To quantify the impacts of human activities and climate change on the evolution of water discharge from the Yellow River into sea, socio-economic water consumption was incorporated into the calculation process. Using restored natural runoff data and the elasticity coefficient method based on the Budyko hypothesis, this study analyzed the evolution characteristics of water discharge from the Yellow River into sea from 1956 to 2022, and identified the driving factors of the changes in water discharge in the period before flow cessation (1956-1971), flow cessation period (1972-1998), and the recovery period (1999-2022). The results indicated that from 1956 to 2022, the water discharge from the Yellow River into sea exhibited a significant declining trend. Although a notable increase occurred during 2018-2022, the average annual water discharge into sea during the recovery period remained lower than that during the flow cessation period. Increased socio-economic water consumption was the dominant factor leading to the decline in water discharge into sea during the flow cessation period, with a contribution rate of 44.45%. In contrast, during the recovery period, underlying surface changes became the primary factor leading to further reductions, accounting for 100.74% of the contribution. The future trajectory of the water discharge from the Yellow River into sea remains uncertain, necessitating further research to elucidate its evolving trends and ensure sustainable water resources utilization in the Yellow River Basin.
- Article type
- Year
- Co-author
Irrigation water sources can greatly contribute to the reserve resources of arable land in northern China. National water network projects have also promoted the arable land reserve resources in recent years. In this study, a systematic evaluation was performed on the potential of cultivated land reserve resources under a water supply project in the northern region. The constraints of natural suitability, efficient use, and stable development were comprehensively analyzed to consider the ecological and spatial fragmentation of arable land reserve resources. The three-dimensional magic square was adopted to select evaluation units. Finally, the arable land reserve resources were optimized to fully meet the three requirements of sustainable ecology, natural quantity, and efficient quality. The results show that: (1) In rain-fed agriculture scenario, the area of unsuitable (Level I) development for cultivated land reserve resources in the unused land in the north was accounted for as high as 96 %, about 1.036 million km2, and the areas of barely suitable (Level II), moderate (Level III) and high (Level IV) were 2.9×104, 1.0×104 and 6.0×103 km2, respectively. Thus, the unused land shared less potential space to meet the reserve development of cultivated land under the limitation of natural precipitation. (2) In the irrigated agriculture scenario, the potential of arable land reserve resources increased significantly in the north region. The area suitable for arable land reserve resources increased to about 2.0×105 km2, accounting for 18% of the total area, mainly located at the edge of the Junggar Basin in Xinjiang, the edge of the Tarim River, the Shule River Basin in Gansu, and part of Inner Mongolia. (3) A comparison was made between the rain-fed and irrigated agriculture scenarios. Irrigation conditions with relatively scarce water resources were required to greatly improve the arable suitability of land resources at the naturally appropriate level. The suitable cultivated area increased from less than 3 000 km2 under the rain-fed scenario to about 48 000 km2, in order to optimize the allocation of land resources. (4) There was a small error in the geographical location and the number of cultivated land reserve resources, compared with the previous. Therefore, the evaluation model of cultivated land reserve resources presented high accuracy and credibility. The findings can provide a strong reference for the development and utilization of arable land reserve resources under the national water network projects in China.
A risk assessment system of water-food system in the Beijing-Tianjin-Hebei region was constructed. Considering the factor of agricultural water footprint, risk assessment of the water food system in the Beijing Tianjin Hebei region from 2000 to 2020 in three time periods was performed. The results showed that the overall water-food system in the Beijing-Tianjin-Hebei region faced a risk of damage from 2000 to 2020, indicating that the system would be at risk and cause significant damage. Cities such as Handan, Zhangjiakou, and Shijiazhuang in Hebei Province had the highest systemic risk, while Beijing had the lowest. In terms of time variation, most areas in the Beijing-Tianjin-Hebei region during the research period were classified as level Ⅲ risk, with four areas of level Ⅳ risk in the first period (2000-2006), two areas in the second period (2007-2013), and 0 in the third period (2014-2020). The system stability has improved over time. In terms of spatial changes, the area with the highest risk in the first two periods was Zhangjiakou, and in the third period was Handan. The regions with the least risk in the three periods are Xingtai, Beijing, and Tangshan. In terms of the contribution of risk indicators, the main factors causing risk of the system from 2000 to 2020 were water shortage rate of agricultural irrigation, and the main factors bearing risk were the degree of water-saving irrigation, the construction status of agricultural irrigation facilities, and the rate of local water resources meeting demand.
