Landsat-based maps of irrigated dry season cropping in Southeastern Anatolia, Turkey

Landsat-based maps of irrigated dry-season cropping in Southeastern Anatolia, Turkey

Long-term monitoring of the extent and intensity of irrigation systems is needed to track crop water consumption and to optimize land use in a changing climate. We mapped the expansion and land use intensity of irrigated dry season cropping in Turkey´s Southeastern Anatolia Project annually from 1990 to 2018 using Landsat time series and Google Earth Engine.

This dataset includes multiple maps documenting the expansion and land use intensity of irrigated dry season cropping in Turkey´s largest irrigation scheme. We aggregated all Landsat imagery acquired during the July through September for the period 1990 to 2018 into spectral-temporal metrics and predicted dry season cropping annually using a machine learning classifier. We performed several post-processing steps to derive multiple map products for all areas with at least two dry season cropping cycles in the study period. The dataset comes in .zip format and includes the following map products:

• gap_dsc_fst.tif: first year of dry season cropping
• gap_dsc_yrs.tif: number of years with dry season cropping
• gap_dsc_frq.tif: dry season cropping frequency (% of years since first dry season cultivation):
• gap_dsc_trd.tif: five-year dry season cropping frequency trend magnitude
• gap_dsc_pvl.tif: significance level (p-values)

Spatial coverage
The maps come in 30m spatial resolution and cover the Southeastern Anatolia Project (Güneydoğu Anadolu Projesi, GAP) region. The region consists of nine provinces which account for approximately 10% of the Turkish land area. 

Temporal coverage
The analyses cover the period 1990-2018. The first year of dry season cropping and the number of years with dry season cropping represent the time period 1990-2017. The temporal coverage of dry season cropping frequency varies on a pixel level, depending on the initial year of dry-season cultivation. The temporal coverage of the trend indicators also vary on a pixel level and furthermore have a constrained maximum temporal coverage of 1992-2012 due to the post-processing steps involved.

Data format
The data are delivered as 16bit single layer GeoTIFFs in EPSG:3035 projection. The images are LZW compressed, and have NoData value 0.

Publication & further information
Please see the publication for further information on the methodology and accuracy of the map products:

Rufin, P.; Müller, D.; Schwieder, M.; Pflugmacher, D.; Hostert, P. (2020): Landsat time series reveal simultaneous expansion and intensification of irrigated dry season cropping in Southeastern Turkey. Journal of Land Use Science. DOI: http://dx.doi.org/10.1080/1747423X.2020.1858198

Acknowledgments
This research contributes to the Landsat Science Team 2018-2023 (http://www.usgs.gov/land-resources/nli/landsat/landsat-science-teams) and the Global Land Programme (https://glp.earth/). We gratefully acknowledge the open cloud processing platform provided by Google.