Hydro-sedimentological Monitoring and Analysis for Material Sites on the Sagavanirktok River

Researchers from the Water and Environmental Research Center at the Institute of Northern Engineering, University of Alaska Fairbanks, are conducting a research project related to sediment transport conditions along the Sagavanirktok River. This report presents tasks conducted from summer 2015 to early winter 2016. Four hydrometeorological stations were installed in early July 2015 on the west bank of the river. The stations are spread out over a reach of approximately 90 miles along the Dalton Highway (from MP 405, the northernmost location, to MP 318, the southernmost location). These stations are equipped with pressure transducers and with air temperature, relative humidity, wind speed, wind direction, barometric pressure, and turbidity sensors. Cameras were installed at each station, and automatic water samplers were deployed during the open-water season. The stations have a telemetry system that allows for transmitting data in near-real time. Discharge measurements were performed three times: twice in July (early and late in the month), and once in mid-September. Measured discharges were in the order of 100 m3/s, indicating that measurements were performed during low flows. Suspended sediment concentrations ranged from 2 mg/l (nearly clear water) to 625 mg/l. The average grain size for suspended sediment from selected samples was 47.8 μm, which corresponds to silt. Vegetation was characterized at 27 plots near the stations. Measurements of basic water quality parameters, performed during winter, indicated no potential issues at the sampled locations. Dry and wet pits were excavated in the vicinity of each station. These trenches will be used to estimate average bedload sediment transport during spring breakup 2016. A change detection analysis of the period 1985–2007 along the area of interest revealed that during the present study period, the river was relatively stable.ABSTRACT ..................................................................................................................................... i LIST OF FIGURES ....................................................................................................................... iv LIST OF TABLES ......................................................................................................................... vi ACKNOWLEDGMENTS ............................................................................................................ vii DISCLAIMER .............................................................................................................................. vii CONVERSION FACTORS, UNITS, WATER QUALITY UNITS, VERTICAL AND HORIZONTAL DATUM, ABBREVIATIONS, AND SYMBOLS ........................................... viii ABBREVIATIONS, ACRONYMS, AND SYMBOLS ................................................................. x 1 INTRODUCTION AND STUDY AREA ............................................................................... 1 2 METHODOLOGY AND EQUIPMENT .............................................................................. 11 2.1 Pit Trenches .................................................................................................................... 12 2.2 Meteorology ................................................................................................................... 13 2.3 Water Level Measurements ............................................................................................ 13 2.4 Runoff............................................................................................................................. 14 2.5 Suspended Sediment ...................................................................................................... 15 2.6 Turbidity ......................................................................................................................... 15 2.7 Substrate and Floodplain Vegetation Survey ................................................................. 16 2.7.1 Site selection ........................................................................................................... 16 2.7.2 Quantifying substrate .............................................................................................. 16 2.7.3 Characterizing vegetation ....................................................................................... 17 3 RESULTS .............................................................................................................................. 19 3.1 Pit Trench Configuration ................................................................................................ 19 3.2 Meteorology ................................................................................................................... 27 3.3 Water Level Observations .............................................................................................. 27 3.4 Runoff............................................................................................................................. 31 3.4.1 Additional runoff observations ............................................................................... 31 3.5 Suspended Sediment ...................................................................................................... 32 3.6 Suspended Sediment Grain-Size Distribution ................................................................ 34 3.7 Turbidity ......................................................................................................................... 35 3.8 Water Quality ................................................................................................................. 37 4 ANALYSIS ........................................................................................................................... 39 4.1 Substrate and Vegetation ................................................................................................ 39 4.1.1 Substrate .................................................................................................................. 39 iii 4.1.2 Vegetation ............................................................................................................... 40 4.2 River Channel Stability .................................................................................................. 42 5 CONCLUSIONS ................................................................................................................... 56 6 REFERENCES ...................................................................................................................... 58 7 APPENDICES ....................................................................................................................... 6

