A global map of irrigated agriculture in dry areas.

Abstract:

With changing socio-economic environments and population growth, it is estimated that agricultural production levels need to double by 2050. One way to achieve this may be through agricultural expansion into drier regions, which cover about 41% of earth’s land area. Currently, about 70% of freshwater withdrawals are used for irrigation, which in turn produces about 40% of global food. However, little is known about the global area under irrigated agriculture in these water-stressed, arid regions which host about 2 billion people. Here we estimate the global area under irrigation in the arid and hyperarid regions. To this end, we analyse the temporal signature of the Enhanced Vegetation Index (EVI) that was derived from the ~500m BRDF-adjusted reflectance data provided by the MODIS sensor since February 2000. This method does not rely on any external data sources and it allows to explore the temporal evolution of irrigation practices. Additionally, compared to other irrigation maps, our dataset can be quickly updated annually to provide the latest estimations. Initial results show that by using a combination of simple metrics quantifying each pixel’s phenology we are able to clearly identify irrigated areas in these dry regions. Our results will be compared to existing global irrigation datasets as well as global land cover maps.