double Qsn = 0;
double totsed = sed + Sj1i*dt; // add upstream sed to sed present in cell
double totwater = vol + Qj1i*dt; // add upstream water to volume water in cell
if (totwater <= 1e-10)
return (Qsn);
Qsn = min(totsed/dt, Qj1i1 * totsed/totwater);
return (Qsn); // outflow is new concentration * new out flux