• Alaska Arctic coastal plain gravel pad hydrology: impacts to dismantlement removal and restoration operations ; a study on the human - hydrology relationship in Arctic environments

      Miller, Ori; Barnes, David L.; Stuefer, Svetlana L.; Shur, Yuri (2019-08)
      To guard against thawing permafrost and associated thaw subsidence, the oil facilities in the Arctic are constructed on gravel pads placed on top of the existing arctic tundra, however the impacts of this infrastructure to the sensitive hydrology are not fully understood. Production in some of the older fields is on the decline; however oil exploration in the Arctic Coastal Plain is resulting in the discovery and development of new reserves. In the coming years, old sites will need to be decommissioned as production transitions to new sites. New facilities will also need to be designed and constructed. Oil companies in Alaska have historically conducted operations under leases issued through the Alaska Department of Natural Resources. The leases stipulate that once resource extraction operations are completed, the facilities must be decommissioned and the sites restored, however they are often vague in their requirements and are variable in their specifics from lease to lease. As the oil companies transition to the new sites, decisions must be made regarding what should be done with vacated gravel pads. The construction of gravel pads essentially destroys underlying arctic tundra. In undisturbed areas in the Arctic, the tundra itself creates an insulating layer that limits the seasonal thaw depth to around 0.5 m. Removal of this layer causes thaw depths to greatly increase impacting the stability of the ground and the hydrology of the surrounding area. Because of this impact, other possible restoration techniques are being considered, such as vegetating and leaving the pads in place. Water movement is one of the major driving factors in the arctic contributing to permafrost degradation. Groundwater carries with it heat, which is transferred to the soil as the groundwater moves. Therefore, hydrology plays a major role in the stability of the arctic environment. This is especially relevant in areas where gravel pads exist. Gravel pads are anthropogenic structures that have significant water storage potential. Because of the unique conditions in the Arctic, pore-water flow through these gravel pads is not yet well understood. The purpose of this study is to develop a more complete scientific understanding of the driving forces behind pad pore-water movement. This study expands on fieldwork from a prior hydrological field study conducted by others. The prior study is expanded through this work by developing an associated groundwater model to the gravel pad from the field study to examine the flow through it and the controlling factors for this flow. The study site used for this project is located in Prudhoe Bay and is the pad constructed for the very first production well in Prudhoe Bay in 1968. This study demonstrates that it is the topography of the silt layer beneath the gravel pads that is the most significant factor controlling pad pore-water movement. The results from the modeling study will assist engineers and environmental scientists in better understanding the groundwater flow. This understanding will aid in the decommissioning and restoration process and help inform decision making in regards to the future of the existing pads. The results may also be used to inform the development of new infrastructure such that any new pads which are built may be constructed with their relationship to the local hydrology more in mind.
    • An assessment of suspended sediment transport in Arctic Alaskan rivers

      Lamb, Erica K.; Toniolo, Horacio; Schnabel, William; Kane, Douglas (2013-05)
      Provided here is an initial assessment of suspended sediment transport in several rivers on the North Slope of Alaska. This study was divided into two parts: the Umiat project, which involved the Chandler, Anaktuvuk and Itkillik Rivers, and the NPR-A study, which considered Prince, Seabee and Fish Creeks, as well as a brief look at the lkpikpuk River, Otuk Creek, Judy Creek and the Ublutuoch River. Methods used included depth-integrated suspended sediment samples, grab samples, automatic pump-style samplers, discharge measurements, bed sediment grain size analysis and the inclusion of a variety of meteorological measurements from other projects. With slightly less than two years of data collection from May 2011 to September 2012, an initial analysis was completed. Suspended sediment rating curves developed for the Anaktuvuk and Chandler Rivers over the two-year study period revealed a strong correlation between suspended sediment concentration (SSC) and discharge. The most data was collected for the Anaktuvuk and Chandler Rivers; on these rivers, suspended sediment discharge was also analyzed, showing that over 90% of suspended sediment transport occurred during the spring melt period in 2011. Spring melt was not measured in 2012, so analysis was only completed for 2011.
    • Climatic and physiographic drivers of peak flows in watersheds in the North Slope of Alaska

