Impacts of artificial dams on terrestrial water storage changes and the Earth's elastic load response during 1950-2016: A case study of medium and large reservoirs in Chinese mainland

The construction of dams for intercepting and storing water has altered surface water distributions, landsea water exchanges, and the load response of the solid Earth. The lack of accurate estimation of reservoir properties through the land surface and hydrological models can lead to water storage simulation and extraction errors. This impact is particularly evident in many artificial reservoirs in China. The study aims to comprehensively assess the spatiotemporal distribution and trends of water storage in medium and large reservoirs(MLRs) in Chinese mainland during 1950-2016, and to investigate the gravity,displacement, and strain effects induced by the reservoir mass concentration using the load elasticity theory. In addition, the impoundment contributions of MLRs to the relative sea level changes were assessed using a sea-level equation. The results show impoundment increases in the MLRs during1950-2016, particularly in the Yangtze River(Changjiang) and southern basins, causing significant elastic load effects in the surrounding areas of the reservoirs and increasing the relative sea level in China's offshore. However, long-term groundwater estimation trends are overestimated and underestimated in the Yangtze River and southwestern basins, respectively, due to the neglect of the MLRs impacts or the uncertainty of the hydrological model's output(e.g., soil moisture, etc.). The construction of MLRs may reduce the water mass input from land to the ocean, thus slowing global sea level rise. The results of the impact of human activities on the regional water cycle provide important references and data support for improving the integration of hydrological models, evaluating Earth's viscoelastic responses under longterm reservoir storage, enhancing in-situ and satellite geodetic measurements, and identifying the main factors driving sea level changes.

Impacts of climate change and land cover factor on runoff in the Coastal Chinese Mainland region

The increasingly frequent storms pose significant threats to the sustainable development of coastal regions,particularly in densely populated and economically vibrant areas.Comprehending the dynamics and intricate mechanisms underlying runoff generation is crucial in the context of climate change and anthropogenic interference.Based on hydro-meteorological and land-use data from 1980 to 2018,this study investigates the runoff variation and its driving factors in the Coastal Chinese Mainland(CCM).The aims of this study are to reveal the temporal and spatial trends of runoff yield,to clarify the sensitivity of runoff in coastal cities to the integrated and individual parameters of climate change and anthropogenic interference,including precipitation(P),potential evapotranspiration(E0),and land cover factor(n),and to support the establishment of spatially tailored adaptation strategies.The results show that:(1)runoff has generally increased over the study period,particularly in regions such as the Yangtze River Delta,Shandong,and Guangxi,while it has decreased in western Liaoning and eastern Guangdong;(2)in the northern CCM with larger aridity index,the land cover factor plays a dominant role in runoff production,while in the wetter southern CCM,precipitation is more influential,and potential evapotranspiration mainly hinders runoff generation all over CCM;(3)urban expansion tends to negatively impact n,while the loss of grasslands and shrinkage of croplands tend to undermine the value of n.To facilitate the achievement of sustainable development goals in the CCM,it is imperative to introduce a more comprehensive and theoretical framework that encompasses the natural,technical,and social dimensions of human-water systems into traditional flood regulation and water resource management.This framework should promote interdisciplinary collaboration from an integrated perspective,to bridge the administrative and watershed boundaries,to effectively address the complex challenges posed by climate change and anthropogenic activities on runoff and water resources in coastal regions,and to enhance the realization of local sustainable development goals(UN SDGs).

Towards fast focal mechanism inversion of shallow crustal earthquakes in the Chinese mainland

We have developed an automatic regional focal mechanism inversion system based on the Earthquake Rapid Report(ERR) system and the real-time three-component seismic waveform stream of 1 000 broadband seismic stations provided by the China Earthquake Networks Center(CENC). The system can rapidly provide a double couple solution and centroid depth within 5–15 min after receiving earthquake information from the ERR system.The data processing is triggered by earthquake information obtained from the ERR system. The system is capable of determining the focal mechanism of all shallow-depth earthquakes in the Chinese mainland with a magnitude of 5.5–6.5. It utilizes waveform data recorded by seismic stations located within 500 km from the epicenter,enabling the reporting of a focal mechanism solution within 5–15 min of an earthquake occurrence. Additionally,the system can assign a corresponding grade(A B C) to the focal mechanism solution. We processed a total of 301earthquakes that occurred from 2021 to June 2022, and after the quality control, 166 of them were selected.These selected solutions were manually checked, and 160 of them were compiled in a focal mechanism catalog.This catalog can be conveniently downloaded online via the Internet. The automatic focal mechanism solution of earthquakes in eastern China exhibits a good agreement with that provided by the Global Centroid Moment Tensor(GCMT), when available. The average Kagan angle between this catalog and GCMT is 22°, and the average difference in MWis 0.17. Furthermore, compared with GCMT, the minimum magnitude of our catalog has been reduced from approximately 5.0 to 4.0. The correlation between the centroid depth and crustal thickness in the Chinese mainland confirms the distribution of the centroid depth.

