Physical versus economic water footprints in crop production: a spatial and temporal analysis for China

Hongrong Huang,Bianbian Feng,Pute Wu,Pengxuan Xie,Xi Yang,La Zhuo

doi:10.5194/hess-25-169-2021

Abstract

Abstract. A core goal of sustainable agricultural water resources management is to implement a lower water footprint (WF), i.e. higher water productivity, and to maximize economic benefits in crop production. However, previous studies mostly focused on crop water productivity from a single physical perspective. Little attention is paid to synergies and trade-offs between water consumption and economic value creation of crop production. Distinguishing between blue and green water composition, grain and cash crops, and irrigation and rainfed production modes in China, this study calculates the production-based WF (PWF) and derives the economic value-based WF (EWF) of 14 major crops in 31 provinces for each year over 2001–2016. The synergy evaluation index (SI) of PWF and EWF is proposed to reveal the synergies and trade-offs of crop water productivity and its economic value from the WF perspective. Results show that both the PWF and EWF of most considered crops in China decreased with the increase in crop yield and prices. The high (low) values of both the PWF and EWF of grain crops tended to cluster obviously in space and there existed a huge difference between blue and green water in economic value creation. Moreover, the SI revealed a serious incongruity between PWFs and EWFs both in grain and cash crops. Negative SI values occurred mostly in north-west China for grain crops, and overall more often and with lower values for cash crops. Unreasonable regional planting structure and crop prices resulted in this incongruity, suggesting the need to promote regional coordinated development to adjust the planting structure according to local conditions and to regulate crop prices rationally.

Highlights

Humanity is facing the increasingly severe threat of water shortage and accompanying rising food risks (Mekonnen and Hoekstra, 2016; Veldkamp et al, 2017), posing great challenges to agricultural water resource management
With the increase in crop yield, the production-based WF (PWF) of grain crops decreased by 20 % from 1.16 to 0.93 m3 kg−1 (Fig. 2a); and the PWF of cash crops decreased by 35 % from 0.70 to 0.46 m3 kg−1 (Fig. 2b)
Cotton had the highest PWF (3.68 m3 kg−1 in 2016), while sugar beet consumed the least water per yield (0.06 m3 kg−1 in 2016)

Summary

Introduction

Humanity is facing the increasingly severe threat of water shortage and accompanying rising food risks (Mekonnen and Hoekstra, 2016; Veldkamp et al, 2017), posing great challenges to agricultural water resource management. The economic benefits of water use form one important pillar of fresh water distribution (Hoekstra, 2014). Traditional studies on efficient agricultural water use focus on crop water productivity from the physical perspective and rarely make comprehensive evaluations combining the results with an economic perspective. The consumptive WF of crop production can be divided into blue and green WFs (Hoekstra et al, 2011). The blue WF measures irrigation water consumption. Green WF refers to the consumption of rainwater (Hoekstra et al, 2011). As a comprehensive index to evaluate types, quantities, and efficiency of water use in the process of crop produc-

Methods

Results

Discussion

Conclusion