Research Articles (Earth Sciences)

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Enhancing target crop discrimination: a novel shadow detection technique for RGB datasets in mixed agricultural environments
(Mapping Sciences Institute Australia, 2025) Dube, Timothy I.; Sibanda, Mbulisi; Mafuratidze, Pride
Shadows pose significant challenges in smallholder farming systems, where mixed cropping is common. This study introduces two novel techniques: the Hue-Intensity-Green-Blue (HIGB) difference method for shadow detection and the Light Intensity Ratio-Based (LIRB) method for shadow compensation. Their performance was tested against the C3 and NSVDI models using five accuracy metrics on RGB imagery. HIGB consistently achieved superior accuracies (77–95%) compared to NSVDI (63–84%) and C3 (69–81%) in five different crop mixtures. Both the models, HIGB and LIRB, provide an integrated, robust solution for shadow detection and compensation in heterogeneous agricultural environments.
Variability in the carbon management index and enzymatic activity under distinct altitudes in the alpine wetlands of Lesotho
(Multidisciplinary Digital Publishing Institute (MDPI), 2025) Mazvimavi, Dominic; Nthebere, Knight; Marake, Makoala Vitalis
Alpine wetlands, key carbon sinks and biodiversity hubs, remain understudied, especially under climate change pressures. Hence, the present study was conducted to assess the variability in soil enzyme activity (SEA) and the carbon management index (CMI) and to utilize principal component analysis (PCA) to explore the variation and correlation between SEA and CMI as influenced by altitudinal gradients in alpine wetlands. This information is essential for exploring the impacts of soil degradation and guiding restoration efforts. The study was designed in blocks (catchments) with six altitudinal variations (from 2500 to 3155 m a.s.l), equivalent to alpine wetlands from three catchments (Senqunyane, Khubelu and Sani) as follows: Khorong and Tenesolo in Senqunyane; Khamoqana and Khalong-la-Lichelete in Sani; and Lets’eng-la-Likhama and Koting-Sa-ha Ramosetsana in Khubelu. The soil samples were collected in February 2025 (autumn season, i.e., wet season) at depths of 0–15 and 15–30 cm and analyzed for bulk density, texture, pH, electrical conductivity (EC), soil organic carbon (SOC), SEA, and carbon pools, and the CMI was computed following standard procedures. The results demonstrated that the soil was loam to sandy loam and was slightly acidic and non-saline in nature in the 0–15 cm layer across the wetlands. The significant decreases in SEA were 45.33%, 32.20% and 15.11% (p < 0.05) for dehydrogenase, fluorescein di-acetate and β-Galactosidase activities, respectively, in KSHM compared with those in Khorong (lower elevated site). The passive carbon pool (CPSV) was dominant over the active carbon pool (CACT) and contributed 76–79% of the SOC to the total organic carbon, with a higher CPSV (79%) observed at KSHM. The CMI was also greater (91.05 and 75.88) under KSHM at the 0–15 cm and 15–30 cm soil depths, respectively, than in all the other alpine wetlands, suggesting better carbon management at higher altitudinal gradients and less enzymatic activity. These trends shape climate change outcomes by affecting soil carbon storage, with high-altitude regions serving as significant, though relatively less active, carbon reservoirs. The PCA-Biplot graph revealed a negative correlation between the CMI and SEA, and these variables drove more variation across sites, highlighting a complex interaction influenced by higher altitude with its multiple ecological drivers, such as temperature variation, nutrient dynamics, and shifts in microbial communities. Further studies on metagenomics in alpine soils are needed to uncover altitude-driven microbial adaptations and their role in carbon dynamics.
Impacts of diagenetic alterations on siliciclastic sediments of the pletmos basin: implications for reservoir quality
(Springer Science and Business Media Deutschland GmbH, 2025) Oghenekome, Monica Enifome; Chatterjee, Tapas Kumar; Van Bever Donker, Jan M.