A Comparative Study of the L2 Pragmatic Competence of University Students in Hong Kong and the Chinese Mainland:The Contributions of Sociocultural Context and Linguistic Proficiency

This study investigates the differences in pragmatic competence between Hong Kong and Chinese mainland university students.Participants included 19 native speakers of English,115 Chinese mainland students,divided into those who had spent time abroad in an English-speaking country(CM A)and those who had not(CM NA),and 97 Hong Kong students,divided into those from an English-medium secondary school(Hong Kong EMI)and those from a Chinese-medium school(Hong Kong CMI).Linguistic proficiency was measured by a C-test,and pragmatic competence by a Metapragmatic Knowledge Test,an Irony Test and a Monologic Role Play.Group scores were compared using ANCOVAs to control for differences in proficiency.The results point to a continuum of pragmatic competence—EMI>CMI>CM A>CM NA—reflecting the groups’access to English in real-life contexts.The differences between the Hong Kong groups and the Chinese mainland groups were clearest in those tests measuring processing capacity(i.e.,Irony Response Time and the Monologic Role Play).CM A,but not CM NA,performed as well as the Hong Kong groups on measures of metapragmatic awareness.The results are discussed in terms of Bialystok’s(1993)distinction between analyzed representation and control of processing.

The Genus Rhithrogena Eaton (Ephemeroptera: Heptageniidae) from Chinese Mainland, with Description of a New Species

In present paper the genus Rhithrogena Eaton from Chinese mainland, including a new species to science (Rhithrogena lutea, sp. nov.), 2 new record species from China (R. bajkovae Sowa, R. lepnevae Brodsky) and 3 known species [R. wuyinensis (Gui et al.) (comb. nov.), R. trispina Zhou et Zheng, R. orientalis You (= R. sangangensis You, new synonym)] are revised besed on the imaginal specimens. A key to 7 species imagos is provided. All materials in this study are deposited in Nanjing Normal University.

A Preliminary Study on the Genus Caenis (Ephemeroptera: Caenidae) from Chinese Mainland, with Description of a New Species

Five species of the genus Caenis from Chinese mainland are reviewed. Among them, C. parviforcipis (Zhou et al.) (nov. comb.) is transferred from the genus Brachycercus The larvae of the C. sinensis Gui et al. are described for the first time. The previously reported C. nigroforceps Zhou et al. is recognized as a new synonym of the Caenis rivulorum Eaton, and the report of C. nigropunctata Klapálek from China is confirmed. Both imagos and larvae of a new species C. melanoleuca, sp. nov. are described and illustrated in detail.

Recurrence behaviors of segment-rupturing earthquakes on active faults of the Chinese mainland

To investigate the recurrence behaviors of segment-rupturing eathquakes on active faults of the Chinese mainland, thispaper analyzes quantitatively earthquake history of 19 fault segments based on earthquake dam of multi-cyclerecurrences. The result shows that, for these fault segments, eanhquake recurring at previous locations is mainlycharacterized by both quasi-periodic (in a ratio of about) and time-predictable (in a ratio of about) behaviors.For the first behavior. intrinsic uncertainty of recurrence interval accounts for 0. 15-0.40 of the average interval, andmagnitudes of event vary from cycle to cycle within the range of the mean magnitUde t0.5. For the second behavior,intrinsic uncertainty of recurrence interval ranges mostly from 0. 19 to 0.40 of the average interval, and for successivetwo cycles the maximum change of event magnitudes is as much as 1.7 magnitude-units. In addition, for a few casesthe first behavior coexists along with either the second or the slip-predictable behaviors.

