Understanding Unsaturated Flow: Richards Equation and Simplified Cases, Exercises of Groundwater Flow and Contaminant Transport

Download Understanding Unsaturated Flow: Richards Equation and Simplified Cases and more Exercises Groundwater Flow and Contaminant Transport in PDF only on Docsity! 1 Unsaturated Flow Governing Equations 1. Richards’ Eq (A) Apply mass conservation principle to REV Mass Inflow Rate ! Mass Outflow rate = Change in Mass Storage with Time For a REV with volume , mass inflow rate through face ABCD is Mass outflow rate through face EFGH is The net inflow rate is thus Similarly, net inflow rate thru face DCGH is and net inflow rate thru face ADHE is The total net inflow rate through all faces is then The change in mass storage is where 2 is the volumetric water content [L3 L!3]. Equating net inflow rate and time rate of change in mass storage, and dividing both sides by gives = (1)