A SURVEY OF EXISTING BANK RESERVATIONS OF SOME MAJOR NATURAL STREAMS IN MAHAWELI SYSTEM B

H M P B Vidyarathne , D M S H K Ranasinghe and M Panapitiya
University of Sri Jayewardenepura

This study focused on the existence, extent and a checklist of flora of stream reservations on two of the major natural streams in the Mahaweli System B area in the Dry zone of Sri Lanka. The Mahaweli Project is the major irrigation and settlement scheme in Sri Lanka.

By comparing the existing reservations with the amount allocated according to the relevant legislation at the beginning of the Project, the rate of degradation of reservations over time was assessed. With the use of transects which were positioned perpendicular to the streams the floristic composition of woody perennials ( > 10 cm dbh ) was enumerated. The socio-economic conditions of the neighboring community were also investigated.

The results of the survey showed that the existing reservations on both of the streams were far inferior to the amounts prescribed in the relevant legislation ( e.g. Crown Lands Ordinance etc.).The farmers who had been settled on either side of the streams had gradually encroached on the reservations especially for paddy cultivation. Other perennial crops like coconut, mango, jak and breadfruit had also been planted as the water level was higher near the streams. In both streams the right side was more encroached than the left side as more farmers were settled on the right side.

There was very little natural vegetation left on the banks. This was partly due to encroachment and partly due to the widening of the streams intermittently to cope with the discharge water in the rainy season. In the floristic survey on streams banks 249 woody individuals (> 10 cm dbh ) were sampled in Menik Ela while 158 individuals were sampled in the Mahaulpotha Ela. The total number of plant species encountered was 32 in the Menik Ela while it was 27 in the Mahaulpotha Ela. The total number of endemics sampled as a proportion of the total number of tree species sampled was 0.09% in the former and 0.11% in the latter. The flora varied from typical dry zone species to wet zone species depending on the bank, soil type and soil moisture content.

The socio-economic survey revealed that the community in the neighbourhood of these streams, who had mostly been settled in these areas from other parts of the country, had a relatively low income, low education and high birth rate. The majority of them were farmers.

As the existing situation regarding reservations is not at all adequate, strict legislation against the encroachment on reservations, planting the encroached land with suitable plant species, possibly with the participation of the farmers, and strengthening the extension programs to make people aware of the environmental benefits of conservation were recommended.

Department of Forestry and Environmental Science,
University of Sri Jayewardenepura,Sri Lanka. 1999. All rights reserved.