Parts Of North China Plain Research Articles

Changes in Water Surplus or Deficit and Possible Drivers in the North China Plain During 1961–2022

ABSTRACTIn the North China Plain (NCP), the assessment of water surplus or deficit (WSD), which is calculated as precipitation minus reference evapotranspiration (ET0), holds significant implications for water resource management and agricultural irrigation decision‐making, given the region's long‐standing severe shortage of water resources. However, the magnitude, trend and climatic drivers of WSD remain poorly understood in the NCP. This study analysed the spatial and temporal characteristics of WSD, and quantified the contribution of climatic factors to WSD based on the sensitivity and contribution rate analysis methods with climatic data from 75 meteorological stations. The result showed that: (1) Annual WSD decreased mainly in northeastern NCP and increased significantly in southern NCP during 1961–2022. Annual WSD increased slightly from 1961 to 2022 at a rate of 1.63 mm a−2 mainly due to the more significant decrease (−1.88 mm a−2) in ET0 compared to precipitation (−0.25 mm a−2). (2) In terms of the sensitivity of WSD to climatic factors, relative humidity had the highest sensitivity, followed by net radiation, wind speed, precipitation and average air temperature. (3) Significant declines of wind speed were the most dominant factor affecting WSD variation in most part of NCP during most of a year, and net radiation of four stations in the western high‐elevation regions played the most important role. This study enhances comprehension of the impact of climate change on WSD in the NCP and provides a reference for improving management of agricultural water resources under NCP's evolving climatic conditions.

Unveiling the importance of VOCs from pesticides applicated in main crops for elevating ozone concentrations in China

Volatile organic compounds (VOCs) are considered as important precursors of ozone in the air, while the contribution of VOCs from pesticide application (PVOCs) to ozone production is unknown. Utilizing data from the Ministry of Agriculture and Rural Affairs of the People's Republic of China and ChinaCropPhen1km, this paper developed PVOC emission inventories with a resolution of 1 km for the main crops (rice, maize, and wheat) from 2012 to 2019 in China. The results revealed that pesticide application is an important VOC emission source in China. Specially, the PVOC emissions from the major grain-producing regions in June accounted for approximately 30% of the annual total PVOC emissions in the local regions. The simulation with the Weather Research and Forecasting Community Multiscale Air Quality model (WRF-CMAQ) indicated that the PVOC emissions increased the mean maximum daily 8-hour average (MDA8) ozone concentration across China by 2.5 ppb in June 2019. During the same period, PVOCs in the parts of North China Plain contributed 10% of the ozone formation. Under the comprehensive emission reduction scenario, it is anticipated that by 2025, the joint implementation of measures including reducing pesticide application, improving pesticide utilization efficiency and promoting solvent substitution will decrease PVOC emissions by 60% compared with 2019, thereby mitigating ozone pollution.

Enhancing groundwater level prediction accuracy at a daily scale through combined machine learning and physics-based modeling

Study regionYongding River alluvial proluvial fan, a part of North China Plain with intense groundwater withdrawals. Study focusThe objective of this study is to enhance the accuracy of groundwater level (GWL) prediction at a daily scale by combining short-term memory (LSTM) and physics-based (PB) models. Two types of LSTM models were developed: LSTM-H-ORI, which predicts GWL, and LSTM-dH-ORI, which predicts simulated errors of the PB model. These models were subsequently refined into LSTM-H-IMP and LSTM-dH-IMP by incorporating the outputs from the PB model. To investigate the influence of groundwater flow processes, LSTM-H-IMP was further enhanced by considering the time lag properties of precipitation, referred to as LSTM-H-IMP-LAG. New hydrological insights for the regionSignificant improvements were found for LSTM-H-IMP when the performance of LSTM-H-ORI was poor (Nash–Sutcliffe Efficiency Coefficient, NSE<0) or the performance of PB model was not bad (NSE≥0). And the prediction accuracy was improved for over 67% of wells in this case. When the performance of PB model was medium and poor (NSE≤0.6), the improvement of LSTM-dH-IMP was more effective, leading to a prediction accuracy enhancement for over 77% of wells. Additionally, LSTM-H-IMP-LAG exhibited further improvement, with an average NSE increase of 0.1. This study provides scientific methods for accurate prediction of GWL at a daily time scale and the combined application of LSTM and PB models.

