Interprovincial food trade and water resources conservation in China

Re-identifying farmland carbon neutrality gap under a new carbon counting and the framework of regional interactions in China

The farmland ecosystem, with its numerous material cycles and energy flows, is an important part of the carbon cycle in terrestrial ecosystems. Focusing on the carbon neutrality of farmland is meaningful for mitigating global warming and serving national low-carbon strategies. This study enriches the carbon accounting items of farmland and establishes a new research framework to check the carbon neutrality of farmland from the aspect of regional interactions and, subsequently, the inequality among China's provinces. The results revealed that there is still a great gap in the capability of China's farmland to reach carbon neutrality, with a gap value of up to 10,503 × 104 t C. All of the provinces presented net carbon emissions, and the per unit area carbon neutrality gaps showed spatial regularity decreasing from the coastal regions to the inland areas. Anthropogenic carbon emissions on farmland played a dominant role compared with soil organic carbon. Five provinces had reduced interior-regional carbon emissions through grain trade, and the amounts were especially high for developed regions, such as Guangdong, Zhejiang, Beijing, Shanghai and Jiangsu. Sixteen provinces gained external carbon emissions through trade; these were the less developed regions located mainly in the north, such as Inner Mongolia, Hebei, Jilin, Heilongjiang and Xinjiang. Under regional inequality, 15 provinces added to the net amount of the carbon emissions generated in external regions, with China's megacities adding the highest percentage, especially Beijing, with 389.95 % compared with its original emissions. Inequality showed that most provinces had a moderate status. Sichuan and Hunan experienced weak advantages, and six provinces had disadvantages. Therefore, constructing compensation and trade-based rights and responsibilities traceability mechanisms is important.

The food security risks in the Yangtze River Delta of China associated with water scarcity, grain production, and grain trade

Grain production consumes a large amount of water and is affected by the degree of water scarcity and participation in the grain trade in various regions. The grain trade has changed the food security risks in regions where grain exports and imports. Therefore, it is crucial to consider regional water scarcity to understand food security risks from the grain trade network. Here, we construct a new framework for measuring regional food security risks associated with water scarcity, grain production, and grain trade based on a cross-city grain trade network combined with virtual water flows to evaluate the regional food security risks in the Yangtze River Delta region (YRD) of China in 2017. The results show that under the current domestic grain trade pattern in China, the YRD and its four provincial-level administrative regions are in a net grain import state. The grain trade within the YRD is concentrated in exports from the two major grain-producing areas of Anhui and Jiangsu to Zhejiang and Shanghai, especially from northern Jiangsu to southeastern Zhejiang. The net import results of virtual blue water in most cities indicate that the YRD has shifted its water resource pressure to other grain exporting regions in China, with Shanghai and Zhejiang being the greatest beneficiaries. Extreme risk only exists in Shanghai, and severe and moderate risks are concentrated in Jiangsu. The current grain trade has reduced the overall food security risk in the YRD by 1.3 % but increased the risks in Shanghai and Zhejiang by 2.1 % and 0.8 % respectively. This study highlights the potential risks that excessive production of food in water-scarce areas in the grain trade system may bring to a stable food supply, providing useful information for a comprehensive understanding of the food and water security situation and for future trade-offs.

Responsibility-sharing and compensation scheme of transboundary water pollution embodied in China's inter-provincial trade: a perspective from economic value capturing

Transboundary water pollution induced by inter-regional trade is a complex and challenging issue due to the multiple jurisdictions involved. This study combined water pollution discharge inventory, multi-regional input-output analysis, discharge responsibility-sharing, and ecological compensation model to advance the collaborative control of water pollution embodied in China's inter-provincial trade. Over a fifth of China's water pollution discharges in 2017, equivalent to 1376 Kt, were a result of inter-provincial trade, which primarily flowed from wealthier coastal provinces to less developed ones. Moreover, the analysis demonstrates a mismatch between economic gains and environmental costs. In particular, Jiangxi and Guangxi bear the greatest environmental impact (64 and 58 Kt, respectively) while only receiving meager economic returns (131 and 80 billion Yuan). The economic benefit shared responsibility results for the great majority of provinces fell between production- and consumption-based discharges, and this compromise-based allocation of responsibility is more likely to gain acceptance across various regions. Provinces such as Shanghai, Jiangsu, and Beijing necessitate the highest compensation volumes to others, with 31 Kt, 25 Kt, and 20 Kt, respectively, while provinces including Guangxi, Jiangxi, and Ningxia require the largest inflows of compensation, totaling 26 Kt, 23 Kt, and 18 Kt, respectively. The compensation outcomes ensure that less developed regions, bearing a greater pollution burden, receive compensation from more developed regions with lower pollution burdens. The compensation values aligned with compensation volumes, with a few exceptions driven by variations in shadow prices of water pollution. Our study sheds light on the inter-provincial water pollution burdens and benefits and provides a quantitative basis for optimizing the responsibility-sharing and compensation strategies in China, thereby promoting regional cooperation on water pollution control.

