Environmental Earth Sciences最新文献

The Hindukush mountain range in northern Pakistan hosts large to medium-sized valley glaciers. These glaciers are continuously retreating due to climate change-induced rising temperatures, leading to erratic discharge and an increasing potential risk to downstream areas. The decadal and annual changes (ablation), snout position, area changes, and associated hazards pose significant risks to downstream communities in the Chitral Valley of the Hindukush Range, northern Pakistan. This study is crucial for understanding the changing dynamics of glaciers and their potential impacts on downstream communities, offering a foundation for developing and implementing evidence-based policies for mitigation and adaptation. This study evaluated glacier risk zones in the Buni Zom valley and the seasonal dynamics of the glacier areas over 28 years (1990–2018) of three glaciers: Khorabhor, Phargam and Gordoghan, using the normalized difference snow index (NDSI) and manual based techniques, utilizing the open-source Landsat images. The Analytical Hierarchy Process (AHP) model was used to identify the risk zones in the study area. The results revealed that the total glacier area is reduced from 16.01% in 1990 to 11.42% in 2018, representing a decline of 4.68%. The highest recession rate was observed between 2015 and 2018, with a 2% loss in the Khorabhor Glacier, 1.5% in the Phargam Glacier, and 0.72% in the Gordoghan Glacier. The glacier snout area receded more at elevations of 3000–4000 m compared to those above 5000 m. The Phargam Glacier, with an area of ≤ 10 km² has receded significantly (4.59%) more than the larger glaciers, such as Gordoghan (≤ 17 km²; 0.09%), and Khorabhor (≤ 15 km²;0.66%). The AHP-based Risk Probability Model showed that the settlements in Phargam Valley, situated 9.7 km from the glacier snout, are at 62.5% risk. The risk arises from the high rate of the glacier recession, resulting in glacial outbursts, water storage in fragile moraine at the terminal area, and increasing the water flow into the Chitral River due to environmental effects. The study is critical to understanding the glacier dynamics in the area, its impacts on the downstream communities and its implications for climate change.

Statistical landslide susceptibility modelling is commonly used for identifying areas with an increased likelihood of landslide occurrence, given evidence of historic events and a potentially arbitrary number of explanatory features. Despite its widespread use, the actual utility and plausibility of the resulting models and maps is sometimes neglected at the expense of model performance. Here we present a landslide susceptibility map for the northern part of Carinthia, Austria, using random forest models within an extensive ensemble modelling and hyperparameter tuning framework. We discuss the importance and effects of the most relevant features retained after feature selection through a geomorphic lens. These results form the basis on a discussion of integrating considerations of geomorphic plausibility, model interpretability and reproducibility next to quantitative model performance metrics for assessing model utility. Including these aspects enhances the applicability of the results for decision-making in landslide risk management, thereby also increasing their reliability under scientific scrutiny.

A comprehensive groundwater quality assessment is carried out in Khulna, which is the coastal mega city of Bangladesh adjacent to southwest Bengal delta. The study was conducted to identify the seasonal variation of ion composition in groundwater and insight into its impact on freshwater availability for the study area. Results of chemical analysis revealed that groundwater is alkaline, with dominant ion concentrations of Mg²⁺, Na⁺, Cl⁻ and HCO₃⁻. Cl⁻ concentration (254.70 mg/L in monsoon; 478 mg/L in winter; 531.75 mg/L in summer) exceed from the prescribed limits, i.e., 250 mg/L of WHO water quality standards. The Piper diagram indicated that groundwater occupies saline and mixed zone that are mostly affected by the seawater through ion exchange mechanism. The Endmember diagrams revealed that silicate weathering plays a major role while evaporite dissolution and carbonate weathering play the minor role for the evolution of groundwater. Saturation indexes reveal that halite saturation increases proportionally to Cl⁻ contents while calcite saturation shows most of the groundwater samples are undersaturated. WQI revealed that summer groundwater quality is poor for drinking purposes. Furthermore, the spatial distribution map of WQI indicated that the northeast and southwest parts of groundwater are vulnerable owing to landscape dynamics. The feedback and outlooks of seasonal ion concentration on freshwater indicated suitable water quality in monsoon and winter, whereas unsuitable, salty and hard water in the summer.

High fluoride (F⁻) groundwater poses a potential health hazard to hundreds of millions of people worldwide. As the largest agricultural growing area in China, the high F⁻ groundwater in the North China Plain is attracting more attention. In this study, a total of 76 groundwater samples were collected in Cangzhou City of North China Plain, to analyze the controlling mechanisms and their relative contribution on groundwater F⁻ enrichment, and evaluate the potential health hazards. Results showed that the exceedance rates of F⁻ in shallow groundwater (SG) and deep groundwater (DG) were 42% and 90%, respectively. Through the characterization of groundwater chemistry coupled with machine learning algorithm, it was found that mineral dissolution and precipitation, cation exchange, competitive adsorption, evaporation and seawater intrusion together control groundwater F⁻ enrichment in the study area, and their contributions were 42%, 34%, 12%, 7% and 5%, respectively. The high water table of SG was more susceptible to evaporation and seawater intrusion, while the geological environment of DG was more conducive to cation exchange and competitive adsorption. Results of health risk assessment showed that 52% of SG samples threatened the health of infants, while 37% and 33% of samples threatened the health of children and adult female. And among DG, more than 71% of samples threatened the health of adults, while 98% and 90% of them threatened the health of infants and children. This study identified the groundwater F⁻ enrichment process in agricultural areas, thereby enhancing our comprehension of the hydrogeochemical evolution groundwater F⁻.

