Crop Water Requirements on Regional Level using Remote Sensing Data - A Case Study in the Marchfeld Region

This research presents an operative application of satellite based technologies to estimate crop Water requirements (CWR) on regional level. The study is located in the agricultural area of Marchfeld (Lower Austria) and focuses on the year 2012. Agricultural production in this region requires irrigation which draws its resources from the groundwater. Due to its impact on hydrology and environment this practice necessitates close monitoring and management. In this process the CWR is an important piece of information, which can be derived from satellite data. We used multi-temporal (6 acquisitions, with an average revisit time of 16 days) and multi-spectral (visible and near-infrared) imagery of the DEIMOS-1 satellite sensor data in combination with local agro-meteorological measurements. In a first step, the leaf area index (LAI) and albedo maps were derived from atmospherically corrected satellite data. Those were used to generate maps of potential evapotranspiration (ETp) by direct application of the Penman-Monteith equation. Then, we produced a crop mask of the areas potentially irrigated. This was achieved by using an unsupervised image classification approach in combination with a post-classification analysis of the time-series of the crop development. Rain gauges data from a number of weather stations were spatially interpolated to produce a map of precipitation (P). Finally, the crop water requirements were calculated as the difference between ETp and the precipitation and aggregated over 10-day interval periods. Reference evapotranspiration (ETo) for the growing period resulted in 391 mm. The extent of irrigated crops covered an area of 21,278 ha with a maximum ETp of 5.6 mm/day at the end of June. The total crop water requirement resulted in 34.26 million m(3) for the year 2012.