Simulated impacts of the wetter arid area of Northwestern China on the energy budget and atmospheric circulation over Tibetan Plateau and central part of North China plain in summer

This paper examines the local and non-local climatic effects of wetter arid areas of Northwestern China (ANWC) in summer using a fully coupled climate model. In response to soil moisture increase, the local air temperature significantly decreases, and precipitation increases in summer. The wetter ANWC results in a warmer and rainless climate over the Central part of North China Plain (CNCP). While the influence of increasing soil moisture on the Tibetan Plateau (TP) precipitation is negligible due to the high altitude. A cooler climate over ANWC leads to an abnormal descending motion occurring. Meanwhile, an anomalous high pressure and an abnormal anticyclonic circulation occurs in 500 hPa over the west of ANWC. Correspondingly, a huge anomalous cyclone circulation occurs over the northeastern part of China and Mongolia, which can hinder the northward movement of the East Asian summer Monsoon (EASM) and reduce the water vapor transport into Central China Plain. As a result, the weakened EASM thus leads to rainless over CNCP. As soil moisture increases over ANWC is stronger, the magnitudes of the influence on the atmospheric field become larger. This study highlights the wetter ANWC effect on local climate and provides more information about the mechanism of wetter ANWC remote effect on non-local climate.

The Hydrogeological Characteristics of Thick Alluvium with High Water Level and the Influence on Zhaogu Mining Area, Henan Province, China

In parts of North China Plain, there are several aquifers in the thick alluvium over the coal seam, which overlays a large amount of coal resources. Roof water inrush accident occurred during coal mining often caused by multiple reasons. Based on the case of roof water inrush in Zhaogu Mining Area, by hydrologic supplementary exploration of the north flank, the stratum data were obtained; combined with previous geological drilling data of the mine, the structural characteristics of five main aquifers and five main aquicludes in the alluvium of the north flank were classified. By pumping test of the No. 1 and the No. 2 supplementary exploration drill holes, the water richness of the 5th aquifer of north flank is identified as medium level. Three thin layers of gravel aquifer beneath the 5th aquifer were found in No. 1 drill hole, and the water richness of the lowest thin gravel (2.95 m thickness) was identified as medium by the followed pumping test, which reveals an important factor leading to the insufficient size of the safety pillar. The leakage self-closed aperture test on the sand soil of the 5th aquiclude clarifies that in case of fracture connection, it cannot resist water and sand crushing under high water pressure of the 5th aquifer. Based on the mechanism of high-pressure water on the working face supports, the calculation method of support resistance under high water pressure alluvial layer is put forward, and the main reason of roof support failure and water inrush is the insufficient support resistance, which leads to abnormal height caving. The methods of experiment and calculation are clarified for preventing water and sand inrush accident of working faces with the similar mining background.

Lithospheric Conductors Shed Light on the Non‐Uniform Destruction of North China Craton

AbstractLow resistivity in the continental lower crust and uppermost mantle has been commonly observed in both Phanerozoic and Precambrian areas. Given different tectonic history, these conductors could be attributed to different conductive mechanisms. The North China Craton (NCC) is one of typical craton that have suffered from extensive destruction, part of which was modified by Phanerozoic tectonic‐thermal events and the others remain stable cratonic lithosphere. We here present a high‐resolution 3‐D electrical resistivity model from the inversion of magnetotelluric data collected in 183 sites of NCC. Beneath the stable craton in the north part of Ordos Block, an E‐W trending conductor extends from lower crust to uppermost mantle, which can be attributed to the concentration of sulfides/graphite emplaced through oceanic subduction during the Paleoproterozoic assembly of Columbia. The conductors beneath the Taihang Mountains and the south part of Ordos Block also reflect ancient sutures. In contrast, the conductor in mantle beneath the south part of North China Plain (SNCP) reflects an on‐going process of craton destruction relating to the subduction of the Pacific Plate in Cenozoic. The MT data, combined with seismic radial anisotropy model suggest the lower crust and uppermost mantle beneath SNCP is anisotropic. And a significant electrical anisotropic layer with the most conductive direction along N70°W and the anisotropy factor of 6.3 is revealed in the 20–70 km depth by 2‐D anisotropic inversion. We attribute the enhanced conductivity along anisotropy direction to the accumulation of melts in sills, resulting from the upwelling of asthenosphere in Cenozoic.

