In what respects is ground water better than surface water? Compare well irrigation with canal irrigation.
What is the meaning of conjunctive use? Why is it useful to consider it in water resources plan-ning?
Compare surface and subsurface methods of ground water exploration.
Discuss in brief the steps for designing various components of a water well.
Describe different methods of well drilling, mentioning their merits and suitability for different field conditions.
What are the benefits of well development? Describe various methods of well development.
A constant head permeability test was carried out on a soil sample of diameter 10 cm and length 15 cm. If 100 cc of water was collected in 100 s under a constant head of 50 cm, determine the coefficient of permeability of the soil sample.
Calculate the amount of water flowing into a coastal aquifer extending to a length of 30 km along the coast for the following data:
Average permeability of the aquifer = 40 m/day
Average thickness of the aquifer = 15 m
Piezometric gradient = 5 m/km
A 20 cm well completely penetrates an artesian aquifer. The length of the strainer is 16 m. What is the well yield for a drawdown of 3 m when the coefficient of permeability and the radius of influence are 30 m/day and 300 m, respectively.
A well with a radius of 0.5 m completely penetrates an unconfined aquifer with K = 32 m/day and the height of water table above the bottom of the aquifer being 45 m. The well is pumped so that the water level in the well remains 35 m above the bottom of the well. Assuming that pumping has essentially no effect on the water table at a distance of 300 m from the well, determine the steady-state well discharge.
A fully penetrating artesian well is pumped at a rate of 1500 m3/day from an aquifer whose S and T values are 4 × 10–4 and 0.145 m2/min, respectively. Find the drawdowns at a distance 3 m from the production well after one hour of pumping, and at a distance of 350 m after one day of pumping.
The values of drawdowns were observed in an observation well located at a distance of 3 m from a fully penetrating artesian well pumping at 2.2 litres per second. The drawdowns were 0.75 and 0.95 m after two and four hours of pumping respectively. Determine the aquifer constants S and
T.
164 IRRIGATION AND WATER RESOURCES ENGINEERING
Two tubewells of 200 mm diameter are spaced at 120 m distance and penetrate fully a confined aquifer of 12 m thickness. What will be the percentage decrease in the discharge of each of these wells as a result of pumping both wells simultaneously with a depression head (i.e. drawdown) of 3 m in either case. Assume permeability of the aquifer as 40 m/day and the radius of influence as 200 m.
