Runoff model (reservoir)

More precisely, it produces a surface runoff hydrograph in response to a rainfall event, represented by and input as a hyetograph.

When the study area is too large, it can be divided into sub-catchments and the various runoff hydrographs may be combined using flood routing techniques.

Otherwise, the factor A can be determined from a data record of rainfall and runoff using the method explained below under non-linear reservoir.

During periods without rainfall or recharge, i.e. when R = 0, the runoff equation reduces to or, using a unit time step (T2 − T1 = 1) and solving for Aq: Hence, the reaction or response factor Aq can be determined from runoff or discharge measurements using unit time steps during dry spells, employing a numerical method.

Figure 4 shows observed and simulated or reconstructed discharge hydrograph of the watercourse at the downstream end of the same valley.

Figures 3 and 4 were made with the RainOff program,[8] designed to analyse rainfall and runoff using the non-linear reservoir model with a pre-reservoir.

This fully object-oriented code provides complete flexibility in spatial discretization, interpolation, process representation, and forcing function generation.

The RS MINERVE software platform simulates the formation of free surface run-off flow and its propagation in rivers or channels.

Its purpose is to assist the hydrologist or water resources engineer to characterise the dynamic relationship between basin rainfall and streamflow.

A watershed or drainage basin
Figure 1. A linear reservoir
Figure 2. A non-linear reservoir
Figure 3. The reaction factor (Aq, Alpha) versus discharge (Q) for a small valley (Rogbom) in Sierra Leone
Figure 4. Actual and simulated discharge, Rogbom valley
Figure 5. Rainfall and recharge, Rogbom valley
Figure 6. Non-linear reservoir with pre-reservoir for recharge
Figure 7. Runoff from the water balance
The Nash Model uses a cascade of linear reservoirs to predict streamflow. Software for this model exists. [ 6 ]