The quantitative evaluation of false colour photography with application of a red filter.

AbstractFor monitoring (homogeneous) agricultural crops, a quantitative analysis of aerial photography tends to favour black and white multi-spectral aerial photography. For monitoring natural vegetation on the other hand, a visual interpretation may be of primary importance, necessitating false colour photography. If an additional quantitative analysis of false colour photography is required, e.g. for biomass assessment, application of a red filter (FCR) provides a considerable simplification of the analysis, resulting in broad-band red and near-infrared reflectance factors. The reflectance factor in the near-infrared shows a decreased contrast compared with black and white multi-spectral aerial photography. In practical applications, this decrease in contrast with FCR has to be weighed against the possibilities of a visual interpretation

The quantitative evaluation of false colour photography with application of a red filter.

AbstractFor monitoring (homogeneous) agricultural crops, a quantitative analysis of aerial photography tends to favour black and white multi-spectral aerial photography. For monitoring natural vegetation on the other hand, a visual interpretation may be of primary importance, necessitating false colour photography. If an additional quantitative analysis of false colour photography is required, e.g. for biomass assessment, application of a red filter (FCR) provides a considerable simplification of the analysis, resulting in broad-band red and near-infrared reflectance factors. The reflectance factor in the near-infrared shows a decreased contrast compared with black and white multi-spectral aerial photography. In practical applications, this decrease in contrast with FCR has to be weighed against the possibilities of a visual interpretation

Flood Risk in Asia's Urban Mega-deltas: Drivers, Impacts and Response

Asia's urbanized mega-deltas are experiencing increased incidences of flooding. Flood risk is increasing due to urban growth, which makes people more vulnerable and threatens economic assets, and due to factors that increase flood hazard, including reduced delta aggradation, subsidence though natural resource extraction, and climate change, including extreme weather events, such as typhoons, and sea level rise. The recent history of flooding in Asia's deltaic cities and the drivers of that risk have been examined in this article. We give particular attention to the Pearl River Delta, and its cities of Guangzhou, Hong Kong and Shenzhen, important economic centres of Asia. The flood risk is substantial, but flood risk management appear to suffer through a lack of sufficient strategic planning, and the difficulty of defending deltaic cities through traditional engineering approaches alone. Drawing on lessons from flood risk management internationally, we suggest that there are ways forward in developing flood mitigation strategies for deltaic cities in the region, which deserve further exploration. © 2012, National Institute of Urban Affairs (NIUA). All rights reserved