Studying the function it is easy to show that the discharge has a maximum at \(t\ =\ \Delta t\) equal to \(A\ p\ \left(1-\ e^{-\frac{\Delta t}{\lambda}}\right)\) and then decrease asymptotically to 0. In this case the concentration time is not defined but for any practical purpose this can be set when \(t\ \ge\lambda\ \ln\left(\frac{1}{\alpha}\left(e^{\frac{\Delta t}{\lambda}}-1\right)^{^{^{-1}}}\right)^{ }\) with \(\alpha>>1\). The discharge qualitative behavior is shown in Figure 5 below.