Expanding South Nahanni National Park, Northwest Territories, Canada, to Include and Manage Some Remarkable Sub-Arctic/Arctic Karst Terranes

South Nahanni National Park Reserve (Lat. 61°N, Long. 124–8°W; ∼4,700 km2) was created in 1972 to protect three great canyons and a major waterfall from hydroelectric development. In 1978, it was one of the first natural sites to be granted UNESCO “World Heritage” status, based substantially on the author’s geomorphic analyses. In the course of that work, extensive tracts of limestone karst landforms, some of them unique, were explored up to 40 km north of the Reserve boundaries. Following agreements with the First Nations peoples of the region, in 2009, these were incorporated into an expanded park of ∼32,000 km2 that now includes most of the hydrologic basin of the South Nahanni plus the smaller Ram River north of it. The case to expand the national park outside of the topographic boundaries of the South Nahanni basin was made in three steps: (1) a demonstration by fluorescent dye tracing that the underground drainage to major karst springs in South Nahanni. First Canyon extended far to the north of the topographic boundary, the catchment being the southern half of a belt of unique karst terrain, and the northern half is drained into the Ram River basin via a second group of major karst springs at the northern extremity; (2) recognition that the headwaters of the Ram River contained an ancient, intensely dissected, remnant karst terrane on an anticline that contrasts sharply with (3) a downstream anticline in the same limestone that has little karst development due to its more recent uplift, with stripping and exposure taking place under permafrost conditions. In 2010, a number of “hub-and-spoke” and “trekking” routes for walkers and backpackers were being proposed to display the karst. Potential management problems for these developments included a possible zinc-silver mine to the west that is accessed by a winter road across the karst belt and accelerating melting of the permafrost in susceptible silts and shales that is creating many new landslides in the karst basins.