North China Region Research Articles

Runoff Responses of Various Driving Factors in a Typical Basin in Beijing-Tianjin-Hebei Area

Changes in land use and landscape caused by human activities, rapid socioeconomic development and climate change disturb the water cycle process and impact the runoff. This study analyzed the runoff responses to different driving factors in a typical basin in the Beijing-Tianjin-Hebei region of North China combined with methods such as geographically and temporally weighted regression, landscape pattern indexes and Budyko theory. The results indicated that the runoff and runoff depth were higher in the central and south part and were lower in the northwest of the basin. Furthermore, the average runoff increased at the later stage of the study period. Artificial surface and land use intensity exerted positive impacts on runoff and runoff depth in most areas. The complex and diverse landscape with a high shape index blocked runoff to some extent. Moreover, runoff depth would increase by 0.724 mm or decrease by 0.069 mm when the rainfall or potential evaporation increased by 1 mm. In addition, population density and the economic development in both rural as well as urban areas put a heavy burden on runoff and water resource in this basin. From above it could be concluded that the impacts on runoff due to environmental change brought by human activities could not be neglected though the runoff was also greatly affected by climate change. This study reflected the runoff responses to driving factors in a typical basin of North China, which will provide reference for water resource protection and give enlightenment to water management.

Forward and reverse courier logistics distribution path planning based on multi-objective optimization genetic algorithm

In order to optimize the express logistics distribution path and improve the distribution efficiency, the multi-objective optimization model of express logistics distribution path with mixed time windows is proposed. The model takes into account the requirements of express substations for on-time arrival, express enterprises' control of logistics costs, quantifying customer satisfaction with on-time arrival rate, and constituting logistics costs with fixed costs and transportation costs. Based on the multi-objective optimization genetic algorithm, the Pareto solution set is obtained, and the optimal solution is selected by combining four evaluation methods. The feasibility of the method is demonstrated by applying the method to the case of a region in North China.

Optimizing drip fertigation management based on yield, quality, water and fertilizer use efficiency of wine grape in North China

Drip fertigation is an advanced technology combining micro-irrigation with fertilization, which is conducive to deliver water and nutrients to crops or fruit trees synchronously. To optimize drip fertigation scheduling for wine grape in North China, a three-year field experiment was conducted to study the effects of irrigation and fertilization quota on yield, berry quality, water use efficiency (WUE) and partial factor productivity of fertilizer (PFPF). Nine treatments were set up based on the combinations of three irrigation levels and three fertilization rates. The three irrigation levels were 100 % (IH), 80 % (IM) and 60 % (IL) of the designed irrigation quota, i.e., 25, 20 and 15 mm per irrigation event. The three fertilization rates were 100 % (FH), 80 % (FM) and 60 % (FL) of the compound water-soluble fertilizer amount locally recommended, i.e., 630, 504 and 378 kg ha−1 yr−1. Both irrigation and fertilization had a significant effect on yield. Irrigation also significantly affected titratable acid and sugar-acid ratio. Averaged across the years and fertilization rates, compared with IH treatment, IM treatment decreased titratable acid by 3.3 % and increased sugar-acid ratio by 12.2 %; IL treatment decreased titratable acid by 10.7 % and increased sugar-acid ratio by 20.0 %. FM treatment presented the richest anthocyanins and condensed tannins among the three fertilizer rates. IWUE was significantly increased with the decrease of irrigation amounts; WUE and PFPF reached the maximum in IM treatment. The decrease of fertilizer rates significantly increased PFPF but was not beneficial for WUE. Interaction effects between irrigation and fertilization were only significant on PFPF. Assessed by gray relational analysis (GRA), technique for order preference by similarity to ideal solution (TOPSIS) and combinational evaluation method (CEM), the combinational evaluation value (Qi) of IMFM treatment (moderate water and fertilizer, 20 mm per irrigation event combined with 504 kg ha−1 yr−1 compound water-soluble fertilizer) was the highest on the whole, indicating that IMFM treatment was the optimal treatment which could balance yield, quality and water-fertilizer use efficiency. These results may provide a benchmark for wine grape cultivation under drip fertigation in North China and other regions with similar environmental conditions.

