Flooding in Cities

Cities are complex, populous and interdependent systems which are extremely vulnerable to threats from natural hazards. Recent years have witnessed a sprawling metropolis which has fostered a large build up of highly vulnerable development (Burby, 2006). There is growing concern about placing these compact urban forms in harm's way as new urban developments are aggravating the growing risk to hazards, by adding even higher density developments than in the past. High-density developments place more people, residential and commercial buildings and infrastructure at risk if hazards are not anticipated and hazard mitigation is not prioritised. Does this trend mean that the worlds cities that accommodate a vast proportion of the population are becoming less disaster-resilient? 

Flooding in Northern England following torrential rain over the Christmas period

In terms of flooding, average economic losses alone exceed $6 billion in the US and these losses have been rising relative to increases in population! The flooding caused by Hurricane Katrina which caused over $200 billion in losses was the most costly natural disaster in US history. Coastal cities such as Bay St Louis, Pass Christian and Waveland have increased exposure to catastrophic losses from disasters and thus were nearly obliterated. Should this mass flooding serve as reminder to densely populated coastal populations around the world of their vulnerability to natural hazards?

The UK was subject to flooding across over the Christmas period: claiming lives, causing evacuations, power cuts and chaos, the costs of being under prepared for natural hazards is huge. The Environmental Agency has released another warning stating that Britain faces another month of flood and that there is 'no end in sight' to the bad weather which has disrupted festivities and already brought misery to more than 10,000 people nationwide. The following table shows the flood warnings in place across the UK as of 30/12/2013 at 12:07.

A study by Berke et al. revealed that local governments in the US give more attention to New Urban developments in applying land use regulatory and incentive techniques, public participation initiatives and technical assistances. They have been criticised for being reluctant to anticipate future risks and giving less attention to the use of non-structural mitigation techniques and storm water BMPs. Experts have suggested that more attention needs to be placed on non-structural hazard mitigation in order to counter the building of high-density developments in flood-prone areas in cities across the globe. High-quality planning would mean that attention would be paid to issues such as hazard mitigation thus losses from flooding would be lower in communities that prepare and implement plans for urban development. However this is frequently ignored and continues to occur - a clear example of this are the huge slum developments that are increasingly vulnerable to flooding. This paper looks into the responses of slum dwellers affected by flooding in India.

Looking into the future, hazard mitigation standards such as Smart Code will play a more important role. They prioritise design features such as pedestrian orientated streets, mixed land uses as well as protection of environmentally sensitive areas given their critical mitigation services. However in order to rely on environmentally sensitive natural systems such as wetlands, sand dunes and mangroves to manage and store flood waters, they must be protected. 

New urban developments are laboratories within which we can cautiously experiment with hazard mitigation and environmental protection strategies. They are a living test of how to deal with emerging hazards such as sea level rise and more intense weather events linked to global climate change.

Next time I will look at ways in which cities are acting to mitigate the impact of flooding via levees, storm surge barriers, etc. In the meantime, if you can't get enough of climate change adaptation strategies and flood risk reduction in cities be sure to check out this paper.