While Houston has been the darling of "best American cities" rankings in recent years, a new study reveals a host of issues for the Bayou City, with a lack of affordable housing, high flooding risks and income inequality topping the list.

Rice University's Shell Center for Sustainability surveyed all 11 city council districts to explore 24 social, economic and environmental indicators affecting Houston's long-term sustainability. The report, titled “Sustainable Development of Houston Districts: The Health of the City,” follows its finding with recommendations based on data compiled in 2010.

Survey author Lester King notes that Houston remains far behind other United States cities in analyzing sustainability performance metrics, a practice that began during the 1990s. “This report will help reduce this gap by using comprehensive intelligence to influence policy decisions and making this information available to citizens to better understand their city and neighborhoods,” he says.

To improve the city's overall quality of life, the Shell survey highlights five key findings for policymakers to address in the next decade.

Housing and transportation

Half of Houston's city council districts miss the mark on housing affordability, which conventional public policy indicators stipulate that households should spend no more than 30 percent on housing. The average Houstonian already spends 30 percent on housing, leaving little room for additional transportation costs.

Considering that Houston citizens spend on average a whopping 16 percent of their income on transit, the city ranks 26th for affordability among the nation's top 50 largest cities. The report notes that only five percent of Houstonians use public transportation, compared to 55 percent in New York, which surprisingly ranked No. 4 for affordability.

Graduation

A look at graduation rates showed sharp disparities across the city with District J (Sharpstown and Gulfton) at 47 percent and District E (Kingwood and Clear Lake) at 96 percent.

Unemployment

In spite of the city's booming economy, poverty looms large in District J and District B (Acres Homes and Fifth Ward), both of which see rates above 30 percent.

Income

Houston remains the sixth-largest metro in the country for personal income, with total median earnings currently hovering around $43,000 in spite of a hit from the 2008 economic recession.

But great disparities emerge when looking at the ends of the income spectrum. The top 20 percent earn a yearly median of $140,000, while the bottom 20 percent earn $10,000 annually.

Flooding

Nearly 400,000 people live in flood-prone areas, putting an estimate $18 billion in city housing stock at risk. Districts J and F (southwest Houston) each have 50,000 residents on active flood plains.

Visit the Shell Center for Sustainability website to view the full report and recommendations.