Response to the following questions:
1. The discharge of a river with a cross-sectional area of 10 m^2 is 2m^3*s^-1. At a time t=0 a dye tracer is released into the river. Calculate the time needed for the tracer to reach a measurement location 500 downstream from the release point, assuming that the tracer is subject only to advection.
2. A flow reactor with a cross-sectional of 16 m^3 s^-1 and a sodium concentration area of 0.8 m^2 is filled with sandy sediment with a dispersivityα of 0.01 m. The sediment is fully saturated with water with concentration of 250 mg I^-1. At a time t=0 a continuous inflow of water with a Cl concentration of 250 mg I^-1 is started with a flow velocity of 1 m d^-1 .
a- Calculate the dispersion coefficient
b- Does this coefficient refer to longitudinal or to transverse dispersion? Give reasons for your answer.
c- Calculate the Cl concentration at x= 1.0 m after 18 hours, using equation (11.32)
d- Calculate the Cl concentration at X=1.0 m after 36 hours.
e- Compare the answers of questions C and D and explain the outcomes.