## 1 Introduction  
The concept of virtual water was first proposed by [PERSON] in 1993 [1] to refer to the amount of water used in the production of goods and services [2]. Since 2002, the concept has received extensive attention around the world [3,4]. In China, virtual water has been forwarded as a potential approach to safeguard water resources, especially in water-scar areas such as the northwest [5]. This interest has prompted many empirical studies on the quantification of virtual water in global crop and livestock products (2352 kg of water in 1 kg of crop, and 6333 kg of water in 1 kg of livestock product, respectively), in Netherlands's and Canada's grain products (1000-2000 kg of water in 1 kg of grain), in Canada's beef products (16,000 kg of water in 1 kg of beef), in American computer chip products (16 kg of water in 1 g of a 32-mesabyte computer chip) [6, 7, 8, 9, 10], and in Brazil's, Chile's and American paper products (1052.8 kg, 1227.3 kg, 3345.8 kg of water in 1 kg of paper, respectively) [11]. Virtual water studies have also been completed for services, for example, the assessment of virtual water in the Spanish tourism industry (9.7 kg of water per \(\epsilon\) 1 of tourism income in 2004) [12]. Virtual water trade, which refers to the practice of transporting this hidden water from one country to another, has also been studied. For example, studies have examined the amount and direction of virtual water in agri-food products transported from Italy to China [13], and the factors influencing its characteristics [14]. When employed appropriately, virtual water trade can be used to alleviate water shortages in water-scar regions and to ensure local water security through the import of water-rich products from water-abundant regions [15,16]. Researchers have investigated the links between virtual water, food security [17], and water footprints [18,19], which is different compared to carbon footprints [20,21]. The former means the cumulative virtual water of all goods and services consumed by one individual or one country [22], while the latter means a measure of the total amount of greenhouse gas emission directly and indirectly produced by an activity or accumulated over the life stages of a product [23,24]. As there is a mutual feedback mechanism between water and carbon footprint, an understanding of water footprint can contribute to reflecting carbon footprint and proposing policies on the utilization of energy resources, and to achieving sustainable development [25, 26, 27].  
A review of the existing empirical studies on virtual water shows that most are large-scale in scope, and focused on economically developed areas. There is a need for studies at the provincial scale, particularly for the less developed, arid inland provinces of China. Gansu province is located in the central region of northwest China and covers a total area of 425,900 km\({}^{2}\). It is a typical arid and semi-arid water-deficient area with a dry climate, sparse rainfall and severe water resource shortages. In addition, the unequitable distribution of industrial water use, low utilization efficiency, and over-exploitation of groundwater have resulted in a decrease in river water supply and an increase in desertification, with significant negative consequences for regional social and economic development [28].  
The current paper analyzes virtual water content, the primary virtual water export industries and their export destinations, and the spatial patterns of virtual water in Gansu province between 2007 and 2012. The results of this study can be employed to support the sustainable use of water resources and the optimization of industry and trade structures in Gansu province.