Citation:

Keith, Darryl J. Coastal and Estuarine Waters: Light Behavior. Coastal and Estuarine Waters: Optical Sensors and Remote Sensing. Chapter N/A, Encyclopedia of Natural Resources: Water. Taylor and Francis, Philadelphia, PA, , 649-661, (2014).

Impact/Purpose:

Estuaries and coastal waters are the nexus between human civilization and environmental conservation/protection and represent the dynamic interface between land and the open ocean. Estuaries cover more than half of the earth’s surface. Most of the world’s population live in coastal areas and contribute significantly to substantial physical changes to the coastline, declines in water quality, and biological/chemical changes to waters with the addition of high volumes of nutrients (primarily nitrogen and phosphorous) from urban, nonpoint source runoff. Satellites and aircraft have proven to be valuable tools for providing synoptic and temporal views of indicators of water quality in coastal environments that could not be obtained using traditional field sampling techniques. When incorporated into specific monitoring plans, remotely sensed information has been shown to provide “added value” to data analysis for better decision support, for assessing environmental conditions at a given point in time, and, when collected over multiple years, for understanding the cumulative effects of human development, including impacts of changes in land cover on coastal water quality or ecosystem health. This chapter will present an overview of the theory and techniques used to retrieve spectral information from nearshore and estuarine waters using airborne and space-based platforms.

Description:

This article summarizes the use of remote sensing techniques and technology to monitor coastal and estuarine waters. These waters are rich in mineral particles stirred up from the seabed by tides and waves and dissolved organic matter transported by rivers. The majority of the literature on remote sensing of the ocean has concentrated, understandably, on techniques and empirical models to retrieve information from the open ocean. However, remote sensing of the near-coastal ocean and estuaries is very important as 30 to 70% of the world’s population lives in coastal and estuarine regions (UNEP, 2007; Wilson and Fischetti, 2010). This article starts with a discussion of the inherent and apparent optical properties which affect the retrieval of color from coastal and estuarine waters. This discussion is followed by comparisons and contrasts of the scanning systems used in ocean color remote sensing to collect radiance and reflectance data. The current suite of spaced-based as well as examples of aircraft - based scanning systems are presented. The article concludes with a discussion of the challenges that the scientific and environmental communities face when incorporating remotely sensed data into monitoring strategies within the framework of the environmental laws and regulations.

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