Hydrochemical evolution characteristics, controlling factors, and high nitrate hazards of shallow groundwater in a typical agricultural area of Nansi Lake Basin, North China

Anthropogenic nitrate contamination in groundwater could not be neglected, which has been a global issue threatening public health, especially in agricultural fields where fertilizers were used intensively. The present study focused on evaluating the groundwater evolution process, quality, and associated health risks from nitrate pollution in Nansi Lake Basin (NLB), a typical intensive agricultural region of North China. For this purpose, fifty-two shallow groundwater samples were collected and analyzed major chemical parameters in June 2022. The groundwater samples are found to be mainly dominated by HCO3–Ca·Mg and SO4·Cl–Ca·Mg types. Water-rock interactions like minerals dissolution/precipitation and ion exchange were found to be the important processes influencing hydrochemistry. Nitrate content in groundwater fluctuated from 1.9 to 750.0 mg/L (average:148.7 mg/L), with about 75% of samples surprisingly exceeding the permissible limit (50 mg/L) set by the World Health Organization (WHO). Anthropogenic activities can be classified as excessive nitrogen fertilizer application, livestock manure, and industrial/domestic sewage, coupled with irrigation return flow, which brought significant hazards to human health. The calculation results of entropy weighted water quality index (EWQI) showed that about half of groundwater samples are unfit for drinking purposes. Most importantly, 88.5%, 88.5%, 73.1%, and 71.2% of the water samples had considerable NO3− health risks (HQ > 1) for infants, children, females, and males, respectively. It is suggested that the groundwater should be chemical and biological denitrification for nitrate removal before being used for drinking purposes. The findings of this work can help policymakers to solve groundwater pollution problems and ensure healthy drinking water in such intensive agricultural basins and other similar regions worldwide.

Ecological restoration exacerbates the agriculture-induced water crisis in North China Region

The North China Region (NCR), a typical grain base and highly populated area in China, is a well-recognized global groundwater funnel. Severe water shortage has been threatening and limiting sustainable development in the region over the past decades. Previous studies have reported the depleted water resources in the NCR and attributed the major driver to intensified agricultural water use, hardly considering the effects of the large-scale implementation of ecological restoration (ER) programs. As terrestrial water storage (TWS) is a critical indicator for measuring and evaluating regional water resources, understanding its spatial and temporal dynamics and responses to ER programs is significant for sustainable water management in the NCR. Here, we examine the interannual variations and trends of TWS in the NCR during 2002–2016 by using Gravity Recovery and Climate Experiment (GRACE) satellite data and the Google Earth Engine cloud computing platform. We find the significantly (p < 0.01) decreasing TWS (-8.9 mm/yr) and identify a hotspot with the most rapid depletion (-12.7±0.45 mm/yr) in the western NCR, where interannual variations and spatial patterns of TWS depletion are consistent with those of ER-induced greening. Attribution analyses of TWS depletion by considering precipitation, evapotranspiration, and runoff suggest increasing evapotranspiration induced by afforestation as the major driver for TWS depletion in the ER regions. Our study highlights ER is posing a new threat to water security in the NCR, and taking ecological water usage into account would be necessary for the synergy of food, water, and ecological securities and regional sustainable development.

Identification of a Function to Fit the Flow Duration Curve and Parameterization of a Semi-Arid Region in North China

The discharge process has undergone major changes in many river basins throughout the world as a result of the simultaneous influences of global climate change and human activity. Flow duration curves (FDCs) are crucial indicators of river basins’ hydrological processes. However, it is challenging to compare FDCs in a quantitative way. This study will identify the best function with which to fit the flow duration curve in a semi-arid region of North China, so as to quantify the FDC, and parameterize the function of the FDC of the region in order to describe the FDCs of ungauged basins. In this work, six small- and medium-sized catchments in North China are selected as the study area, and three functions, i.e., log normal, generalized Pareto and H2018 functions, were chosen to fit the FDC at nineteen hydrological stations. The relationship between the parameters of the FDC and the basin characteristics, such as the climatic factors and geographical features, were analyzed. A regression formula of the parameters of the FDC function was established, and its spatial and temporal distributions were examined. Based on the evaluation of four indicators, the Nash–Sutcliffe efficiency, the root mean square relative error, the logarithmic Nash efficiency coefficient and the coefficient of determination, the results demonstrate that the H2018 function can match FDCs the best. Through the annual runoff, annual precipitation, precipitation in summer, potential evapotranspiration, catchment area, mean elevation, length of the main channel and maximum flow frequency, the parameters of a, b, and k in the H2018 function can be formulated. The regression formula constructed in this study can obtain a regional flow duration curve with satisfactory performance, which provides a reference for the validation of remote-sensing-based runoff data in ungauged regions.

