ABSTRACT
Evaluation of groundwater resources requires the knowledge of the capacity of aquifers to store and transmit ground water. This requires estimates of key hydraulic parameters, such as the transmissivity, among others. The transmissivity T (m2/sec) is a hydraulic property, which measures the ability of the aquifer to transmit ground water throughout its entire saturated thickness. It is defined as the product of the hydraulic conductivity K (m/sec) and the saturated thickness B (m), in the direction normal to the base of the aquifer:
T ¼ KB ð1Þ
CONCEPTS
Fig. 1 illustrates a confined unit, or permeable unit sandwiched between impervious or semipervious layers. The hydraulic (or piezometric) head gradient in the two piezometers tapping the aquifer and separated by a unit distance is unity, since they measure a drop in the hydraulic head of magnitude one. The flow through the shaded window of height B and unit width normal to the flow direction is the aquifer transmissivity T. This follows from Darcy’s law, which requires that groundwater flow rate per unit area normal to the flow direction is equal to the hydraulic conductivity, if the hydraulic head gradient is unity.
