One of the most important ecological and socio-economic problems in the 21st century is water shortage. In the 2015 annual risk report, the World Economic Forum ranked the “water crisis” as the world’s largest potential risk (
Journal of Geographical Sciences, Volume. 30, Issue 11, 1909(2020)
Changes in agricultural virtual water in Central Asia, 1992-2016
In recent years, flows of many rivers and lakes have become reduced in arid and semi-arid regions around the world. The most typical examples of this phenomenon occur in Central Asia, and the reduction of the Aral Sea area is closely related to agricultural water use. However, due to a lack of continuous data in Central Asia spanning many years, “virtual water” is used to evaluate changes in agricultural water use. Based on virtual water theory, 325 kinds of agricultural products in eight categories are selected as the research object, and changes in virtual water are calculated for Central Asia from 1992 to 2016. Results indicate that: (1) The average annual net export of agricultural virtual water (TVWNE) in Central Asia is about 9 billion m3, concentrated in Kazakhstan, whose annual TVWNE reaches 8.1 billion m 3. (2) Since 2007, the TVWNE in Central Asia has dropped significantly, with a drop rate of 86%, while the total volume of agricultural virtual water has gradually increased since 1998. (3) The upstream and downstream countries in Central Asia have different characteristics in the change of virtual water quantity.
1 Introduction
One of the most important ecological and socio-economic problems in the 21st century is water shortage. In the 2015 annual risk report, the World Economic Forum ranked the “water crisis” as the world’s largest potential risk (
Water resource shortages in arid and semi-arid regions of the world directly affect human demand for water, food irrigation, and industrial production. As an arid and semi-arid region, Central Asia faces serious water problems and is listed as one of the seven high-risk areas for water disputes in the world (
Figure 1.
Therefore, studying the changes in agricultural water use in Central Asia has become very important for the sustainable development of the region.
However, there are many kinds of agricultural production, which makes it difficult to compare water use changes in a country with a small amount of water use data (
Recent studies have focused on water issues in Central Asia from several perspectives;. First, these have included cross-border water conflicts. For example,
This study aims to calculate the flow of agricultural water resources for Central Asian countries accurately, using the method of virtual water, to better understand comprehensively the state of their agricultural water resources. On this basis, we analyze the causes of agricultural water resource change, put forward management measures for the efficient use of agricultural water resources (
2 Study area
Central Asia is located within 50°-80°E and 35°-55°N and consists of five countries: Kazakhstan, Tajikistan, Kyrgyzstan, Turkmenistan, and Uzbekistan. Because it is located in the hinterland of Eurasia, far away from the oceans, Central Asia has a unique continental climate. Seasonal and daily temperature differences vary widely, and precipitation is sparse and mainly concentrated in spring and summer, especially in spring (
Figure 2.
3 Data and methods
This study is based on the AQUASTAT database from FAO. According to the global average unit mass virtual water content of agricultural (VWC) and livestock products, the five Central Asian countries are used as research units. Using dynamic change analysis of the total virtual water production (TVWP), the total virtual water import (TVWI), and the total virtual water export (TVWE) of agriculture, this study focuses on the dynamic changes of agricultural virtual water in the five Central Asian countries from 1992 to 2016, and discusses the influencing factors of agricultural virtual water change.
Eight categories of agricultural products are included in this study, essentially covering all types of agricultural products in the FAO’s statistics for Central Asia, and fully reflecting the production and trade of such products. Thus, this paper uses the five Central Asian countries as the research area, and selects a total of more than 300 kinds of agricultural products as calculation objects.
To calculate the virtual water content of crops, we must calculate the water demand for agricultural production. The main factors affecting water demand are meteorological factors, including precipitation, temperature, and water pressure, as well as crop type, soil conditions, and planting times. Because of the lack of water use data for the agricultural products in Central Asia, it is impossible to accurately calculate their water demand. In addition, this paper mainly studies the dynamic changes in virtual water in Central Asia for the past 25 years. The focus is not on the calculation of the virtual water content of unit quality agricultural products. Therefore, the global average of the virtual water content of unit quality agricultural products is used to calculate the change of virtual water in Central Asia (
Global average water footprint of some primary crops and derived crop products (m3 ton-1)
Global average water footprint of some primary crops and derived crop products (m3 ton-1)
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The TVWP in agriculture includes the amount of water used for cereal production and the amount of water used for livestock production. The production method is used to calculate the agricultural production in water resource utilization. The calculation of virtual water is equal to the output of a certain agricultural product in a certain area times the VWC of the agricultural product and then sums up the total virtual water of all kinds of agricultural products—the formula is expressed as (3.1); the virtual water trade is obtained by multiplying the import or export volume of a certain agricultural product times the VWC of the agricultural product separately; the formula for calculating the virtual water import volume is expressed as (3.2) and the formula for calculating the virtual water export volume is expressed as (3.3):
where
4 Results and analysis
4.1 Changes in TVWP of agriculture in five countries
The virtual water for the production and consumption of cereals and livestock products in Central Asia in 1992-2016 decreases and then increases, with 1998 as the turning point (
Figure 3.