Distribution of empirical recurrence intervals for segment-rupturing earthquakes onactive faults of the Chinese mainland

For the two main recurrence behaviors of segment-rupturing earthquakes on active faults of the Chinese mainland,this paper establishes corresponding empirical distributions forearthquake recurrence interval. The results show that, for the time-predictable recurrence, the normalized recurrence interval, T/Tt, obeys very well the lognormal distributions: LN (μ1=0.00, σ21 =0. 152), where, T is an observed recurrence interval, and Tt is the average recurrence interval that is correlative with the size of the preceding event. For the quasi-periodic recurrence, the normalized recurrence interval, T/T, follows the lognormal distribution : LN(μq=0.00, σ2q=0.242), where, T is the median of recurrence intervals for various cycles. A statistical test suggests that, there is no significant difference between the latter distribution, built by this paper, and the recurrence interval distribution for the characteristic earthquakes of the Circum-Pacific Plate boundaries (NB model). Accordingly, this paper combines these two distributions into one and obtains a more stable lognormal distribution :LN (μ = 0.00, σ2 = 0.222), for the quasi-periodic recurrence interval.

Surface wave tomography of the crust and upper mantle of Chinese mainland and its neighboring region

The three dimensional S wave velocity structure of the crust and upper mantle of Chinese mainland and its neighboring region is obtained by genetic algorithm of surface wave tomography, with smoothness constraint, based on 25 wave group velocities for the periods from 10 s to 92 s, measured from long period Rayleigh waves recorded by 11 stations of CDSN and 12 digital seismometers surrounding China. The S wave velocity image is shown on two latitudinal sections along 30°N and 38°N, two longitudinal sections along 90°E and 120°E, and four horizontal slices at the different depths.

Boundary conditions of the dynamicnumerical model for the Chinese mainland lithosphere

The numerical dynamic model of Chinese mainland lithosphere's stress and strain field was constructed withelasto-viscous creep constitive relation. The most recent data of the stress field of Chinese mainland and thehorizontal movement velocity of the crust blocks were used as constraint conditions. The values of the boundalsforce were computed by trial-and-error method. The effect of the Qinghai-Xizang Plateau's excess potential energyto the movement of Chinese mainland was studied also in this model. The results of the numerical computing showthat, recent rapid raising of the Qinghai-Xizang Plateau and the generation of normal faults in the southem part ofthe plateau resulted from the convergence of Indian Plate to the Eurasian Plate, and also from the rapid convectivethinning of the lower lithosphere. Horizontal extension of the Qinghai-Xizang Plateau is the main dynamic factorto torm the present tectonic framework of the Chinese mainland. The compressive loads on the eastern boundaryof the model were mainly applied by the subduction of the Pacific Plate. The compression from the PhilippinePlate maybe slight.

ANALYSIS ON THE CHARACTERISTICS OF TROPICAL CYCLONES MAKING LANDFALL ON DIFFERENT REGIONS OF CHINESE MAINLAND

The locations(longitudes and latitudes)of the tropical cyclones(TCs)making landfall on the Chinese mainland from 1949 to 2008 are investigated in detail by using ArcGis and FORTRAN routine.The southeast coastline[110 to 122°E)with most landfall TCs was selected as the key region,which was divided into 12 subsections with 1°intervals of longitude.The study period was from July to September in each year.The result showed that the average sustaining time of TCs making landfall on the subsections east of 118°E is longer than those west of 118°E.Before landfall,the averaged TC intensity in the subsections east of118°E is stronger than that west of it.After landfall,however,the difference between the west and east is not significant.The index of destructive potential for the period before/after landfall was defined as TDP1/TDP2.The maximum of TDP1/TDP2 occurred in the subsection of[119,120°E)/[110,111°E).The ENSO impact on the frequency and average location of landfall TC over the whole region at 110 to 122°E is not obvious,but the effect varies with specific subsections.There is little differences of averaged TDP1 in the subsections between different phases of ENSO events,but the averaged TDP2 is larger in the warm events than that in the cold events.The rainstorm days of each station caused by TCs in different subsections were counted respectively.The results suggested that the rainstorm days of the subsections east of 118°E are much more than those west of 118°E.The larger values are primarily distributed at the subsections of[119,120°E)and[110,111°E).

