There are several processes that may occur individually or in conjunction with other processes to recharge groundwater in the alluvia: infiltration, discharge from surrounding water bearing geologies, and inundation. This conceptual model illustrates the recharge process of alluvial aquifers during inundation events (e.g. flooding).
- During a flood event channel flow increases and water levels rise. This may result in groundwater in the alluvia and surrounding geologies being recharged from the channel (see top box).
- After a flood event channel flow decreases and water levels drop. The additional groundwater stored in the alluvia and surrounding geologies will slowly discharge to the channel over time. During this period vegetation on terraces surrounding the channel may depend on the sub-surface presence of groundwater to meet some or all of their water requirements provided the vegetation can access the capillary zone (see middle box).
- Recharge from surrounding fractured hard rock or porous sedimentary rock may assist in maintaining groundwater levels in the alluvia and supporting specialised aquatic fauna, stygofauna, which are groundwater dependent (see bottom box).
Pictorial conceptual model PDF