IV. ANALYSIS OF SECTOR-LEVEL MEASURES USED TO INTEGRATE ENVIRONMENTAL CONSIDERATIONS IN TERMS OF PERCEIVED EFFECTIVENESS IN ACHIEVING POLICY OBJECTIVES
A. Types of measures and intended impacts: ministries and agencies responsible
1. Soil erosion and soil degradation: their effect on the tea sector, and other environmental hazards
The pattern of land use in Sri Lanka has changed dramatically over the past 40 years. Changes in the pattern of land use in the hill country are of special significance since the off-site economic effects of such changes, particularly in relation to soil erosion, are as significant as the on-site effects.
During the past four decades, land under human settlements has doubled, while the land brought under crops other than tea, rubber, coconuts and paddy has increased by 234 per cent. On the other hand, total land under forests and wild life and nature reserves has declined by 43 per cent, while that taken up by tea plantations and rubber has fallen by 34 29 per cent, respectively (table 5).
Table 6. Changes in land use in Sri Lanka
Sources:Data for 1956 and 1984 from the Natural Resources, Energy and Scientific Authority (1991); data for 1994 are based on estimates from various sources.
Changes in land-use patterns in the hill country of Sri Lanka, defined as areas 300 metres above mean sea level, also present an interesting picture. The hill country covers approximately 9,000 sq km or 14 per cent of the total land area of Sri Lanka. The most important watershed and catchment area in economic terms is the upper Mahaweli catchment which also happens to be the best documented in terms of land-use data. Approximately 54 per cent of the total hydropower capacity (or 49 per cent of the total power generation capacity) in Sri Lanka, and 23 per cent of lands irrigated under major irrigation schemes on the island, are dependant on the water resources of the upper Mahaweli catchment, under a major diversion scheme on the Mahaweli River. The types of land use which have shown a decrease in the upper Mahaweli catchment include tea plantations (12.7 per cent) and rubber plantations (0.98 per cent) (table 6).
Source:Mahaweli Authority of Sri Lanka.
With respect to on-site effects of land erosion in Sri Lanka it has been found that alternative uses of land in a given agro-ecological environment, under different technologies and cultural management practices, result in significantly different rates of on-site loss of soil resulting from erosion. Estimates covering a wide range of land uses under different levels of management are shown in table 7.
The impact of differences in the management of perennial as well as annual crops on erosion rates, as illustrated by the erosion hazard ratings (EHR) on a scale of 0 to 40 for upper Mahaweli catchment area, is shown in table 8. Tea with less than 40 per cent cover has an EHR of 32 while tea with over 80 per cent cover has an EHR of 1.