Simulated Impacts of the Wetter Arid Area of Northwestern China on Energy Budget and Atmospheric Circulation Over Tibetan Plateau and Central Part of North China Plain in Summer

Simulated Impacts of the Wetter Arid Area of Northwestern China on Energy Budget and Atmospheric Circulation Over Tibetan Plateau and Central Part of North China Plain in Summer

Climate change impact on yields and water use of wheat and maize in the North China Plain under future climate change scenarios

Climate change has already and will continue to exert a vital impact on crop yield and water use in the North China Plain (NCP). Currently, this plain is facing a dilemma between groundwater depletion and grain production demand. It is urgent to identify the impact of future climate change on crop yield and water consumption and then develop efficient adaptation strategies in the region. In this study, we used statistically downscaled daily climate data from 33 global climate models (GCMs) and two Representative Concentration Pathways (RCP4.5 and RCP8.5) for 61 stations distributed across the NCP and drove the well-validated APSIM model to simulate crop yield and water use for two future periods of 2031–2060 (2040s) and 2071–2100 (2080s). Data from all 33 GCMs show an increase in annual mean temperature and almost all the GCMs also show increases in annual mean solar radiation and annual total precipitation across the NCP. Future climate warming led to an advance in phenology for both winter wheat and summer maize, two typical crops in the NCP. However, the length of the reproductive growth period (RGP) of winter wheat was prolonged while that of summer maize was shortened under future climate scenarios across the NCP. Our simulated results show that future climate change had negative impacts on maize yield but positive impacts on wheat yield across the NCP. Mainly due to the shortening of the whole growth period, crop water consumption was largely decreased under future climate scenarios. The amount of irrigation required was also reduced mainly due to increased precipitation and decreased ET. Although future climate change would likely mitigate groundwater overdraft in most part of NCP, some areas in the northern NCP still had groundwater over-pumping in the future. Therefore, we suggest that it might be a good choice to change cropping system for reducing planting area of water-consuming crop (e.g. winter wheat) in those over-pumping areas to balance groundwater use and crop yield.

Visibility-Based PM2.5 Concentrations in China: 1957-1964 and 1973-2014.

China established ground PM2.5 monitoring network in late 2012 and hence the long-term and large-scale PM2.5 data were lacking before 2013. In this work, we developed a national-scale spatiotemporal linear mixed effects model to estimate the long-term PM2.5 concentrations in China from 1957 to 1964 and from 1973 to 2014 using ground visibility monitoring data as the primary predictor. The overall model-fitting and cross-validation R2 is 0.72 and 0.71, suggesting that the model is not overfitted. Validation beyond the model year (2014) indicated that the model could accurately estimate historical PM2.5 concentrations at the monthly (R2 = 0.71) level. The historical PM2.5 estimates suggest that air pollution is not a new environmental issue that occurs in the recent decades but a problem existing in a longer time before 1980. The PM2.5 concentrations have reached 60-80 μg/m3 in the north part of North China Plain during 1950s-1960s and increased to generally higher than 90 μg/m3 during 1970s. The results also show that the entire China experienced an overall increasing trend (0.19 μg/m3/yr, P < 0.001) in PM2.5 concentrations from 1957 to 2014 with fluctuations among different periods. This paper demonstrated visibility data allow us to understand the spatiotemporal characteristics of PM2.5 pollution in China in a long-term.

Assessment of SMAP soil moisture for global simulation of gross primary production

In this study, high quality soil moisture data derived from the Soil Moisture Active Passive (SMAP) satellite measurements are evaluated from a perspective of improving the estimation of the global Gross Primary Production (GPP) using a process-based ecosystem model, namely the Boreal Ecosystem Productivity Simulator (BEPS). The SMAP soil moisture data are assimilated into BEPS using an Ensemble Kalman Filter. The correlation coefficient (r) between simulated GPP from the sunlit leaves and Sun-Induced chlorophyll Fluorescence (SIF) measured by Global Ozone Monitoring Experiment–2 (GOME-2) is used as an indicator to evaluate the performance of the GPP simulation. Areas with SMAP data in low quality (i. e. forests), or with SIF in low magnitude (e. g. deserts) or both are excluded from the analysis. With the assimilated SMAP data, the r value is enhanced for Africa, Asia, and North America by 0.016, 0.013, and 0.013, respectively (p<0.05). Significant improvement in r appears in single-cropping agricultural land where the irrigation is not considered in the model but well captured by SMAP (e. g. 0.09 in North America, p<0.05). With the assimilation of SMAP, areas with weak model performances are identified in double or triple cropping cropland (e. g. part of North China Plain) and/or mountainous area (e. g. Spain and Turkey). The correlation coefficient is enhanced by 0.01 in global average for shrub, grass, and cropland. This enhancement is small and insignificant because non-water-stressed areas are included.

