Early Warning Systems: A Review

Numerous scientific research and engineering programs are being carried out globally in an effort to monitor environmental degradation, natural and anthropogenic disasters. These are part of a process to predict possible catastrophic events and help minimize their devastating impact on the environment and human life. Many of these programs, sometimes referred to as Early Warning Systems (EWSs), have been documented with detailed information on approach and technology utilization in the areas of sensor design for realtime multiple-source data collection, data transmission, evaluation and analysis, timely dissemination of early warning information and efficient response to such information. While some EWSs are indispensable in our efforts for environmental sustainability, others have not performed as expected or designed. This paper examines the literature on EWSs, the level of utilization of remote sensing technology and the potential trends for future systems. An evaluation of the strengths and weaknesses of the different systems was performed. Status and processes were reviewed for early warning systems, as related to land degradation, biodiversity, atmospheric and air quality, aquatic environments and freshwater quality assessment. The review indicated not all monitoring systems constituted fully integrated EWSs, and not all natural or anthropogenic pollution categories and consequent disasters have working EWSs. Remote sensing and related technologies have been successfully used to analyze and predict adverse impacts related to land degradation and certain physical and biological pollution variables related to water quality. Advances in sensor technologies have also resulted in more reliable, high frequency and automated samplers for data collection in water quality studies. Europe and North America have some of the most advanced EWSs, while EWS applications in Africa and Asia have improved considerably in recent years. EWSs have generally been reliable in helping reduce some of the negative impacts of environmental degradation, pollution and disasters. Acronyms and abbreviations are listed beginning on page 40 for readers not familiar with some of the many acronyms/abbreviations used in this paper.