A stream containing no biochemical O2 demand (obviously a hypothetical situation) has a DO of 5.00 mg/L and a flow rate of 8.70 m3/s.  The temperature of the stream is 15 degrees Celsius.  The average velocity in the stream is 0.174 m/s.  The average depth is 5 m.  Determine the reaeration coefficient and the rate of reaeration.

Hydraulic conductivity (K) in the vadose (unsaturated) zone is affected by of the following subsurface properties. Select all that apply.      moisture content            Fick's condition            Zubov's condition            Pore water pressure            Darcy's condition            Hysteresis wetting/drying stage           Gregorian chant in e minor

The flow net constructed for the dam is shown in the figure below. Taking the coefficient of permeability as 3.8 x 10-6 m/s, the quantity of flow (in cm³ /s) under the dam per meter of dam is 6.3 m 17.2 m 9.4 m 1.6 m 50 m A A • A. V Impermeable stratum TXXX

The initial rate of infiltration of a watershed is estimated as 53 mm/hr, the final capacity is 5 mm/hr, andthe hydraulic conductivity, k as 0.4hr-1. Use Horton’s equation to find: • The infiltration capacity at t = 3 hr and 6 hr• The total volume of water infiltrated over the 6-hr period.

Question 1 The discharge from a fully penetrating well under steady state pumping in a confined aquifer is (1000 two wells located at 6 and 12 meters from the well are 3.0 m and 2.0 m respectively. Čalculate the permeability of the aquifer. Show the data on the neat sketch. liters per minutes. The aquifer has a thickness of 20 m. The drawdowns observed at

(6) Derive an expression relating effluent concentration to influent concentration, hydraulic residence time, and the reaction rate constant for a second-order reaction in a batch at non-steady state. Repeat the exercise for a CMFR and a PFR at steady state. Explain your results.

Calculate the minimum fluidization velocity for an anthracite bed having following characteristics; d90 = 2.9 mm, ?anthracite = 1600 kg/m3, ?water = 998 kg/m3 at 20°C; µ = 1.002x 10-3 kg/m.sec

A water treatment plant treats 6000 m³ of water per day. As a part of the treatment process, discrete particles are required to be settled in a clarifier. A column test indicates that an overflow rate of 1.5 m per hour would produce the desired removal of particles through settling in the clarifier having a depth of 3.0 m. The volume of the required clarifier, (in m³, round off to 1 decimal place) would be

The base of a river in in contact with the top of an aquifer. A truck carrying bags of powdered cyanide is on a bridge crossing the river when a large bump causes one of the bags to fall into the river. The water in the river suddenly becomes polluted by the cyanide with a concentrations of 6.78 mg/L. The aquifer has an average linear ground water velocity of 0.256 m/day. Laboratory analyses data indicates that longitudinal dispersivity can be found through the equation: a = 0.86(log Ls)² where Ls is the length of the straight line path between two points along the path of transport. Find the longitudinal dispersion 108 m downstream from the bridge. Assume that the cyanide solute has a diffusion coefficient of 3.6 x 10 -5 m²/s and the aquifer has a coefficient related to tortuosity (o) equal to 0.8. Find the coefficient of hydrodynamic dispersion.

A settling tank having a depth of 3.5 m and surface area of 1000 m2 is used to remove particles of size 0.01 mm and specific gravity of 2.7. Calculate the removal percentage of the tank for a discharge of 7000 m3/d. Take viscosity of water as 10-3 kg/m.s.