Sagavanirktok River Spring Breakup Observations 2016

In 2015, spring breakup on the Sagavanirktok River near Deadhorse was characterized by high flows that destroyed extensive sections of the Dalton Highway, closing the road for nearly 3 weeks. This unprecedented flood also damaged infrastructure that supports the trans-Alaska pipeline, though the pipeline itself was not damaged. The Alaska Department of Transportation and Public Facilities (ADOT&PF) and the Alyeska Pipeline Service Company made emergency repairs to their respective infrastructure. In December 2015, aufeis accumulation was observed by ADOT&PF personnel. In January 2016, a research team with the University of Alaska Fairbanks began monitoring and researching the aufeis and local hydroclimatology. Project objectives included determining ice elevations, identifying possible water sources, establishing surface meteorological conditions prior to breakup, measuring hydrosedimentological conditions (discharge, water level, and suspended sediment concentration) during breakup, and reviewing historical imagery of the aufeis feature. Ice surface elevations were surveyed with Global Positioning System (GPS) techniques in late February and again in mid-April, and measureable volume changes were calculated. However, river ice thickness obtained from boreholes near Milepost 394 (MP394) in late February and mid-April revealed no significant changes. It appears that flood mitigation efforts by ADOT&PF in the area contributed to limited vertical growth in ice at the boreholes. End-of-winter snow surveys throughout the watershed indicate normal or below normal snow water equivalents (SWE 10 cm). An imagery analysis of the lower Sagavanirktok aufeis from late winter for the past 17 years shows the presence of ice historically at the MP393–MP396 area. Water levels and discharge were relatively low in 2016 compared with 2015. The mild breakup in 2016 seems to have been due to temperatures dropping below freezing after the flow began. Spring 2015 was characterized by warm temperatures throughout the basin during breakup, which produced the high flows that destroyed sections of the Dalton Highway. A comparison of water levels at the East Bank Station during 2015 and 2016 indicates that the 2015 maximum water level was approximately 1 m above the 2016 maximum water level. ii Maximum measured discharge in 2016 was approximately half of that measured in 2015 in the lower Sagavanirktok River. Representative suspended sediment sizes (D50) ranged from 20 to 50 microns (medium to coarse silt). An objective of this study was to determine the composition and possible sources of water in the aufeis at the lower Sagavanirktok River. During the winter months and prior to breakup in 2016, overflow water was collected, primarily near the location of the aufeis, but also at upriver locations. Simultaneously possible contributing water sources were sampled between January and July 2016, including snow, glacial meltwater, and river water. Geochemical analyses were performed on all samples. It was found that the overflow water which forms the lower Sagavanirktok aufeis is most similar (R2 = 0.997) to the water that forms the aufeis at the Sagavanirktok River headwaters (Ivishak River), thought to be fed by relatively consistent groundwater sources.ABSTRACT ..................................................................................................................................... i LIST OF FIGURES ........................................................................................................................ v LIST OF TABLES ......................................................................................................................... ix ACKNOWLEDGMENTS AND DISCLAIMER ........................................................................... x CONVERSION FACTORS, UNITS, WATER QUALITY UNITS, VERTICAL AND HORIZONTAL DATUM, ABBREVIATIONS, AND SYMBOLS ............................................. xi ABBREVIATIONS, ACRONYMS, AND SYMBOLS .............................................................. xiii 1 INTRODUCTION ................................................................................................................... 1 2 STUDY AREA ........................................................................................................................ 6 3 METHODOLOGY AND EQUIPMENT ................................................................................ 6 3.1 Aufeis Extent .................................................................................................................... 7 3.1.1 Field Methods ........................................................................................................... 7 3.1.2 Structure from Motion Imagery ................................................................................ 8 3.1.3 Imagery ..................................................................................................................... 8 3.2 Surface Meteorology ...................................................................................................... 10 3.3 Water Levels .................................................................................................................. 11 3.4 Discharge Measurements ............................................................................................... 13 3.5 Suspended Sediment ...................................................................................................... 16 3.6 Water Chemistry ............................................................................................................ 17 3.6.1 Sampling ................................................................................................................. 17 3.6.2 Trace Element Analysis .......................................................................................... 19 3.6.3 Data Analysis .......................................................................................................... 19 4 RESULTS .............................................................................................................................. 20 4.1 Air Temperature ............................................................................................................. 20 4.2 Wind Speed and Direction ............................................................................................. 29 4.3 Annual Precipitation ....................................................................................................... 30 4.4 Cold Season Precipitation .............................................................................................. 32 4.5 Warm Season Precipitation ............................................................................................ 36 4.6 Aufeis Extent .................................................................................................................. 40 4.6.1 Historical Aufeis at Franklin Bluffs ........................................................................ 40 4.6.2 Delineating Ice Surface Elevation with GPS and Aerial Imagery .......................... 46 4.6.3 Ice Boreholes .......................................................................................................... 55 iv 4.6.4 Ice Accumulation (SR50) ....................................................................................... 58 4.6.5 Ice Thickness and Volume ...................................................................................... 60 4.7 Surface Water Hydrology............................................................................................... 62 4.7.1 Sagavanirktok River at MP318 (DSS4) .................................................................. 67 4.7.2 Sagavanirktok River at Happy Valley (DSS3) ....................................................... 70 4.7.3 Sagavanirktok River Below the Ivishak River (DSS2)........................................... 73 4.7.4 Sagavanirktok River at East Bank (DSS5) Near Franklin Bluffs ........................... 76 4.7.5 Sagavanirktok River at MP405 (DSS1) West Channel .......................................... 85 4.7.6 Additional Field Observations ................................................................................ 86 4.8 Suspended Sediment ...................................................................................................... 87 4.9 Water Chemistry ............................................................................................................ 91 5 CONCLUSIONS ................................................................................................................... 96 6 REFERENCES ...................................................................................................................... 99 7 APPENDICES ..................................................................................................................... 10

