Assessing green and blue water utilization in wheat production of Tajikistan: a survey of regions, 1980-2015

The water footprint (WF) of national wheat production has been previously estimated for Tajikistan in regional (Central Asia) and global-scale studies. However, due to the large scale, those reports may provide a general view of the country's wheat production water usage, which can not fully identify the regional demand on water resources. The aim of this study is to estimate the green and blue water use of wheat irrigated crop in Tajikistan (1980-2015). The results were evaluated by comparison with previous documented results for the WF of wheat production in Tajikistan. We compared the water use for product (t/ha) among four regions and analyzed the water consumption by dekhkan (peasant) farms, households and agriculture enterprises in 2015. The National WF of wheat production for the period 1980-2015 were approximately 990.6 Mm3/yr (34.3% green and 65.7% blue). There is a notable difference among regions: the WF is low in the eastern region, while it is relatively high in Khatlon region i.e. Southern Tajikistan. The major portion of WF (61.4%) comes from dekhkan farms (DF), while agriculture enterprises (AE) with households (H) are share 38.6 % of the country total water utilization. Blue water (BW) dominates in the four regions, whereas highest BW proportions are found in the districts located in Central and Southern Tajikistan. Productivity plays an important role in food production by reducing the WF of crop (wheat) production. Due to the low irrigation efficiency, more water is needed or has been consumed per-hectare in farmlands of Sughd region. WF calculated according to the Aldaya and Hoekstra (2011) methodology. Crop water requirement is calculated based on the CROPWAT model outputs. Daily reference evapotranspiration (Penn Man- Montheith) were estimated in CROPWAT as well. Statistical data on the annual crop yield, productivity and total seeded area, as well as on the distribution of the agricultural land between/among DF, AE and H in four regions, were referenced from the country statistical yearbooks (https://stat.tj). Crop coefficients planting and harvesting dates for the different regions are obtained from FAO. The meteorological data on temperature, precipitation (1980-2015), humidity, wind speed and sun duration (2000-2015) were provided by the National Meteorological Agency (https://meteo.tj).