The Pletmos sub-basin of Outeniqua Basin, South Africa hosts heterogeneous siliciclastic reservoirs sediments deposited under a complex tectonic setting and its diagenetic processes remain largely undefined. This study focuses on Cretaceous reservoir sediments, aiming to evaluates the impact of diagenetic alterations on the reservoir quality. Despite the basin’s recognition as a prolific hydrocarbon prospect, no detailed investigation into the diagenetic evolution of its reservoir rocks is available. This is the first integrated Petro-sedimentological characteristics in the basin, combining petrographic and petrophysical data derived from conventional core samples of 100% recovery and well logs data from three exploratory wells. The siliciclastic reservoirs are primarily composed of moderately to poorly sorted feldspathic litharenites and lithic arkoses sandstones deposited in fluvial environment. Two major porosity–permeability trends are identified; due to primary intergranular pore networks and secondary porosity generated by mineral dissolution. High effective porosity is attributed to the coexistence of preserved primary pores and timely development of secondary porosity, supporting enhanced fluid migration and reservoir quality. Diagenetic processes include early mechanical compaction, quartz and clay cementation, calcite and iron oxide precipitation, and extensive feldspar dissolution into kaolinite. Authigenic chlorite coatings, variations in quartz and calcite cementation are especially influential in porosity distribution. These changes reflect eogenetic and mesogenetic phases, which significantly modify petrophysical properties. The reservoir porosity ranges between 13.5 and 16.3%, primarily controlled by grain compaction, quartz, calcite cementation, and mineral dissolution. Diagenesis directly influences reservoir quality, making this study a valuable reference for reservoir assessment, exploration, and regional diagenetic comparison.
A general chopping peak function for a reservoirs group flood control regulating
(Elsevier B.V., 2025) Liu, Dedi; Mu, Zhenyu; Wang, Zhenyu
Flood event is one of the natural hazards and has affected the most people in the world. As the peak of the flood event is the most striking feature to its hazard, chopping flood peak is often the main goal of preventing flood hazard. To integrate the regulation of the flood storages in a reservoirs group for chopping flood peak, a general relationship among the flood events, the flood storages and the chopping peak has been quantified through Chopping Peak Function (CPF). And we have derived the analytical solutions for a single, a parallel or a cascade reservoirs group while numerical solution for a mixed reservoirs group to their corresponding CPF. Based on the solutions to their CPF, the mechanism is clarified for the integrated reservoirs flood storages regulation. The derived analytical solutions have also been proven to be more efficient for integrating the reservoirs regulation than for only every single reservoir regulation. The numerical solutions for the mixed reservoirs groups are found to be better than that of optimal reservoirs regulation model through NSGA-II in terms of the number and the distribution range of the Pareto frontier. Therefore, our study will not only help understand the regulation of the f lood storages in reservoirs groups for chopping flood peak, but also find an efficient way to prevent flood hazard.
The southwesternmost piece of the Grenville Orogen in Laurentia – New U-Pb and Sm-Nd ages, and P-T estimates from the Sierra del Cuervo, Chihuahua, Mexico.
(Elsevier B.V, 2025) Frei, Dirk; Weber, Bodo; Nayeli Chacón-Olivas C.
