CHARACTERIZING THE IMPACTS OF SEISMIC EXPLORATION LINES ON THE HYDROLOGIC BUDGET AND VADOSE ZONE OF A WEST-CENTRAL ALBERTA WATERSHED

A project assessing the effects of seismic exploration lines on the eco-hydrology of a 700 km² forested region in the Fox Creek watershed, west-central Alberta, with a focus on the vadose zone, was initiated in June 2021. This area was selected because it has been one of the most active regions for hydrocarbon production in Canada for the past 50 years, having a density of 3.3 km/km² of seismic exploration lines in the region. These seismic lines have impacted localized surficial hydrology, vegetation, predator-prey dynamics, and showed minimal regeneration back to pre-disturbance conditions. Data collection has occurred at five locations in the study area over two growing seasons on a monthly basis. Each study site is instrumented at disturbed (i.e., areas impacted by seismic exploration lines) and undisturbed sites.

Vadose zone data are collected using soil moisture and temperature sensors along with porewater lysimeters monitored at three depths. Preliminary results show that soil moisture and temperature values in the vadose zone are quite different between the disturbed and undisturbed, indicating differences in the various water budget components. Soil-water geochemistry data show a variation in seasonality, depth of sampling, and ecosite types. The vadose zone water throughout the study area is predominantly of the CaHCO₃ type, corresponding to relatively young water (i.e., little chemically evolved), that is strongly influenced by the mineralogical composition of the soil. The chemical analyses of the soils have indeed shown that calcium is by far the most dominant element. This same type of water is found in the underlying bedrock aquifer, in its upstream parts (along the perimeter), while the central parts of the aquifer contain more of the NaHCO₃ type of water (a little more chemically evolved). Soils impacted by seismic exploration lines show a slightly higher bulk density compared to those not impacted, particularly in the upper 30 cm of the soil profile. Rainwater collectors were installed and are being used to establish a local meteoric water line for the area to aid in interpreting groundwater provenance and recharge for the Paskapoo Aquifer. Weather station data collected on site indicates profound differences in evapotranspiration in disturbed and undisturbed sites.