Groundwater Hydrology - Speech or Presentation Example

Q1. Graphically determine the hydraulic gradient and the groundwater flow direction in the figure below. Assume that each unit square is 10m x 10m. Hydraulic heads in meters above mean sea level (AMSL) are shown in parenthesis next to each well symbol.Answer: Graphical depiction of flow of water and hydraulic gradient.Hydraulic gradient (i) = ∆H/LAssume that well A is at 12m, B is at 11.1 m and Well C is at 10m. While keeping the scale in consideration the following calculations are carried.

The hydraulic gradient between A and B is:12-11.1/60m = 0.015And hydraulic gradient between B and C is 11.1-10/70m= 0.0152. (a) What is the Darcy velocity of groundwater in a sand-gravel aquifer (hydraulic conductivity of 0.06 cm/s) showing a change in piezometric head of 1 ft in wells located 500 feet apart?(b) What is the seepage velocity (or average linear velocity) of the aquifer, given the aquifer porosity is 30%?a. Solving for Darcy Velocity or FluxV= KiK= Hydraulic conductivity I= Hydraulic gradientV= 0.

06 x 500V= 30 cm/sb. Solving for seepage VelocityVs= V/nVs = 30/0.3 = 100 cm/s3. What is the hydraulic conductivity of a 10m thick unconfined aquifer that has been pumped at a flowrate of 1000 m3/day for a long time using a 0.2m-diameter fully-penetrating well? (Given:The drawdown (s) in the pumping well is 0.7m and it is 0.2m in an observation well located 10maway)Solving for KsKs= -Q x 1/A x ds/dhQ= 1000 m3/ day dh= .5mA= πr2ds= 10Putting the values,Ks= - 1000 m3/day x 1/3.14(0.1)2 x - 10m/ 0.

5mThe sign of ds/dh is negative because as s increases, h decreasesSo,Ks = 6.3 x 104 m/dayQ4.Describe what happens when fresh groundwater discharges into saline seawater.The seaward flow of fresh groundwater to coastal ecosystems is very important as it delivers the nutrients and dissolved constituents to these systems. There are numerous ways in which the ground water interacts with, and affect the coastal. It maintains the flow and aquatic habitats of coastal streams during periods when surface runoff is low.

Groundwater discharge also facilitates water levels and water budgets of freshwater lakes, ponds, and wetlands. ReferencesBy Janick F. Artiola, I. L. (2004). Measuring Hydraulic gradient in the saturation Zone. In I. L. By Janick F. Artiola, Environmental Monitoring and Characterization (pp. 230-232). california: Elsevier Academic Press.