Translational Geomorphology for Disturbed and Managed Landscapes

Surface-process science for post-fire, mined, and water-resource systems.

We will continue the applied work where surface-process science meets land and resource management: post-fire sediment and water-quality response, the characterization and remediation of abandoned mine lands (including our current BLM program in Perry Canyon), and the resilience of watersheds and infrastructure such as hydropower and water-delivery systems to hazards amplified by climate and land-use change. (Cramer et al., 2021; Cramer, 2021; Felling et al., 2019; East et al., 2021)

This direction keeps our group working alongside the agencies and communities that use our science, ensuring that the fundamental advances above are returned to the people who depend on them. Across all of it runs the same logic that has guided our work to date: measure and map the process, model the mechanics, read the landscape, and deliver prediction.

References

2021

Mapping Potentially Acid Generating Material on Abandoned Mine Lands Using Remotely Piloted Aerial Systems

Alison S. Cramer, Wendy M. Calvin, Scott W. McCoy, and 3 more authors

Minerals, Apr 2021

Number: 4

Abs DOI

Weathering and transport of potentially acid generating material (PAGM) at abandoned mines can degrade downstream environments and contaminate water resources. Monitoring the thousands of abandoned mine lands (AMLs) for exposed PAGM using field surveys is time intensive. Here, we explore the use of Remotely Piloted Aerial Systems (RPASs) as a complementary remote sensing platform to map the spatial and temporal changes of PAGM across a mine waste rock pile on an AML. We focus on testing the ability of established supervised and unsupervised classification algorithms to map PAGM on imagery with very high spatial resolution, but low spectral sampling. At the Perry Canyon, NV, USA AML, we carried out six flights over a 29-month period, using a RPAS equipped with a 5-band multispectral sensor measuring in the visible to near infrared (400–1000 nm). We built six different 3 cm resolution orthorectified reflectance maps, and our tests using supervised and unsupervised classifications revealed benefits to each approach. Supervised classification schemes allowed accurate mapping of classes that lacked published spectral libraries, such as acid mine drainage (AMD) and efflorescent mineral salts (EMS). The unsupervised method produced similar maps of PAGM, as compared to supervised schemes, but with little user input. Our classified multi-temporal maps, validated with multiple field and lab-based methods, revealed persistent and slowly growing ‘hotspots’ of jarosite on the mine waste rock pile, whereas EMS exhibit more rapid fluctuations in extent. The mapping methods we detail for a RPAS carrying a broadband multispectral sensor can be applied extensively to AMLs. Our methods show promise to increase the spatial and temporal coverage of accurate maps critical for environmental monitoring and reclamation efforts over AMLs.
Mapping Temporal Changes of Erosion and Potentially Acid Generating Material on Abandoned Mine Lands Using Remotely Piloted Aerial Systems

Alison S. Cramer

University of Nevada, Reno, 2021

Publication Title: ProQuest Dissertations and Theses

Abs

Erosion, transport, and weathering of potentially acid generating material (PAGM) on abandoned mine lands (AMLs) can degrade downstream environments and contaminate surface and groundwater resources through exposure to acid mine drainage (AMD) and secondary sulfate minerals. Current AML monitoring techniques rely on field measurements, which can make monitoring the thousands of AMLs for exposed PAGM and erosion of cover material on mine waste rock piles time intensive. Remotely Piloted Aerial Systems (RPASs) provide a platform that can be combined with remote sensing and structure from motion photogrammetry techniques to quantify erosion from mine waste covers, and to map the temporal dispersion of PAGM. Here, we explore the use of RPASs as a complementary remote sensing platform to quantify erosion and map the spatial and temporal changes of PAGM on a mine waste rock pile remediated with a soil cover at the Perry Canyon, NV, USA AML. We carried out eleven flights over 29 months. We built five different mm resolution 3D point clouds using a RPAS equipped with a standard camera. We focused on quantifying erosion of the soil cover and erosion and deposition occurring in the creek adjacent to the mine waste rock pile. From these data, cm-scale surface changes on waste rock piles, soil covers, and subsequent erosion and deposition in the adjacent stream were mapped. Quantitative differencing of point clouds showed that 10.2 m3 of soil cover and waste rock were eroded over a 29-month time period. Additionally, we measured continued incision of the distinct rill network incised into the mine waste rock pile, indicating active and focused removal of cover material. Using a RPAS equipped with a 5-band multispectral sensor measuring in the visible to near infrared (400-1000 nm), we created six different 3 cm resolution orthorectified reflectance maps. We focused on testing the ability of established supervised and unsupervised classification algorithms to map PAGM on imagery with very high spatial resolution, but low spectral sampling. The unsupervised method produced similar maps of PAGM, as compared to supervised schemes, but with little user input. Our classified multi-temporal maps, validated with multiple field and lab-based methods, revealed persistent and slowly growing ’hotspots’ of jarosite, a secondary sulfate mineral, on the mine waste rock pile. The mapping methods we detail for RPASs carrying a broadband multispectral sensor can be applied extensively to AMLs. RPASs with standard cameras can provide high resolution data sets to calibrate and test erosion and transport models for more accurate predictions of cover maintenance and design. Our methods show promise to increase the spatial and temporal coverage of accurate maps critical for environmental monitoring and reclamation efforts over AMLs.
Watershed Sediment Yield Following the 2018 Carr Fire, Whiskeytown National Recreation Area, Northern California