Changes in water virtual water varied country during the study period. First, it should be mentioned that Tajikistan’s seven-year civil war began in 1992, which was also a major factor resulting in the decrease of total agricultural production in Central Asia (
From the perspective of agricultural product types (
4.2 Changes in TVWI of agriculture in five countries
From the perspective of a country’s import volume (
From the perspective of import types (
Figure 4.
4.3 Changes in TVWE of agriculture in five countries
From the perspective of a country’s total export volume (
Figure 5.
In addition, the TVWE in Kazakhstan increased year by year, and the TVWE in Uzbekistan decreased year by year. Since Kazakhstan’s cultivated land area increased significantly, but its population did not greatly increase (
From the perspective of export types (
The virtual water volume of agriculture in Central Asia is currently in an overall trade surplus (
Figure 6.
Therefore, against the background of shrinking Aral Sea lake and rising food consumption, Central Asia is still a region with a net export of water resources; this affects the sustainable development of the region, exacerbating its attendant ecological crisis (
5 Conclusions and policy implications
5.1 Conclusions
This paper calculates and analyzes changes in Central Asia’s agricultural TVWP, TVWI, and TVWE from the perspective of virtual water. The conclusions are as follows:
(1) After the disintegration of the Soviet Union, some countries were independent, which resulted in a rapid decline in agricultural TVWP in Central Asia from 1992 to 1998. With an increasing population and improvement in economic conditions, the TVWP of agriculture increased gradually after 1998. Among the five Central Asian countries, Uzbekistan and Kazakhstan consumed the largest amount of virtual water for agriculture. In addition, the categories with the most obvious increase in TVWP in Central Asia were cereals, fruits, vegetables and nuts, oils, and livestock products, which reflects the improving quality of life in Central Asia.
(2) From 1992 to 2016, the TVWI volume of agriculture in Central Asia exceeded the TVWE for only three years. In addition, the total TVWE of rice in the 25 years reached 850,000 tons, totaling 1.4 billion m3 of virtual water. This will definitely aggravate the water shortage in Central Asia. However, in recent years, the TVWE volume of agriculture has gradually decreased.
(3) In terms of export trade, the five Central Asian countries must strengthen their cooperation, achieve regional integrated development, and build a risk-prevention mechanism of trade to avoid food crises and water crises.
(4) In the future, with growth in living standards and an increasing population, the demand for agricultural water will be greater in Central Asia. Therefore, it is necessary to make reasonable and effective policies that solve the shortage of water resources.
5.2 Policy implications
Based on our results, the following suggestions are proposed for achieving the use of agricultural water resources sustainably and efficiently in Central Asia:
(1) Change water resources use strategy and control the output of high-water consumption agricultural products. In the past 25 years, the TVWI volume of agriculture in Central Asia has exceeded the TVWE for only 3 years, and the total net of TVWE in the 25 years is 220.1 billion m3. Therefore, control of the output of high-water consumption agricultural products is essential to alleviate pressure on water resources in Central Asia.
(2) Optimize the structure of agricultural planting and control the planting scale of high-water consumption agriculture. In the past 25 years, the TVWP of agriculture in Central Asia has generally increased. In addition, the total area where rice is harvested—rice being a high water-consuming crop—continues to increase. In recent years, Kazakhstan and Uzbekistan, two downstream countries, have begun to optimize the planting structure and reduce the planting area of rice. At present, Uzbekistan’s rice planting area is 72,000 ha, less than half of that in 1992, providing a case for optimizing the planting structure for the other four countries.
(3) Develop water-saving agriculture, increase agricultural investment, and implement water-saving technology sharing. The principle of water-saving agriculture is to improve the utilization of water resources and reduce waste, which is key to achieving the sustainable supply of water resources and meeting food demand (
Based on virtual water theory, this paper takes the five Central Asian countries as the basic unit of state and uses the period 1992-2016 as a time scale to calculate the virtual water of agriculture in Central Asia, and to describe the dynamic changes in virtual water. Due to the lack of field research and more accurate data, the analysis of agricultural water resources in Central Asia is simple. In the future, more detailed research should be carried out while observing the following:
(1) Combine local meteorological data, differences in agricultural production techniques, and differences in the natural environment to accurately quantify the unit content of virtual water in agricultural products.
(2) Research time scales can be accurate to quarterly changes in order to explore the time distribution of water resources in Central Asia. In this way, we can make better strategies to ease water shortages; this is necessary for maintaining regional and even global water security and achieving sustainable development of water resources.
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Ziyan YAN, Minghong TAN. Changes in agricultural virtual water in Central Asia, 1992-2016[J]. Journal of Geographical Sciences, 2020, 30(11): 1909
Received: Mar. 19, 2020
Accepted: Aug. 14, 2020
Published Online: May. 7, 2021
The Author Email: TAN Minghong (tanmh@igsnrr.ac.cn)