HYDROLOGY QUESTION 3. The image above is from the United States Geological Surve

Question

HYDROLOGY QUESTION

3. The image above is from the United States Geological Survey (USGS). Atrazine is an herbicide with potentially carcinogenic qualities. Describe what is going on over the 3 months shown here. In particular

                a. Is the river gaining or losing in each month? If it changes, describe why. (Hint: look at the elevation of the river.)

                b. The materials are sand (larger grain sizes, well-sorted) and glacial till (poorly sorted with a large range of grain sizes. Make educated guesses about the relative porosity and permeability between the sand aquifer and glacial till aquifer

                c. How does the atrazine concentration change in the river and groundwater over these 3 months?

Sampling period February 20 to 22 Sand Water table 670 0.3 0.3 0.2 0.3 650 -640 630 0.2 0.1 Glacial till Sampling period March 20 to 22 680 Sand Water table i 660 650 -640 630 Sand Glacial till Sampling period April 3 to 5 Sand Water table 670 i 660 650 -640 630 Sand. Glacial till 100 200 FEET VERTICAL EXAGGERATION X 4 DATUM IS SEA LEVEL EXPLANATION -0 1- Line of equal atrazine concentration, Well location in micrograms per liter Direction of (0.21) Concentration of atrazine in river at time round-water of sampling, in micrograms per liter

Explanation / Answer

A) it shows increase in water table of lake and ground water during march. Also ground water flow direction shows that water is coming from river only during march. Feb and april has lossing river , flow is from ground water to river.

B)sand porosity range from 30% to 50% and permeability nearly 5000md

Glacial till porosity range from 10 to 20% and permeability is very low, around 10-100md

Atrazine conc was less in February. But due to overflow in river in march, more amount of Atrazine came with water. In april, flow reduced and atrazine conc also reduced with it.

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