Quantifying ground water recharge at multiple scales using PRMS and GIS

Area of Science:

• Hydrology and Hydrogeology
• Water Resource Management
• Geographic Information Systems (GIS)

Background:

• Effective groundwater resource management necessitates accurate recharge rate calculations at various scales.
• Existing recharge estimation methods often fall short in accuracy, scalability, or data requirements.
• Distributed parameter models offer potential but are typically input-intensive.

Purpose of the Study:

• To present a GIS-aided procedure for defining inputs for distributed parameter models.
• To simplify the calibration of the Precipitation Runoff Modeling System (PRMS) for accurate recharge estimation.
• To validate the model's accuracy and applicability in both gauged and ungauged watersheds.

Main Methods:

• Development of a procedure to define model inputs using GIS and hydrogeological data.
• Simplification of PRMS calibration by reducing degrees of freedom from dozens to four.
• Application and validation of the GIS-aided model across seven watersheds (60-500 km²) and 63 subwatersheds (avg. 37 km²).

Main Results:

• GIS-aided calibration achieved average errors of 5% for recharge and 2% for total streamflow in gauged watersheds.
• Calculated average recharge rates for the study area were 11 cm/yr.
• Soil/rock conductivity, porosity, and water table depth were identified as key factors influencing recharge variability.
• The model reproduced total annual discharge and recharge within 9% and 10% in uncalibrated watersheds.

Conclusions:

• The developed GIS-aided distributed parameter model provides accurate and efficient groundwater recharge estimation.
• The methodology successfully simplifies model calibration and input definition, enhancing practicality.
• The model demonstrates significant potential for application in ungauged watersheds using available GIS and climate data.