S49. Geomorphology of landscapes altered by wildfires and humans

Humans have altered the supply of water and sediment from landscapes in ways that challenge regional economies and ecosystems. In the western U.S. and the Pacific high islands, wildfires and feral ungulates expose soils and lower infiltration rates. Rainfalls that used to soak into hillslopes now initiate the runoff that causes hazardous floods and debris flows, and brings sediment pollution to reservoirs and nearshore ecosystems.  Below we describe two projects that illustrate the challenges these two landscape alterations bring, and the role that new technology could have improving our ability to forecast impacts. Our intent is to recruit a talented, motivated post-doctoral fellow who can leverage expertise in geomorphology and hydrology with the many technology opportunities in Silicon Valley.  This is an urgent need.

Project 1: Return-to-Reference Runoff, Post-wildfire Geomorphic Processes in northern & central California For the last several years in Northern California, communities have experienced devastating wildfires that killed more than 100 people and threatened local economies. Thousands of structures have been lost, as over 400,000 acres of suburban landscapes and steeplands burned. These events also change California’s landscapes overnight. The burned hillslopes they leave behind are much more susceptible to runoff, sediment movement and dust generation. Rains that once soaked into the soil may now generate floods and debris flows as well as threaten water quality. When winter storms hit these burned lands, downstream communities are threatened by:

• More severe flooding
• Reduced water quality for human and ecosystem needs
• Loss of lives and infrastructure from flooding and mass wasting processes

Local communities, non-governmental organizations (NGOs), and state and federal agencies spend hundreds of millions of dollars annually to mitigate the effects of wildfire and land degradation. In post-wildfire landscapes, they apply treatments to hillslopes and engineer temporary flood routing measures. California’s communities recognize the need for science that helps them prioritize mitigating these hazards, using scarce resources. They need to understand how long wildfire’s effects increase risk, and when the landscape has returned to reference runoff conditions. This effort will provide some of those tools by:

• Mapping geomorphic processes in fire-prone watersheds
• Using field experiments to monitor post-wildfire processes, including runoff and infiltration rate recovery post-fire
• Measuring soil and geologic properties that inform post-fire processes
• Estimating rainfall thresholds for runoff and sediment transport
• Delivering improved models for the time to return to pre-fire conditions (Return-to-Reference Runoff) and the spatial distribution of post-wildfire geomorphic processes

Possible outcomes for this project include: (a) geomorphic process maps; (b) measurements of soil hydrologic properties through time, (c) a timescale for post-fire soil hydrologic recovery (d) estimates of wildfire amplification of saturated hydraulic conductivity; (e) rainfall intensity thresholds for geomorphic processes; and (f) post-wildfire hillslope sediment and contaminant flux estimates.

Project 2: Ridge-to-Reef-Quantifying Geomorphic Processes in Hawaii to Protect Coral Reefs In the Hawaiian Islands, coral ecosystems support a vibrant tourist industry and provide tangible economic benefits to the community. This economy depends on a healthy coral ecosystem, which is increasingly under threat from local land based pollution caused by both wildfire and feral ungulate overgrazing.  During intense rainstorms, Hawaiian streams and bays are impacted by:

• Increased runoff from terrestrial sources
• Reduced water quality for human and ecosystem needs
• Impacts to infrastructure from flooding and turbid waters

Every year, federal, state and NGO partners invest substantial resources to mitigate coastal pollution and coral ecosystem degradation in the Pacific, Caribbean and elsewhere. The threat to coastal ecosystems is one that local communities can strongly influence, but they often lack the necessary tools and expertise to map sources of sediment pollution and quantify their supply rates and thresholds. This effort will provide some of those tools by:

• Mapping geomorphic processes to identify the major sources of terrestrial fine-sediment pollution to Hawaiian nearshore on Lanai or Maui
• Using field experiments to estimate what rainfalls trigger widespread erosion
• Using historic data to estimate the recurrence interval of geomorphically effective storms
• Modeling to improve estimates of annual sediment yield

Ultimately, the work will provide a logic for prioritizing mitigation strategies, such as ungulate control and revegetation. Possible outcomes for this project include: (a) geomorphic process maps; (b) rainfall intensity thresholds; (c) recurrence intervals for rainfalls causing sediment pollution; (d) modeled estimates of fine sediment erosion from the watershed.

What are we asking for? We are looking for proposals that cover the broad theme of mapping and monitoring water and sediment yields from altered landscapes through time by harnessing emerging new technologies using the triad of mapping, monitoring, and modeling (M3). For example, we could improve our ability to map the onset of different geomorphic processes from radar-derived rainfall intensity fields using machine learning on training data from time series of imagery (Planet or Capella radar) and high-resolution topography from lidar or structure-from motion. Within map units, we could harness new low-power wide area network technologies like LoRa to reduce the cost of real-time monitoring of soil moisture, rainfall intensity, hillslope runoff generation and streamflow in steepland streams. This level of mapping and monitoring data should inform and improve existing models for forecasting the supply of sediment and water from altered landscapes.  In short, choosing the most rewarding mitigation efforts in an environment of limited resources requires defensible landscape models that connect geology, hydrology, ecology, and meteorology.

Who will you work with? This opportunity is for a candidate who will use mapping, monitoring and modeling tools within the broad disciplines of geomorphology, hydrology, geologic mapping and soil science. No one Agency or institution has the ability to achieve all of the needed science by itself. That is why USGS is partnering with NASA, Carnegie-Mellon and the University of Southern California Viterbi School of Engineering on next-generation mapping and sensor technology. Our partnerships with industry and NGOs provide us with resources and testing areas in California and Hawaii. You will be part of a multi-disciplinary team that is mapping, monitoring, and modeling ecologic, hydrologic and geologic processes within altered landscapes. You will join over 200 hundred USGS scientists in the new USGS Moffett Field facility, located next door to NASA Ames, Carnegie Mellon Silicon Valley, and the Defense Innovation Unit. These partnerships and your funding will give you the opportunity to conduct cutting-edge geomorphology across altered landscapes in California and Hawaii.

Interested applicants are strongly encouraged to contact the Research Advisor(s) early in the application process to discuss project ideas.

Proposed Duty Station:  Moffett Field, CA

Areas of PhD: geology, hydrology, geography or related fields (candidates holding a Ph.D. in other disciplines, but with extensive knowledge and skills relevant to the Research Opportunity may be considered).

Qualifications: Applicants must meet the qualifications for Research Geologist, Research Hydrologist, Research Geographer.

(This type of research is performed by those who have backgrounds for the occupations stated above.  However, other titles may be applicable depending on the applicant's background, education, and research proposal. The final classification of the position will be made by the Human Resources specialist.)

Human Resources Office Contact: Audrey Tsujita, 916-278-9395, atsujita@usgs.gov