Task 1 GAAR Landcover Classification

Study Area

Gates of the Arctic National Park is approximately 11 million acres spanning the Brooks Range in northern Alaska. Six Landsat Thematic Mapper scenes were mosaiced to capture the Park in its entirety (see below). The transition from interior boreal forest to the arctic of the North Slope occurs within the park. Black Spruce forest dominates the southern slopes, while arctic and tussock tundra dominate the north. The higher elevations of the Brooks Range consist of rocky slopes and spires, and there are many permanent snow fields.

Project Background

The Alaska Support Office (AKSO) of the National Park Service (NPS) seeks to develop a digital landcover map of the Gates of the Arctic National Park and Preserve (GAAR). This project is part of the Inventory and Monitoring Program of the NPS, a program designed to provide reliable and consistent scientific information to assess the status and trends in condition of national park ecosystems. Vegetation mapping is conducted under the inventory portion of the program in order to provide basic information immediately useful in the parks for making resource management decisions, to provide data that can be aggregated on a service wide level, and to design monitoring programs. This map will be used to understand habitat and fuel availability, model the occurrence of archeological sites and sensitive species for park planning, and to provide baseline information about natural resources in GAAR. It is recognized that the largeness and remoteness of Alaska's parks requires that mapping be done at coarser resolution than for other areas of the NPS system.

Project Objective

The objective of this task order is to develop a landcover map of GAAR at intermediate scales (1:63,360 - 1: 100,000) and at a level of classification detail appropriate to the intended uses describes above. We anticipate that mapping under this task order will be at the formation and alliance level of the National Vegetation Classification System or Viereck's level III and IV, with approximately 30-35 classes. Preliminary mapping classes for GAAR have been developed by NPS and the Project Team.

Landcover map development will include collection and analysis of ground truth data, evaluation of the final classes to be mapped, selection of the best available remotely sensed imagery (satellite or aerial photography or both), image analysis and interpretation, accuracy assessment and documentation of procedures and findings. The analysis may include preprocessing, classification, reclassing, and development and application of models using ancillary digital data to distinguish among confused spectral classes, interpretation of aerial photography, polygon delineation, and automation.

Accuracy Requirements

All final products will be required to meet the spatial accuracy of the National Mapping Accuracy Standards (NMAS) for 1:63,360 scale products. Classification accuracy of the interpretation shall be >= 75% for each individual landcover class. Minimum mapping unit will vary depending on the class and the methods used, but should be no more than 2 acres.

Walker Lake, located along the southern edge of the Brooks Range, is GAAR's largest lake and is easily accessible by float plane from Bettles.

An oblique view of Walker Lake, portrayed as a false-color Landsat TM Image draped over a Digital Elevation Model of the area.