Hydrological and Meteorological Observations on Seven Streams in the National Petroleum Reserve–Alaska (NPR–A)

This report summarizes the hydrological and meteorological data collected from 2003 to 2017 at 7 stations in the National Petroleum Reserve–Alaska. During an 8-year period, from May 2010 to December 2017, a research team from the University of Alaska Fairbanks, Water and Environmental Research Center, and personnel from the Bureau of Land Management performed 351 discharge measurements and collected and analyzed data on air temperature, rainfall, wind speed, and wind direction at stations distributed on a southwest–northeast transect from the foothills of the Brooks Range to the Arctic Ocean. In general, the air temperature data indicate an evident warming trend for the entire region. Rainfall data suggest a trend in increasing precipitation during the summer months from the coastal plain to the foothills, though there are some exceptions. The overall highest mean monthly wind speed was recorded in February; the overall lowest mean monthly wind speed varied from station to station. Wind roses indicate two main wind directions—approximately from the northeast and southwest—with winds from the northeast predominant at the northern stations and winds from the southwest predominant at the southern stations.List of Figures ................................................................................................................................ iii List of Tables ................................................................................................................................. iv Acknowledgments and Disclaimer ................................................................................................. v Abstract .......................................................................................................................................... vi CHAPTER 1 Introduction ........................................................................................................... 1 CHAPTER 2 Study Area ............................................................................................................. 2 CHAPTER 3 Discharge Measurements ...................................................................................... 3 3.1 Fieldwork ......................................................................................................................... 3 3.2 Data Processing ................................................................................................................ 9 CHAPTER 4 Meteorological Data ............................................................................................ 11 4.1 Methodology .................................................................................................................. 12 4.2 Results ............................................................................................................................ 12 4.2.1 Rainfall .................................................................................................................... 12 4.2.2 Air Temperature ...................................................................................................... 18 4.2.3 Wind ........................................................................................................................ 24 CHAPTER 5 Data Analysis ...................................................................................................... 37 CHAPTER 6 Conclusions and Recommendations.................................................................... 42 References ..................................................................................................................................... 43 Appendices .................................................................................................................................... 4

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