LANDSCAPE CHANGE OF LAND USE IN THE KARST REGION OF JINAN CITY, NORTH CHINA

With the rapid development of urbanization, land use change has occurred in most karst mountain regions of North China over the last decade, so studying landscape pattern changes induced by urbanization would have implicational significance to regional planning and sustainability. Based on RS, GIS, and field investigation, land use change induced by urbanization in Jinan city belonging to the karst mountainous area of North China was analyzed over 30 years from 1987 to 2018, and further the landscape response of these changes was explored. The results indicate that (1) the most obvious changes have occurred in both urban/built-up land area and cropland area with rapid urbanization development in Jinan’s karst area, and the former increased by 246.4 km2 but the latter decreased by 343.3 km2 from 1987 to 2018; (2) landscape pattern of land use is profoundly changed by quick urbanization in the period from 2000 to 2018, but does not siginificently from 1987 to 2000; and (3) in the monitoring period, the cropland’s shape inclines to fragmentation and regularization, and the shapes of urban/built-up land and barren land have become increasingly distinct from the patch class level; from patch landscape level, the artificial landscape type (urban/built-up land) is increasingly dominant but the natural landscape type (grassland) is decreasingly dominant, thereby resulting in the disturbance of urban karst environment of Jinan city. Therefore, a protection policy should be taken to achieve strong urban karst sustainable development of North China.

A Comparison between 2D and 3D Rescaling Masks of Initial Condition Perturbation in a 3-km Storm-Scale Ensemble Prediction System

Abstract Using a 3-km regional ensemble prediction system (EPS), this study tested a three-dimensional (3D) rescaling mask for initial condition (IC) perturbation. Whether the 3D mask-based EPS improves ensemble forecasts over current two-dimensional (2D) mask-based EPS has been evaluated in three aspects: ensemble mean, spread, and probability. The forecasts of wind, temperature, geopotential height, sea level pressure, and precipitation were examined for a summer month (1–28 July 2018) and a winter month (1–27 February 2019) over a region in North China. The EPS was run twice per day (initiated at 0000 and 1200 UTC) to 36 h in forecast length, providing 56 warm-season forecast cases and 54 cold-season cases for verification. The warm and cold seasons are verified separately for comparison. The study found the following: 1) The vertical profile of IC perturbation becomes closer to that of analysis uncertainty with the 3D rescaling mask. 2) Ensemble performance is significantly improved in all three aspects. The biggest improvement is in the ensemble spread, followed by the probabilistic forecast, and the least improvement is in the ensemble mean forecast. Larger improvements are seen in the warm season than in the cold season. 3) More improvement is in the shorter time range (&lt;24 h) than in the longer range. 4) Surface and lower-level variables are improved more than upper-level ones. 5) The underlying mechanism for the improvement has been investigated. Convective instability is found to be responsible for the spread increment and, thus, overall ensemble forecast improvement. Therefore, using a 3D rescaling mask is recommended for an EPS to increase its utility especially for shorter time range and surface weather elements. Significant Statement A weather prediction model is a complex system that consists of nonlinear differential equations. Small errors in either its inputs or model itself will grow with time during model integration, which will contaminate a forecast. To quantify such contamination (“uncertainty”) of a forecast, the ensemble forecasting technique is used. An ensemble of forecasts is a multiple of model runs at the same time but with slightly “perturbed” inputs or model versions. These small perturbations are supposed to represent true “uncertainty” in inputs or model representation. This study proposed a technique that makes a perturbation’s vertical structure more resemble real uncertainty (intrinsic error) in input data and confirmed that it can significantly improve ensemble forecast quality especially for a shorter time range and lower-level weather elements. It is found that convective instability is responsible for the improvement.