Effects of long-term full straw return on yield and potassium response in wheat-maize rotation

The effect of long-term straw return on crop yield, soil potassium (K) content, soil organic matter, and crop response to K from both straw and chemical K fertilizer (K2SO4) were investigated in a fixed site field experiment for winter wheat-summer maize rotation in 6 years for 12 seasons. The field experiment was located in northern part of North China Plain with a sandy soil in relatively low yield potential. Two factors, straw return and chemical K fertilizer, were studied with two levels in each factor. Field split design was employed, with two straw treatments, full straw return of previous crop (St) and no straw return, in main plots, and two chemical K fertilizer treatments, 0 and 60 kg K2O ha−1, as sub-plots. The results showed that straw return significantly increased yields of winter wheat and summer maize by 16.5 and 13.2% in average, respectively, and the positive effect of straw return to crop yield showed more effective in lower yield season. Straw return significantly increased K absorption by the crops, with significant increase in straw part. In treatment with straw return, the K content in crop straw increased by 15.9 and 21.8% in wheat and maize, respectively, compared with no straw return treatment. But, straw return had little effect on K content in grain of the crops. Straw return had significant influences on total K uptake by wheat and maize plants, with an increase of 32.7 and 30.9%, respectively. There was a significant correlation between crop yield and K uptake by the plant. To produce 100 kg grain, the wheat and maize plants absorbed 3.26 and 2.24 kg K2O, respectively. The contents of soil available K and soil organic matter were significantly affected by the straw return with an increase of 6.07 and 23.0%, respectively, compared to no straw return treatment. K2SO4 application in rate of 60 kg K2O ha−1 showed no significant effect on wheat and maize yield, K content in crop straw, total K uptake by the crops, soil available K content, and soil organic matter. The apparent K utilization rate (percentage of applied K absorbed by the crop in the season) showed difference for wheat and maize with different K sources. In wheat season, the K utilization rate from K2SO4 was higher than that from straw, while in maize season, the K utilization rate from straw was higher than that from chemical fertilizer. In the whole wheat-maize rotation system, the K absorption efficiency by the two crops from straw was higher than that from K2SO4.

Evaluation of nitrate source in groundwater of southern part of North China Plain based on multi-isotope

Nitrate pollution in groundwater is a serious water quality problem that increases the risk of developing various cancers. Groundwater is the most important water resource and supports a population of 5 million in Anyang area of the southern part of the North China Plain. Determining the source of nitrate pollution is the challenge in hydrology area due to the complex processes of migration and transformation. A new method is presented to determine the source of nitrogen pollution by combining the composition characteristics of stable carbon isotope in dissolved organic carbon in groundwater. The source of groundwater nitrate is dominated by agricultural fertilizers, as well as manure and wastewater. Mineralization, nitrification and mixing processes occur in the groundwater recharge area, whereas the confined groundwater area is dominated by denitrification processes.

Fault plane parameters of Sanhe-Pinggu M8 earthquake in 1679 determined using present-day small earthquakes

The great Sanhe-Pinggu M8 earthquake occurred in 1679 was the largest surface rupture event recorded in history in the northern part of North China plain. This study determines the fault geometry of this earthquake by inverting seismological data of present-day moderate-small earthquakes in the focal area. We relocated those earthquakes with the double-difference method. Based on the assumption that clustered small earthquakes often occur in the vicinity of fault plane of large earthquake, and referring to the morphology of the long axis of the isoseismal line obtained by the predecessors, we selected a strip-shaped zone from the relocated earthquake catalog in the period from 1980 to 2009 to invert fault plane parameters of this earthquake. The inversion results are as follows: the strike is 38.23°, the dip angle is 82.54°, the slip angle is −156.08°, the fault length is about 80 km, the lower-boundary depth is about 23 km and the buried depth of upper boundary is about 3 km. This shows that the seismogenic fault is a NNE-trending normal dip-slip fault, southeast wall downward and northwest wall uplift, with the right-lateral strike-slip component. Moreover, the surface rupture zone, intensity distribution of the earthquake and seismic-wave velocity profile in the focal area all verified our study result.

