Annual rainfall (mm)	Run-off (mm)	Recharge (mm)	Change in groundwater storage (mm)	Natural groundwater recession (mm)	Human use (mm)	Balance to evapo- ration, change in soil moisture and other losses (mm)
1994–1995: 738	4	38	-34	72	1	695
1995–1996: 990	93	262	+100	162	1	634
1996–1997: 937	84	296	+62	234	1	556

Notes: Maximum values of recharge are calculated as rainfall minus potential evaporation and run-off during the period of groundwater rise, assuming no lateral flow or change in storage in the unsaturated zone. Specific yield S_y = 0.045 for the whole catchment, inferred from maximum values of recharge and measured groundwater rise across a network of piezometers. Change in groundwater storage is the annual change in groundwater level multiplied by specific yield. Recession is the difference between recharge and change in groundwater storage. Balance is calculated as rainfall minus run-off, recharge, and human use.