| Abstract | Samanalawewa catchment covering an area of 536 km2 is considered one of the most
important catchments in Sri Lanka because of its diverse land uses. The Samanalawewa
hydropower reservoir which was constructed in early 1990s in this catchment generates
about 10% of country's hydro energy supply. However, such development has been
alleged to have caused some noticeable changes in the ecosystem that influenced the
livelihoods of the people.
Thus, the overall objective of this research is to analyze the level of degradation of land
and rural livelihoods in the study area. The specific objectives are to examine the climate
variability in the study area, investigate the causes and consequences of land use/cover
changes (LUCC), assess the rate of soil erosion and the associated determinants, assess the
adaptability of soil and water conservation (SWC) practices, assess the status of
livelihoods before and after the construction of the Samanalawewa reservoir, and finally
recommend options for livelihood improvement.
The data used for the study were gathered from field experiments, remote sensing (RS) and
geographic information system (GIS), meteorological, and socioeconomic data through a
household (HH) survey of201 households (HHs).
Moreover, it was noted from the time series analysis of rainfall and temperature data in the
study area, that the annual rainfall from 1922 to 2008 was decreasing by approximately 5.5
mm yr1 while the average annual temperature from 1973 to 2008 was increasing at a rate
of 0.02°C yr-1
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From 1986 to 2008, the identified proximate causes of LUCC were population growth,
expansion of agriculture, infrastructure development, gem and mineral mining activities,
man-made forest fires, and timber extraction. In addition, the underlying causes were
inappropriate policies on land use, construction of the Samanalawewa reservoir, climate
variability, unsecured land ownerships, natural hazards, shifting cultivation, and lack of
awareness on the importance of conserving the natural resources. As consequences of
LUCC, several negative impacts had occurred. These included increased production cost of
agriculture operations, increased temperature, increased soil erosion, prolonged droughts,
and silting of water ways while biodiversity had decreased so with the annual rainfall as
well as water availability and quality.
The results of the assessment of the level of soil erosion in the study area in 2008 indicated
that erosion was mainly caused by anthropogenic activities. The rate of soil erosion ranged
from 0 to 289 t ha-1
yr1 with an average of 4.3 t ha-1
yr-1 (SD = 4.1), although the average
rate of soil erosion has been declining from 20.0 to 4.3 t ha-1
yr1 during the period from
1986 to 2008. However, the average human-induced soil erosion is about 14 to 33 times
greater than the rate of natural soil erosion. The socioeconomic factors and people's
perception of soil erosion were therefore evaluated using the data collected through the HH
survey. The multiple regression analysis with eighteen covariates of socioeconomic
characteristics yielded eleven socioeconomic variables, viz. HH size, farm labor, education,
land tenure, soil conservation cost, training, committee membership, professional
competencies, income, distance, and financial capital as the predictor variables of soil
erosion. Meanwhile, the farmers identified improper soil and crop management practices
as the major causes of the current soil erosion.
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Furthermore, the people's perception of adopting the SWC measures was also evaluated
using binary logistic regression. The results showed that six parameters were seen as
highly significant factors that influenced the adoption of SWC measures in the study area.
These parameters are the farmer's perception of soil erosion problem, gender of HH head,
past awareness about technology, off-farm income, training on SWC, and advice from the
extension officers.
Using the socioeconomic data compiled through the HH survey, the livelihood dynamics at
two separate points in time, in 1988 and 2008 were analyzed employing a sustainable
livelihood framework (SLF). The results showed that in both upstream and downstream
areas, livelihood assets such as physical, social, and human resources increased
significantly while access to natural capital had decreased significantly. However, financial
capital decreased only slightly during the last two decades. The impacts of the livelihood
determinants on HH livelihood were also analyzed using the factor and regression analysis
techniques followed by optimization procedure. The results suggested that some
improvements would be needed in the study area.
Lack of reliable and updated information on the status of the natural resources specifically
on activities related to monitoring, mitigation and policy formulation had been a hindrance
for planning the long term sustainability of the catchment. Hence, the information
established through this research is envisaged to be immensely helpful for the formulation
of policy recommendations that could assist in decision making processes.
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