基于发生指数的中国森林生物灾害趋势与突变特征

PDF HTML阅读 XML下载 导出引用 引用提醒 基于发生指数的中国森林生物灾害趋势与突变特征 DOI: 10.5846/stxb202110132891 作者: 作者单位: 作者简介: 通讯作者: 中图分类号: 基金项目: 中国林业科学研究院基本科研业务费专项（CAFYBB2016SY014，CAFYBB2020ZD001） Trend and abrupt change analysis of forest biological disasters in China based on forest pest outbreak index Author: Affiliation: Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:监测分析森林生物灾害时空变化特征对了解森林生物灾害的动态演变和综合治理具有重要意义。基于1998-2019年森林有害生物灾害面积及同期森林面积增长统计数据，计算衍生了森林有害生物发生指数（FPOI）、灾害发生率（FPOAR）两个系列指标集，分别采用Sen's斜率估计（Sen+Mann-Kendall）和曼-肯德尔（Mann Kendall，M-K）突变检验、滑动T检验、变异系数和赫斯特指数（Hurst exponent）指数方法分析中国森林生物灾害的时空分异特征。研究表明：（1） FPOI、FPOAR指标用于森林生物灾害不同尺度分析具备可操作与适用性，两指标均可分析有害生物发生趋势与突变，但表现程度有所差别。（2）历史变化特征，全国尺度FPOI森林生物灾害总体表现为下降趋势，FPOAR表现为上升趋势，省区尺度，新疆、西藏、天津等局部省区森林生物灾害呈上升趋势，而华北、东北、华东、西北等大部分省区表现为下降态势。（3）突变特征，全国尺度上趋势突变仅在2001年发生，其它年度趋势未变。在省区尺度则大部分区域并未展现突变，局部省区多展现一次趋势改变，且不同省区突变时间有一致性。（4）稳定性特征，全国大部分省区显示稳定，但FPOI、FPOAR指标衡量存在差异，以FPOAR指标海南、青海、浙江、重庆、上海等5省区表现不稳定，但以FPOI指标，不稳定区域扩大到11省区，增加了除以上省区的甘肃、西藏、山西、河南、江苏、吉林6省区。（5）未来趋势特征，全国森林生物灾害与历史趋势保持一致，大部分省区呈现持续下降趋势。局部省区如新疆、西藏仍然显示持续增加态势。 Abstract:Monitoring and analyzing the spatio-temporal patterns changes is of great significance for understanding the dynamic evolution and integrated management of forest biological disasters. Based on the open statistical data of forest pest disaster area and forest cover area at national and provincial scale from 1998 to 2019, two series of indicators, the Forest Pest Outbreak Index (FPOI) and the Forest Pest Occurrence Area Rate (FPOAR), were calculated and derived. The spatial and temporal differentiation characteristics of forest biological disasters in China were revealed by the indicators data analysis with various methods. Sen's Slope Estimator and Mann Kendall test, Mann Kendall mutation test, sliding T test, coefficient of variation, and Hurst exponent were adopted separately in analyzing the trend, sudden changes and stability of occurred disasters. The results are as follows:(1) Both of FPOI and FPOAR indicators are suitable for different scales analysis of forest biological disasters. With the clearly differentiation of the consistent spatio-temporal data of the two indicators, the characteristics of forest biological disasters could be analyzed and quantitative visualized. However, there might be partially different between the results by the two indicators. (2) Regarding the characteristics of historical trend, the FPOI indicator with more weight on severe and moderate disasters showed downward trend at the national scale, while the FPOAR indicator was an upward trend. At the provincial scale, both indicators disclosed that forest biological disasters in Xinjiang, Tibet, Tianjin and a few other provinces were on the rise. However, more provinces in most regions of North, Northeast, East, and Northwest China showed a downward trend. (3) In terms of mutation characteristics, at the national scale, the trend mutation occurred only in 2001, and there was no mutation in other years. At the provincial scale, most regions did not show abrupt changes, and a few provinces showed one trend changes in the same years. (4) According to the stability characteristics of forest biological hazards, forest pest disasters showed stable in most provinces across the country. The performance of 5 provinces included Hainan, Qinghai, Zhejiang, Chongqing, Shanghai were unstable by the FPOAR indicator, the unstable provinces numbers expanded to 11 by the FPOI indicator, 6 more provinces included Gansu, Tibet, Shanxi, Henan, Jiangsu, Jilin provinces were joined. (5) For the characteristics of the future trend, forest pest disasters at the national scale and in regions at the provincial scale are consistent with historical trends, showing a continuous downward trend in most provinces. A few provinces, such as Xinjiang and Tibet, still show a continuous upward trend. 参考文献 相似文献 引证文献