Spatio-temporal variation of drought in China during 1961–2012: A climatic perspective

Summary Understanding the spatial and temporal variation of drought is essentially important in drought assessment. In most previous studies, drought event is usually identified in space and time separately, ignoring the nature of the dynamic processes. In order to better understand how drought changes have taken place in China during the past half-century, we carried out a comprehensive analysis of their spatio-temporal variation based on multiple drought indices from a climatic perspective. A 3-dimensional clustering method is developed to identify drought events in China from 1961 to 2012 based on the 0.25° gridded indices of SPI3 (3 months Standardized Precipitation Index), RDI3 (3 months Reconnaissance Drought Index) and SPEI3 (3 months Standardized Precipitation Evapotranspiration Index). Drought events are further characterized by five parameters: duration, affected area, severity, intensity, and centroid. Remotely sensed soil moisture data were used to validate the rationality of identified drought events. The results show that the two most severe drought events in the past half century which occurred in the periods 1962–1963 and 2010–2011 swept more than half of the non-arid regions in China. Large magnitude droughts were usually centered in the region from North China Plain to the downstream of Yangtze River. The western part of North China Plain, Loess Plateau, Sichuan Basin and Yunnan-Guizhou Plateau had a significant drying trend, which is mainly caused by the significant decrease of precipitation. The three drought indices have almost the same performance in the humid regions, while SPI and RDI were found to be more appropriate than SPEI in the arid regions.

Fluvial system development and subsequent marine transgression in Yellow River (Huanghe) delta and its adjacent sea regions during last glacial maximum to early Holocene

Paleotopography of the Yellow River (Huanghe) delta area and the western Bohai Sea during the last glacial maximum (LGM) is important to understand fluvial activities of the Yellow River linked with the LGM climate. By integrating data sets of both onshore and offshore borehole cores and offshore high-resolution seismic profiles, we reconstructed the paleotopography of this area from the LGM to the early Holocene. The fluvial sediment facies of the LGM identified in these cores was characterized by poorly sorted medium- to coarse-grained sands, which shows chaotic patterns in seismic profiles. REE characteristics and clay mineral components of the fluvial sediments suggest that they were derived mostly from the paleo-Yellow River. The basal and top bounding surfaces of the fluvial sediments slope very gently toward the northeast, similar to the present morphology of the North China Plain formed by the Yellow River. No incised valley morphology is detected in the basal topography, because of the long distance from the study area to the paleoshoreline during the LGM, and also because of the very gentle gradient of the paleo-Yellow River from the northern part of North China Plain to the continental shelf area, with concave-upward morphology. Aggradational stacking of the fluvial sediments over the entire North China Plain and in the study area indicates that the Yellow River flowed in these areas during the LGM to the early Holocene. The Holocene marine and coastal sediments onlap onto the underlying fluvial sediments. These basal marine or brackish sediments are diachronous from offshore areas of the Bohai Sea to the Yellow River delta area, with older sediments in the east and younger sediments in the west, which clearly reflects the early Holocene marine transgression from the North Yellow Sea to the Bohai Sea.

Drought hazard assessment and spatial characteristics analysis in China

Based on the monthly precipitation data for the period 1960–2008 from 616 rainfall stations and the phenology data of main grain crops, the spatial characteristics of drought hazard in China were investigated at a 10 km×10 km grid-cell scale using a GIS-based drought hazard assessment model, which was constructed by using 3-month Standard Precipitation Index (SPI). Drought-prone areas and heavy drought centers were also identified in this study. The spatial distribution of drought hazard in China shows apparent east-west difference, with the eastern part of China being far more hazardous than the western part. High hazard areas are common in the eastern and central parts of Inner Mongolian Plateau, the central part of Northeast China Plain, the northern part of Heilongjiang, the southeastern part of Qinghai-Tibet Plateau, the central and southern parts of Loess Plateau, the southern part of North China Plain, the northern and southern parts of Yangtze River Plain, and Yunnan-Guizhou Plateau. Furthermore, obvious differences in drought hazard were found both within and between different agricultural zonings.