GIS guides flood planning

Iowa Emergency Management Division

Iowa's first line of defense against the swelling Mississippi River is a

makeshift wall of sandbags that protects the communities along the riverbanks.

But when the Mississippi breached a sandbag levy near LeClaire this

week, state officials working at the emergency operations center in Des

Moines turned to geographic information system (GIS) software.

By pulling up an elevation map for the region, state officials were

able look at the contours of the land along the river to get a quick view

on the direction the water would take and how much damage it might do.

GIS has played a vital role in predicting problems and coordinating

responses since the emergency operations center went into full operation

April 16. Electronic maps, which can be displayed on three large screens,

give staff members a multifaceted view of the 10 counties along the river.

The maps combine elevation data, river maps, street maps and other vital

information.

"So many things have a spatial component, so it can be mapped onto GIS,"

said Bret Voorhees, preparedness director for the Iowa Emergency Management

Division.

The emergency operations center, located in the State Area Command Armory,

brings together staff from the Emergency Management Division and the departments

of Public Health, Public Safety, Transportation and — because prisoners

help stack sandbags — Corrections.

As the center geared up, one of the first things the officials wanted

was a map showing the location of mile markers along the river, to serve

as reference points for planning, said Jake Freier, GIS coordinator for

the Emergency Management Division. Eventually he put together maps for all

10 counties, with different layers of data available.

The river maps show channels and islands, some of which have houses

that might be endangered. And in the event of a breach, roadmaps will help

the center's staff determine road and bridge closings and how to plan detours.

Staff members also use mapping software to coordinate their response to

communities' requests for assistance.

As the waters recede, the center will use GIS to assess the damage.

Staff members going out into the field will take along Global Positioning

System units to lock in coordinates for flooded properties.

Beyond backing up damage claims, GIS will help the state develop a historical

view of Mississippi River flooding. "It's the most exact way to track year-to-year

where damage occurs," Freier said.