Contributions to Geophysics and Geodesy

Groundwater is a significant resource that supports almost one-fifth population globally, but has been is diminishing at an alarming rate in recent years. To delve into this objective more thoroughly, we calculated interannual (2002–2020) GWS (per grid) distribution using GRACE &amp; GRACE-FO (CSR-M, JPL-M and SH) Level 3 RL06 datasets in seven Indian river basins and found comparatively higher negative trends (−20.10 ± 1.81 to −8.60 ± 1.52 mm/yr) in Basin 1–4 than in Basin 5–7 (−7.11 ± 0.64 to −0.76 ± 0.47 mm/yr). After comparing the Groundwater Storage (GWS) results with the CHIRPS (Climate Hazards Group Infrared Precipitation with Stations) derived SPI (Standardized Precipitation Index) drought index, we found that GWS exhausts analogously in the same period (2005–2020) when SPI values show improvement (∼1.89–2), indicating towards wet condition. Subsequently, the GWSA time series is decomposed using the STL (Seasonal Trend Decomposition) (LOESS Regression) approach to monitor long-term groundwater fluctuation. The long term GWS rate (mm/yr) derived from three GRACE &amp; GRACE-FO solutions vary from −20.3 ± 5.52 to −13.19 ± 3.28 and the GWS mass rate (km3/yr) lie in range of −15.17 ± 4.18 to −1.67 ± 0.49 for basins 1–3. Simultaneously, in basin 4–7 the GWS rate observed is −8.56 ± 8.03 to −0.58 ± 7.04 mm/yr, and the GWS mass rate differs by −1.71 ± 0.64$ to −0.26 ± 3.19 km3/yr. The deseasonalized GWS estimation (2002–2020) states that Himalayan River basins 1,2,3 exhibit high GWS mass loss (−260 to −35.12 km3), with Basin 2 being the highest (−260 km3). Whereas the Peninsular River basin 4,6,7 gives moderate mass loss value from −26.72 to −23.58 km3. And in River basin 5, the GWS mass loss observed is the lowest, with a value of −8 km3.

Tandrila SARKAR

Anuradha KARUNAKALAGE

Suresh KANNAUJIYA

Charan CHAGANTI

Quantification of groundwater storage variation in Himalayan &amp; Peninsular River basins correlating with land deformation effects observed at different Indian cities

喜马拉雅和半岛河流流域地下水储量变化的量化及其与印度不同城市地面变形效应的相关性

This contribution presents a new velocity field describing the crustal motion of Nigeria from more than 5years continuous GNSS data at 8 of 14 permanent stations distributed across the country. GAMIT/GLOBK GNSS processing software was used for processing. The horizontal velocity field of NigNET stations which showed a North-East trend and the selected IGS stations were obtained from cleaned position time series of daily GNSS solutions. The velocity describe the horizontal and vertical motion the selected 8 GNSS stations assuming Flicker +White noise model, which optimally describes the geophysical error source of the adopted GNSS stations. Bland and Altman statistical method shows that residual velocity solutions of our study and others (in ITRF2008) and also MORVEL plate motion model are in agreement.

Swafiyudeen BAWA

Lazarus Mustapha OJIGI

Joseph Danasabe DODO

Kola Muideen LAWAL

A methodology for estimating accurate velocity field of NigNET based on new ITRF realization

基于新ITRF实现的NigNET速度场精确估算方法

Tidal strain time series recorded at the Vyhne Tidal Station are used to test thirteen different ocean tide loading models. Ten models have been calculated using SPOTL: EOT11a, HAMTIDE11a, OSU.TPXO72atlas, OSU.TPXO72, TPX070, DTU10, CSR4.0, FES2004, FES95.2.1, SCHW1 and three other models were chosen from the Free Ocean Tide Loading Provider (FOTLP) created by Scherneck and Bos: FES2012, FES2014b, GOT00.2. Hourly sampled strain data, corrected for temperature, were subjected to correction for ocean tide loading. The test of models was focused on the diurnal and semi-diurnal tidal harmonic constituents O1, P1, K1 and M2. A negligible difference between the individual global ocean tide loading models was only found mainly due to using different Earth models and Green functions. The amplitude factors for O1, P1, K1 and M2 derived from the measurements are 1.019, 1.226, 0.842 and 1.131, respectively. The average amplitude factors for these tidal components were obtained after ocean load correction using SPOTL routines: 1.121, 1.332, 0.916, 1.283, and in the case of the three models using FOTLP: 1.046, 1.486, 1.067, 1.317. The corrected amplitude factor became closer to the theoretical value only for K1.