Crustal deformation on the Chinese mainland during 1998—2004 based on GPS data

This study focuses on resolving moderate amounts of crustal motion at the continental scale based on a large volume of global positioning system（GPS） data during 1998e2014. A state-of-the-art GPS processing strategy was used to resolve position time series and velocities from carrier beat phases for all available data. Position time series were closely analyzed to estimate linear constant, coseismic displacements, postseismic motions, and other parameters. We present coseismic offsets inferred from the GPS data for the 2010 Yushu and 2014 Yutian earthquakes, and also illustrate transient postseismic motions following the 2001 Kokoxili, 2008 Wenchuan, and 2011 Tohoku-Oki earthquakes. Since not all GPS position time series dominated by postseismic motions can be modeled and corrected reasonably, we present contemporary horizontal velocities from 2009 to 2014 for campaign stations and from 1998 to 2014 for continuous stations, irrespective of postseismic deformations. Our study concludes that we need to accumulate observations over a greater duration and apply accurate postseismic modeling to correct for transient displacement in order to resolve reasonable interseismic velocity.

Numerical calculations of tectonic stress field of Chinese mainland and its neighboring regions and their applications to explanation of seismic activity

This paper made a numerical simulation to the basic tectonic stress field of Chinese mainland and its neighboringregion using the visco-elasticity finite element model and the new published displacement rate result. Main contents include the simulation of maximum shear stress and its varying rate, the maximum shear strain and its varyingrate, the shear strain energy density and its varying rate. In view of the high inhomogeneous distribution characterof seismicity in space and time in Chinese mainland and its neighboring area, the normalized background energyvalue was given by means of normalized treatment to the earthquake energy release in the eastern and westernparts of Chinese mainland. And the comparison of the simulation result with the actual seismicity was made. Thefesults show that the simulation values can explain well the earthquake distribution character of Chinese mainlandand its neighboring area.

Current crustal motion and deformation inthe Chinese mainland and its surroundingarea determined from GPS data

Based on the geodetic data taken from the National GPS Network established by China Climbing Program 'Investigation of Crust Motion and Geodynamics in Modern Time', we derived the movement velocities of the GPS sites.In terms of the power series expansion of a rotation function for horizontal velocities on a spherical surface proposed by Hames and Holt (1993), we computed the horizontal velocity and strain-rate field.We preliminarilystudied the appearances and characteristics of the present-day crustal movement and deformation in the Chinesemainland with the computed results. The researches demonstrated (1)The present-day crustal movement anddeformation in the Chinese mainland are being jointly controlled by indian, Pacific and Philippines Ocean Platesand Siberia-Mongolia block, and these three large plates and block form a situation of triparite confrontation, butIndian Plate seems to play a leading role;(2) The North-South Earthquake Zone plays an important adjustment rolein the present-day crustal movement and deformation process. displaying clear characteristics of demarcation lineof tectonics in large areas, (3)There seems to be another adjustment zone along the latitude line approximate N35,but its characteristics are less obvious than that of the former; (4) Dynamic actions of these three large plates andblock on the Chinese mainland are dynamic stable; appearing in stable push-press velocities. These results aregenerally accorded with the results determined from geology, geophysics, and seismology. By the contrast withseismicities. if appears preliminarily that there is some corresponding relation between intense shear st fain zoneand future strong seismicity area. but this problem needs further examination of earthquake examples.

Recent crustal horizontal movement in the Chinese mainland

According to the results of careful re-proeessing of data obtained from two GPS survey campaigns of crustal movement monitoring network in Chinese mainland carried out in 1994 and 1996, the crustal horizontal movement characteristics in Chinesc mainland are studied in the paper.In the analysis, a relatively consummate deformation model in which the deformation is described by the relative movement between the tectonic blocks with interior strain and the corresponding analysis method are used. The magnitude of movement along the boundary zones between the tectonic blocks is calculated. And the characters and intensities between the main boundny zones are compared.

