In earlier blogposts the Assistant Physical Planners asserted that Lesotho needs each and every bit of spatial data that can be got in order to support their decision making, and perhaps to strike a new balance between stakeholder wishes and the evidence of the effect on the environment.

After some of the QGIS analysis done with the Planners under the guidance of Colin Broderick a stark conclusion was arrived at in regards to flood risk in one of the more populated districts. More than 38% of the buildings mapped in Leribe are within 300 metres of a water body. The percentage of buildings tagged as “under construction” is even higher at over 50%. This shows two things, there’s a lot of vulnerable buildings in general, and  worse again is that those buildings that were more recently constructed are encroaching into the flood planes and near the river systems.

[caption id=”attachment_350” align=”aligncenter” width=”567”] Lesotho Flood 2010-2011[/caption]

A rainy eight weeks from December 2010 to February 2011 manifestly proved how vulnerable Lesotho really is. Reports from the time are startling demonstration the breathe of the adverse effects and the number of people involved. This involved the highest level of rain since 1933. Some local conditions were so bad that 3,360 people were evacuated from their homes. The Lesotho Government estimated that 22 million US dollars worth of damage was done to homes in the Kingdom. Relief schemes were set up for farmers and business to assist their recovery from the losses. All in all around 580,000 people (31%) were adversely affected. It also included a crop failure of 60% and the loss of 5,000 or so livestock. The cost to the Government took several years to estimate, but came back as 463 million Maloti, which would be 3.2% of GDP. Unsurprisingly a country already so hard-pressed economically needed to seek much of this assistance from foreign aid sources.

There’s a high level of urbanisation in Lesotho, which is measured at 3% growth in urban population per annum. Much of the urban population is living in quite low densities, but as acknowledged by the Government of the Kingdom the demand for land is threatening food security, ground water quality and biodiversity. Unauthorised, unregulated and spuriously designed and built residential land doesn’t cause bad weather. But it seriously does affect the ability to respond to weather based disasters if more people are in harms way than need to be. As we know in Ireland from SUDS and CFRAMs any building in a floodplain has an aggregate flood loading factor which reduces attenuation and spreads the area of risk.

Outside of the scope of emergency management, more proactive preventative measures in uplands are seen as the most cost-effective way to reduce demands on emergency services. And in a Lesotho context this of course includes management of overgrazing and deforestation. The official UN rating for environmental vulnerability and disaster preparedness for Lesotho shows that up to half a million people are at risk, or have the risk of losing their livelihoods if there is a catastrophic weather event. Does anyone really want to contemplate this number of people needing emergency aid?

At least for the moment all these conversations are possible because of well drawn and well tagged features on openstreetmap, and using that data to start a conversation about flood risk is one of countless practical uses. The information above shows why the hotosm regards Mapping Lesotho as being a unique disaster-preparedness initiative.