Amy E. East, Joshua B. Logan, Peter Dartnell, and 4 more authors

Earth and Space Science, Sep 2021

Abs DOI

Wildfire risk has increased in recent decades over many regions, due to warming climate and other factors. Increased sediment export from recently burned landscapes can jeopardize downstream infrastructure and water resources, but physical landscape response to fire has not been quantified for some at-risk areas, including much of northern California, USA. We measured sediment yield from three watersheds (13–29 km2) that drain to Whiskeytown Lake, California, within the area burned by the 2018 Carr Fire. Structure-from-Motion photogrammetry on aerial images combined with sonar bathymetric mapping of submerged areas indicated first-year post-fire sediment yields of 4,080 ± 598 t/km2 (Brandy Creek), 2,700 ± 527 t/km2 (Boulder Creek), and 305 ± 58.0 t/km2 (Whiskey Creek)—some of the first post-fire yields measured in northern California and 64, 42, and 4.8 times greater than pre-fire yields, respectively. These were measured during a wet year and resulted largely from rilling erosion and fluvial sediment transport, without post-fire debris flows. Rilling preferentially developed in contact with dirt roads, aided by thin soils and exposed bedrock, and on slopes vegetated by chaparral pre-fire. The second post-fire year (a dry year) was characterized by fluvial reworking and delta progradation of the first-year deposits and relatively little new sediment export. First-year sedimentation of 111,000 m3 represented minor loss of storage capacity in Whiskeytown Lake but would be detrimental to smaller reservoirs; in general, increased sediment yields from western US watersheds as fire and extreme rainfall increase will likely pose risks to water quality and storage.

2019

Post-fire debris-flow hazard analysis for Interstate 80, Truckee River Canyon, near the California-Nevada state line, USA.

Garrett Felling, Andrew Myers, and Scott W McCoy

2019

Abs

On July 9, 2017, west of the California-Nevada state line, USA, the 2.8 km2 Farad fire burned steep slopes above Interstate 80. On the evening of August 18, 2017, a localized convective storm produced short-duration, moderate-intensity rain, which in turn triggered debris flows in a historically inactive basin. These flows impacted Interstate 80. At least four additional debris flows, not related to wildfire, have occurred along this section of road since 2013, but during much higher intensity rainfall. Here we utilize the history of pre- and post-fire debris flows along this section of Interstate 80 to explore the impacts of wildfire on debris flows. Specifically, we combine pre- and post-fire rainfall data and field measurements with empirical debris-flow models to quantify the impacts wildfire had on debris-flow generation and to estimate the likelihood and magnitude of future events. A characteristic pre-fire debris flow occurred on July 25, 2013 in a susceptible path ~30 minutes after rainfall began and during peak 15-minute intensities of ~50 mm/hr. This event closed both east and westbound lanes of Interstate 80. No other nearby paths had debris flows during this rainstorm. In contrast, one month post-fire, on August 18, 2017 a debris flow occurred in a historically inactive path, but within an area of high burn severity. Debris-flow initiation occurred ~30 minutes after the beginning of rainfall, but with peak 15-minute intensities of only ~26 mm/hr. This amplified rainfall-runoff response is consistent with fire-induced changes in soil hydraulic properties for which we measured post-fire decreases of a factor of 2 in field-saturated hydraulic conductivity and a factor of 4 in sorptivity. From field measurements, total volume estimates for the August 18, 2017 post-fire debris-flow event ranged between 1270 and 4700 m3 depending on assumptions regarding pre-event channel geometry and volume of hillslope sediment transported. A shallow landslide that liquefied and flowed into the channel contributed ~450 m of material and was apparently triggered by concentrated overland flow off an old road into the toe slope of a much older deepseated landslide. Debris flows eroded most of the travel path above the fan to bedrock and contributed \textgreater850 m of debris, at a nearly uniform spatial rate, both of which suggest this event was likely limited by sediment availability. Just 100-150 m above Interstate 80 the flow transported boulders with maximum diameters in excess of 1 m, at peak velocities of ~2-5 m/s. We used the analysis of the August 18, 2017 debris-flow event to verify empirical equations developed by the USGS for predicting the probability, total volume, and runout distance of post-fire debris flows. We found good agreement between model output and observations and hence used these equations to predict characteristics of debris flows likely to occur in the near future.