Hydrological, Sedimentological, and Meteorological Observations and Analysis on the Sagavanirktok River

The Dalton Highway near Deadhorse was closed twice during late March and early April 2015 because of extensive overflow from the Sagavanirktok River that flowed over the highway. That spring, researchers from the Water and Environmental Research Center at the University of Alaska Fairbanks (UAF) monitored the river conditions during breakup, which was characterized by unprecedented flooding that overtopped and consequently destroyed several sections of the Dalton Highway near Deadhorse. The UAF research team has monitored breakup conditions at the Sagavanirktok River since that time. Given the magnitude of the 2015 flooding, the Alyeska Pipeline Service Company started a long-term monitoring program within the river basin. In addition, the Alaska Department of Transportation and Public Facilities (ADOT&PF) funded a multiyear project related to sediment transport conditions along the Sagavanirktok River. The general objectives of these projects include determining ice elevations, identifying possible water sources, establishing surface hydro-meteorological conditions prior to breakup, measuring hydro-sedimentological conditions during breakup and summer, and reviewing historical imagery of the aufeis extent. In the present report, we focus on new data and analyze it in the context of previous data. We calculated and compared ice thickness near Franklin Bluffs for 2015, 2016, and 2017, and found that, in general, ice thickness during both 2015 and 2016 was greater than in 2017 across most of the study area. Results from a stable isotope analysis indicate that winter overflow, which forms the aufeis in the river area near Franklin Bluffs, has similar isotopic characteristics to water flowing from mountain springs. End-of-winter snow surveys (in 2016/2017) within the watershed indicate that the average snow water equivalent was similar to what we observed in winter 2015/2016. Air temperatures in May 2017 were low on the Alaska North Slope, which caused a long and gradual breakup, with peak flows occurring in early June, compared with mid-May in both 2015 and 2016. Maximum discharge measured at the East Bank station, near Franklin Bluffs was 750 m3/s (26,485 ft3/s) on May 30, 2017, while the maximum measured flow was 1560 m3/s (55,090 ft3/s) at the same station on May 20, 2015. Available cumulative rainfall data indicate that 2016 was wetter than 2017. ii In September 2015, seven dry and wet pits were dug near the hydro-sedimentological monitoring stations along the Sagavanirktok River study reach. The average grain-size of the sediment of exposed gravel bars at sites located upstream of the Ivishak-Sagavanirktok confluence show relatively constant values. Grain size becomes finer downstream of the confluence. We conducted monthly topo-bathymetric surveys during the summer months of 2016 and 2017 in each pit. Sediment deposition and erosion was observed in each of the pits. Calculated sedimentation volumes in each pit show the influence of the Ivishak River in the bed sedimenttransport capacity of the Sagavanirktok River. In addition, comparison between dry and wet pit sedimentation volumes in some of the stations proves the complexity of a braided river, which is characterized by frequent channel shifting A two-dimensional hydraulic model is being implemented for a material site. The model will be used to estimate the required sediment refill time based on different river conditions.ABSTRACT ..................................................................................................................................... i LIST OF FIGURES ......................................................................................................................... i LIST OF TABLES ....................................................................................................................... xiv ACKNOWLEDGMENTS AND DISCLAIMER ........................................................................ xvi CONVERSION FACTORS, UNITS, WATER QUALITY UNITS, VERTICAL AND HORIZONTAL DATUM, ABBREVIATIONS, AND SYMBOLS .......................................... xvii ABBREVIATIONS, ACRONYMS, AND SYMBOLS .............................................................. xix 1 INTRODUCTION ................................................................................................................... 1 2 STUDY AREA ........................................................................................................................ 2 2.1 Sagavanirktok River near MP318 Site 066 (DSS4) ......................................................... 7 2.2 Sagavanirktok River at Happy Valley Site 005 (DSS3) .................................................. 7 2.3 Sagavanirktok River below the Confluence with the Ivishak River (DSS2) ................... 9 2.4 Sagavanirktok River near MP405 Site 042 (DSS1) ....................................................... 10 3 METHODOLOGY AND EQUIPMENT .............................................................................. 13 3.1 Pits .................................................................................................................................. 13 3.1.1 Excavation............................................................................................................... 13 3.1.2 Surveying ................................................................................................................ 14 3.2 Surface Meteorology ...................................................................................................... 15 3.3 Aufeis Extent .................................................................................................................. 17 3.3.1 Field Methods ......................................................................................................... 18 3.3.2 Imagery ................................................................................................................... 18 3.4 Water Level Measurements ............................................................................................ 