Browsing by Author "Galagedara, L.W."

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    Factors Affecting Farmers' Willingness to Pay for Jatropha Biodiesel
    (Uva Wellassa University of Sri Lanka, 2015) Sivashankar, P.; Weerahewa, J.; Pushpakumara, D.K.N.G.; Galagedara, L.W.
    Sri Lanka in its principle policy aims to produce at least 20% of energy requirement by renewable energy source by 2020. Still not much attention has been paid on bio fuels. Jatropha curcas L. is found to be a potential alternative source of renewable energy since its cultivation and oil extraction contribute to sustainable development, poverty alleviation, combating of desertification, reduction of greenhouse gas emissions and women empowerment in developing countries (Pushpakumara et al, 2008, and Francis et al, 2005). Jatropha has various socio-economic benefits which makes it more economical when cultivated on commercial scale. Like other vegetable oils, Jatropha oil can be used directly in modified diesel engines for automobile applications. Its adaptability to marginal conditions is an advantageous feature, which other oil producing crops do not have (Pushpakumara et al, 2008), thus it has the ability to reclaim problematic lands and restore eroded areas (Francis et al 2005). Jatropha originated biodiesel is less expensive to produce than other energy crops such as rapeseed and soybeans. This study looks at the demand for Jatropha produced biodiesel. Initially, it is unlikely to be used as a substitute for diesel. Jatropha biodiesel or Straight oil can be used at village level to operate farm machinery and for day to day activities at small scale. If there exist a willingness from farmers to use biodiesel at least in short term then Jatropha could be used as an additional income source. By- products of Jatropha biodiesel can also be sold. Thus this study looks at what factors affect rural farmers' willingness to pay for Jatropha biodiesel. Methodology Welfare estimation is based on Indirect utility and Minimum expenditure functions. Lancaster's (1971) theoretical model for demand estimation is expanded to include other empirical variables. Contingent Valuation Method (CVM) can be viewed as a direct measure of welfare change.
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    Understanding the Effect of Unsaturated Hydraulic Conductivity of Surface Soils on Landslide Triggering: A Case Study in Yahalabedda Landslide Risky Area, Sri Lanka
    (Uva Wellassa University of Sri Lanka, 2020) Shanika, K.K.A.; Nirujan, B.; Wijewardana, Y.N.S.; Herath, H.M.S.K.; Galagedara, L.W.
    Hydraulic conductivity (K) is one of the most important soil properties for rainfallinduced landslide triggering. Yahalabedda receives higher rainfalls in Northeast and Southwest monsoon seasons and considered a potential landslide risky area in Sri Lanka. The objective of this study was to evaluate the unsaturated K (Kunsat) of surface colluvium soils using a minidisk tension infiltrometer together with relevant basic soil properties. Field investigations were conducted at three soil depths; 0, 30, and 60 cm of a prepared soil profile in September 2019. The infiltration test was conducted at each soil depth using three tension levels of -0.03, -0.02, and -0.01 m. The Kunsat has been calculated using the Kunsat = C1/A, where C1 is the slope of the curve of the cumulative infiltration versus the square root of time, and A is a value relating the van Genuchten parameters for a given soil type to the suction rate and radius of the infiltrometer disk. Kunsat increased with the soil profile depth for each tension value. Kunsat values for -0.03 m tension, are 1.35 × 10-6, 2.62 × 10-6 and 7.77 × 10-6 m s-1 ; for -0.02 m tension, are 2.13 × 10-6, 3.91 × 10-6 and 1.02 × 10-5 m s -1 and for -0.01 m tension, are 4.23 × 10- 6, 7.86 × 10-6 and 1.42 × 10-5 m s-1 for 0, 30 and 60 cm depths, respectively. Kunsat increases with decreasing the tension values at each depth as expected. 0 and 30 cm depths show nearly the same bulk density (1.0 g cm-3 ), while the 60 cm depth shows higher bulk density (1.1 g cm-3 ). The soil texture is clay loam for the entire soil profile while the uniformity coefficient (Cu) is higher (6.8) in upper soil resulting in a lower chance to interlock between soil particles and higher pore spaces. As the Kunsat increases with the depth, more water will be percolated to deeper soils resulting in the increasing soil weight in deeper soils and the landslide risk. The study reveals that the Yahalabedda area has a threat to landslide triggering in rainy seasons. Keywords: Minidisk tension infiltrometer, Hydraulic conductivity, Infiltration, Landslide risky soils
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    Variability of Unsaturated Hydraulic Conductivities of Landslide Risky Soils in Uva Province of Sri Lanka
    (Uva Wellassa University of Sri Lanka, 2020) Nirujan, B.; Shanika, K.K.A.; Wijewardana, Y.N.S.; Galagedara, L.W.
    Localized slope failures resulting in massive landslides can occur during the rainy season in the central highlands of Sri Lanka. The objective of this research was to measure and assess the variability of the field hydraulic conductivities using a minidisk tension infiltrometer. The selected sites were located in Uva Wellassa University of Sri Lanka, Haputale, Haldummulla, and Meegahakiula which are located in the Uva province of Sri Lanka. Using the minidisk infiltrometer, infiltration rates were measured for soil depths of 0-5, 30-35, and 60-65 cm under suction levels of -3, -2, -1, and -0.5 cm. Soil core samples were collected to measure bulk densities of respective soil depths while the soil textural class was identified using the simple method of feeling by hand. The field moisture content was measured using the oven-dry method. Sieve analysis was performed to identify particle size distribution and coefficient of uniformity. Field hydraulic conductivity values were calculated using infiltrometer readings with respect to each suction rate and soil texture class for all three depths. Textural classes of tested soils were identified as clay loam to sandy clay loam and the coefficient of uniformity value is ranging from 4.4 to 6.8. The gravimetric moisture content of soil samples ranged from 0.021 to 0.233 g g-1 for all sites and bulk density ranged from 1.0 g cm-3 to 1.5 g cm-3 . The highest unsaturated hydraulic conductivity 6.9 × 10-5 m s-1 was observed in Meegahakiula soil at -0.5 cm suction at a gravimetric moisture content of 0.212 g g-1 for 60-65 cm depth. The lowest hydraulic conductivity 1.0 × 10-6 m s-1 was observed in the Uva Wellassa University site at -3 cm suction at a gravimetric moisture content of 0.040 g g-1 for 0-5 cm depth. Identifying relationships between hydraulic conductivity and the soil properties individually and developing prediction equations to demarcate landslide risky areas are expected to be done in the future. Keywords: Slope failure, Hydraulic conductivity, Suction, Minidisk infiltrometer