Ladislav BRIMICH

Martin BEDNÁRIK

Jozef BÓDI

Gyula MENTES

Test of ocean tide loading models on the basis of strain data measured at the Vyhne Tidal Station, Slovakia

基于斯洛伐克Vyhne潮汐站应变数据对海洋潮汐负荷模型的检验

The land of Iran is situated in a compression zone with a high seismicity rate due to the convergence of Arabian and Eurasian plates. In this study, the stress field of two provinces of Kopeh Dagh and Eastern Iran, which are located in the east and northeast of Iran, has been studied and compared. These two provinces are different in terms of seismicity patterns so that Kopeh Dagh is much more active than Eastern Iran. To achieve this goal, the iterative joint inversion method for stress and fault orientations developed by Vavryčuk (2014) has been used. The average direction of the maximum principal stress (σ1) and the maximum horizontal stress (SHmax) in the study area are estimated to be N30.1°E and N12.1°E, respectively. These directions are in agreement with the convergence of the Arabian plate and the Eurasian plate. The value of the optimal friction coefficient was determined for both regions and it was found that this coefficient is lower in Kopeh Dagh than in Eastern Iran. This indicates a potential relationship of the fault friction with the activity pattern and seismicity of in the region.

Ghasem Ghorbani ROSTAM

Determination of the stress field in the Kopeh Dagh and Eastern Iran regions

确定科佩达格和东伊朗地区应力场的研究

The Gaurikund town falls on the way of the famous trekking route to Kedarnath that faced the wrath of the 2013 flood disaster. This fateful event severed more than 5000 casualties, demolished several infrastructures, and shifted the course of Gaurikund spring from its original position. Nevertheless, the Gaurikund geothermal spring system located in the Himalayan Geothermal Belt of the Garhwal region is preeminent for religious beliefs, balneotherapeutic values and a gateway to delve within the geothermal and hydrological characteristics of the area. In this perspective, restoration of Gaurikund geothermal spring system becomes a necessity. A multiparametric approach comprising geospatial, geology, hydrochemistry and geophysics has been used to study and justify these aspects at Gaurikund. The geological studies infer that the geothermal spring gets recharged by the steep, southerly dipping joints in granite gneiss. Subsequently, the deep percolated water heats up due to the high geothermal gradient and then emerge along the Vaikrita Thrust and its sympathetic minor fault-thrust system by advection. Moreover, four spring outlets are inventoried, with discharge varying from 7.46 to 95.54 L/min. The normal emissivity model uses the pre and post-disaster satellite data and generates maximum kinetic temperature images, showing a positive correlation between land surface temperature and spring discharge. Two-dimensional Electrical Resistivity Tomography (Schlumberger, Wenner and Gradient configurations) survey revealed two low resistivity zones proximal to the geothermal spring on the right bank of the Mandakini river. The engineering interventions carried out by bank protection and construction of small gully plugs in the catchment area is recommended along Gaurikund-Sonprayag section on the right bank of Mandakini river.

