Water footprint inventory database of Thai rice farming for water policy decisions and water scarcity footprint label.

Purpose: Rice is a major economic crop which has created local livelihood, careers and incomes in the agricultural sector in Thailand, one of the leading rice producers at global scale. Rice is a key commodity in the agriculture sector requiring the highest portion of water demand, around 40% out of the total sector demand of 65%. This study was aimed to develop the water footprint database of rice farming at the national level to support the information for area-based water management and water footprint label based on the methodology described in ISO14046. Methods: The water footprint inventory data associated with the 8 main cultivated rice species were gathered in accordance with the ISO 14046 Water Footprint. The statistical data of rice cultivation area and production in 2016 were used as the basis for sampling to cover 62% of the national annual production with a 90% confidence interval. Eight rice species were sampled by simple random sampling method, covering 62% of the national annual production with a 90% confidence interval. The total number of samples was 817, covering 114 samples of Khao Dok Mali 105, 103 samples of Pathumthani 1, 103 samples of Phitsanulok 2, 112 samples of RD41, 112 samples of Chainat 1, 103 samples of RD6, 70 samples of San Pah Tawng 1 and 100 samples of riceberry. Results and discussion: The study found that the rice cultivation in Thailand had an average water footprint inventory of 1665 m³/t and a water scarcity footprint of 334 m³H₂Oe/t paddy rice. One hectare of rice cultivation normally required water around 6340 m³/ha on the average. The results showed that Khao Dok Mali 105 has the highest water scarcity (598 m³H₂Oe/t paddy rice) as the Northeastern area where it is cultivated, has the highest water stress index. This was followed by RD6, Riceberry, Phitsanulok 2, Pathumthani 1, San Pah Tawng 1 and RD41. Chainat 1 species has the lowest water scarcity footprint (220 m³H₂Oe/t paddy rice). Conclusions: The replacement of rice with sugarcane/cassava could potentially reduce the water scarcity footprint by more than half. The shifting of cultivation period when the average rainfall was higher could slightly decrease the amount of total water requirements, whereas the implementation of alternate wet and dry farming system instead of continual flooding system would moderately reduce the amount of total water requirements. It is expected to use the water footprint national database for more effective water resource management for rice cultivation and to support the decisions on national water policy and the implementation of water scarcity footprint label. [ABSTRACT FROM AUTHOR]