Can someone help me to solve these questions? 1. The typical consumption of wate

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Can someone help me to solve these questions?

1. The typical consumption of water for drinking is 2 liters per day. However, someone exercising vigorously perspires at a rate of about 1 liter per hour. Compare the water use for drinking, cooking, toilet flushing (4 flushes/day), and showering for a "couch potato" who drinks 2 liters/day and an exercise freak" who also must replace fluids for 6 hours/day of vigorous exercise. The couch potato showers once per day for 3 minutes, while the exercise freak showers 3 times per day for 10 minutes per shower. Express your results in L /day, and then convert them to gallons/day. 2. For a typical gravel and sand aquifer, how far will a conservative compound travel in one year if the water-table elevation drops 1 m in a distance of 10 kilometers? How long will it take a non-conservative tracer with a retardation factor of 1.5 to travel the 10 km between wells? 3. Two wells are located 1.5 kmapart. The elevation difference between the wells is 0.8 The aquifer material is characterized as sandy m. (a) For a conservative tracer, estimate the travel time between the two wells. (b) An organic contaminant has a retardation factor of 10. How long will it take for the contaminant to travel between the wells?

Explanation / Answer

1. We need to compare the water consumption by 'couch patato' and 'exercise freak' on the following 4 parameters :-

i) water used for drinking

ii) water used for shower

iii) water used for cooking

iv) water used in toilet

Water used for drinking - The 'couch potato' doesn't exercise and hence drinking 2 litres(0.538 US gallons) is sufficient for him,on the other hand the 'exercise freak' exercises for 6 hours a day hence he loses 6litres of water perspiring and hence must drink 8litres(2.11 Us gallons) (6litres+ 2litres) of water to stay healthy.

Water used for shower - the exercise freak showers for 30minutes compared to 3 minutes for the couch potato and hence,exercise freak uses 10times the volume of water for shower than the couch potato.

Water used for cooking- it is best to assume that both excercise freak and couch potato eat the same food,hence their water consumption for cooking must be same.

Water used in toilet- it is best to assume that both couch potato and exercise freak use the toilet for the same time hence,their water consumption is the same ie. 4flushes a day

2. Given, the auifer is a typical sand gravel aquifer ,hence assuming that the porosity(n) is 30% and hydraulic conductivity (k) is 1cm/sec ,we have

Vs= k/n * (dh/dl)

Where Vs= velocity of fluid flow in aquifer

dh/dl= Slope of water ttable

dh/dl = 1/10000= 0.0001 (from the question)

So we obtain Vs= 3.33 * 10^(-7) m/sec = 10.50 m/year

Hence a Conservative tracer will travel 10.50 m in 1 year

For a non Conservative tracer with retardation factor of 1.5 velocity of flow = 10.50* 1.5= 15.75 m/year

Hence,to travel 10km ,time taken = 10000/15.75 =634.92 years.

3. From the question we have , dh/dl = 0.8/1500 = 0.000534

For Sandy aquifer let the porosity be 25% and hydraulic conductivity be 1*10^(-4) m/sec

So,velocity of flow= Vs= k/n*(dh/dl) = 2.13*10^(-7) m/sec

So,for Conservative tracer time taken to travel 1500m =1500/(2.13 * 10^(-7))= 6.52*10^9 sec=206.11 years

For organic contaminants with retardation factor 10 time taken is 6.52. * 10^ 8 sec =20.67 years, as it travels 10 times faster than a Conservative tracer.

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