The low-carbon operation of sewage treatment systems has received significant attention globally as an important source of greenhouse gas emissions. However, existing research shows a deficiency in the prognostic analysis of future trends in urban sewage treatment systems, and insufficient attention is devoted to greenhouse gases from the sewage pipe network and sludge treatment facilities in greenhouse gas accounting. Consequently, the calculated results fall significantly below the actual values, thus impeding the formulation of targeted emission reduction measures. Although Beijing is one of the cities in China with the highest level of wastewater reuse, the large-scale use of wastewater could significantly increase greenhouse gas emissions. Researching greenhouse gas emissions from Beijing's wastewater treatment system could bear reference significance for other cities under the strategic backdrop of China's carbon peaking by 2030 and carbon neutrality by 2060.
A greenhouse gas accounting system of the sewage treatment system was established to measure the scale of greenhouse gas emissions from 2010 to 2020 based on the sewage treatment process in Beijing. The greenhouse gas accounting system for Beijing's sewage treatment system consisted of three stages: sewage pipeline network, sewage treatment, and sludge disposal. The accounting scope comprised direct emissions of CH4, N2O, and fossil fuel CO2, as well as indirect emissions of CO2 resulting from equipment operation and chemical consumption. Greenhouse gas emissions for each stage were computed using the emission factor method. Additionally, various calculation formulas and parameters were introduced, such as CH4 emission factors, N2O emission factors, and chemical emission factors. Therefore, the greenhouse gas emissions of each stage were calculated and aggregated, using the sewage treatment plant as the calculation unit, to obtain the overall greenhouse gas emissions of Beijing's sewage treatment system. Additionally, the scenario analysis method was used in this study to predict the characteristics of greenhouse gas emissions under different scenarios in 2035.
The following research results are presented: (1) From 2010 to 2020, there has been a significant increase in the level of greenhouse gas emissions emitted by Beijing's sewage treatment system, rising from 1.191 3 to 2.269 1 million tons. Sewage treatment is the most significant stage, accounting for 51.27% of total emissions, followed by sludge disposal (39.92%) and sewage pipeline network (8.81%). (2) The sources of greenhouse gas emissions vary significantly across different stages. The sewage pipeline network is mainly associated with electricity consumption and CH4 emission, whereas sewage treatment is primarily associated with electricity consumption and N2O emission. The sludge disposal stage mainly contributes to CH4 and N2O emissions. Generally, it can be observed that indirect emissions, which include the consumption of electricity and chemical, constitute 62.79% of the total greenhouse gas emissions from Beijing's sewage treatment system. (3) The emission intensities of different treatment standards and processes are different: the emission intensity of the Beijing landmark exceeds the national standard, and the emission intensity of the membrane bio-reactor technology is 1.77 times that of anaerobic-anoxic-oxic technology. (4) The greenhouse gas emissions of Beijing's sewage treatment system in 2035 will increase in the baseline, high standard effluent, and low carbon emission scenarios by 59.87%, 110.69%, and 41.37% compared with 2020. Although the low carbon emission scenario has the smallest increase, its realization requires an additional investment of 4.995 billion Yuan and an area of 1.92 million m2.
The research results show a significant increase in greenhouse gas emissions from Beijing's sewage treatment system and provide pertinent emission reduction recommendations.
京公网安备11010802044758号