Water supplied to alluvial aquifers from streams during flood events, from irrigated agriculture, or from direct infiltration through the streambed is an important component of a river’s hydrology in many areas. Groundwater recharge controls shallow aquifer levels that support agricultural or municipal water well production, revitalizes wetlands, supports soil fertility, and may supply late- season baseflows to some streams and rivers. Groundwater recharge to alluvial aquifers may be limited by confinement of river with dikes or other flood control infrastructure, bisection of alluvial floodplains by transportation infrastructure, reduction in flood flow magnitude and recurrence interval due to dam operation, or alteration of irrigation application practices.
Groundwater recharge patterns may be important in the implementation phase of an SMP. For example, recharge patterns are relevant when developing riparian habitat plans or understanding how changes in irrigation practices affect river flows.
Assessing groundwater recharge can be done directly (through site specific studies of water flow) or indirectly (through models or indicators such as plant and soil types). SMPs in areas affected by groundwater recharge may want to assess:
Alluvial aquifer water table heights
Riparian and floodplain wetlands presence/absence/acreage
Flood overbanking frequency
Seasonal/annual groundwater level monitoring
Potential Data Sources
Each basin’s Water Resources Planning Model User’s Manuals calculates generalized return-flow patterns for different areas/types of water use in the basin