Abstract

Oil and gas exploration operations use large amounts of water for ice roads and ice pads construction during the long-lasting winter of the Alaska's Arctic Slope (AAS). A traditional water source is water withdrawal from the lakes. Hydrological regimes of these lakes are characterized by a large spring snowmelt providing much of the recharge, followed by a subsequent drying of the lake in summer when evaporation generally exceeds precipitation. This study evaluates the use of snow management and snow fences to augment lake water supplies in the AAS.

We implemented snow control practices to enhance snow drift accumulation, which leads to increased melt water production, and an extended melting season that will recharge a depleted lake despite potentially unfavorable climate and hydrological conditions (i.e. surface storage deficit or/and low precipitation). Specifically, we constructed a snow fence in the vicinity of Prudhoe Bay (AAS) and evaluated its effect on lake's hydrology. Two lakes with similar water balances were selected and monitored in their natural regimes. Afterwards, a snow fence was installed in the watershed of experimental lake, while second lake served as control.

This paper presents field observations, modeling and sensitivity analyses of snow transport by wind, and hydrological assessment of snow fence effect on the lake. Our observations and model show that snow drift created addition 32 days of water supply through the summer, reduced snow sublimation losses in winter by 40%, and elevated lake levels despite low precipitation conditions. These results yield practical insight on using snow management to provide additional water recharge to the lake systems and lead to more efficient use of water resources for ice road and ice pad construction.

Introduction

Snow is central to activities in polar latitudes of Alaska over a very significant part of each year. The snow environment makes obsolete the technologies and tactics of the snow-free season and imposes new challenges and opportunities (Gray and Male, 1981). Most of the industrial activities can benefit from the use of snow technology in design and planning, as well as in operations and maintenance.

The oil and gas industry owns very little land on Alaska's Arctic Slope. Most of the oil and gas operations are located on state, federal or Native-owned lands. Many oil and gas exploration activities require a permit, authorization or notification before initiating work. Among others activities, permits are needed for construction of roads, pads, or islands, even during winter (e.g., tundra travel) and withdraw of water from any natural source (lake, river, wetland) for ice road construction. The general reasoning behind ice road construction is that, unlike gravel roads, they leave little or no trace behind and require no mitigation or reclamation activities once they are no longer used. The Bureau of Land Management estimates that 3.8 million to 5.7 million liters (1 to 1.5 million gallons) of water is needed per mile to build an ice road 15 cm (6 inches) thick and 9–11 meters (30–35 feet) wide (Cumulative environmental effects of oil and gas activities on Alaska's North Slope, 2003). The University of Alaska Fairbanks (UAF) Arctic Slope Tundra Lake project (Hinzman et al., 2006) assessed the potential impacts to tundra lake ecosystem resulting from the withdrawal of water for ice road construction. Current regulation allows withdrawing 15% of water from lakes with fish. Arising from the Arctic Slope Tundra Lake study and presenting current questions for federal and state land agencies is whether the lakes completely recharge after use.

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