Assessing the contribution of open crop straw burning to ground-level ozone and associated health impacts in China and the effectiveness of straw burning bans

In recent years, ozone pollution in China has been shown to increase in frequency and persistence despite the concentrations of fine particulate matter (PM2.5) decreasing steadily. Open crop straw burning (OCSB) activities are extensive in China and emit large amounts of trace gases during a short period that could lead to elevated ozone concentrations. This study addresses the impacts of OCSB emissions on ground-level ozone concentration and the associated health impact in China. Total VOCs and NOx emissions from OCSB in 2018 were 798.8 Gg and 80.6 Gg, respectively, with high emissions in Northeast China (31.7%) and North China (23.7%). Based on simulations conducted for 2018, OCSB emissions are estimated to contribute up to 0.95 µg/m3 increase in annual averaged maximum daily 8-hour (MDA8) ozone and up to 1.35 µg/m3 for the ozone season average. The significant impact of OCSB emissions on ozone is mainly characterized by localized and episodic (e.g., daily) changes in ozone concentration, up to 20 µg/m3 in North China and Yangtze River Delta region and even more in Northeast China during the burning season. With the implementation of straw burning bans, VOCs and NOx emissions from OCSB dropped substantially by 46.9%, particularly over YRD (76%) and North China (60%). Consequently, reduced OCSB emissions result in an overall decrease in annual averaged MDA8 ozone, and reductions in monthly MDA8 ozone could be over 10 µg/m3 in North China. The number of avoided premature death due to reduced OCSB emissions (considering both PM2.5 and ozone) is estimated to be 6120 (95% Confidence Interval: 5320–6800), with most health benefits gained over east and central China. Our results illustrate the effectiveness of straw burning bans in reducing ozone concentrations at annual and national scales and the substantial ozone impacts from OCSB events at localized and episodic scales.

Linum usitatissimum ABI3 enhances the accumulation of seed storage reserves and tolerance to environmental stresses during seed germination and seedling establishment in Arabidopsis thaliana

Flax (Linum usitatissimum) is an important oil crop in arid and semi-arid regions of North and Northwest China, and its seeds are rich in nutritious storage reserves, such as polyunsaturated fatty acids (FAs) and proteins. However, the regulatory networks that control the accumulation of seed storage reserves in flax are still largely unknown. In this study, we found that LuABI3-1 and LuABI3-2 homologs from the flax cultivar ‘Longya 10’ play important roles in regulating the accumulation of seed storage reserves in Arabidopsis thaliana. The results of subcellular localization and transcriptional activity assays showed that both LuABI3-1 and LuABI3-2 function as transcription factors. Overexpression of either LuABI3-1 or LuABI3-2 resulted in the significant increase in the contents of total seed FAs and storage proteins, but did not alter other key agronomic traits in A. thaliana. Accordingly, the expression of key genes involved in the biosynthesis of FAs and storage proteins was also greatly up-regulated in the developing seeds of LuABI3-1-overexpression lines. Additionally, both LuABI3-1 and LuABI3-2 enhanced the tolerance to the high salt and mannitol stresses during seed germination and seedling establishment in A. thaliana. These results increase our understanding of the LuABI3 regulatory functions and provide promising targets for genetic manipulation of L. usitatissimum to innovate the germplasm resources and cultivate high yield and quality varieties.

