Alaotra, region mined by “lavaka”

Some traditional habits like cultivation on burnt ground, over-pasture, deforestation and all actions going to the vegetation lost without renewal further increase the erosion phenomena. At Madagascar, the mountains are especially fragile and vulnerable to this action. The “tanety” (plateau) keep opened wounds and some indelible prints of these acts. These large wounds are irreversible and create the lost of the equilibrium between the ground and its vegetation that we call “lavaka”.

This is on the national Road 44, from Moramanga to Ambatondrazaka in Alaotra region, Madagascar first loft of rice, that this phenomenon is really evident. The striking contrast between the bare mountain chains full of “lavaka” located on the right of the national road and Fanalamanga pine forest on the left shows the importance of the vegetal cover for the mountain protection. The Alaotra region where we have rice fields as far as the eye can see, is today circled by wounded hills which corrupt the whole region.

Lavaka are a very serious threat for the 75.000 ha of rice fields, which stretch out in the basin. The tanety erosion leads out inexorably the rice fields silting up and the sanding of the networks of irrigation and drainage. Then, the consequence is the decreasing of the cultivable area, the fertility of the soil and by the way, a more important cost for the rice fields maintenance.

The Japanese government is for the moment the first and the alone sponsor who has highlighted this phenomenon. They have paid since two years for a pilot project of stabilization of the “lavaka? in order to reduce the speed of the water with earth and sand which drop in the rice fields. The works are based on barrages construction inside of the “lavaka” .For the long term, preventive actions like building irrigation channels and planting vegetal species have been started to avoid that the water flow in the “lavaka”.

This vegetation will try to re-create a vegetal cover able to decrease the rain aggressive effects and the flowing erosive phenomena.

As now, the actions are really sporadic and the farmers have noticed each year that the cultivable area of his fields is decreasing more and more.
The phenomenon is not new. Starting sixty years ago already, we are able to read in the scientific writings some signals of alert about this situation. Today the Alaotra situation is very serious!