Alternatives to Landsat-5 Thematic Mapper for operational monitoring of vegetation cover: considerations for natural resource management agencies

Abstract

There is a serious concern as to whether the Landsat-5 Thematic Mapper (TM) will provide imagery up until the launch of the Landsat Data Continuity Mission (LDCM), which is expected in December 2012. The concern is due to fuel shortages and sporadic satellite and sensor problems. The Landsat-7 Enhanced Thematic Mapper (ETM+) scan-line corrector (SLC) malfunction in 2003 means that ETM+ imagery contains strips of missing data. Consequently there is concern that the highest quality Landsat imagery may not be available for monitoring for the years 2011 and 2012. Natural resource monitoring agencies, therefore, are faced with the serious challenge of determining a suitable alternative to Landsat-5 TM imagery should the need arise. While literature exists on possible alternatives, there is a lack of studies that provide guidelines to monitoring agencies on the issues to be explored when considering an alternative data source. We undertook a study that identified Landsat-7 ETM+, SPOT4 HRVIR, SPOT5 HRG, and IRS-P6 LISS-III as the most suitable alternatives for monitoring vegetation cover in Queensland and New South Wales (NSW) in eastern Australia. None of the sensors were found to be ideal candidates due to a combination of one or more of lower radiometric quality, increased data volumes, additional processing requirements, and higher purchasing costs. We found that the low cost and ease of access to Landsat-7 ETM+ made it a technically and economically viable option for annual monitoring of woody vegetation extent and change in eastern Australia. However, Landsat-7 ETM+ may not be an option in many areas of the world due to high cloud coverage. We used the experiences gained through this work to recommend a process that natural resource management agencies can use to explore the issues related to selecting an alternative to Landsat-5 TM for land cover monitoring.