26 Computational Modelling in Hydraulic and Coastal Engineering
% Renewal of the contaminant concentrations;
C0=Cnew0;
C1=Cnew1;
C5=Cnew5;
m=n;
Cplot0(m)=C0;
Cplot1(m)=C1;
Cplot5(m)=C5;
end
m=n;
Cplot0(m)=C0;
Cplot1(m)=C1;
Cplot5(m)=C5;
plot(1:m,Cplot0,'b')
hold on
plot(1:m,Cplot1,'g')
plot(1:m,Cplot5,'m')
xlabel('Number of time steps')
ylabel('Contaminant concentration [g/m^3]')
text(800,6, 'pumping rate 5 m^3/s')
text(800,18, 'pumping rate 1 m^3/s')
text(800,34, 'no pumping')
PROBLEM 2.3
Solve the same problem by making the following suggested changes while
keeping the rest of the data constant:
1. Change the industrial discharge rate from 0.1 m 3 /s to 5.0 m 3 /s, and
plot the contaminant concentration for six tidal cycles.
2. Change the decaying rate from 10 –6 s –1 to 0.01 s –1 , and plot the difference of contaminant concentration between the two cases.
3. Change the initial concentration from 1.0 g/m 3 to 10.0 g/m 3 , and estimate the pumping rate required to drop the maximum concentration
level to less than 35 g/m 2 .
4. Estimate the pumping rate required to reduce the maximum contaminant concentration in the lagoon below the value of 15.0 g/m 3 if the
tidal effects are reduced by 50%.
5. For a zero pumping rate, estimate the necessary reduction in the
contaminant concentration of the industrial effluent in order for the
maximum concentration in the lagoon to be reduced by half.
Compare the solution data obtained by running these modifications, derive
conclusions and discuss the significance of the various variables involved in
the estimation of the contaminant concentration within the lagoon.