Lavaka

They are most common in tropical regions between the Cancer and Capricorn latitudes, especially the Central Highlands of Madagascar, where approximately one metre thick laterites develop on steep terrains in a monsoonal climate.

They are usually shaped like a tear-drop with a steep, round headwall that narrows downhill into a shallow outlet channel.

Among the natural controls on Lavaka formation are the amount of seismic activity in the region, the topographic relief (or slope), and hydraulic conductivity of materials in the saprolite.

During the monsoon season, heavy rains carry away all the eroded material from the lavaka, which can destroy surrounding crops and infrastructure.

They provided a sheltered environment for trees and other plants that would not survive on the grassy slopes, and in many cases farmers take advantage of more fertile soils and greater water availability within lavaka to grow crops.