Groundwater Drought Sensitivity of Southern Manitoba

Abstract

Groundwater level observations in Manitoba show that a drought affecting soil and surface water does not necessarily correspond to low water levels in aquifers. In fact, the opposite has been observed; groundwater levels have been at maximum high while a drought has been reported and, on the other hand, very low groundwater levels have been observed while summer precipitation has been well above average. Consequently it is necessary to differentiate a drought in the general sense from a groundwater drought. Hence the term groundwater drought should be used where drought in respect to groundwater is meant. Groundwater drought takes place when water level in an aquifer or a part of an aquifer that usually yields adequate supply drops to the base of the aquifer or to a level where wells are practically dry. Most aquifers in Manitoba are groundwater drought proof. In particular, major high yield aquifers developed for municipal and industrial requirements are drought proof. Only a few small areas in Manitoba, where the only potable water aquifers are formed by shallow surface sand with minimal saturated thickness, are groundwater drought sensitive. Drying up of wells should not be confused with groundwater drought; indications are that wells dry up now and did so more frequently in the past for various other reasons and only rarely can a dry well be related to groundwater drought.