Incorporating water loss from water storage and conveyance into blue water footprint of irrigated sugarcane: A case study of Savannah Sugar Irrigation District, Nigeria

Assessing the impacts of irrigation on water resources is crucial to effectively understanding how water is withdrawn for irrigation purposes. Consequently, the extraction of water from rivers, reservoirs and aquifers for irrigation purposes usually exceeds the net requirement for irrigation due to water lost in its delivery from source to the crop fields. In this this study, we have proposed a model for incorporating seasonal water loss from storage reservoir and conveyance canal into the crop water footprint of irrigated sugarcane. By taking into consideration the duration of seasonal irrigation water release for sugarcane production, we present a method for allocation of blue water footprint using savannah sugar irrigation district as case study. Results have shown that significant volume of water is evaporated seasonally due to irrigation of sugarcane, despite the introduction of an allocation factor to account of evaporation loss to irrigation. For the study period of 2007-2017, the reservoir is the main contributor to water loss by evaporation, it accounts for an average seasonal water loss of 1.1 x 10(8) m(3), followed by evapotranspiration from the crop field 0.26 x 10(8) m(3) and then seepage and evaporation losses from the canal 7.9 x 10(4) m(3). The average seasonal blue water footprint of sugarcane for the period considered is 877 m(3)/ton which exceeds the global average 209 m(3)/ton. Plans to expand hectares of cultivated land by the company to boost sugarcane productivity, coupled with the ongoing effort to incorporate hydroelectric power plant to the existing dam to augment electric power supply in the district, will greatly influence the availability water resources in the region. This study highlighted the need for a comprehensive evaluation of water use in irrigated agriculture and may serve as an indicator for optimizing future objectives and strategies associated with water resource planning globally. (C) 2020 Elsevier B.V. All rights reserved.