19 3.5 Runoff............................................................................................................................. 20 3.6 Suspended Sediment ...................................................................................................... 21 3.7 Turbidity ......................................................................................................................... 22 3.8 Stable Isotopes................................................................................................................ 22 4 RESULTS .............................................................................................................................. 23 4.1 Meteorology ................................................................................................................... 23 4.1.1 Air Temperature ...................................................................................................... 23 4.1.2 Precipitation ............................................................................................................ 31 4.1.2.1 Cold Season Precipitation ................................................................................ 31 4.1.2.2 Warm Season Precipitation ............................................................................. 36 4.1.3 Wind Speed and Direction ...................................................................................... 39 iv 4.2 Aufeis Extent .................................................................................................................. 40 4.2.1 Historical Aufeis at Franklin Bluffs ........................................................................ 41 4.2.2 Delineating Ice Surface Elevation with GPS and Aerial Imagery .......................... 45 4.3 Surface Water Hydrology ............................................................................................... 52 4.3.1 Sagavanirktok River at MP318 (DSS4) .................................................................. 58 4.3.2 Sagavanirktok River at Happy Valley (DSS3) ....................................................... 61 4.3.3 Sagavanirktok River near MP347 (ASS1) .............................................................. 65 4.3.4 Sagavanirktok River below the Ivishak River (DSS2) ........................................... 66 4.3.5 Sagavanirktok River at East Bank (DSS5) near Franklin Bluffs ............................ 70 4.3.6 Sagavanirktok River at MP405 (DSS1) West Channel .......................................... 78 4.3.7 Additional Field Observations ................................................................................ 82 4.3.8 Preliminary Rating Curves and Estimated Discharge ............................................. 85 4.4 Stable Isotopes................................................................................................................ 86 4.5 Sediment Grain Size Distribution .................................................................................. 90 4.5.1 Streambed Sediment Grain Size Distribution ......................................................... 90 4.5.2 Suspended Sediment Grain Size Distribution ......................................................... 94 4.6 Suspended Sediment Concentration ............................................................................... 95 4.6.1 Sagavanirktok River near MP318 (DSS4) .............................................................. 95 4.6.2 Sagavanirktok River at Happy Valley (DSS3) ..................................................... 100 4.6.3 Sagavanirktok River below the Ivishak River (DSS2) ......................................... 105 4.6.4 Sagavanirktok River near MP405 (DSS1) ............................................................ 111 4.6.5 Discussion ............................................................................................................. 114 4.7 Turbidity ....................................................................................................................... 116 4.7.1 Sagavanirktok River near MP318 (DSS4) ............................................................ 116 4.7.2 Sagavanirktok River at Happy Valley (DSS3) ..................................................... 119 4.7.3 Sagavanirktok River below the Ivishak (DSS2) ................................................... 124 4.7.4 Sagavanirktok River near MP405 (DSS1) ............................................................ 126 4.7.5 Discussion ............................................................................................................. 130 4.8 Analysis of Pits............................................................................................................. 130 4.8.1 Photographs of Pits ............................................................................................... 130 4.8.2 GIS Analysis of Pit Bathymetry ........................................................................... 141 4.8.3 Pit Sedimentation .................................................................................................. 142 4.8.4 Erosion Surveys .................................................................................................... 149 4.8.5 Patterns of Sediment Transport Along the River .................................................. 156 v 4.9 Hydraulic Modeling ..................................................................................................... 158 4.9.1 Model Development .............................................................................................. 160 4.9.2 Results of Simulation ............................................................................................ 165 5 CONCLUSIONS ................................................................................................................. 171 6 REFERENCES .................................................................................................................... 174 7 APPENDICES ..................................................................................................................... 18

Reviews and syntheses: Changing ecosystem influences on soil thermal regimes in northern high-latitude permafrost regions

