Modelling of Groundwater Flow in Fractured Rocks

Traditional groundwater flow modelling is based on the Darcy's law which is valid when the flow is laminar. However, the water flow in fractured aquifers can be non-laminar in discontinuities and in this case the Darcy's law is not valid. That is why a numerical solver is needed which is able to model both laminar and non-laminar flows. The MODFLOW-CFP by USGS is one of the programs that can be used for this issue.Additionally to numerical experiments physical modelling can be also a useful and effective tool to explore the flow in fractured media in details. Besides some international published case studies exists a less-known Hungarian conduit model by Öllős & Németh (1960). In this study the Öllős-Németh's conduit model was rebuilt in the modified MODFLOW-CFP (CFPv2). The goal of this modelling study was to reach good agreement between the results of the numerical model and the measurements. After having studied many numerical cases and by means of sensibility analysis, the CFP model was verified. Based on the verification the model is applicable to simulate non-laminar flows in fractured rocks not only in laboratory-scale but even in real cases.Following the international practice the MODFLOW-CFP is a usable tool to learn more about a well-developed karst aquifer in Hungary. Using the numerical model the flow in this karst area can be described in detail and more precisely.