VCARS 2008

ESTIMATION OF POTENTIAL SOIL EROSION IN KHLONG YAI SUB-WATERSHED OF THAILAND: A GIS MODELING APPROACH

Tue, 11 Nov 2008 00:00:00 GMT

ESTIMATION OF POTENTIAL SOIL EROSION IN KHLONG YAI SUB-WATERSHED OF THAILAND: A GIS MODELING APPROACH Gnanavelrajah, N. Soil erosion is a serious environmental problem causing threat to sustainable land management. Inappropriate agricultural practices, intense rainfall and steep sloppy topography are the main causes of soil erosion. Estimation of the potential erosion of a land area will be useful to plan proper preventive measures. This study was undertaken to find the potential soil erosion of agricultural land-uses in Khiong Yai sub-watershed in Thailand, using Geographic Information System (GIS). The Khlong Yai sub- watershed lies in the Eastern coastal region of Thailand. It is located between 12° 65 ‘ to 13° 14" N fatitudes and 101° 03° to 101° 44” F longitudes. The total area of the sub- watershed is 170175 ha. Almost 80% of the land-use is agriculture. A modified Universal Soil Loss Equation (USEL) was used in this study. Each component was estimated using appropriate equations using rainfall, soil, topographic and land-use data. The factors were integrated using GIS and an erosion hazard map was produced based on the potential rate of erosion. Results indicated that 84% of the agricultural land-uses had potential crosion rate less than 2 tons ha! yr'!. Only 3% of agricultural land-uses had potential erosion rate higher than maximum permissible limit (12 tons ha’! yr’). Among the areas where potential erosion was above permissible limit, 37%, 23%, and 19 % were under cassava, para rubber and 8S: land uses respectively. Similar methodology could be used to estimate potential erosion of agricultural land- uses elsewhere.

EFFECT OF EXOGENOUS ORGANIC MATTER AND FERTILIZER APPLICATION ON THE DISTRIBUTION OF ORGANIC CARBON IN SOIL FRACTIONS

Tue, 11 Nov 2008 00:00:00 GMT

EFFECT OF EXOGENOUS ORGANIC MATTER AND FERTILIZER APPLICATION ON THE DISTRIBUTION OF ORGANIC CARBON IN SOIL FRACTIONS Herath, H.M.S.K. Soil organic carbon (SOC) pools were studied in sandy loam soil using physical fractionation in a short term (one year old) arable field experiment in Belgium (experimental site of Gent University, Melle) which was started in spring 2005. Replicate experimental plots of six different manure and fertilizer treatments and two unfertilized control plots were sampled in March 2006. Samples from all plots were separated into five size and density fractions according to the physical fractionation procedure for the isolation of coarse free particulate organic matter (coarse fPOM), fine free POM (fine {POM), intra-microaggregate POM (iPOM) and silt and clay sized OM, with indication of the four isolated conceptual soil organic matter pools according to the model of Six et af. (2002). Fertilization had a distinct influence on OC amount present in different fractions. The total organic carbon content was significantly increased (P<0.05) by only two applications of organic fertilizers: between 1.10 and 1.51% OC for the amended plots versus 0.98-1.08% for the unamended plots. The amount of OC in the free particulate organic matter (POM) fraction was also significantly increased (P<0.05), but there was no significant difference in the OC content in POM occluded in micro-aggregates and in the silt + clay-sized organic matter fractions could be observed after one year. Difference in the amount of OC present in different fractions consequently resulted in shifts of the relative proportion of the OC present in these conceptual OC pools. The results showed that even in less than one year period of applying organic matter pronounced effects on the distribution of OC in the SOM fractions occurred.

NITRATE POLLUTION IN DUG WELLS IN THE VAVUNIYA DISTRICT

Tue, 11 Nov 2008 00:00:00 GMT

NITRATE POLLUTION IN DUG WELLS IN THE VAVUNIYA DISTRICT Loganathan, P.; Navaneethan, P. Ground water is an important resource for domestic and agricultural purpose and water pollution is found to be a serious problems. Ground waters are generally polluted by leachates from sewage and agricultural land. The main pollutants from sewages are nitrate nitrogen and feacal coli form, Both are hazardous at high concentration in drinking water. There is no simple way to remove all nitrates from contaminated water. Finding and correcting the source of nitrate contamination is the best course of action. The objective of the study was to evaluate the nitrate nitrogen in dug wells and identify the wells that are not suitable for drinking purpose in the Vavuniya District. Thirty three dug wells were selected around the general hospital Vavuniya to measure the Nitrate Nitrogen (NO;-N), Electrical Conductivity (EC), pH and fecal coli form count from March 2008 to June 2008. The Nitrate Nitrogen ranged from 0,10- 14.04 mg/l with a mean value of 6.1 and 30% of the wells showed above the permissible limit of 10 mg/l in March 2008. The study reveals that nitrate nitrogen was higher in wells located in the high lands compare to the wells located in low lands (paddy lands), Feacal coli form was much higher in almost all the wells. pH and EC of all the wells were within the permissible limit for drinking water. The research shows that nitrate nitrogen and feacal coli form were high in wells located around the hospital area and this may be due to improper sewage disposal system.

GAS PARAMETERS IN DEVELOPING LANDFILL BIOREACTOR LYSIMETER

Tue, 11 Nov 2008 00:00:00 GMT

GAS PARAMETERS IN DEVELOPING LANDFILL BIOREACTOR LYSIMETER Sangeetha, T.; Basnayake, B.F.A.; Thayananthan, K. Municipal Solid Waste (MSW) has attained an alarming dimension for their management in developing counties during the last few decades due to rapid ur and dev In Sri Lanka, management of MSW has become a serious problem due to increase in waste generation and lack of suitable disposat facilities. Open dumping is the most common solid waste disposal method in. the region. Landfills are needed in any integrated solid waste management system and it is the core of the ies available for ing wastes. As a this study on landfill bioreactor is an attempt to upgrade prevailing dumpsites by improving the reduction in gaseous emissions. The constructed landfill bioreactor lysimeter mainly consists of main reactor, leachate collection, storage, and recirculation and gas collection systems. The parameters of gas production and composition were anal sized in the lysimeter for 116 days. This lysimeter produced maximum of 119 liters of gas/day (6.639516 m/kg of dry matter/year), which comprises cent percent H2 up to 42 days and gradually reduced towards meth is. The analyzed showed that the same trends like in previous literature even though the accelerated degradation in this lysimeter shortened the each phases due to leachate re-circulation. It was shown that the bioreactor 1 the dation process by shortening the acid phase and early initiation of methanogenesis phase.