Coupling distributed stormwater collection and managed aquifer recharge: Field application and implications.

Area of Science:

• Hydrology
• Water Resource Management
• Environmental Engineering

Background:

• California faces increasing freshwater demand, making groundwater crucial.
• Groundwater overdraft has negative environmental consequences.
• Managed aquifer recharge (MAR) strategies, including distributed stormwater collection (DSC)-MAR, can augment groundwater supplies.

Purpose of the Study:

• To evaluate six years of DSC-MAR operational data.
• To analyze precipitation, runoff, infiltration, and sediment transport.
• To discuss implications for regional water resource management.

Main Methods:

• High-resolution analysis of precipitation, runoff generation, infiltration rates, and sediment transport over six years.
• Monitoring of 40-400 hectare drainage areas for DSC-MAR projects.
• Regional soil analyses to identify infiltration capacity and sediment sources.

Main Results:

• DSC-MAR projects infiltrated 5.3 × 10⁵ m³ of water over six years, including during a drought.
• Runoff generation strongly correlated with sub-daily storm characteristics.
• Average infiltration rates were 1-3 m/d, with significant spatial and temporal variation.
• 8.2 × 10⁵ kg of fine sediment accumulated in three years, potentially reducing infiltration.

Conclusions:

• DSC-MAR is a viable strategy for increasing groundwater supply and mitigating overdraft.
• Sediment management is critical for maintaining long-term infiltration efficiency.
• Regional soil characterization and strategic placement of DSC-MAR projects can optimize benefits, including improved water quality and flood mitigation.