| Life of reservoir || <math>t = \left( \frac{1}{D} \right) \ln \left( \frac{q_{\text{i}}}{q_{ec}} \right)</math> || <math>t = \left( \frac{q_{\rm i}}{q_{\rm ec}} \right)^n -\frac{1}{nD_{\rm i}}</math> | | Life of reservoir || <math>t = \left( \frac{1}{D} \right) \ln \left( \frac{q_{\text{i}}}{q_{ec}} \right)</math> || <math>t = \left( \frac{q_{\rm i}}{q_{\rm ec}} \right)^n -\frac{1}{nD_{\rm i}}</math> |