This paper elucidates the origin and tectonic setting of Mesoproterozoic metaigneous rocks of the Sierra de Cuervo, Chihuahua, Mexico, providing new evidence for the southwestern extension of the Grenville Orogeny in North America. Several geochronological approaches were used, including U-Pb zircon dating by LA-ICP-MS and the Sm-Nd isochron technique, using ID-TIMS. Igneous zircon domains reveal crystallization ages for felsic igneous protoliths ranging from ~ 1.38 Ga to ~ 1.33 Ga, with ~ 1.42 b.yr. old inherited zircon. Whole-rock SmNd isotopic data define an isochron at 1.52 ± 0.03 Ga, suggesting crustal growth during the early Mesoproterozoic. The timing of metamorphism is constrained by Sm-Nd leached garnet-whole-rock isochrons and by U-Pb zircon dates between ~ 1.06 and ~ 1.05 Ga. Metamorphic pressure and temperature conditions were estimated from a metamafic rock sample at 6.4 ± 1 kbar and 520 ± 20 ◦C using conventional geothermobarometry and pseudosection modeling. The results contextualize the Precambrian rocks of the Sierra del Cuervo with metamorphic rocks of the West Texas Uplift thrust over the Laurentian margin. We propose that this thrust represents a remnant of the unexposed Grenville Front and that the Chihuahua and West Texas metamorphic basement is characterized by contemporaneous magmatism and reworked from the Granite-Rhyolite Province of the North American midcontinent during the Grenville Orogeny, comparable to the low-medium pressure allochthonous Ottawan metamorphic belt of the Grenville Province in Canada
Short-term effects of cover crop species and termination methods on soil ph and key enzymatic activities (β-glucosidase, phosphatase and urease activities) in a citrus orchard (eureka lemons)
(Multidisciplinary Digital Publishing Institute (MDPI), 2025) Jovanovic, Nebo; Silwana, Sibongiseni; Mulidzi, Azwimbavhi Reckson
The best management practices for cover cropping in citrus orchards, particularly in terms of species selection and termination methods, remain unclear. This study assessed the short-term effects of different cover crop species (vetch, medics and oats) and termination methods (slashed vs. non-slashed) on soil pH and enzyme activities (β-glucosidase, acid phosphatase, and urease) in a citrus orchard with sandy soil. A randomized complete block design with a factorial treatment structure and six replications was used. Soil samples were collected before and one year after cover crop establishment. The results showed that cover cropping increased soil pH from 5.42 to 6.00 after one year. However, no statistically significant differences were observed in soil pH or enzyme activities among cover crop species or termination methods. Marginal increases in enzyme activities were observed under leguminous cover crops, and these changes were insufficient to indicate strong treatment effects. Correlation and principal component analyses revealed that soil enzyme activities were more strongly influenced by soil properties (depth, carbon content and moisture) than by cover crop species or termination methods. These findings suggest that, under sandy soil conditions and within a one-year period, cover cropping has limited immediate effects on soil biological indicators in citrus orchards. Longer-term studies are recommended to assess cumulative impacts
Impacts of inter-basin water diversion projects on the feedback loops of water supply–hydropower generation–environment conservation nexus
(Copernicus Publications, 2025) Liu, Dedi; Wang, Jiaoyang; Guo, Shenglian
To balance water resource distribution in different areas, inter-basin water diversion projects (IWDPs) have been constructed around the world. Unclear feedback loops of water supply-hydropower generation-environment conservation (SHE) nexus in IWDPs increase the uncertainty in rational scheduling of water resources for water receiving and water donation areas. To address the different impacts of IWDPs on a dynamic SHE nexus and explore synergies, a framework is proposed to identify these impacts across multiple temporal and spatial scales in a reservoir group. The proposed approach was applied to the Hanjiang River Basin (HRB) in China as a case study. Runoff series from the HRB at multiple temporal and spatial scales were provided through the Variable Infiltration Capacity hydrological model. Multi-level ecological flows were determined by the modified Tennant method based on a multi-level habitat condition method. 30 scenarios were set and modeled in a multisource input-output reservoir generalization model. Differences between scenarios were quantified with a response ratio indicator. The results indicate that without IWDPs there is negative feedback between water supply (S) and hydropower generation (H) and between S and environment conservation (E), while there is positive feedback between H and E. The negative feedback of S on H and the positive feedback of E on H are weakened or even broken in abundant-water periods. With IWDPs, water donation basins experience strengthened feedback loops, while water receiving basins experience weakened feedback loops. Feedback loops exhibit intrinsic similarity and stability across different time scales. Feedback loops in reservoirs with a regulation function remain stable under varying inflow conditions and feedback loops for downstream reservoirs are influenced by their upstream reservoirs, especially in low-flow periods. Simply increasing water receiving flow cannot resolve inherent SHE conflicts because of the persistent feedback polarity with IWDPs, and adaptive allocation rules are needed that account for these stable feedback patterns. The proposed approach can help quantify the impacts of IWDPs on SHE nexus and contribute to the sustainable development of SHE nexus.