Anurag KHANNA

Debasish BAGCHI

A multiparametric approach for rejuvenation of the Gaurikund geothermal spring system in the Northwest Himalayan region

西北喜马拉雅地区Gaurikund地热泉系统修复的多参数方法

The construction of dam is important for many reasons. Prior to construction, it is essential to assess the dam's base reservoir to identify any subsurface cavities. This study was conducted along nine electrical resistivity (ERT) profiles and eight induced polarization (IP) profiles, which are traditional ERT profiles, trending SW to NE direction in the reservoir part of the failed Chaq-Chaq dam NW of Sulaimaniyah city. The aim of this study was to delineate subsurface layers, underground features, determine the depth to bedrock, and investigate indications of the causes of collapse of the constructed Chaq-Chaq dam. The Res2Dinvx64 program used in the inversion method to obtain true 2D resistivity sections using a Schlumberger-Wenner array, which is highly sensitive to changes in resistivity both vertically and laterally. Based on the resistivity values, it was found that the area consists of three geological layers; the first layer consists of soil, while the second layer consists of rock fragments, the interface between them has disappeared because the first layer is thin, and the third layer is specified as consolidated and cohesive limestone of the Kometan Formation. The surface of the Kometan limestones is irregular due to weathering and faulting resulting from tectonic movements leading to the collapse of the area and later filled with sediments of recent deposition. The IP method was only used to distinguish clay and water. According to IP values, water is present in the subsurface of the study area. According to the ERT sections, a sinkhole with a depth range of (15 – 39 m) was encountered at the beginning of most of the profiles.

Abdulla K. AMIN

Sazan S. MOHAMMED

Ezzadin N. BABAN

Delineation of subsurface features by electrical resistivity tomography and induced polarization in upstream basin of Chaq-Chaq dam – northeastern Iraq

利用电阻率层析成像和激发极化法在上游盆地划分地下特征——伊拉克东北部查奇查克大坝

In climatology, transitioning from conventional manual weather stations (MWS) to automatic weather stations (AWS) presents challenges in maintaining the homogeneity of long-term data series. At the Skalnaté Pleso Observatory (1778 m a.s.l., High Tatras), manual meteorological measurements have been conducted since 1943 using the same methods and devices at the same location. In 2014, the AWS Physicus was installed to record meteorological data parallelly with manual measurements. This study processed six years of parallel measurements (2017–2022) to derive corrections for AWS monthly atmospheric precipitation totals and maximum (Tmax), minimum (Tmin) and mean air temperatures (Tmean) measured in 2023. Two correction approaches were proposed: monthly regressions (MR) and cumulative distribution functions (CDF), including Generalized Extreme Value (GEV) distribution, normal distribution (GAUSS), and Gamma distribution (GAMMA). Analyses of monthly data revealed an underestimation of precipitation totals in AWS data, with a mean bias error (MBE) of −6.8 mm and a root mean squared error (RMSE) of 20.0 mm. The most suitable correction method was the MR, which decreased MBE to 1.5 mm and RMSE to 11.1 mm. AWS monthly air temperature data were overestimated by 0.1 °C, 0.3 °C, and 0.1 °C for Tmax, Tmin, and Tmean, respectively. For Tmax, correction using the MR and GEV methods reduced the MBE to 0.0 °C and achieved RMSE of 0.1 °C for both. After applying GAUSS, MBE and RMSE decreased to 0.1 °C. The most appropriate correction method for Tmin was the MR resulting in MBE of 0.0 °C and RMSE of 0.3 °C. For Tmean, the MR and GEV methods reduced the MBE to 0.0 °C and the RMSE to 0.1 °C for both methods. These results demonstrate that AWS monthly data, when corrected using the presented methods, have the potential to maintain the continuity of historical climate data series at Skalnaté Pleso.

Veronika LUKASOVÁ

Svetlana VARŠOVÁ

Milan ONDERKA

Dušan BILČÍK

Anna BUCHHOLCEROVÁ

Pavol NEJEDLÍK

Continuity of long-term climate data series after the transition from manual to automatic weather station

