Detection of flooded rice fields in Italy

In the enhanced image of 26 April, the flooded rice fields in the Provinces of Novara and Vercelli appear as dark areas due to the low reflectivity of the water surfaces. The same area appears much brighter on 2 April, before the flooding.

The oldest documents mentioning rice cultivation in Italy date back to the second half of the 15th century. Rice was initially grown mostly on swampy, poor quality land unsuitable for other types of cultivation.

However, as the profitability of rice growing became more significant, rice fields gradually extended, in particular, to the wide plains of Piedmont, Lombardy, Emilia and Veneto. An ideal environment was provided by the dense network of canals, built by local governments authorities, which conveyed water from the Po Valley rivers to the rice fields.

Today, rice cultivation and processing are concentrated in the Provinces of Vercelli and Novara in northern Italy, between the Dora Baltea and Ticino rivers. In these provinces, situated to the west of Milan in the region of Piedmont, rice growing is carried out on hundreds of farms producing several hundred thousand tons of rice each year and supplying to both the national and international markets.

After preparing the fields and sowing the rice, the fields are usually flooded in the second half of April or early May. The flooding of such a large area (approximately 80 x 40km^₂) can easily be seen from satellite images, both in the visible and in the microwave channels.

As an example, the Meteosat-7 visible images show an area of Northern Italy on two cloud free days in April 2001: one image taken before the flooding (2 April) and the other taken after the flooding (26 April). Both images are from 11:00 UTC in order to avoid any effects caused by the anisotropy of the surface.

In the enhanced image of 26 April, the flooded rice fields in the Provinces of Novara and Vercelli appear as dark areas due to the low reflectivity of the water surfaces. The same area appears much brighter on 2 April, before the flooding. The water surfaces of the flooded rice fields are interrupted by streets, villages other fields (see picture above), hence the flooded fields do not appear as dark as the lakes, which are also clearly visible in the images (e.g. Lago di Garda, Lago Maggiore).

The flooded rice fields are also clearly visible in imagery from other satellite sensors, such as AVHRR (Advanced Very High Resolution Radiometer) on the NOAA platforms, MODIS (MODerate resolution Imaging Spectrometer) on the Terra platform, and TM (Thematic Mapper) on the Landsat-7 platform. Some typical images (at reduced resolution) are shown below.