Proximity to water shapes the distribution of natural elephant mortality in Hwange National Park, Zimbabwe
(Nature Research, 2025) Mpakairi, Kudzai Shaun; Kavhu, Blessing; Ngwenya, Nobesuthu
While elephant poaching has received considerable attention, natural mortality can at times surpass human-induced deaths, especially under environmental stress. Understanding the ecological drivers of natural elephant mortality is therefore crucial for informing reintroduction efforts and preventing mass die-offs. In this study, we investigated environmental predictors of natural elephant mortality in Hwange National Park, Zimbabwe, using mortality records from 2020 to 2022. We applied four machine learning species distribution models, Random Forest, Gradient Boosting, Maximum Entropy, and Extreme Gradient Boosting, along with their ensemble to model mortality hotspots. The ensemble model outperformed individual models, achieving a True Skill Statistic of 0.54 and a Receiver Operating Characteristic of 0.83. Among all predictors, distance to water sources was the most influential variable (accounting for > 55% of model importance), with most mortalities occurring within 6 km of water points. Other key predictors included climate water deficit, normalized difference vegetation index (NDVI), tree cover percentage, and elephant density (each contributing > 5%). In contrast, maximum temperature of the warmest month and elevation had minimal predictive power (< 4%). Our results provide actionable insights for conservation planning. Areas close to water sources, particularly during dry periods, should be prioritized for monitoring and veterinary intervention. Meanwhile, regions with historically low mortality prevalences may serve as safer sites for reintroduction. This spatially explicit framework can help reduce post-release losses and enhance the long-term success of elephant conservation initiatives, especially in the face of ongoing environmental change.
Fine-scale mapping of irrigation suitability in South Africa using ensemble modelling
(Nature Research, 2025) Mpakairi, Kudzai Shaun; Dube, Timothy; Sibanda, Mbulisi
Food insecurity, exacerbated by a growing population and environmental change, poses a significant challenge in Southern Africa. Enhancing agricultural productivity through efficient irrigation practices is crucial for achieving food and water security and sustainable development goals. This study applied an ensemble modelling approach to identify and assess irrigation suitability areas across South Africa, combining the predictive power of Random Forest, Extreme Gradient Boosting (XGBoost), and Gradient Boosting Machine (GBM) algorithms. These machine learning models were applied using cropland presence/pseudo-absence data and a suite of predictor variables. The ensemble model, leveraging a weighted averaging approach based on individual model performance, outperformed the individual models, achieving a TSS of 0.66 and an AUC of 0.90. Land use, population density, and elevation were identified as key factors determining irrigation suitability. The ensemble model also revealed substantial spatial variation in irrigation potential across South Africa, with the Northern Cape and Western Cape provinces exhibiting the largest suitable areas. The results provide critical information for targeted irrigation development, enabling efficient resource allocation, and maximising agricultural productivity. This data-driven approach offers a robust framework for sustainable agrarian planning in the face of increasing food demands and climate change, contributing to enhanced food security and economic development in South Africa.
