The influence of geologic factors in controlling flow patterns in hydraulic systems is evaluated by hydraulic models which are constructed as a porous consolidated media that simulates the interstitial geometry of consolidated rocks. Colored inks are injected into the flow system and are observed through the transparent sides of the model case. Visual analysis of the flow system, leads to salient conclusions concerning fundamental aspects of complex flow systems. Empirical experiments were conducted on the following aspects: Refraction of flow lines across lithologic interfaces: The law of streamline refraction, as described by King Hubbert, was found to be correct where boundary conditions do not interfere. Continuity of flow around and through highly permeable and impermeable lenses of different lithologies: The flow system around impermeable lenses indicates the nonexistence of stagnant areas where a hydraulic gradient is imposed on a saturated ground water system. Flow net system caused by a single pumping well: Transient changes of individual flow vectors, within the immediate area of influence, were analyzed at the moment pumping began. The absence of a transition phase indicates a rapid adjustment of the flow system to the pumping condition. Flow net system of mutual interference of depression cones caused by pumping multiple wells: This permitted an analysis of the ground water divide. Flow bands divided into flow paths which moved in opposite directions. Effects of emplacing pumping wells in highly permeable media: The increased area of influence of water movement to wells was clearly illustrated. This analysis demonstrates the capture of partially confined flow from great dths. The relation of the shape of artificial recharge pits to infiltration rate: Variations of flow net systems of rectangular and wedge-shaped pits were analyzed. When all other factors were held constant, the shape of the recharge pit was found to have no important effect upon recharge rate. Flow toward an effluent stream: The potential head of ground water beneath the stream was found to increase with depth. The relationship between hydraulic gradient and flow net configuration: The hydraulic gradient was found to have no effect on the flow net of a confined system, but a definite effect upon unconfined flow systems, in as much as it alters the water table which is the upper flow boundary. Flow pattern through tilted and faulted sedimentary structures: The geometric convergence of the aquifer boundaries caused the convergence of flow lines through a brecciated fault zone. A possible genesis of a hydrothermal vein ore was suggested by this flow pattern. Formation of perched water tables: The mechanisms by which saturated ground water mounds can be formed on a low permeability lens was demonstrated. Evidence was found which indicates that perched ground water probably escapes through the perching body as well as around its extremities. Confluence of gravity water and saturated flow: Unsaturated flow arriving at the water table of the saturated ground water body becomes an integral part of that body which acts as a single hydrodynamic system. Artesian ground water systems: A model illustrating the classic artesian aquifer situation was constructed, andflowing and non-flowing artesian wells were studied. A ground water mound was formed in the water table aquifer by water discharging naturally from the artesian aquifer through a fault in the confining layer. Subsidence around a pumping well: Water was pumped from a simulated artesian well, the piezometric surface in the vicinity of the well was lowered and the overburden was observed to subside while compressing the artesian aquifer. Cone of depression formed around single and multiple well systems: The drawdown at any point within the area of influence of a multiple well system was shown to be equal to the sum of the individual drawdowns of each well in the multiple well system, provided recharge and evaporation are neglected. Information resulting from these studies will provide guides for scientific development and exploitation of ground water supplies. Contributions were made that will advance the use of hydraulic models as exploratory tools in scientific hydrology. Further, this work brought into focus the importance of hydraulic models as couinunication media for interpreting cause-effect relationships in highly complex flow systems, of the type that so often are involved in regional problems of water resource development and management.hydrology collectio
