17. Data is collected from a 2.0km leach of a river somewhere as the river traverses a 20km wide farmland. The total runoff across the 2.5km reach is 275L/s and the concentration in the runoff is 185mgL. Conditions at point A are reported to be flow rate, Qn4=280000m3/d, and cross-sectional area, A= 42.20m2. UBOD along A-B decays with a rate coefficient of K1=0.43d1, base e. Assuming the loading conditions calculated in the 2.0km control zone apply across the whole farmland, and ignoring the effects of dilution along the section AB : (a) Calculate the flow rate and UBOD concentration in the river at the point B before adding the Point Source 1. (12pts) (b) Calculate the flow rate and UBOD concentration in the river at the point B after adding the Point Source 1 . ( 6 pts) (b) Using MS Excel or any other graphical software, plot the full profile from A to B to C in the river with the distributed loading A-B, and point source at B. ( 15pts) (c) Calculate the UBOD concentration at a downstream point C, 38km from point B, assuming constant velocity in the stream. The microbial community downstream of B is highly enriched by the incoming waste stream at B such that a higher degradation rate coefficient, K2=0.71d1, is observed. (4pts) (d) The 38km location downstream of B is used as an intake to fish farms and the UBOD limit at this location is stringently regulated at 10mgUBOD/L. Assuming that load superimposing could work, determine the distance upstream of the point C where a second waste load of UBOD =92.6 mg/L and Qw2=0.50m3/s shouk be located without violating the ambient limit of UBOD10 mg/L at point C. (12pts)