Long-term land use and land cover dynamics in the Okavango River Basin: impacts on wetlands ecohydrological conditions using satellite data and machine learning
(Routledge, 2025) Sigopi, Maria; Moropane, Lebogang Mmasechaba; Dube, Timothy
The Okavango River Basin (ORB), one of sub-Saharan Africa’s most ecologically significant and well-preserved endorheic system, is critical for sustaining biodiversity and providing ecosystem services. However, increasing anthropogenic pressure and environmental change demand continuous and precise monitoring to safeguard its natural assets. This study utilized Google Earth Engine (GEE) to present a robust 34-year (1989–2023) analysis using Landsat 5 and 8 at 30 m resolution. The study examined the relationship between the normalized difference vegetation index (NDVI), soil-adjusted vegetation index (SAVI), and normalized difference phenology index (NDPI), coupled with Climate Hazards Group Infrared Precipitation (CHIRPS), ERA5 Land, and TerraClimate products. Utilizing a Random Forest (RF) classifier, we achieved accuracies of 95-98% across nine intervals. Wetlands maintained 3% coverage from 1989-2004, while forest occupied 20-26%. Water bodies declined from 1989-2016, then gained 6419 km2 (2017–2020). Wetlands gained 19144 km2 (1989–1992) and 8406 km2 (2017–2020), but lost -10986 (1993–1996) and -7734 km2 (2009–2012). Higher temperatures are correlated with NDPI (β = 0.05, p = 0.003, R2 = 0.32) and NDVI (β = 0.106, p = 0.0045, R2 = 0.29), while precipitation and evapotranspiration were not significant. SAVI presented no significant relationship (R2 = 0.27, p = 0.027). These findings underscore the urgent need for continuous LULC monitoring to inform adaptive management strategies for the ORB.
In the minor key: the minuscular mycelium and its implications for citizen science
(John Wiley and Sons Inc, 2025) Goldin, Jaqui; Suransky, Carolina
In an era marked by ecological precarity and growing demands for knowledge systems that are more inclusive, situated, and responsive, grassroots initiatives have begun to challenge dominant models of science and expertise. Among these, citizen science has emerged as a powerful mode of inquiry that brings together university-based scientists with communities to highlight lived experience, local knowledge, and collective sense-making. One such initiative, which is grounded in a commitment to care, justice, and co-creation is the project Diamonds on the Soles of our Feet (DSF) which originated as a locally rooted water literacy project in the province of Limpopo in South Africa. Since its inception in 2019, the project has evolved in unexpected, generative and at times even unfathomable ways. From its start in one rural village, it grew into a multi-sited, transnational, and increasingly entangled exploration of environmental justice and relational care. This paper seeks to make sense of these developments through the conceptual lens of a ‘fungal turn’ and the aesthetics of care. Engaging with the entanglements of citizen science, we found, can open up forms of learning that stretch beyond conventional scientific frameworks. Here the image of the fungal as a (dis)organizing principle allows us to contrast it with the more rigid image of science as a container. As DSF networ(ld)s extend into uncharted geographical terrains, the application of an ethics of care, coupled with fungal imagery, offers a valuable lens to interpret the unexpected and indeterminate textures that characterize our unfolding DSF journey. By equipping both learners and educators, DSF aims to create a collaborative model that supports long-term behavioral change and where authentic, value-transparent conversations become the fertile ground for meaningful engagement. We thus aim to create a pedagogy of connection, one that links ecology, identity, and imagination, resisting the impulse to fix, explain away or simplify, but instead to cultivate the capacity to remain present with the troubling complexity of it all. Once we took citizen science out of the container, we began to inhabit a space where encounters became unpredictable, often uncomfortable and occasionally deeply troubling. By resisting the impulse to command, to classify and to control and by resting instead in the minor key, meaning in the unfolding process rather than the singular event, we allowed ourselves to become entangled. Mushrooms offer more than a biological metaphor; they become a lens to reimagine ecological entanglement and the often-invisible networks that shape our understanding of science, learning, and care.
