Historical irrigation extent mapped for 1900-2005

Information on the historical evolution of irrigated lands is very limited but is needed for many applications, e.g. to study changes in hydrology and water resources, crop productivity, or surface energy balances. We developed the new dataset HID (Historical Irrigation Dataset) where we panned the extent of area equipped for irrigation (AEI) for 1900 to 2005 in 5 arc-minute resolution. To achieve that, we collected subnational irrigation statistics for this period from various sources and found that the global extent of AEI increased from 63 million ha (Mha) in 1900 to 111 million Mha in 1950 and 306 Mha in 2005. We used different rules to maximize consistency of the gridded products to either subnational irrigation statistics or to historical cropland and pasture datasets (presently HYDE and EARTHSTAT but other datasets can be implemented too).


The dataset and its documentation are made available in an open-data repository at https://mygeohub.org/publications/8 (doi:10.13019/M20599).

Reference to the article where dataset is described in details:
Siebert S, Kummu M, Porkka M, Döll P, Ramankutty N, and Scanlon BR. 2015. A global dataset of the extent of irrigated land from 1900 to 2005, Hydrol. Earth Syst. Sci. 19: 1521-1545. doi: 10.5194/hess-19-1521-2015


New article on Modifiable Areal Unit Problem in a case of water shortage in Monsoon Asia

An article by WDRG members on exploring the Modifiable Areal Unit Problem (MAUP) in a case of water shortage in Monsoon Asia was published in Water.

The article provides a systematic analysis on how the extent of water shortage and the population affected by it vary depending on the spatial analysis unit used. Altogether 21 different criteria for defining the spatial unit of analysis (i.e. zonings) were examined. The results for population under high water shortage ranged between 780 million to 2.1 billion people. The article shows how important it is to acknowledge the significant influence of the spatial unit of analysis and recommends the use of multizonal and multiscale approaches in spatial water assessments to minimise the effects of MAUP.

The article is available online: http://www.mdpi.com/2073-4441/7/3/898