In depth: tackling flood management with GIS

By on 26 April, 2018

Banana Council Shire’s council chambers complex during a 2015 flood event.

You won’t find any bananas in central Queensland’s Banana Shire. What you will find is plenty of coal and gold exploration and extraction, power generation, large scale dry-land and irrigation cropping, and beef production — which is the source of the Shire’s unusual name.

Banana Shire was named after a bullock called Banana, and while the original Banana is long gone, the shire named after him continues to thrive as a tourist destination, as well as a farming and mining community.

The Shire boasts prime agricultural land as much of it is located on floodplains, and the waters have spread valuable nutrients throughout the soil over time. But these same waters that have helped create the area’s unique fertility cause havoc for the 16,000-strong population that inhabits the Shire’s 28,577 square kilometres.

Regular flooding with no way to report accurately

Banana Shire experiences regular flooding from the Dawson, Dee and Don Rivers, and overflow from the Callide and Kroombit Dams. In 2010, the Shire experienced a flood so large that the entire town of Theodore had to be evacuated by helicopter.

Peter Lefel, principal GIS coordinator at Banana Shire Council, said that this and other significant flood events, such as ex-Tropical Cyclone Oswald in 2013 and Cyclone Marcia in 2015, caused the council to upgrade its disaster management plan and the adopt their floodplain management plan. “We wanted to find a way to provide earlier warnings to people who may be affected by floods so they could evacuate sooner,” he said.

“This required council to develop a clear understanding of where people were likely to be when a flood event was imminent, as well as how that flood event was likely to affect them. For example, the Shire attracts so-called grey nomads in high numbers because it offers many free and short-term camping areas. If those areas were to be affected by a flood, it would be crucial to notify the tourists as early as possible to keep them safe.”

Peter Lefel of Bana Shire Council.

During a flood event, the prime group within council that is tasked with controlling and coordinating all emergency response activities is the Local Disaster Coordination Centre (LDCC).

A GIS support role within the LDCC provides location intelligence for any queries from within the LDCC, and can create spatial data sets on an as-needed basis for the current event.

An example of this function is to create a new Emergency Alert Polygon (EAP), which is used by the State Disaster Coordination Centre to send to Telstra, and phone numbers of residents within this polygon can be extracted to send text message event warnings pertaining to their location.

Previously, the LDCC GIS support comprised of paper maps stored in a metal trunk. This did not facilitate an efficient process and aspiring to be a progressive, technology-driven organisation, the council looked for ways to make disaster response planning and support activities more accurate, reliable, and easily updated.

“My review of the LDCC spatial capabilities identified a need for a dedicated GIS workstation to be located in the LDCC and the creation of a range of spatial data sets that would provide the ability to answer complex spatial queries around the impacts of an event on the people and infrastructure of the Shire,” Lefel said.

“There was also a need to be able to show spatial information related to the event to the entire LDCC at the same time, so a large screen TV was installed on the wall of the LDCC for displaying maps and spatial information.”

Better data for a comprehensive disaster management plan

Lefel created a large number of data sets for the LDCC using Council’s corporate GIS, and MapInfo Pro.

One glaring hole in these datasets was the lack of building data, especially attributes indicating building type, function or elevation.

“As a component of the post-event recovery process after a flood event occurs, the State Government wants to know how many buildings have been affected. In the past, we couldn’t answer that question accurately,” Lefel said.

“We needed a way to determine which buildings would be affected and, depending on the height of the flood waters, to what extent they would be affected. For example, if the buildings are on stilts and the floor level is up high, they may not be affected by the flood even though they’re right in the middle of it.”

To fill this data hole, Council chose to use GeoVision from Pitney Bowes, an enhanced version of PSMA Australia’s Geoscape product. Banana Shire Council is the first council in Australia to utilise the Geoscape data for the important purpose of disaster management.

“We chose GeoVision because its foundational dataset Geoscape is the only data available today that shows all the building outlines within the Shire. No other product has captured the same level of accuracy. This type of data hasn’t been available in the past for Australia, so we’re very excited,” Lefel said.

“This level of detail allows Banana Shire Council to query the building data against a modelled flood event and determine the anticipated scale of the impact on residents and the built environment. And post-event, provide a more accurate answer to the State Government on impact of the flood.”

The building heights in this data can be used in Council’s waterRIDE flood modelling tool, the basis of its floodplain management plan capabilities. Banana Shire aims to add value to this building dataset so that it fulfils more spatial and modelling roles, such as adding a floor elevations to anticipate flood height and visualise the impact on individual buildings.

Saving lives with instant, accurate information

Banana Shire Council can now provide instant, accurate reports to State government regarding the number and type of buildings that have been affected by a flood event.

“This solution is ideal to help the Council respond to a flood event effectively. Once buildings at risk and therefore residents, have been identified, we can initiate warnings and deploy first responders to where they’re needed most, so they can help those who are most adversely affected by the event. This will ultimately save lives,” Lefel said.

“I’d highly recommend this spatial data to other councils. It can also help with things like bushfire risk, swimming pool compliance, and building development, just to name a few. Thankfully Council has not yet had to use this data for a flood event, but we are ready for when it does happen.”

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