An improved method for calculating the regional crop water footprint based on a hydrological process analysis

Xiao-Bo Luan,Yu-Bao Wang,Ya-Li Yin,Xue-Rui Gao,Jing Liu,Shi-Kun Sun,Pu-Te Wu

doi:10.5194/hess-22-5111-2018

Abstract

Abstract. Fresh water is consumed during agricultural production. With the shortage of water resources, assessing the water use efficiency is crucial to effectively manage agricultural water resources. The water footprint is an improved index for water use evaluation, and it can reflect the quantity and types of water usage during crop growth. This study aims to establish a method for calculating the regional-scale water footprint of crop production based on hydrological processes, and the water footprint is quantified in terms of blue and green water. This method analyses the water-use process during the growth of crops, which includes irrigation, precipitation, groundwater, evapotranspiration, and drainage, and it ensures a more credible evaluation of water use. As illustrated by the case of the Hetao irrigation district (HID), China, the water footprint of wheat, corn and sunflowers were calculated using this method. The results show that canal water loss and evapotranspiration were responsible for most of the water consumption and accounted for 47.9 % and 41.8 % of the total consumption, respectively. The total water footprint of wheat, corn and sunflowers were 1380–2888, 942–1774 and 2095–4855 m3 t−1, respectively, and the blue footprint accounts for more than 86 %. The spatial distribution pattern of the green, blue and total water footprints for the three crops demonstrated that higher values occurred in the eastern part of the HID, which had more precipitation and was further away from the irrigation gate. This study offers a vital reference for improving the method used to calculate the crop water footprint.

Highlights

Human activities and climate change have serious effects on the availability of water resources (Nijssen et al, 2001; Haddeland et al, 2014)
Based on the water footprint theory framework provided by Hoekstra et al (2011), this study suggests a new way of quantifying the regional-scale water footprint of crop production (Fig. 3)
In China, the irrigation water consumption was 360 × 109 m3, and the effective utilization coefficient of irrigation water was 0.53 (MWR, 2015), which indicated that about 169.2 × 109 m3 of water resources were lost in the process of transportation and irrigation

Summary

Introduction

Human activities and climate change have serious effects on the availability of water resources (Nijssen et al, 2001; Haddeland et al, 2014). Agricultural production is major consumer of global water resources and accounts for 85 % of the global blue water (surface or groundwater) consumption (Shiklomanov, 2000; Vörösmarty et al, 2010). In China, 63 % of all water is used for agricultural production each year, and the area of irrigated farmland is 39.6 % of the total arable land. Environmental pollution reduces water availability (Jiang, 2009; Schwarzenbach et al, 2010), and these changes place great pressure on regional water resources (Piao et al, 2010; Wang et al, 2014); climate change aggravates the situation (Elliott et al, 2014). Economic demand for water will inevitably and gradually take up the agricultural water use, which is a challenge for maintain-

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Results

Discussion

Conclusion