Complex fault geometry of the 1976 Ms 7.8 Tangshan earthquake source region in North China

Investigating the fine structure of fault zones is essential for understanding the mechanism of large earthquake nucleation. In this paper we study the complex fault geometry of the Tangshan fault zone in North China using a new seismic data set from 2010 to 2020 that spans ∼10 years. Based on the well-located hypocenters and focal mechanism solutions, we obtained more detailed information on the fault zone structural features: (1) the fault zone is divided into five segments according to different dip angles of the fault plane; (2) the spatial distribution of seismicity reveals conjugate fault branches and a flower-shaped structure at the northern part of the fault zone; and (3) the fault zone is dominated by a strike-slip type, but their intersecting segments are characterized by a normal-fault type. We further obtained high-resolution seismic images of Vp, Vs and Vp/Vs around the Tangshan source region. Combining the fault geometry with the low-velocity anomalies below 10 km depth, we infer that the ascending of hot mantle material into the lower crust may have weakened the Tangshan fault zone and generate the 1976 Ms. 7.8 Tangshan earthquake.

Can Health Literacy in Patients with Chronic Atrophic Gastritis Improve the Ability to Identify Rumors? A Cross-sectional Study

Objective: To examine the connection between rumor recognition and health literacy in people with chronic atrophic gastritis (CAG). Methods: In this study, a cross-sectional design was employed. From May 6, 2020 to January 24, 2021, a total of 10 hospitals in each of the 5 major administrative regions of East China, North China, Central China, South China, and Northwest China were used as survey sites, and researchers were recruited to intercept CAG patients for questionnaire surveys through convenience sampling. We collected data using a self-designed questionnaire based on the functional, communicative, and critical health literacy and anti-rumor platforms. The t-test, analysis of variance, Pearson correlation analysis, and multiple stepwise linear regression analysis were all performed using SPSS 26.0. Results: A total number 602 valid samples were obtained in this study. CAG patients had a health literacy score of (51.07±11.03). For patients with CAG, the rumor recognition ability score was (8.44±2.95), with a mean correct rate of 52.8%. There were statistical differences in the ability to read rumors among patients with atrophic gastritis by place of residence (P&lt;0.01), age (P&lt;0.001), nation (P&lt;0.001), marital status (P&lt;0.05), and level of health literacy (P&lt;0.001). Patients had a weak positive link between health literacy and rumor recognition, according to Pearson correlation analysis (r=0.236, P&lt;0.01). After adjusting for the nation, marital status, residence, and age, multiple stepwise linear regression analysis revealed that the capacity of patients to read rumors increased with increasing levels of functional health literacy (β=0.136, P&lt;0.001) and critical health literacy (β=0.195, P&lt;0.001). Conclusion: This study found CAG patients had lower rumor recognition, and that critical health literacy had a stronger positive effect on their rumor recognition after adjusting for demographic correlations. The use of targeted interventions is recommended to increase critical health literacy and lessen the harmful effects of rumors.

A spatio-temporal prediction model theory based on deep learning to evaluate the ecological changes of the largest reservoir in North China from 1985 to 2021

Miyun Reservoir, located in the Miyun District, Beijing, China, is the largest comprehensive water conservancy project and is an important ecological protection area in the North China region. Changes within the basin are the driving factors affecting the ecosystem in the watershed; therefore, it is important to analyze the changes in the ecological environment of Miyun Reservoir. For the analysis of a long time series of image data remotely sensed by satellite, the outliers caused by atmospheric, lighting, and sensor measurement errors are significant, and it is difficult for traditional algorithms to effectively recover the true image value. To address this, this paper proposes a theoretical model for predicting spatio-temporal variation based on deep learning to identify and correct invalid and anomalous values in extended time series data. This study corrected and analyzed the results of Remote Sensing based Ecological Index inversion of Landsat data of the Miyun Reservoir watershed from 1985 to 2021. The findings and conclusions of this study are important for the analysis of long time series image data from satellite remote sensing and for improving regional ecological evaluation and sustainable development planning.