Nanoscale mapping of ZrSiO4phases in naturally shocked zircon using electron energy loss spectroscopy
(Walter de Gruyter GmbH, 2025) Kovaleva, Elizaveta; Roddatis, Vladimir; Syczewski, Marcin
Coexistence in natural samples of zircon (ZrSiO4) and reidite (a high-pressure polymorph of ZrSiO4) is attributed to the effects of hypervelocity impact events. The grains and intergrowths in those minerals can be merely a few nanometers in size, which makes phase identification by standard methods of structure analysis difficult. However, analytical scanning transmission electron microscopy (STEM) utilizing electron energy loss spectroscopy (EELS) can provide important information on phase transition mechanisms and pressure-temperature conditions associated with the shock event at the nanoscale. Here we demonstrate that the valence as well as oxygen core-loss EELS can be employed for nanoscale mapping of zirconreidite distributions in zircon-reidite aggregates. Moreover, other accompanying phases, e. g., baddeleyite, could also be identified and mapped by this method. We further compare the EELS maps with a 4D-STEM nanobeam precession electron diffraction data, and demonstrate the advantages of the EELS mapping, which provides spatial resolution down to the nanometer scale and is independent of crystal orientation.
Integrated water resources management for sustainable development in East and Southern Africa
(Elsevier Ltd, 2025) Dube, Timothy; Dzwairo, Bloodless Rimuka; Kgabi, Nnenesi
The 23rd WaterNet/WARFSA/GWP-SA Symposium was held at Sun City Conference Centre, in South Africa and online from 19 to October 21, 2022. The symposium, whose main theme was “Integrated Water Resources Management for Sustainable Development in East and Southern Africa”, drew over 400 participants from the academia, practitioners, policy makers and development partners from the Eastern and Southern Africa (ESA) region and beyond. The symposium was jointly convened by the International Association of Hydrological Sciences (IAHS), AU/NEPAD Southern African Network of Water Centres of Excellence (AU/NEPAD SANWATCE), and the Local Organizing Committee led by the North-West University, South Africa, with support from the Government of South Africa.
Remote sensing of land cover change dynamics in mountainous catchments and semi-arid environments: a review
(Taylor and Francis Ltd., 2025) Yono, Anothando; Dube, Timothy; Mokua, Retang Anna
This paper investigates the impacts and dynamics of land use/land cover (LULC) change dynamics in mountainous catchments in semi-arid regions, focusing on drivers, methods, and hydrological impacts. This study reviews studies using the application of remotely sensed data and spatially modified data, highlighting advancements in LULC assessments through GIS integration and predictive modelling. Key drivers include agricultural expansion, population growth, urbanisation, and infrastructure development, which transform forests and grasslands into built environments, affecting ecosystem services and biodiversity. LULC changes significantly impact hydrology, leading to increased surface runoff, poor water quality, and disruptions in the hydrological cycle. Agricultural expansion also contributes to habitat fragmentation ad biodiversity loss. This study underscores the importance of sustainable land management and informed policy decisions to mitigate negative impacts and enhance ecological resilience in semi-arid regions.
Mapping human fatalities from megafauna to inform coexistence strategies
(Scientific Reports, 2025) Mpakairi, Kudzai Shaun; Kavhu, Blessing; Mutema, Courage
Human fatalities from human–wildlife conflict (HWC) represent a critical dimension of conservation, often triggering retaliatory actions and post-traumatic stress in affected communities. However, most studies focus on the economic implications of HWC, neglecting human fatalities which may have far-reaching long-term implications. This study investigates the spatial and temporal patterns of human fatalities caused by megafaunal species in Zimbabwe, using data collected from 2016 to 2022. Through spatial and statistical analyses based on the Getis-Ord Gi* hotspot analysis and Mann–Kendall trend test, we assess fatalities caused by six megafaunal species: Nile crocodile (Crocodylus niloticus), African elephant (Loxodonta africana), hippopotamus (Hippopotamus amphibius), African buffalo (Syncerus caffer), African lion (Panthera leo) and spotted hyena (Crocuta crocuta). The results of the study showed that crocodiles and elephants account for over 80% of human fatalities in Zimbabwe. These fatalities also significantly increased over the study period (p < 0.03). In contrast, fatalities involving lions, hyenas, hippos, and buffaloes showed no significant increase, indicating more stable but still concerning risks. Fatality hotspots were concentrated in Kariba, Binga and Hwange districts in northern and western Zimbabwe, highlighting areas needing urgent interventions. These insights have broader implications for HWC management across Africa, where megafaunal species frequently interact with human populations. By adopting data-driven, species-specific strategies, other countries facing similar conflicts can foster human–wildlife coexistence and improve conservation outcomes.