      Hinzman, Alexa Marion Hassebroek; Stuefer, Svetlana; Arp, Christopher; Barnes, David (2017-08)
      The failure to accurately predict peak discharge can cause large errors in risk analysis that may lead to damage to structures and in some cases, death. Creating linear regression (LR) equations that accurately predict peak discharges without historic data provides a method to estimate flood peaks in ungauged watersheds on the North Slope of Alaska. This thesis looks at the independent variables that drive, or are significant in predicting snowmelt peak discharge in the North Slope watersheds. The LR equations created use independent variables from meteorological data and physiographic data collected from four watersheds, Putuligayuk River, Upper Kuparuk River, Imnavait Creek and Roche Moutonnée Creek. Meteorological data include snow water equivalent (SWE), total precipitation, rainfall, storage, length of melt. Physiographic data summarize watershed area (2.2 km2 to 471 km2) and slope (0.15:100 to 2.7:100). This thesis compared various Flood Frequency Analysis techniques, starting with Bulletin 17B, multiple USGS regional methods and finally created LR equations for each watershed as well as all four watersheds combined. Five LR equations were created, three of the LR equations found SWE to be a significant predictor of peak flows. The first equation to estimate peak flows for all watersheds used only area and had a high R2 value of 0.72. The second equation for all watersheds included area and a meteorological independent variable, SWE. While the evidence presented here is quite promising that meteorological and physiographic data can be useful in estimating peak flows in ungauged Arctic watersheds, the limitations of using only four watersheds to determine the equations call for further testing and verification. More validation studies will be needed to demonstrate that viable equations may be applied to all watersheds on the North Slope of Alaska.
    • Long term evaporation pan data to estimate potential evaporation during the warm season on the Alaskan North Slope: Imnavait Creek basin

      Mumm, John Paul; Kane, Douglas L.; Toniolo, Horacio; Schnabel, William (2017-12)
      Evapotranspiration plays a significant role in the hydrologic cycle of all basins, yet is only ccasionally measured in the Arctic. One simple index method to evaluate evapotranspiration is the evaporation pan. The energy environment surrounding the simple evaporation pan varies considerably from that of the natural environment. Yet, an evaporation pan is a sound way to determine and estimate the potential evapotranspiration, and actual evapotranspiration can be estimated from evaporation pan data by determining and employing a pan coefficient. An evaporation pan was initially installed in 1986 in the northern foothills of the Brooks Range on the North Slope of Alaska in Imnavait Creek Basin, collecting data for 22 years. The total summer maximum, average, minimum and standard deviation of pan evaporation were 34.9 cm, 29.9 cm, 19.7 cm and 9.3 cm, respectively from 1986 to 2008 (1989 missing). Both, the seasonal water balance and the Priestley-Taylor method for the 2.2 km² Imnavait Creek catchment were used to produce seasonal estimates of actual evapotranspiration. When used in conjunction with the evaporation pan measurements, an average pan coefficient of 0.58 was found in both cases, which was very similar to what was found in an earlier study on Imnavait Creek Basin. The evaporation pan results can also be correlated effectively with other measured variables (such as thawing degree days, air temperature, net radiation, vapor pressure deficit, precipitation, wind speed, and wind direction); this is a method that allows one to predict potential evapotranspiration in areas where it is not measured at broader spatial scales.
    • Processes controlling thermokarst lake expansion rates on the Arctic coastal plain of Northern Alaska

      Bondurant, Allen C.; Arp, Christopher D.; Jones, Benjamin M.; Daanen, Ronald P.; Shur, Yuri L. (2017-08)
      Thermokarst lakes are a dominant factor of landscape scale processes and permafrost dynamics in the otherwise continuous permafrost region of the Arctic Coastal Plain (ACP) of northern Alaska. Lakes cover greater than 20% of the landscape on the ACP and drained lake basins cover an additional 50 to 60% of the landscape. The formation, expansion, drainage, and reformation of thermokarst lakes has been described by some researchers as part of a natural cycle, the thaw lake cycle, that has reworked the ACP landscape during the course of the Holocene. Yet the factors and processes controlling contemporary thermokarst lake expansion remain poorly described. This thesis focuses on the factors controlling variation in extant thermokarst lake expansion rates in three ACP regions that vary with respect to landscape history, ground-ice content, and lake characteristics (i.e. size and depth). Through the use of historical aerial imagery, satellite imagery, and field-based data collection, this study identifies the controlling factors at multiple spatial and temporal scales to better understand the processes relating to thermokarst lake expansion. Comparison of 35 lakes across the ACP shows regional differences in expansion rate related to permafrost ice content ranging from an average expansion rate of 0.62 m/yr on the Younger Outer Coastal Plain where ice content is highest to 0.16 m/yr on the Inner Coastal Plain where ice content is lowest. Within each region, lakes vary in their expansion rates due to factors such as lake size, lake depth, and winter ice regime. On an individual level, lakes vary due to shoreline characteristics such as local bathymetry and bluff height. Predicting how thermokarst lakes will behave locally and on a landscape scale is increasingly important for managing habitat and water resources and informing models of land-climate interactions in the Arctic.