Water productivity mapping (WPM) using landsat ETM+ data for the irrigated croplands of the Syrdarya river basin in Central Asia

Alexander Platonov*, Prasad S. Thenkabail, Chandrashekhar M. Biradar, Xueliang Cai, Muralikrishna Gumma, Venkateswarlu Dheeravath, Yafit Cohen, Victor Alchanatis, Naftali Goldshlager, Eyal Ben-Dor, Jagath Vithanage, Herath Manthrithilake, Shavkat Kendjabaev, Sabirjan Isaev

*Corresponding author for this work

Research output: Contribution to journalReview articlepeer-review


The overarching goal of this paper was to espouse methods and protocols for water productivity mapping (WPM) using high spatial resolution Landsat remote sensing data. In a world where land and water for agriculture are becoming increasingly scarce, growing "more crop per drop" (increasing water productivity) becomes crucial for food security of future generations. The study used time-series Landsat ETM+ data to produce WPMs of irrigated crops, with emphasis on cotton in the Galaba study area in the Syrdarya river basin of Central Asia. The WPM methods and protocols using remote sensing data consisted of: (1) crop productivity (ton/ha) maps (CPMs) involving crop type classification, crop yield and biophysical modeling, and extrapolating yield models to larger areas using remotely sensed data; (2) crop water use (m 3/ha) maps (WUMs) (or actual seasonal evapotranspiration or actual ET) developed through Simplified Surface Energy Balance (SSEB) model; and (3) water productivity (kg/m3) maps (WPMs) produced by dividing raster layers of CPMs by WUMs. The SSEB model calculated WUMs (actual ET) by multiplying the ET fraction by reference ET. The ET fraction was determined using Landsat thermal imagery by selecting the "hot" pixels (zero ET) and "cold" pixels (maximum ET). The grass reference ET was calculated by FAO Penman-Monteith method using meteorological data. The WPMs for the Galaba study area demonstrated a wide variations (0-0.54 kg/m3) in water productivity of cotton fields with overwhelming proportion (87%) of the area having WP less than 0.30 kg/m3, 11% of the area having WP in range of 0.30-0.36 kg/m3, and only 2% of the area with WP greater than 0.36 kg/m3. These results clearly imply that there are opportunities for significant WP increases in overwhelming proportion of the existing croplands. The areas of low WP are spatially pin-pointed and can be used as focus for WP improvements through better land and water management practices.

Original languageEnglish
Pages (from-to)8156-8180
Number of pages25
Issue number12
StatePublished - Dec 2008


  • Central Asia
  • Crop productivity
  • Crop yield modeling
  • Remote sensing
  • Simplified surface energy balance model
  • Syrdarya river basin
  • Water productivity mapping
  • Water use


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