The behavior of groundwater flow in a fra ctured rock mass in Pahala Mattala area, southern Sri Lanka was studied. Hydrogeological data obtained by Water Resources Board in Sri Lanka (WRB)and Japan International Cooperation Agency (JICA) was used in this study. Idealized models of fractured rock mass were constructed on the basis of the fracture data. Don-Chan (Donen-Saitama Channeling Flow Model), channel network model, was adopted for the analysis of groundwater flow and it was assumed that the fractures are divided into three types: major fractures, minor fractures and fault zones. Pumping test results obtained by two wells were analyzed with the' aim to calibrate channel transmissivity values of different fracture types. Model verification was done using pumping test results obtained by another combination of wells. It was found that, the channel network model in the Pahala Mattala area had the capability to predict accurately the groundwater flow for new pumping operations that will be planned in future to develop groundwater resources in deep underground.
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