Modeling Land Use and Land Cover Change
Photo of gas drilling rigs and well pads with Wind River Range, Wyoming in the background.

The physical footprint of well pads and roads associated with energy development results in the direct loss and fragmentation of species’ habitat. As energy development continues, it becomes increasingly important to important to identify design options that may minimize the effects to wildlife habitat and populations for specific energy production goals.

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How Can Modeling Change in Land Use and Land Cover Help Wildlife?

Southwestern Wyoming contains one of the Nation’s largest oil and natural gas reserves, a significant portion of the remaining intact sagebrush steppe, and some of the largest populations of sagebrush-associated wildlife species in the United States. The recent rate of oil and natural gas development in southwestern Wyoming is unprecedented (12,140 new wells between 2000 and 2012 compared to 9,664 wells over the preceding 100 years), and future development is expected at a similar rate (22,573 wells over the next 20–30 years). The effects of this future development on wildlife populations are important to determining conservation efforts in this sagebrush steppe ecosystem.

USGS ecologists developed an energy footprint model that simulates well, pad, and road patterns for oil and gas extraction options that vary in well types (vertical and directional) and number of wells per pad. Simulation models results were used to quantify physical and wildlife-habitat impacts. The model was applied to assess tradeoffs among 10 conventional and directional-drilling scenarios in a natural gas field in southwestern Wyoming. These simulation efforts address WLCI management needs to refine approaches and models for predicting future scenarios of land-use change and wildlife responses to these changes. Products of this work will help WLCI Local Project Development Teams prioritize habitat projects and provide information to land management agencies on the conservation potential of alternative energy build-out designs.

Key Findings
  • We found that for each reduction of 1,000 well pads, well pad and road surface disturbance declines by 17.7 square kilometers (km2).
  • Reducing pad numbers with directional-drilling technology reduced surface disturbance area and impacts on spatially extensive habitats (48–96% of study area) such as sagebrush-obligate songbird habitat, elk winter range, and sagebrush core area.
  • Impacts declined for spatially restricted mule deer migration corridors (24% of study area) and greater sage-grouse leks until energy infrastructure densities within corridors and near leks were similar to the initial landscape.

Study Objectives

The goal of this project is to develop and use a simulation approach to portray patterns of future oil and gas development and assess its potential effects on wildlife habitat in Southwest Wyoming. Scenario simulations and tradeoff assessments will identify land-management strategies that maximize persistence of habitat for wildlife species of special concern (such as sage grouse and sagebrush songbirds) and will help decision-makers identify development designs that best achieve both energy development and wildlife conservation goals.

Maps of simulated infrastructure (well pads and roads) density patterns in the Atlantic Rim Project Area in 2012 and 2027 using 500, 1000, and 2000 well pads.  Click to enlarge.

Energy infrastructure (wells and pads) in the Atlantic Rim Project Area at the start of the simulations (2012) and examples of simulated infrastructure patterns after 15 years (2027) using 500, 1000, and 2000 well pads.

How Can Modeling Future Energy Development Help Wildlife?

The model simulates future footprint of energy development under different assumptions of development rates, patterns, and densities. Integrated with the model are procedures to assess the potential effects of simulated footprints on wildlife. The footprint model uses energy build-out parameters and maps of exist­ing oil and gas infrastructure, subsurface mineral rights, and development restrictions to simulate the annual establishment of new wells, pads, and roads on the landscape. Build-out parameters, such as the total number of oil and gas wells, well density (number of wells per Public Land Survey System section), and the number of wells per pad, may be from an approved energy-development plan or may be experimental to assess a range of alternative well and pad configurations. The main outputs from the simulation model are time-stamped maps of initial and simulated pads and roads. Planners and wildlife managers can use these maps to assess potential effects on wildlife using published information about species’ responses to road, well, or pad densities. Measures of energy production (number of simulated wells), pad- and road-surface disturbance, and potential effects on wildlife are used to identify build-out designs that minimize the physical and ecological footprint of infrastructure for different levels of energy production and development costs.

A Model Example for Sage-grouse

Low to moderate reduction in sage-grouse lek activity (less than a 27% reduction) occurs with less than 1.2 wells/km2 (per square kilometer) and high to extreme reduction (greater than a 41% reduction) occurs with 1.2 or more wells/km2 within 3.2 km of a lek. For all three designs, all 42 leks in the study area had at least 0.5 well/km2 within 3.2 km.

Bar graph showing increasing amount of simulated surface disturbance after a 15 year development period
Bar graph showing

The model simulates the amount of surface disturbance after a period of time during which development takes place (here 15 years or 60 simulation replications). Click to enlarge.

Modeled effects of simulated energy development on Greater Sage-Grouse lek activity after a 15-years. Low to moderate reduction (<27%) in lek activity occurs with <1.2 wells/sq. km; high reduction (>41%) with >1.2 wells/sq. km within 3.2 km of leks.