Assessment of strong earthquake risk in the Chinese mainland from 2021 to 2030

The long-term earthquake prediction from 2021 to 2030 is carried out by researching the active tectonic block boundary zones in the Chinese mainland.Based on the strong earthquake recurrence model,the cumulative probability of each target fault in the next 10 years is given by the recurrence period and elapsed time of each fault,which are adopted from relevant studies such as seismological geology,geodesy,and historical earthquake records.Based on the long-term predictions of large earthquakes throughout the world,this paper proposes a comprehensive judgment scheme based on the fault segments with the seismic gap,motion strongly locked,sparse small-moderate earthquakes,and apparent Coulomb stress increase.This paper presents a comprehensive analysis of the relative risk for strong earthquakes that may occur in the coming 10 years on the major faults in the active tectonic block boundary zones in the Chinese mainland.The present loading rate of each fault is first constrained by geodetic observations;the cumulative displacement of each fault is then estimated by the elapsed time since the most recent strong earthquake.

Grouping occurrences being the fundamental feature of the strong earthquakes in Chinese mainland

The temporal and spatial distributions of all the 259 M≥6 earthquakes of eastern Chinese mainland (λ≥108° E) and its adjacent area and all the 153 M≥7 earthquakes of western Chinese mainland (λ<108°E) and its adjacent area up to 1991 were analyzed systematically.These earthquakes are called as strong earthquakes and those of the east before and after 1600,and those of the west before and after 1900, are called respectively as former ones and latter ones.Most of these events were divided into 45 sets of which the each relatively concentrated in both time and space and took the form of group.In the grouping form,the probability of occurrence of a strong earthquake higher than the average appeared simultaneously in time and space.The grouping occurrences of the strong earthquakes of Chinese mainland has been determined as a fundamental feature of the seismicity.

Model analysis of crust motion in the Chinese mainland by CMONOC

We report a new horizontal Global Positioning System velocity field in the Chinese mainland from the data analysis of about 2000 GPS sites observed in 2009, 2011 and 2013 through three campaigns of the CMONOC project. Assuming the crustal block to characterize their kinematic behaviors, we estimate parameters of 22 crustal blocks to fit the GPS-derived velocity by using GIPSY software. We restrict us to compare two competing models in which the rigid blocks and the deforming blocks are involved. Our modeling suggests that the most crustal blocks characterized by coherent movement and internal strain may be better in describing the kinematics of crustal deformation in the Chinese mainland.

Precipitation changes in the mid-latitudes of the Chinese mainland during 1960–2014

Based on daily precipitation data from 163 meteorological stations, this study investigated precipitation changes in the mid-latitudes of the Chinese mainland（MCM） during 1960–2014 using the climatic trend coefficient, least-squared regression analysis, and a non-parametric Mann-Kendall test.According to the effects of the East Asian summer monsoon on the MCM and the climatic trend coefficient of annual precipitation during 1960–2014, we divided the MCM into the western MCM and eastern MCM. The western MCM was further divided into the western MCM1 and western MCM2 in terms of the effects of the East Asian summer monsoon. The main results were as follows：（1） During the last four decades of the 20^（th） century, the area-averaged annual precipitation presented a significant increasing trend in the western MCM, but there was a slight decreasing trend in the eastern MCM, where a seesaw pattern was apparent. However, in the 21^（st） century, the area-averaged annual precipitation displayed a significant increasing trend in both the western and eastern MCM.（2） The trend in area-averaged seasonal precipitation during 1960–2014 in the western MCM was consistent with that in the eastern MCM in winter and spring. However, the trend in area-averaged summer precipitation during1960–2014 displayed a seesaw pattern between the western and eastern MCM.（3） On an annual basis,both the trend in rainstorms and heavy rain displayed a seesaw pattern between the western and eastern MCM.（4） The precipitation intensity in rainstorms, heavy rain, and moderate rain made a greater contribution to changes in the total precipitation than precipitation frequency. The results of this study will improve our understanding of the trends and differences in precipitation changes in different areas of the MCM. This is not only useful for the management and mitigation of flood disasters, but is also beneficial to the protection of water resources across the MCM.

Influence of the 2011 Mw9. 0 Japan earthquake on groundwater levels in Chinese mainland

This paper gives a description of the co-seismic and post-seismic groundwater level changes induced in Chinese mainland by the 2011 Mw9.0 Japan earthquake, and the corresponding stress changes calculated on the assumption of linear elasticity. The result shows that the main types of changes were oscillations and step increases. The North-South Seismic Belt and the Shanxi Seismic Belt were the main areas affected by the earthquake.