GOROKA - It would be absurd to blame effects of climate change as the sole reason for sudden and unprecedented flooding in certain parts of Papua New Guinea, such as the recent case here in the Highlands.
But the truth is that we humans have abetted and induced flooding through land use changes, especially massive vegetation clearance.
This is because trees, bushes, grass, vines and creepers act as buffers to assist hold back surface water flow, or runoff, and diminish the accelerated flow of water into streams during rainfall events.
Trees and vegetation also help percolate rainfall into groundwater that otherwise would have made its way straight to rivers had there been no vegetation.
However, in recent times vegetation clearance has happened at a much faster rate than before due to population pressures impacting everywhere in the country.
This is creating a dangerous scenario because rainwater now flow as if on a freeway with high speed and increasing volume because there is nothing to reduce its strength and volume.
So we have to be careful and consider this, especially when removing trees and vegetation from mountain slopes, in water catchment sites or at high altitudes because this will lead to unprecedented flooding events and destruction along the waterway.
During heavy and continuous downpours, the infiltration capacity of soils is quickly exceeded, leading to surface run off referred to as Hortonian flows, where rivers quickly become flooded, carrying away debris (logs, fallen trees, branches) and the bedload (silt, sand, mud, soil, rocks).
What happens now is the sediment fills the river channel leading to over-flooding - incisions, undercutting, collapsing banks and overland flow - causing so much destruction.
The peak wet season adds greatly to the problems, and authorities need to consider this when planning civil works such as roads, bridges, culvert or drains.
People living within the headwaters and water catchments need to be warned of the dangers, as do people downstream.
The Kyoto Protocol identified land use change from deforestation as being the main cause of CO2 increases globally and the cause of habitat destruction, extinction of flora and fauna and dysfunction of the natural cycles which govern rainfall events.
Hence, when we clear vegetation, we are inviting unforeseen events that bring devastating consequences, including loss of life.
Kerry Kimiafa is an environmental scientist specialising in surface and groundwater investigations. He is also a volunteer with the Travel4Green (T4G) PNG project (www.t4gpng.org) which is advocating for climate change remediation, forest conserving and carbon sequestration. Email firstname.lastname@example.org