4 4. A linear coastal aquifer has a mean hydraulic conductivity of 50 meters per day.The density of fresh water is 1.000 g cm³ and the density of underlying saline water is 1.025g cm³. Groundwater discharge along the coastline is 5 m³ d-¹ per meter of coastline.a.Sketch a cross-section of the aquifer, labeling the shoreline, salt waterinterface, and the outflow face.b. What are the elevation of the water table in m above sea level and the depthof the salt water interface in m below sea level at a point 1,000 m inland?What is the depth to the salt water interface at the shoreline and the widthof the outflow face?c.

The given data is shown below: Mean hydraulic conductivity=50m/dDensity of fresh water=1g/cm3Density of saline water=1.025 g/cm3Discharge=5m3/da. A cross-section of the aquifer is a follows:b. The elevation of the water table is given by h=2q'xGK....................1where,h is elevation of water tableq' is groundwater dischargex is point below sea level inlandG is specific gravityK is hydraulic conductivity Th specific gravity is G=ρwρs-ρwwhere,G is specific gravityρw is density of fresh waterρs is density of saline waterSubstituting the values G=ρwρs-ρwG=11.025-1G=40From equation(1) h=2q'xGKh=2×5×100040×50h=2.24 m The depth of the salt water at a point 1000 m inland will be z=G2×q2K2+2×G×q×xK Putting all the values, z=402×52502+2×40×5×100050z=16+8000z=8016z=89.532 m Hence, The depth of the salt water at a point 1000 m inland = 89.532 m c. The depth to the salt water interface is z=Gq'Kwhere,z is depthG is pecific gravityq' is groundwater dischargeK is hydraulic conductivitySubstituting the values z=Gq'Kz=40×550z=4m The width of the outflow face will be width=G×q2×Kwidth=40×52×50width=200100width=2 m Hence, The width of the outflow face = 2 m b) The elevation of the water table in m above sea level and the depth of the salt water interface in m below sea level at a point 1,000 m inland is 2.24m. The depth of the salt water at a point 1000 m inland = 89.532 m c) The depth to the salt water interface at the shoreline and the width of the outflow face is 4m. The width of the outflow face = 2 m