Infiltration to Groundwater at High Altitude

Abstract

Infiltration (or recharge) is the ultimate source of groundwater, and controls mine inflow, groundwater supply, and flow and solute transport behavior in large-scale groundwater systems. However, infiltration is rarely directly measurable, and is difficult to quantify. An 18 square kilometer area at 3,000 meters above sea level in the Rocky Mountain Cordillera of North America has been de-watered for the last century by a system of drainage tunnels, which has provided a rare opportunity to directly measure infiltration. Infiltration to deep groundwater was found to average 175 mm per year to the district, or 39% of the total precipitation of approximately 445 mm per year. These infiltration rates are significantly higher than the normal range of 5% to 10% of total precipitation that are identified at lower altitudes in this region, due to the effects of altitude, temperature, storm intensity, and thin soil cover in the district.