Assessing CO2 storage potential in a structurally complex depletedgas reservoir, offshore South Africa
(Elsevier Ltd, 2025) Mhlambi, Sanelisiwe; Agbor, Fritz Ako; van Bever Donker, Jan M
As global efforts to mitigate greenhouse gas emissions intensify, carbon capture and storage (CCS) has emerged as a key strategy for reducing the environmental impact of fossil fuel use. However, geological storage of CO₂ in structurally complex and heterogeneous reservoirs presents a range of issues due to the geological intricacies, with implications for storage capacity estimation, CO₂ injection, migration, and even long-term containment, which pose environmental risks. Therefore, this study assesses the CO₂ storage potential of the depleted F-O Gas Field in the Bredasdorp Basin, offshore South Africa, using a robust modelling approach based on the analysis of a suite of exploration and production datasets from the field. A high degree of structural compartmentalisation with a fault-bounded anticlinal trap characterises the field. The Valanginian-age marine sandstone reservoirs exhibit low to moderate porosity and permeability. In total, a CO₂ storage capacity of 185.3 Mt was determined for the F-O gas field, which reduces to 37.1–74.1 Mt after accounting for reservoir heterogeneity and sweep efficiency. This reduction reflects the impact of the field's complex structural architecture, variable facies distribution, and petrophysical variability, which collectively limit the effective pore volume accessible for CO2 storage. By rigorously integrating the structural architecture of the field, sedimentary processes, facies distribution, and petrophysical variability of the candidate reservoir, this study provides critical insights and strategies into the feasibility of CCS in structurally complex depleted gas fields. Significantly, these findings contribute to ongoing national CCS assessments and support South Africa's long-term decarbonisation agenda.
Estimation of hydrogeological spring catchment area: case of Jinci spring in North China
(Springer Nature, 2025) Xu, Yongxin; Zhang, Zhixiang; Wang, Zhaoliang
Hydrogeological spring catchment area of Jinci spring is the starting point for all hydrogeological analyses and one of the fundamental datasets for karst groundwater modeling. Unfortunately, there is a lack of detailed research on the hydrogeological spring catchment area. To sustainably utilize and protect the karst groundwater resources of Jinci spring, this paper investigates the variation pattern of the spring flow decrease coefficient from 1956 to 1994, estimates the hydrogeological spring catchment area by using the linear regression method and the Turc method. The results show that: (1) The spring flow decrease coefficient generally shows an increasing trend over time, and its variation indicates the time-varying characteristics of the hydrogeological spring catchment area. (2) The hydrogeological spring catchment areas estimated by the linear regression method are 2143, 2084 and 2037 km2, with an average of 2088 km2. (3) The hydrogeological spring catchment area estimated by the Turc method exhibits a series of values, and its time-varying characteristics is the dynamic change with time, resulting from the joint effects of natural and anthropogenic factors. This study provides a theoretical foundation for the protection and management of karst groundwater in the semi-arid region of northern China.
