Question

3. (20 pt) The following field notes were taken at a nest of piezometers installed side by side at a single site (this are used to find the vertical flow): means that the these piezometers В A Piezometer 200 200 200 Elevation at surface (mean average sea level) 20 40 50 Depth of piezometers (m) 15 25 10 Depth to water (m) Let A, B, and C refer to the points of measurement of piezometers A, B, and C. Calculate A, B, and C (m). (a) The hydraulic head at (b) The pressure head at A, B, and C (m). (c) The elevation head at A, B, and C (m). (d) The hydraulic gradient between A and B and between B and C.

Answer 1

Hydraulic Head = Elevation head + Pressure head. @) Hydraulic head at A . zoom A B HA - 200m - 10m 15- poo = 190 m Hydraulic head at B -240 He = 200m - 25 m 50R = 175 m Hydraulic head at c Datum He = 200m - 15m. = 185 m Pressure head at A a hea antica de esa De Premam deno ground water = = Depth of piezometer - depth of 50m - 10 m = 40m pressure head at B - Depth of piezometer a depth of groundwater = 15 40-25 m groundwater Pressure head Depth of - 20 - 15 at c piezometer - depth of = 5 m

(c) Elevation head at A - Hydraulic head - Pressure head = 190m - 40m 150 m Elevation head at B 195m - 15 m = 160m Elevation head at c = 185m - 5m 180m d) Hydraulic gradient is given by i dh where dh = difference between two hydraulic heads de = path lengths between two piezometers. Here the distance between A & B and B&C is not given. I am taking here distance between A & B som en B&Co tom, r B&Co tom. You and between can put the exact value if you have the values. Hydraulic gradient between ne B (ing) = DH Ho-HA de 175 m - 19om - 15m 10m = -1.5 Hydraulic gradient between BRC BC & He- HB - 185m - 175m - som Jom ti TBC - Jom