Global rain-fed, irrigated, and paddy croplands: A new high resolution map derived from remote sensing, crop inventories and climate data

• Published in: ITC journal Vol. 38; pp. 321 - 334
• Main Authors: Salmon, J.Meghan, Friedl, Mark A., Frolking, Steve, Wisser, Dominik, Douglas, Ellen M.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.06.2015
• Subjects: Cropland; Irrigation; MODIS; Paddy; Remote sensing; Water management; Cropland; Irrigation; Water management; Paddy; MODIS; Remote sensing
• ISSN: 1569-8432; 0303-2434; 1872-826X
• DOI: 10.1016/j.jag.2015.01.014

•Through integrating information from national and sub-national surveys, remote sensing, and gridded climate data sets, we estimate that 314Mha worldwide were irrigated circa 2005.•Similarly, we estimate that 128Mha worldwide were managed under flooded conditions, called paddies, including 66Mha of irrigated paddy-style cropland and 63Mha of rain-fed paddy-style cropland.•Our results demonstrate that global mapping of irrigated, rain-fed, and paddy croplands is possible by combining information from multiple data sources. Irrigation accounts for 70% of global water use by humans and 33–40% of global food production comes from irrigated croplands. Accurate and timely information related to global irrigation is therefore needed to manage increasingly scarce water resources and to improve food security in the face of yield gaps, climate change and extreme events such as droughts, floods, and heat waves. Unfortunately, this information is not available for many regions of the world. This study aims to improve characterization of global rain-fed, irrigated and paddy croplands by integrating information from national and sub-national surveys, remote sensing, and gridded climate data sets. To achieve this goal, we used supervised classification of remote sensing, climate, and agricultural inventory data to generate a global map of irrigated, rain-fed, and paddy croplands. We estimate that 314 million hectares (Mha) worldwide were irrigated circa 2005. This includes 66Mha of irrigated paddy cropland and 249Mha of irrigated non-paddy cropland. Additionally, we estimate that 1047Mha of cropland are managed under rain-fed conditions, including 63Mha of rain-fed paddy cropland and 985Mha of rain-fed non-paddy cropland. More generally, our results show that global mapping of irrigated, rain-fed, and paddy croplands is possible by combining information from multiple data sources. However, regions with rapidly changing irrigation or complex mixtures of irrigated and non-irrigated crops present significant challenges and require more and better data to support high quality mapping of irrigation.