Groundwater Recharge in a Fire-Adapted, Semi-Arid Forest: A Watershed Water Balance Approach

Area of Science:

• Hydrology
• Forest Ecology
• Climate Science

Background:

• Climate change and settlement have altered Arizona's ponderosa pine forests, increasing wildfire risk.
• Forest restoration programs aim to protect these forests and their watersheds.
• A paired-watershed study monitors forest thinning impacts on hydrology in the Upper Lake Mary watershed.

Purpose of the Study:

• To analyze historical water balance data in experimental watersheds.
• To quantify groundwater recharge and its influencing factors.
• To understand how forest restoration affects watershed hydrology.

Main Methods:

• Synthesized precipitation, runoff, groundwater recharge, soil moisture, and evapotranspiration (ET) data.
• Performed regression analyses for holistic water balance.
• Quantified seasonal groundwater recharge using the water table fluctuation method.

Main Results:

• Groundwater recharge did not occur annually and depended on winter precipitation and snowpack duration (P < 0.05).
• Recharge averaged 9% of the total water budget when present.
• Established a holistic water balance for seven experimental watersheds.

Conclusions:

• Forest restoration's impact on northern Arizona's forest hydrology is being understood.
• Findings provide crucial data for water policy and resource management.
• Informs future water availability planning in the region.