Assessment of Sectoral Virtual Water Flows and Future Water Requirement in Agriculture Under SSP-RCP Scenarios: Reflections for Water Resources Management in Zhangye City

Water scarcity is a core issue that constraints the high-quality development of arid areas in northwestern China. Zhangye is an oasis city located in the Heihe River Basin in northwestern China. It is populated with an agriculture-dominated economy and faces more and more serious water crises. Virtual water is an indicator that can measure the embodied water in the traded products, which has been widely applied for making rational policies for water resources management. In addition, clarifying water requirements in agricultural sectors under future climate change scenarios is essential to develop more appropriate adaptation strategies. From this perspective, this study aims to evaluate and compare virtual water flows among various sectors in Zhangye for the years 2012 and 2017 with a single regional input-output model and to further clarify the future water requirement tendency in agriculture during 2020–2050 under different shared socioeconomic pathways and representative concentration pathways (SSP-RCP) scenarios. The results showed that the planting sector directly contributed most of the total water consumption with the highest direct coefficient of 3307.5 m3/yuan in 2012, whereas the manufacture of food products and tobacco processing sector had the largest proportion of indirect water consumption (99%) mainly from intermediate inputs of agricultural products. Water consumption intensity of all sectors on average decreased by 22% during 2012–2017, indicating an increasing water utilization efficiency in economic industries. Household consumption also can improve water utilization efficiency as the major pathway for final consumption (86.4% in 2017). Water scarcity in Zhangye was becoming increasingly prominent since virtual water net exports were higher than local consumption, especially in the agriculture, manufacturing, and energy supply industries. Moreover, under climate change scenarios, we found the highest level of water requirement per unit area occurred in 2000, but it still had an incremental potential by 2050, especially in SSP585. The high requirement intensity and large-scale maize planting caused a rising tendency of total crop water requirement with an annual increasing rate of 8.4% from 1980 to 2050. This makes it possible to adapt to climate change through scientific management measures and technical means. We further made policy implications for adaptive management of water resources in Zhangye.

Disclosing the future food security risk of China based on crop production and water scarcity under diverse socioeconomic and climate scenarios

Climate change and human development may lead to a serious crisis in food security in China, especially in areas with both water shortages and large grain production. Thus, the quantitative evaluation of future food security risk considering water scarcity is increasingly important. Here, we combined water scarcity and crop production data under different scenarios of representative concentration pathways (RCPs) and shared socioeconomic pathways (SSPs), incorporating demographic, food habit and water resource factors, to develop a new framework for measuring China's food security risk. The results show that the water scarcity and crop production-water crisis (CPWC) of China would both be aggravated during the 21st century. In particular, northern China might face more serious water scarcity than southern China and has a higher contribution rate to the national crop production-water crisis. Food scarcity in China might occur at some point in the 21st century under all SSP scenarios, except SSP1 (sustainability development pathway). The next 40 years could be the most critical period for ensuring China's food security. Moreover, by comparing the RCP2.6 and RCP6.0 scenarios, we also find that higher food production does not represent lower food security risk. The food security risk of the RCP26 scenario with higher food production was significantly higher than that of the RCP6.0 scenario at the same SSP because higher grain production comes from water shortage areas. From the perspective of societal development scenarios, SSP1 provided better results for both the risk of food security and water security in the 21st century. Our findings therefore provide useful information for a comprehensive understanding of long-term food security and water security of China.

Unfolding the synergy and interaction of water-land-food nexus for sustainable resource management: A supernetwork analysis

Given the large amounts of water, land, and food embodied in the trade of goods and services, a key step in decoupling extensive resource consumption from the economic system is to understand the full impact of socioeconomic development on the water-land-food nexus. This study integrates input-output analysis, ecological network analysis, and Dempster-Shafer evidence theory into a supernetwork model to detect the water-land-food nexus among economic sectors with an aim to explore effective strategic paths for resource management and to facilitate the construction of a resource-saving society. Results show that most sectors of China are resource inefficient and that all resource systems are unsustainable as reflected in the low performance of their Finn's cycling index and system robustness. Meanwhile, results of flow networks analysis show an extremely uneven land resource allocation where more than 94% of the land used in China is classified as direct agricultural land. The water-land-food nexus can gain resource saving bonus via enhancing the robustness of economy. However, the co-benefits from the nexus are negligibly small for the resource utilization efficiency. The results also indicate that the relevant resource-saving policies on food and water are highly likely to gain resource co-benefits due to their similarities in sectoral importance. Correspondingly, a set of strategic measures, including adopting a tiered resource price, deepening industrial convergence of agriculture, enhancing agriculture-food nexus, and managing water or land use from the food consumer side, are designed to build a resource-saving society. The findings of this study can provide additional insights into the impacts of the economy on the water-land-food nexus, which is beneficial for achieving an efficient and coordinated management of resources.

Effect of Water-Saving Society Policy on Water Consumption in the Cities of China: A Propensity Score Matching Analysis

The increased demand for water resources due to urban population and economic growth has worsened the urban water crisis. In order to address this issue, a policy of "developing a water-saving society" (namely, water-saving society policy) has been implemented in some Chinese cities. This study takes 285 cities at the prefecture level and above as the sample and uses the propensity score matching (PSM) method to analyze the effect of China's urban water-saving society policy on the reduction of water consumption per CNY 10,000 gross domestic product (GDP) from 2005 to 2017. The results show that the water-saving society policy significantly (p < 0.01) reduced water consumption in the study period; however, the effects differed between cities with different water resource endowments, economic development level, and urban scale. Specifically, there was a positive water consumption reduction effect in cities in humid areas, with low economic development, or of large scale, while the effect was limited in cities in arid areas, with high economic development, or of small scale. Therefore, for areas where water resource supply is insufficient, water-saving policy should be designed and implemented suiting local conditions, and it is also necessary to explore more water sources.