Multispectral remote sensing technology is widely used in agriculture and is appropriate for vegetation analysis. Vegetation has characteristic spectra, often showing characteristic absorption maxima or minima at particular wavelengths. Most vegetation indices are based on the sharp increase in reflectance from vegetation that occurs around 700 nm (the red-edge), a change that is characteristic of green vegetation and not found for most other natural surfaces that show relatively slow changes of reflectance with wavelength over this region [36]. In particular since 2002, new opportunities exist for producing better data for calculations thanks to the MODIS Aqua and Terra satellites, which provide free 36-band numbers, with 1-day repeating cycles and 250 to 500 m pixel size time series data sets. For agricultural water management today, remote sensing time series analysis (RS-TSA) is one of most important solutions for measuring agricultural droughts and their effects.
This case study, developed in the framework of ICPDR activities, aims to fill the knowledge gap in this field by developing agricultural drought-related decision parameters and applying them in practice from raw spectral datasets. Signaling levels of this activity, and free-of-charge available homogeneous remote sensing data (MODIS NDVI spectral indices) and land use (CORINE database) datasets, can be applied on national and Central and Eastern European scales.
The methods and databases explored include employment of remote sensing data on land use, as well as biomass production, soil characteristics for better integration and understanding of cropping patterns influenced by hydrology and soil types. Internationally available land use (CORINE database, topographic maps) remote sensing data, MODIS NDVI spectral indices, soil data (agro topographic map, soil water management properties, map of water management properties of soils), hydrology (soil water table), and digital elevation models have been processed and integrated to determine yield loss thresholds and soil water-holding capacities.