallas unveiled changes to the 100-year flood plan to upgrade the Trinity River levees. Although the changes were developed during a break that the agency took to study a new risk assessment approach, the new plan does not reflect a new strategy, according to Corps officials. “I can sum up two reasons of the pause. The first was to explore the new risk assessment process. And the second one was to continue to explore more cost effective methodologies for 100-year-fix,” said Richard J. Muraski Jr., commander of the agency’s Fort Worth district.