Investigation of water use and trends in South Africa: a case study for the Mzimvubu to Tsitsikamma Water Management Area 7 (WMA7)
(Multidisciplinary Digital Publishing Institute (MDPI), 2025) Jovanovic, Nebo; Mulangaphuma, Lawrence
This paper investigated sectoral water use and trends in the Mzimvubu to TsitsikammaWater Management Area 7 (WMA7). The investigation considered the Water Authorisation and Registration Management System (WARMS) database and field surveys as a source of water use information. The study was able to successfully make use of time series statistical analysis to show water use trends for identified priority sectors over a 5-year period by sourcing historical water use data of the study area. Further, the groundwater stress index and streamflow impact were applied to assess water use impacts on the surface and groundwater. The WARMS database and field survey results identified major sectoral water users such as agriculture (irrigation), municipal water services, dam storage, afforestation, power generation, recreation, mining, and industries. Study findings revealed that the agricultural sector is a major water user, with an estimated 60% of the total waterrequirement over a 5-year period (2018 to 2022). The application of the groundwater stress index revealed that the majority of the Quaternary catchments have surplus groundwater available. The application of streamflow impact revealed that the majority of catchments have low flow or no flow. The rise of water use clearly indicates a lack of water use compliance and enforcement. An increase in total water use could put water resources under stress, including an impact on the aquatic ecosystem, reduced water quality, and economic and social consequences. Therefore, the study recommends that a follow-up on compliance of surface water and groundwater use licenses be regularly conducted.
Petrogenetic characterization of La Vasca alkaline complex and its relationship to the Eastern Mexican Alkaline Province
(Elsevier Ltd, 2025) Frei, Dirk; Martínez-Salinas, Edgar; Weber, Bodo
Peralkaline and agpaitic igneous rocks with local eudialyte mineralization have been reported in the La Vasca alkaline complex (LVAC) but no detailed information on its age and relationship to the Eastern Mexican Alkaline Province (EMAP) has been available. We present petrological, geochemical, isotopic, and geochronological data from the LVAC and the surroundings, located in northwestern Coahuila. The main intrusion is composed of ferroan granitoids that are classified by their alumina saturation index into metaluminous and peralkaline. The metaluminous rocks are monzonite and syenite with post-collisional geochemical affinity. Middle Eocene zircon ages of these rocks range between 47.6 ± 0.3 Ma and 45.4 ± 0.3 Ma and are significantly older than other alkaline rocks from the EMAP. The peralkaline rocks are composed of syenite and eudialyte-bearing foid-syenite with intraplate geochemical affinity that probably coevolved with the metaluminous rocks. Both groups show minimal crustal contamination, with affinity to an Ocean Island Basalt mantle source. The LVAC is explained by a similar formation model than other rocks of the EMAP, suggesting its extension into northwestern Coahuila. Furthermore, the eudialyte foid-syenites represent the first occurrence of agpaitic rocks in Mexico
Integrated flood modelling and risk assessment in urban areas: a review on applications, strengths, limitations and future research directions
(Elsevier B.V., 2025) Pakati, Sibuyisele; Dube, Timothy; Shoko, Cletah
Study region: Global scale. Study focus: The purpose of this study is to provide a comprehensive global assessment of urban flood modelling by: (i) critically reviewing the most widely used flood models in urban settings; (ii) synthesizing their operational mechanisms, including the integration of diverse data types and validation techniques; and (iii) evaluating each model’s strengths and limitations in simulating flood dynamics and assessing urban flood susceptibility. Furthermore, the paper establishes a framework for selecting acceptable modelling methodologies for successful flood risk management in real-world urban scenarios. New hydrological insights for the region: Hydraulic-hydrological models, and cloud-based geospatial platforms have been widely applied in flood modelling and risk and vulnerability assessment. Despite these advancements, accurate flood modelling remains a challenge due to limitations in input data quality. Among earth observation tools, radar satellite data was identified as the most effective due to its reliability under cloudy and rainy conditions. Enhancing model accuracy and validation remains possible through the integration of both optical and radar data with hydraulic and hydrological models. For example, radar backscatter intensity can be used to estimate flood depths. However, key research gaps remain, notably, the integration of high-resolution climate projections and socio-economic factors into flood risk models, and the application of modelling tools in poorly planned urban areas to assess real-time changes in land use following flood events.

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