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Local government in Texas: dispatch two
Simon Mutonhori from Wairoa District Council was winner of a Marsh Overseas Manager Exchange in 2021. He is currently visiting local government counterparts in Texas. In this dispatch he looks at how his host region deals with the increasingly severe flooding events it is experiencing due to climate change.
Pictured above: Simon (right) with hosts Clay and Jennifer Pearson
In this blog I have identified flooding as a key issue in Pearland, Friendswood, and Texas City. I had the privilege of visiting Friendswood and Texas City which share the same regional problem of flooding. I will focus on Pearland City and the steps they are taking to mitigate the risk of flooding. Hurricane Harvey of 2017 wreaked havoc in the city with significant damage to a significant number of properties.
The issue of flooding is due to a combination of things: among them the significant rainfall events which come as hurricanes originating from the Gulf of Mexico and beyond during hot summer months. The soil texture is clay, which quickly absorb water, swells and seals all airspaces (pores) and become impervious, severely limiting further infiltration and creating runoff on the surface. The third factor is the flatness of the land, with very little gradient for water to flow naturally. Pearland City drains from west to east. The distance from the highest side of the city to the lowest side, where the waterways discharges, is about 20km and the fall (gradient) within that distance is only 10 metres. This creates a very shallow gradient of 0.0002 per cent which is not enough to allow the free flow of water in the event of a significant rainfall event. Therefore, to mitigate against this risk, water has to be temporarily stored somewhere and has be discharged slowly to avoid overwhelming the waterways.
Well maintained main waterway through the city
The City of Pearland has done very well at creating a network of open spaces that doubles up as recreational, sporting, and storm water detention ponds. They also maintain their drains in good shape, removing any debris that can impede the flow of water. The City also requires roads to be designed with lower elevations to houses so that streets can also temporarily act as storm water detention ponds in the event of high rainfall.
Since streets are also designed to flood temporarily, there is an issue of evacuating people in deep water in the streets. To manage the risk of people being trapped in their homes, the City has state-of-the-art emergency management equipment and a highly motivated team. They acquired high clearance former army vehicles which can navigate deep water. On my second day at Pearland I had the privilege to witness a mock exercise in which a large number of staff from across all City departments were involved and it was a success.
Neatly manicured roadside storm water swale.
Releasing a rescued turtle into one of the storm water detention ponds.
4 July 2022