Hello everyone,
I am simulating transient (seasonal recharge) groundwater flow and contaminant transport. I used a 2nd type boundary conditions for the contaminant source. The mass flux increase steadily for the fist half of the simulation and remains stable after. I am using a 3-D phratic model, and water-table fluctuation are important (5 m).
There is a drainage system, represented as a seepage nodes, 1 m of the 2nd type contaminant transport boundary and over 25 % of the source. The seepage nodes are active locally and mostly during high water conditions.. There are springs and rivers downgradient of the source. After some times, the mass inflow (2nd type) and the mass outflow (1st type) became stable. The concentration profiles became stable as well. Although this would indicate that steady state is reached, the mass outflow is about 20% higher than the inflow and at the end of the simulation, the imbalance is negative. What would be the cause of this? Is there is something in the mass balance that is calculated twice? For the inflow, I calculated the flux by the area and I obtain the same value as obtained with the budget analyser. The error might come freom the inflow
Also, I observed that when I do not consider seasoal recharge, the mass inflow is equal to the mass outflow at thr end of the simulation.
thanks in advance
driveshoe
