Jackwells
The difference in the physiography, topography, rock types and
rainfall meant that the tribes in the different islands followed
different methods of harvesting rain and groundwater. For instance,
the southern part of the Great Nicobar Island near Shastri Nagar
has a relatively rugged topography in comparison to the northern
part of the islands. The shompen tribals here made full use
of the topography to harvest water. In lower parts of the undulating
terrain, bunds were made using logs of hard bullet wood, and
water would collect in the pits so formed. They make extensive
use of split bamboos in their water harvesting systems. A full
length of bamboo is cut longitudinally and placed along a gentle
slope with the lower end leading into a shallow pit. These serve
as conduits for rainwater which is collected drop by drop in
pits called Jackwells. Often, these split bamboos are placed
under trees to harvest the throughfalls (of rain) through the
leaves. A series of increasingly bigger jackwells is built,
connected by split bamboos so that overflows from one lead to
the other, ultimately leading to the biggest jackwell, with
an approximate diameter of 6 m and depth of 7 m so that overflows
from one lead to the other. |
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