Use of the Alaska Geotechnical Asset Management Database in Evaluation of Retaining Structures After an Earthquake

Since 2010, the Alaska Department of Transportation and Public Facilities, U.S., has been a leader in the development of geotechnical asset management (GAM) as part of a proactive approach to identify and rate the condition of geotechnical infrastructure. Efforts have included, for example, a retaining structure database that has cataloged retaining structures throughout Alaska. On November 30, 2018, a moment magnitude (MW) 7.1 earthquake struck southcentral Alaska, home of more than half of the state’s population. Damage to infrastructure was significant in several roadway corridors in the region. The GAM database was utilized as an important tool to assist in the identification of earthquake damaged retaining structures. Lessons learned from this effort are outlined in this paper. They include discussion on the elements of the database that were effective and others that may be improved on in the future. The information gathered from the field observations was also collected in such a manner that it could be added to the GAM database in the future as another snapshot in time for the retaining structures evaluated after the earthquake.

Vulnerability of Pacific salmon to invasion of northern pike (Esox lucius) in Southcentral Alaska

The relentless role of invasive species in the extinction of native biota requires predictions of ecosystem vulnerability to inform proactive management strategies. The worldwide invasion and range expansion of predatory northern pike (Esox lucius) has been linked to the decline of native fishes and tools are needed to predict the vulnerability of habitats to invasion over broad geographic scales. To address this need, we coupled an intrinsic potential habitat modelling approach with a Bayesian network to evaluate the vulnerability of five culturally and economically vital species of Pacific salmon (Oncorhynchus spp.) to invasion by northern pike. This study was conducted along 22,875 stream km in the Southcentral region of Alaska, USA. Pink salmon (O. gorbuscha) were the most vulnerable species, with 15.2% (2,458 km) of their calculated extent identified as “highly” vulnerable, followed closely by chum salmon (O. keta, 14.8%; 2,557 km) and coho salmon (O. kisutch, 14.7%; 2,536 km). Moreover, all five Pacific salmon species were highly vulnerable in 1,001 stream km of shared habitat. This simple to implement, adaptable, and cost-effective framework will allow prioritizing habitats for early detection and monitoring of invading northern pike.

Emerging Anthropogenic Influences on the Southcentral Alaska Temperature and Precipitation Extremes and Related Fires in 2019

The late-season extreme fire activity in Southcentral Alaska during 2019 was highly unusual and consequential. Firefighting operations had to be extended by a month in 2019 due to the extreme conditions of hot summer temperature and prolonged drought. The ongoing fires created poor air quality in the region containing most of Alaska’s population, leading to substantial impacts to public health. Suppression costs totaled over $70 million for Southcentral Alaska. This study’s main goals are to place the 2019 season into historical context, provide an attribution analysis, and assess future changes in wildfire risk in the region. The primary tools are meteorological observations and climate model simulations from the NCAR CESM Large Ensemble (LENS). The 2019 fire season in Southcentral Alaska included the hottest and driest June–August season over the 1979–2019 period. The LENS simulation analysis suggests that the anthropogenic signal of increased fire risk had not yet emerged in 2019 because of the CESM’s internal variability, but that the anthropogenic signal will emerge by the 2040–2080 period. The effect of warming temperatures dominates the effect of enhanced precipitation in the trend towards increased fire risk.