MADAGASCAR AND LANDSLIDES

     Madagascar has a problem with landslides, especially in the central and eastern regions.  During the months of November thru May, torrential rains from various tropical storms and cyclones saturate the ground making mountains and hillsides more susceptible to landslides. This can result in damage and destruction of structures, roads, pipelines and agriculture land.  In the capital city of Antananarivo, people lost their homes and some their lives because of landslides the first several months of this year.  Although Madagascar was experiencing a much more powerful cyclone season this year, landslides are disasters that Madagascar has to contend with every year.  Madagascar is a poor country even by third world standards.  The infrastructure that is used to decrease the chance of landslides in a wealthy country may not always be present in Madagascar.  The infrastructure in areas that do have dykes, levees and drainage systems are not always well constructed and poorly maintained.  I am also assuming that Madagascar may not have enough qualified people to assess the risks for landslides in various areas and there may be no enforcement to prevent people from building homes where there may be a risk of landslides.

     Deforestation is also resulting in more landslides in Madagascar.  Deforestation is the result of slash and burn agriculture, illegal logging, fuel wood and forest cleared because of mining.  Slash and burn agriculture results in areas of the rainforest cut down and in its place rice and other crops are planted or the land is used for grazing animals.  After a couple years of production the land is left fallow for 4 to 6 years and then planting resumes for a couple of years.  This process occurs 2 to 3 times until the soil is exhausted of nutrients and abandoned.  The vegetation that ends up growing in these abandoned areas like scrubs or alien grasses may not be sufficient to anchor the soil on slopes which may result in a landslide.  Illegal logging is the result of extreme poverty and government corruption.  Only 15% of the population in Madagascar has access to electricity and in rural areas it is less than 4%.  Wood is used for cooking, heat and light during the night.  Soil erosion is another result of deforestation with some areas losing as much as 400 tons/ha per year.  Agriculture is the foundation of Madagascar’s economy and may be put at risk due to soil erosion.       

     The weather in Madagascar, which can result in torrential rains during the rainy season, cannot be prevented.  The infrastructure though can be improved to decrease the chances of landslides.  Drainage systems, levees and dykes that are structurally sound and maintained properly can help.  More needs to be done in assessing landslide risks and increasing slope stability.  Retaining walls to help support slopes and grading, removing material from the upper slope and placing it at the bottom, should also be used.  In some areas that are too dangerous, people may need to be moved or prevented from building in certain areas. People, especially in the rural areas, need to have access to electricity instead of cutting down trees for fuel which contributes to deforestation. In the short term this may not be realistic but hopefully help from other countries can enable more Madagascans in the future access to electricity.  Farmers and foresters have also planted Eucalyptus, pine and silky oak in deforested areas.  Reforestation of native plants in rainforest corridors have resulted in mixed results.  An alternative to slash and burn agriculture is inga ally cropping.  This involves planting Inga tree in a row and in between the trees planting crops.  Inga trees grow fast which produces a canopy that cuts off light so weeds won’t grow.  The trees also converts nitrogen into a form that can be used by plants and a fungus that grows on its roots recycles phosphorus. Research has found that soil loses its fertility when phosphorus is washed out by the rain.  This allows farmers to use the land over and over again.  Larger branches from the trees can be pruned and used as firewood while smaller branches and leaves are left on the ground to decompose, releasing phosphorus and used as mulch.  The famers punch holes in the mulch to plant crops that are in turn fed by the mulch as they grow. The mulch also helps shield the soil from the hot sun and rain.  This method has been used in Costa Rica, Honduras and Peru.  Discussions have been underway to start this is Madagascar. If inga ally cropping is implemented in Madagascar, deforestation can be decreased which would prevent landslides. 

 

REFERENCES

Kellor, Edward A., Devecchio, Duane E., (2015) Natural Hazards, Earth's processes as Hazards, Disasters, and Catastrophes (4TH ED).

Deforestation in Madagascar – NC State University. www4.ncsu.edu.edu/-tlbolton/world_forestry.

Heavy rains turn Antananarivo into a city of landslides.  floodlist.com/africa/heavy-rain-antananarivo-landslides.

Inga ally cropping. en.wikipedia.org/wiki/Inga_Alley_Cropping