FINER-SCALE MONITORING AND ANALYSIS OF 2016–2021 DUST STORMS DISASTERS IN CHINA BASED ON HIMAWARI-8 SATELLITE IMAGERIES

Abstract. Today, remote sensing is one of the important techniques for natural disasters monitoring. Using the Himawari-8 new generation of geostationary meteorological satellite image data, we identified and monitored 2016–2021 dust storm disasters in China at the finer scale, and compared the object-oriented classification, supervised and unsupervised classification methods. Taking the dust storm on May 5, 2016 as example, the average accuracy and kappa coefficient of the supervised classification were 0.78 and 0.68, while the object-oriented classification were 0.81, 0.73. We used the object-oriented classification method to classify the 2016-2021 dust storm incidents across China. In 2021, the largest area affected by sandstorms was about 68.33km2, the smallest area was about 2.08km2, and the average area was about 22.25km2. During 2016–2021, the most severe and wide-spreading sandstorm occurred on March 14–18 2021. The dust storm first appeared in northwestern Mongolia on March 14, and then spread southeast to China. The dust area covered Beijing on the 15th, and then spread from eastern China to the western regions of North China and Northeast China, including most of the Hexi Corridor. On the 16th and 17th, the influence of the dust storms narrowed to central and western Inner Mongolia, northern Gansu and southern Mongolia. The dust storm gradually disappeared on the 18th.

Environmental Factors Driving the Transpiration of a Betula platyphylla Sukaczev Forest in a Semi-arid Region in North China during Different Hydrological Years

More and more droughts happened during the last decades, threatening natural forests in the semi-arid regions of North China. The increase in drought pressure may have an impact on stand transpiration (T) in semi-arid regions due to rising temperature and changes in precipitation. It is unclear how the transpiration of natural forest in semi-arid regions respond to drought, which is regulated by environmental factors. In this study, a relatively simple but mechanism-based forest stand T model that couples the effects of the reference T, solar radiation (Rn), vapor pressure deficit (VPD), and relative extractable water (REW) in the 0–80 cm soil layer was developed to quantify the independent impacts of Rn, VPD, and REW on T. The model was established based on the observed sap flow of four sample trees, and environmental factors were observed from May to September in different hydrological years (2015, 2017, 2018, and 2021) in a pure white birch (Betula platyphylla Sukaczev) forest stand in the southern section of the Greater Khingan Mountains, northeastern China. The sap flow data were used to calculate tree transpiration (Tt) and T to calibrate the T model. The results indicated that (1) The Tt sharply declined in the ‘dry’ year compared with that in the ‘wetter’ year. The daily Tt for small trees in the ‘dry’ year was only one-fifth of that in the ‘wetter’ year, and the daily Tt of large trees was 48% lower than that in the ‘normal’ year; (2) Large trees transpired more water than small trees, e.g., the daily Tt of small trees was 89% lower than that of the large trees in the ‘normal’ year; (3) Daily T increased with the increase in Rn, and the response conformed to a binomial function. Daily T responded to the rise of VPD and REW in an exponential function, first increasing rapidly, gradually reaching the threshold or peak value, and then stabilizing; (4) The driving factors for the T shift in different hydrological years were the REW in the ‘dry’ year, but the Rn and REW in the ‘wet’, ‘normal’, and ‘wetter’ years. The REW in the ‘wet’ and ‘wetter’ years exerted positive effects on T, but in the ‘normal’ and ‘dry’ year, exerted negative effects on T. Thus, the environmental factors affecting T were not the same in different hydrological years.

Mapping rainfall interception for assessing ecological restoration sustainability in China

Ecological restoration (ER) programs play an important role in local and global climate change and carbon management policy interventions. Water resource is a key criterion for assessing the sustainability of ERs. Herein, we explored the spatiotemporal patterns of rainfall interception (RI, an important component of ecosystem water budgets), and its drivers after ER implementation in China. Further, we assessed whether ERs are sustainable by analyzing the trends of RI and water supply. As expected, we found that ERs caused an increase in RI in China from 2001 to 2018 (0.64 mm yr−1, p < 0.01). Changes in the normalized difference vegetation index and leaf area index contributed to a higher change in RI compared with other drivers. The decrease in RI was mainly recorded in the Qinghai–Tibet Plateau in Southwest, northern North, and southern Central and Southern China. Conversely, an increasing trend of RI was recorded in the Loess Plateau in Northwest, Northeast, and East China. Moreover, ERs are not always unsustainable in China, especially in Northeast, East, Central and Southern, and high-latitude regions of northern North China. Even in the Loess Plateau, which was criticized by previous studies, the unsustainability occurred only in the semi-humid region. Future ERs should be prioritized in southern parts of Eastern, Central, and Southern China, and must be appropriately considered in the Northeast and high-latitude regions in North China. It should be alert to the pressures of ERs on water supply, and its demand remains vigilant in the Qinghai–Tibet Plateau and semihumid areas of the Loess Plateau. This study provides new ideas for accurately evaluating the impact of ERs on water security and the sustainability of ERs.

