Abstract:
The dry zone covers much of low lands of Sri Lanka and receives an annual rainfall
lesser than 1750 mm. This rainfall feeds about 233 major and minor ancient reservoirs
and more than 10,000 small ancient village tanks in the dry zone where dominates a low
water retention capacity of the unique soil group (reddish brown earth) most part of the
"•dry zone. These tanks and reservoirs in the country maintain higher ground water table
so that water is accessible for wildlife and large scale agriculture. Up to very recent
times, the agricultural activities and settlements of the dry zone were always associated
with tank irrigations. Due to lack of government intervention, cascades of the tank
catchment appeared to be seriously affected by the current land use pattern of these
settlements. Soil erosion has increased the sedimentation of the tank beds and
incompatible land uses, pesticides and many other human activities has hindered the
capacity of the tank as well as quality of the water. Recently it is common practice that
large tanks in dry zone are over spilling and large part of the commanding area affected
by sudden floods ever than before. These pathetic situations emphasize the importance
of ancient irrigation technology. There are some evidences that the decisions taken to
the development programs implemented at the remote areas are seriously affected to the
existing ecosystem of the tanks in the area, after a time period. The objective of this
study was to conduct a qualitative assessment of adverse effect to the Yodawewa in
Thissamaramaya as a part of eco system, due to the existing land uses. This study was
confined to the Yodawewa, its cascades in catchment and existing commanding
area. The secondary data collection were done on two aspects. The land use analysis
was based on field survey data. The data on weather conditions and tank details were
obtained from the Department of Meteorology and Irrigation Department. Published
topographical and thematic maps were taken as supportive documents. Two SWOT
analysis have been carried out to investigate how the indigenous people manage their
water and tank as a part of the eco system with the cultivations and their settlements
comparing with Five human activities which may be responsible for damaging the
sustainability of the Yoda wewa. The study reviels that social activities and unplanned
physical developments taken place in the area during the previous three decades, has
created severe effect on the eco system of the Yoda wewa and suggest to consider how
to apply indegenous peoples’ knowledge to the present development projects as a legacy
of the ancient hydraaulic civilization.
