Question

Q3a(i) Field pumping test An unconfined aquifer consists of a permeable sandy soil followed by an impermeable very stiff clay. Pumping test from a well is conducted as shown in Figure. XXX XXX GL B G.W.L. DH h h drawdown water level, due to pumping well Impermeable Stiff Clay Using Darcy's law, derive the following expression for the field permeability (k) of the sandy soil in terms of pumping rate (q), radial distances (r7 and rz), pheareatic level (h and ha)

Answer 1

& GL GWL hz hi well Y2 a Vyz soir At madeal distance or from the well, the piezometric head, the velocity of flow by Dary's law. is k= coefficent of permeability. kdhl der discharge. The cylinderical surface through which this velocity occurs is darh, hence Q = lånrh) v, - 2017kh (dhldr). Lalank dolu Integrating b/w limits r. &re where the wates-table depths are hi & ha respectively & on rear rearranging OF Tik[ he-hi? |[in valm]} r2 in 2 Thah Thi

This is equilibrium Ish for well in an Unconfined aquifer K Q lureri (h2h) Ans