The first set of date is during the pumping stage, and a second set after the pump is turned off, when recovery levels are recorded in the observation well. In most models used to determine aquifer parameters, the discharge of the pumping well is supposed to be held constant. In practice, constant discharge is difficult to maintain. Deviations may be caused by voltage fluctuations, and the vertical increases in pumping distance caused by drawdown in the well. Recovery data is recorded after the pump is turned off and is free of these mechanical problems and a constant negative discharge is assumed.
Many modern geologists lump alluvial fans with braided river systems or gravel bed rivers.
Fans are grouped with braided streams based on comparative morphology not stratigraphic evidence. Geologist attribute these channels to fluvial processes. The best way to separate alluvial fans deposits and river systems deposits is to focus on the processes that built them. Alluvial fans are constructed in a unique environment, different than that of river systems. Slope is the critical difference between river systems and alluvial fans.