自动气象站转换后长期气候数据序列的连续性

Significant copper mineralization are observed to be associated, in most cases, with some radioactive anomalies related to increased uranium and thorium contents in Southern Sinai, Egypt. These mineralizations are related to intense post-magmatic, structurally controlled hydrothermal activities in many localities. Wadi Khosh El-Daba area is one of these locations which is mainly composed of monzogranites dissected by andesite dyke and pegmatite vein. This work deals with the application of ground magnetic and self-potential methods to establish the magnetic sources governing the mineralization, to interpret the significant trends that affected the study area, and to delineate the mineralized zones. The magnetic data were processed, enhanced and interpreted using advanced techniques, such as the first-order vertical derivative (FVD), the tilt derivative (TD), Euler deconvolution (ED), and source parameter image (SPI). The main structural lineaments/contacts that control the distribution of hydrothermal alterations and mineral distributions are oriented to the NW–SE, NE–SW, and NNW–SSE directions. The self-potential (SP) data show that there are numerous mineralized zones; most of them are distributed mainly along the structural lineaments deduced from the magnetic study. The quantitative interpretation revealed that the mineralized bodies are at shallow depths ranging from 5.6 m to 12.7 m, with half-width from 5 m to 13 m. These bodies are shallow to moderate dipping towards the south and north directions. Based on this study an anomaly map is originated to locate the preferred structural elements that may be controlling the mineralization in the area for further future exploration.

Mohamed H. M. YOUSEF

The structural elements controlling the subsurface mineralization as deduced from the integration of magnetic and self-potential methods, Wadi Khosh El-Daba area, southern Sinai, Egypt

从磁法和自电位法综合推断的控制地下矿化的结构要素——埃及南西奈Wadi Khosh El-Daba地区

The National Network of Seismic Stations of Slovakia (NNSS) consists of eight short period and six broadband permanent seismic stations and a data centre located at the Earth Science Institute of the Slovak Academy of Sciences (ESI SAS). The NNSS recorded and detected 11996 seismic events from all epicentral distances in 2022. Totally 76 earthquakes originated in the territory of Slovakia in 2022. This paper provides basic information on the configuration of the NNSS, routine data processing, seismic activity on the territory of Slovakia in 2022 as well as macroseismic observations collected in 2022.

Róbert KYSEL

Andrej CIPCIAR

Martin ŠUGÁR

Kristián CSICSAY

Lucia FOJTÍKOVÁ

Jozef KRISTEK

Seismic activity on the territory of Slovakia in 2022

2022年斯洛伐克领土的地震活动

Enhancing the detection accuracy of the edges of the geological features within the subsurface remains a significant objective in geophysical data interpretation. Despite numerous advancements, approaches stemming from the directional gradients of gravity and magnetic fields still grapple with challenges such as low-resolution outcomes and susceptibility to noise contamination. In this study, we introduce a novel filtering framework based on the total horizontal gradient and its derivatives, designed to yield more precise and coherent edges free from false boundaries or disruptive artifacts. Validation using synthetic Bishop complex magnetic and gravity datasets, alongside Tuangiao aeromagnetic data from Vietnam, substantiates the robustness and applicability of our modified approach. Furthermore, recognizing the inherent susceptibility of edge detection filters to noise contamination resulting from directional derivatives, we employ the recently developed modified non-local means (MNLM) algorithm to alleviate noise effects prior to the analysis of noisy synthetic and real datasets. Our findings confirm the efficacy of the proposed method in reducing false artifacts and identifying edges with heightened precision, positioning MHGA as a valuable alternative for processing potential field data.

Hanbing AI

Hazel DENIZ TOKTAY

Ahmad ALVANDI

Roman PAŠTEKA

Kejia SU

Qiang LIU

Advancing potential field data analysis: the Modified Horizontal Gradient Amplitude method (MHGA)

推进位场数据分析：改进的水平梯度振幅法（MHGA）

短名	Contrib. Geophys. Geod.
Journal Impact	0.76
国际分区	GEOCHEMISTRY & GEOPHYSICS(Q4)

ISSN	1335-2806, 1338-0540
h-index	20

出版信息	出版商: The Earth Science Institute of SAS，出版周期: ，期刊类型: journal，开源期刊: 否
基本数据	创刊年份: 2000，原创研究文献占比: ，自引率:， Gold OA占比:

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Quantification of groundwater storage variation in Himalayan & Peninsular River basins correlating with land deformation effects observed at different Indian cities