ISERME - 2019

Permanent URI for this collectionhttp://192.248.9.226/handle/123/14735

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Browsing ISERME - 2019 by Author "Dassanayake, ABN"

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    Analysis of beachrock samples along Southern and Western coasts of Sri Lanka by spectroscopic methods
    (Department of Earth Resources Engineering, 2019-08) Edirisooriya, KVUI; Thilakarathna, MADP; Vijitha, T; Dassanayake, ABN; Jayawardena, CL; Dissanayake, DMDOK; Samaradivakara, GVI
    Beachrocks are sedimentary structures commonly observed where there is warm sea water in tropical and subtropical regions as a result of cementation by CaCCb of coastal sediments in the tidal zone. Comprehensive studies have been carried out to determine the formation mechanisms of beachrocks specially Japan to improve an alternative countermeasure against erosion by man-made rocks. When focusing on formation mechanism of beachrocks elemental and mineralogical composition is vital. Considering this important application, we used spectroscopic techniques to understand composition of beachrocks in southern coastal region between Ahangama to Kaikawala and Uswetakeiyawa in the western coastal region of Sri Lanka. The presence of minerals in beach rock samples in southern coast were identified by FT-IR spectroscopic technique. The constituents of minerals present in the beach rocks are further confirmed by XRD technique. Elemental concentrations of beach rock samples have been analyzed using technique of WDXRF spectrometry. Uswetakeiyawa beachrock was mainly analyzed by using EDX in SEM. Beachrocks in southern coasts is comprise higher percentage of Aragonite which is the polymorph of CaCCb, frequently founded in most of the sites in the world. Further the composition shown similarities with Indian (Tiruchendru) and Japan (Okinawa) beachrock occurrences. Comparative to the composition of southern coast beachrock, XRD analysis did not indicate any CaC03 polymorphs Uswetakeyyawa, beachrocks. Instead it indicated the presence of Kutnohorite (Ca(Mn,Mg,Fe)(C03)2).
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    Analyzing the seasonal variation of groundwater characteristics in the Attanagalu Oya basin
    (Department of Earth Resources Engineering, 2019-08) Athukorala, DRM; Kohilan, C; Danushka, U; Jayarathna, WHDP; Chaminda, SP; Dassanayake, ABN; Hewavidana, SM; Dissanayake, DMDOK; Samaradivakara, GVI
    Gampaha district which has the second largest population in the country consists of many industrial establishments and residential areas. Attanagalu Oya Basin which almost entirely the Gampaha district is a major hydrologic feature in determining the seasonal variations of groundwater characteristics in the region. In this study, the groundwater characteristics in the Attanagalu Oya Basin analyzed both quantitatively and qualitatively to identify variations in the pre and post monsoon periods. The qualitative parameters such as pH, conductance, turbidity, calcium, magnesium, nitrate, phosphorous, ferrous, and heavy metal concentrations were analyzed for samples taken throughout the entire basin for the two time periods: pre and post monsoons. The groundwater quantity variations were observed through data loggers and field surveys of water wells. These recorded values were used to model the groundwater resources in the region using two numerical models, MODFLOW by USGS and a self-written Fortran code. The qualitative and quantitative variations were then analyzed spatially and temporally to correlate with the upstream to downstream flow and the monsoonal recharge. The possible reasons for the observed trends and variations were also studied to provide recommendations for the sustainable management of the groundwater resources in the Attanagalu Oya Basin.