Views are still divergent on whether human impact on the planet has been so profound as to herald a new environmental epoch, the Anthropocene. Its impacts include man-made climate change with increased flooding and droughts at an unprecedented scale.
Greenhouse gases emitted from human activity, mostly in far flung industrialised countries, form an expanding hurdle in the upper atmosphere, trapping heat that warms the earth’s surface. Laws of physics dictate that warmer seas evaporate more quickly and warmer air will hold more water vapour, increasing the intensity of resultant rainfall.
Many will characterise the scale of the current flooding in Kenya as unprecedented and could fit into a pattern of climate change attributed weather events experienced globally from the landslides in West Pokot, recent flooding in Paris to the recent deluges in South East Asia.
Scientists warn that climate change is likely to increase flood risk and drought. There is thus an overwhelming imperative for our government to tackle the causes and effects of climate change, including flooding.
While climate change has exacerbated flooding in Kenya, there is now a growing consensus that unchecked development in areas that naturally absorb excess water is also to blame. There is not much we can do on climate change precipitated by actions in distant lands, but sustainable development is our gift.
In most urban areas, sprawling developments have replaced farmland that once absorbed and stored vast amounts of water. Increased concreted surfaces have resulted in more runoff entering man-made and natural drainage systems, increasing the intensity of flooding. River channels have been compromised in the quest for development.
No mitigation is provided for loss of permeable water storage land and flood flow paths disruption. Only sustainable siting of developments with effective mitigation for flood storage can minimise flood risk. Our development codes should be revised to take cognisance of flood risk and climate change.
Environmental damage from climate change and unsustainable development is often irreversible but can be managed. We cannot stop flooding completely, but we can mitigate its effects. Improved drainage systems to store and convey runoff effectively should be provided. This will include upgrading sizes of drainage pipes for increased runoff and providing flood plains for flood storage, among other measures.
There has been extensive deforestation in Kenya to accommodate requirements for farmland, residential, commercial and industrial activity.
Forests are vital in absorbing greenhouse gases and tropical deforestation is estimated to contribute more than 10 per cent of global emissions. The current tree planting campaign offers redress and should be expanded.
There has been a large increase in car ownership characterised by imports of older, less efficient vehicles, some of which emit highly polluting gases. It’s vital to devise minimum emissions standards to improve air quality.
It is ignominious that the scourge of the current flooding will in a few weeks be replaced with the misery of an inadequate water supply as the runoff makes its way to the Indian ocean untapped!
Extensive flooding in a country as far flung from leading greenhouse emitters as Kenya may be a sign from Mother Nature that we may already be in a new and more dangerous environmental era, where cumulative human activity precipitates weather patterns with calamitous effects. We owe to the next generation an environmentally sustainable biosphere.
Mr Kuria, a chartered consulting engineer based in the United Kingdom, is a Fellow of the Chartered Institute of Highways and Transportation. [email protected]