Irrigation technology and water rebound in China's agricultural sector

Abstract

By using the data of 30 provinces from 1998 to 2016 in China, this paper estimates the water rebound effect in the agricultural crop farming by combining Slacks-based Measure (SBM-based) of Malmquist Index and Logarithmic Mean Divisia Index (LMDI) method. We find that the average water rebound effect is 70.3%, implying that over two-thirds of the water saving from irrigation technology improvement is offset by higher water consumption. We find evidence on the regional heterogeneity in terms of the magnitude of rebound: Southwest is the highest, whereas Northwest is the lowest. The heterogeneous rebound effect across regions is mainly due to the difference in water endowment and irrigation land availability. Our results indicate that irrigation technology improvement is not necessarily sufficient for achieving agricultural water conservation. In particular, the difference in natural geography conditions across regions needs to be considered in designing water conservation policies at a sub-regional level. K E Y W O R D S crop farming, irrigation land availability, logarithmic mean divisia index (LMDI), SBM-based Malmquist index, water endowment, water rebound 1 INTRODUCTION Water shortage has become one of the most important factors that restrict China's sustainable development. The agricultural water use (AWU) in China has increased over years, accounting for 62.38% of total water consumption in 2016. In order to achieve the dual goal of saving agricultural water and ensuring agricultural development, the Central Government's document (2016) 1 clearly proposed that it should control the total amount of AWU by improving the agricultural irrigation technology. The ratio of water-saving irrigation area (water-saving irrigation area per unit effective irrigation area, hereinafter abbreviated as "the ratio") is often used as a measure of agricultural irrigation technology. As shown in Figure 1, we can see that the ratio has increased continuously from 29.14% in 1998 to 49.95% in 2012 with an average annual increasing rate of about 4%. The remaining periods are still growing with a rate of 4.63% except for the period 2012-2013. However, the total AWU in China shows a slight increasing trend with an average annual rate of 0.06% during the whole period. Therefore, although China's irrigation technology has improved steadily for decades, the realized water conservation in the agricultural sector is lower than expected. At regional level, we can find a result similar to that at the national level. From the scatter plots of provincial average AWU and the ratio in six regions 2 (Figure 2), we can see that AWU does not decrease in the three regions including Southwest, Northeast, and Southcoast when the ratio

Agricultural Water Use Efficiency and Rebound Effect: A Study for China

“…In this paper, it was also found that the relatively arid region experiences a greater agricultural water rebound effect than the relatively humid area in China, which corresponds with the results of Song et al [7], but is different from the results of Fang et al [17] on heterogeneity of the magnitude of rebound effect. The northern and western regions will be more arid than southern and eastern regions in China, and Song et al [7] found that the northern and western regions of China experience a greater agricultural water rebound effect than the southern and eastern regions.…”

“…This means the average agricultural water rebound effect is 88.81% in China, which is greater than that in the results of Song et al [7], Fang et al [17], and Fei et al [4]. Song et al [7], Fang et al [17] and Fei et al [4] all focused on the magnitude of rebound effect in the agricultural sector with different methods. Song et al [7] found the agricultural water rebound effect in China from 1998 to 2014 is 61.49%.…”

“…The northern and western regions will be more arid than southern and eastern regions in China, and Song et al [7] found that the northern and western regions of China experience a greater agricultural water rebound effect than the southern and eastern regions. However, Fang et al [17] found that the agricultural water rebound effect in the southwest is the highest, whereas agricultural water rebound effect in the northwest is the lowest. Hence, heterogeneity of the agricultural water rebound effect does indeed exist in China.…”

“…Song et al [7] found the agricultural water rebound effect in China from 1998 to 2014 is 61.49%. Fang et al [17] found that the average agricultural water rebound effect is 70.3% using data of China from 1998 to 2016. Fei et al [4] found that the agricultural water use efficiency will offset 49.32% of the potential water saving in the short run and counteract 66.01% in the long run.…”

“…Although there are some differences between the two views, they both agree that the rebound effect of irrigation water is a measure of the degree to which the water-saving is offset, while the second view only emphasizes the situation that the expected water-saving amount is completely offset, which can be regarded as a special case of the first view. Some researchers have quantitatively measured the rebound effect [4][5][6][7][14][15][16][17]. However, measurements of the rebound effect do not reflect the casual effect of agricultural water use efficiency on water use because they ignore other factors, such as climatic and economic factors, which will lead to misunderstanding of the agricultural water rebound effect.…”