Multi-cell aquifer model: 4Xcell
The 4Xcell model has been developed to assist the study of the hydrological basin of Viotikos Kifissos River. The main goal is neither to replace existing fully-distributed models that have been developed for the specific basin nor to bring new theoretical knowledge in the field of water modelling. The needs that this model would serve regard the water management in large hydrological units, through a combined use of surface and ground water data, resulting in predictions for the groundwater level and the availability of surface water.
Description: Modelling the hydrological processes in a river basin, has been one of the main problems of hydrology. Several kinds of models have been developed. In this tool, the newly constructed semi-distributed model 4Xcell is presented, for the simultaneous simulation of evapotranspiration, runoff and karstic groundwater. It requires the subdivision of the area and the river κοίτη into sub-regions, a more or less continuous aquifer for the simulation of which quadruple cells are used. 4Xcell is accommodated in the very user-friendly environment of MS Excel®, it is calibrated by means of the advanced edition of the built-in Solver and the results include artificial time series for the aquifer water-levels, the groundwater storage, the actual evapotranspiration and the total runoff at the Karditsa outlet. It can be used on day, month or year basis.
4Xcell has been applied to the basin of Viotikos Kifissos in Central Hellas. It was calibrated for a five year period, due to lack of longer time-series, and verified for several other five-year periods. The results of the calibration show that the model is set on a very realistic platform, and that with more complete input data, great accuracy can be achieved. The results of the model verification, emphasize latter, as well as the need for long period calibration.
The model is constructed in the MSExcel® environment, which is user-friendly, and it does not make use of any VBA program or routine. Thus, it responds very quickly to any change of data or equation. The equations are being solved by means of an explicit method with a time step of a tenth of a month (almost 3 days). The calibration uses a combination of the “trial and error” method with the Excel® Solver, for the minimization of the objective function.