Soils in Arctic and boreal ecosystems store twice as much carbon as the atmosphere, a portion of which may be released as high-latitude soils warm. Some of the uncertainty in the timing and magnitude of the permafrost–climate feedback stems from complex interactions between ecosystem properties and soil thermal dynamics. Terrestrial ecosystems fundamentally regulate the response of permafrost to climate change by influencing surface energy partitioning and the thermal properties of soil itself. Here we review how Arctic and boreal ecosystem processes influence thermal dynamics in permafrost soil and how these linkages may evolve in response to climate change. While many of the ecosystem characteristics and processes affecting soil thermal dynamics have been examined individually (e.g., vegetation, soil moisture, and soil structure), interactions among these processes are less understood. Changes in ecosystem type and vegetation characteristics will alter spatial patterns of interactions between climate and permafrost. In addition to shrub expansion, other vegetation responses to changes in climate and rapidly changing disturbance regimes will affect ecosystem surface energy partitioning in ways that are important for permafrost. Lastly, changes in vegetation and ecosystem distribution will lead to regional and global biophysical and biogeochemical climate feedbacks that may compound or offset local impacts on permafrost soils. Consequently, accurate prediction of the permafrost carbon climate feedback will require detailed understanding of changes in terrestrial ecosystem distribution and function, which depend on the net effects of multiple feedback processes operating across scales in space and time

Landsat time series analysis documents beaver migration into permafrost landscapes of arctic Alaska

Landscape-scale impacts of climate change in the Arctic include increases in growing season length, shrubby vegetation, winter river discharge, snowfall, summer and winter water temperatures, and decreases in river and lake ice thickness. Combined, these changes may have created conditions that are suitable for beaver colonization of low Arctic tundra regions. We developed a semi-automated workflow that analyzes Landsat imagery time series to determine the extent to which beavers may have colonized permafrost landscapes in arctic Alaska since 1999. We tested this approach on the Lower Noatak, Wulik, and Kivalina river watersheds in northwest Alaska and identified 83 locations representing potential beaver activity. Seventy locations indicated wetting trends and 13 indicated drying trends. Verification of each site using high-resolution satellite imagery showed that 80 % of the wetting locations represented beaver activity (damming and pond formation), 11 % were unrelated to beavers, and 9 % could not readily be distinguished as being beaver related or not. For the drying locations, 31 % represented beaver activity (pond drying due to dam abandonment), 62 % were unrelated to beavers, and 7 % were undetermined. Comparison of the beaver activity database with historic aerial photography from ca. 1950 and ca. 1980 indicates that beavers have recently colonized or recolonized riparian corridors in northwest Alaska. Remote sensing time series observations associated with the migration of beavers in permafrost landscapes in arctic Alaska include thermokarst lake expansion and drainage, thaw slump initiation, ice wedge degradation, thermokarst shore fen development, and possibly development of lake and river taliks. Additionally, beaver colonization in the Arctic may alter channel courses, thermal regimes, hyporheic flow, riparian vegetation, and winter ice regimes that could impact ecosystem structure and function in this region. In particular, the combination of beaver activity and permafrost dynamics may play an important role in the formation of habitats conducive to colonization by Pacific salmon. Beaver activity in arctic tundra regions may amplify the effects of climate change on permafrost landscapes and lead to landscape-scale responses not currently being considered in ecosystem models

Impacts of Vegetation on the Decoupling between Air and Soil Temperatures across the Arctic

A rise in global air temperatures is expected to increase permafrost thaw and alter ecosystem carbon and water cycles in Arctic regions. The coupling between the soil temperature in the active layer (soil between the ground surface and permafrost) and air temperature is a key component in understanding permafrost stability and ecosystem change. Vegetation can affect soil temperature through a variety of mechanisms such as canopy shading, impacts on soil thermal conductivity via soil organic inputs or soil water uptake, albedo, and winter snow trapping. However, the relative importance of the vegetative effects on soil temperature is uncertain across large spatial scales and across different vegetative communities and ecosystem types. We compiled data on a Pan-Arctic scale pairing air and soil temperature with vegetation and ecosystem data to examine the impacts of vegetation on the decoupling of air and soil temperatures. We analyzed the summer thawing degree days, winter freezing degree days, and n factors (degree days soil/degree days air) from sites across the Arctic. Our results indicate that the decoupling between summer air and soil temperatures is more variable in boreal ecosystems than tundra ecosystems, and boreal ecosystems have lower winter n-factors than tundra ecosystems. Summer n-factors were more variable than winter n-factors, and had high variability within study sites. Vegetative and ecosystem characteristics can be key drivers of spatial and temporal variability in active layer soil temperature, particularly during the summer. Quantifying the impacts of vegetation on active layer temperature is critical to understanding how changes in vegetation under climate change can further affect permafrost stability and soil temperature