Heat extraction by deep coaxial borehole heat exchanger for clean space heating near Beijing, China: Field test, model comparison and operation pattern evaluation

Deep coaxial borehole heat exchangers (CBHEs) are being widely used in clean space heating of buildings in winter. Here we report a new field test on a 1800m deep CBHE in the southern Daxing uplift, Beijing, a representative geological region in North China. Under the economic flow rate of 20–25 m3/h, the steady heat extraction power is 237.24–256.54 kW. Further, numerical modelling and simulation calculations are performed to compare the applicability of the Eskilson-Claesson model and Al-Khoury model for different operation patterns and then analyze the operation performance of deep CBHE during the whole heating season. For typical flow rates, compared with the continuous pattern, the intermittent pattern can increase the heat extraction power per unit depth by 25.4–31.0% and reduce the thermal influence radius by 1.46–1.89 m due to a better ground temperature recovery around the borehole. In addition, a new contribution factor (CF) is introduced to evaluate the temperature contribution of different ground layers during the heat extraction, which can reveal the influences of flow conditions, geothermal gradient, thermal properties, and even groundwater flow. The present results support that deep CBHEs have more obvious advantages for space heating of buildings with intermittent heating requirements.

Quantifying the Space-Time Variations of Water Demands for Major Crops in Hebei Province, China

Hebei Province is a typical water-scarce agricultural region in North China. Quantifying the water demands of major crops and their variations in this region is crucial for the sustainable use of agricultural water resources. Based on meteorological data and crop growth parameters of 21 national weather stations in Hebei Province from 2007 to 2017, this study analyzed the crop water requirement, irrigation water demand, and water deficit index and their dynamic changes for several grain and vegetable crops including winter wheat, summer maize, soybean, potato, tomato, cucumber, eggplant, cowpea, Chinese cabbage, cabbage, and carrot. In addition, regional total irrigation water demands of these water-intensive crops were estimated. The results indicated that, except for summer maize, the crop water requirements and irrigation water demands of grain crops during the growth periods were mostly higher than those of vegetable crops. Winter wheat and cabbage had the highest water deficits among grain and vegetable crops, respectively, while summer maize had the lowest water deficits. Temporally, the irrigation water demands of winter wheat, summer maize, cabbage, and eggplant have increased for years, along with the increase in planting areas. Spatially, the total irrigation water demand in the southeast of Hebei Province was higher than that in the northwest, and the total irrigation water demand of winter wheat was much higher than that of the other crops. To mitigate water scarcity while ensuring food security, the planting areas of crops with higher yields and lower water consumptions, including summer maize, potato, cabbage, and carrot could be appropriately expanded. In contrast, the scale of water-intensive crops such as winter wheat and tomato should be strictly controlled. Our findings will be of great significance for constructing sustainable water-saving cropping systems in a changing climate.

The strengthening relationship between summer rainfall over North China and PDO since the mid-2000s

The interdecadal change of the summer (July–August) rainfall over North China (SRNC) is of great concern to the climate research community. Based on the sliding correlation and interdecadal difference analysis, the interdecadal change of SRNC was studied. Results show a significantly wetter period of SRNC since the mid-2000s, which was associated with strengthening negative relationship between SRNC and PDO. PDO affected the SRNC through the jet stream in the upper-level and the East Asia–Pacific (EAP) teleconnection pattern. In the negative phase of the PDO since the mid-2000s, the contractive upper-level jet stream in the west of North China resulted in the abnormal updraft over the southern region of North China. Meanwhile, the positive phase of the EAP teleconnection pattern brought warm and wet southeast flow entering North China from its eastern boundary, both bringing more rainfall in North China. The abnormal water vapor transport from the western Pacific was very different from that accompanying the East Asian summer monsoon.