Environmental geology is the scientific study of the interaction between humans and the geological environment, applying geological principles to environmental problems. It examines how Earth’s natural processes affect people, such as through natural hazards, and conversely, how human activities impact Earth’s systems, like water resources and land stability. This field works to identify, prevent, and remediate environmental issues, focusing on public safety and environmental health. Environmental geologists provide foundational data necessary for informed land-use planning and sustainable development decisions.
Defining the Interdisciplinary Field
Environmental geology is an applied science that integrates knowledge from various specialized geological disciplines to address human-Earth interactions. It draws heavily from hydrogeology, which studies groundwater movement, and engineering geology, which applies geological data to civil engineering projects. Soil science is also closely related, as environmental geologists must understand the composition and behavior of near-surface materials affected by human activity.
Considering both spatial and temporal scales is a fundamental aspect of this work. Geologists must assess immediate human impacts, occurring over years or decades, against natural processes like rock weathering or mountain building, which unfold over thousands to millions of years. This requires distinguishing between the traditional study of Earth’s history and the practical, present-day focus of environmental geology on solving conflicts related to natural environment use.
The field differs from traditional geology because its primary objective is not merely to understand Earth’s past, but to forecast future environmental conditions and minimize degradation caused by human use. By analyzing the lithosphere, hydrosphere, and biosphere, environmental geologists create models to predict development outcomes. This multidisciplinary approach ensures that planning and policy decisions are grounded in a deep understanding of subsurface conditions and surface processes.
Assessment of Geologic Hazards
A major focus of environmental geology is assessing, mapping, and mitigating risks posed by natural geological events that threaten human infrastructure and life. This involves analyzing geohazards, including earthquakes, volcanic activity, and landslides. Geologists conduct fault zone mapping to determine the location and activity level of seismic structures, which is essential for developing local building codes and risk zoning.
Slope stability is analyzed through engineering geology techniques to identify areas prone to landslides, especially in mountainous or highly developed terrain. This analysis involves evaluating factors such as soil type, rock structure, water saturation, and the angle of repose, which determine the likelihood of mass movement. Data from these assessments create susceptibility maps that categorize areas for land-use planning.
For coastal regions, environmental geologists study the impact of tectonic movement and sea-level rise on shorelines. They analyze erosion rates and subsidence to predict coastal development vulnerability, informing protection and retreat strategies. Hazard data is translated into risk assessments that factor in event probability and population vulnerability, providing a basis for reducing potential losses through mitigation measures like zoning.
Management of Water and Mineral Resources
Resource management focuses on the sustainable utilization of Earth materials and the environmental consequences of extraction. Hydrogeology is central to understanding groundwater resources, studying aquifer properties like porosity and hydraulic conductivity to manage water supply. Environmental geologists assess the vulnerability of these water sources to contamination, recognizing that over-extraction can lead to aquifer depletion or saltwater intrusion in coastal areas.
Extraction activities for minerals and energy sources, such as mining and quarrying, present specific geological challenges. The removal of subsurface material can lead to ground subsidence, where the land surface collapses or sinks. Furthermore, exposing sulfide-rich rock to air and water can initiate a chemical reaction resulting in acid mine drainage (AMD).
AMD is highly acidic water rich in heavy metals like copper and zinc, which can persist long after mining operations have ceased. Environmental geologists assess the potential for AMD formation and design mitigation plans to control and treat this toxic runoff, managing tailings and waste rock. Similarly, oil and gas extraction, including hydraulic fracturing, requires geological input to manage the risk of contaminating freshwater aquifers with produced water, which can have high salinity.
Geologic Role in Waste Disposal and Cleanup
Environmental geology plays a role in managing the aftermath of human activity, specifically in safe waste disposal and site remediation. When selecting sites for landfills and hazardous waste facilities, geologists analyze subsurface conditions to ensure the location acts as a natural barrier to pollutant migration. This process prioritizes areas with low-permeability materials, such as clay or shale formations, and considers the water table depth to minimize groundwater contamination risk from leachate.
Understanding contaminant transport is a core function, involving modeling how pollutant plumes move through the soil and rock. This requires detailed characterization of subsurface heterogeneity, including fracture networks and lithological variations, which control the rate and direction of groundwater flow. Geologists use this information to define the site’s permeability architecture for predicting contaminant behavior.
For existing contaminated sites, environmental geologists use this data to develop conceptual site models that inform cleanup strategies. Subsurface knowledge dictates the feasibility of remediation methods, such as pump-and-treat systems, by predicting the effectiveness of pollutant removal from geological material. This application of geological principles ensures that cleanup efforts are targeted and efficient, restoring the quality of soil and water resources.