Accurate river network and underlying surface data are crucial for runoff simulation, and the generation effect of river networks is directly affected by the resolution of digital elevation model (DEM). However, the distortion of elevation resampling with different resolutions changes the river network structure. In addition, the spatial resolution and timeliness of the default underlying surface data in the weather research and forecasting model (WRF) are poor, and thus cannot meet the application needs of accurate hydrological forecasting. To overcome this issue, this study proposes a runoff simulation method by combining optimal river network and underlying surface data. The method introduces multiple metrics to evaluate the simulation effect of the river network based on multiresolution topographic and geomorphic data, and the WRF-Hydro is used to simulate the runoff process under different topographic and geomorphic scenarios. The Yuehe River Basin is selected to perform the experiments, and results show that the river network discrepancy can well reflect the simulation effect of the river network in WRF-Hydro GIS. The river network discrepancy obtained by replacing the elevation data SRTM1 DEM is 1.24%, which demonstrates that the simulation effect of the river network is the best. In addition, the mean values of the determination coefficient (R²) and Nash–Sutcliffe efficiency coefficient (NSE) of the proposed method are increased by 5.1% and 16.58%, respectively, when compared with the existing methods. Such results demonstrate the good prospect of the runoff simulation method proposed in this study.

Sand mining activities in the Mekong Delta river have caused localized erosion holes, altering the once stable flow patterns. Additionally, mining conducted too close to the riverbanks has resulted in bank instability and serious erosion issues. This study aims to evaluate the impact of sand mining on the riverbed changes, particularly the working operations of 26 sand pits along the upper reaches of the Tien River from Tan Chau to My Thuan. The results indicate that sand mining primarily affects the immediate vicinity of the mining areas, leading to heightened scouring levels and causing the mined areas in the floodplain to not fully regenerate within a year following extraction. As a result of sand mining activities, the riverbed experiences increased erosion in comparison to periods with no mining operations. The increased erosion is simulated in two sections of the Tien River, namely the Tan Chau – Hong Ngu and the segment of Tien River passing through the Gieng islet, where the highest additional erosion rates are recorded at 1.2 m/yr and 1.21 m/yr, respectively, compared to the scenario without sand mining. The simulation results also indicate that accretion from the mining sites almost returns to its original state in the segment of the Tien River passing through Sa Dec. However, the recovery of other mining sites in lower areas is significantly less. The findings of this study provide important implications for sand mining planning and natural disaster management, especially concerning erosion control measures.

Human pressures and global change are threatening water resources. Circumstances vary in each location; therefore, finding solutions that address local issues helps achieve comprehensive water management strategies. In the Andean basins, the pre-Inca cultures used nature-based water management techniques to deal with the dry seasons. This knowledge and these techniques have been recognized as a strategy to increase water security. Additionally, they have been unconsciously applied to improve hydrological conditions in areas affected by extreme land-use changes. Water sowing and harvesting techniques have been used to manage territories dedicated to livestock and agriculture. This research evaluates three traditional infiltration ditch systems on two types of land use (páramo and cultivated pastures) in the Andean region of Azuay (Ecuador). The objective was to establish the potential for better management of water resources in dry seasons. Eosin-traced water diverted through channels or ditches, infiltrated into the soil, was retained for an average of 31 days in the páramo soil and from 90 to 111 days in the cultivated pasture soil. Controlled water infiltration contributes to effective water management by retaining water in the soil for extended periods. We conclude that nature-based systems perform better on soils with higher water retention capacity. These techniques are suitable for managing water in areas where land changes have reduced water storage potential.

The Hindukush-Himalayan (HKH) region, known for its eco-environmental importance, has been witnessing transformations in recent years governed by factors such as climate variability, land use shifts, and population growth. These changes have profound implications for regional sustainability, water resources, and livelihood. This study attempts to explore the spatial and temporal variability in selected environmental parameters including land surface temperature (LST), normalized difference vegetation index (NDVI), precipitation patterns, and normalized difference snow index (NDSI), and land use land cover (LULC) from 1990 to 2022 using Landsat imageries (30 m spatial resolution), CHIRPS precipitation data at 0.05° spatial resolution. The study area spans 32,000 km² covering two major political/administrative divisions (Malakand and Hazara) in the HKH region of Pakistan. The study area was selected primarily because of the unprecedented changes over the last three decades. For detailed spatial analysis, the area was divided into five elevation zones and LST, NDVI, NDSI, and LULC analyses were conducted utilizing primarily the Google Earth Engine (GEE) platform and climate engine. The study results revealed a notable rise in LST in the lowest elevation zone. The NDVI and LULC analyses revealed a noticeable decline in vegetation cover from 5988 km² in 1990, to 4225 km² by 2010, followed by a growth to 7669 km² in 2022, since 2010 after the launching of the Billion Tree Tsunami Afforestation Project (BTTAP) in 2013. Likewise, the precipitation patterns exhibit transitioning from low to high precipitation levels. However, the most notable finding of the study is the marked decline in snow covered area 7000 km² to 3800 km² between 1990 and 2022.

In coastal aquifers, the seawater intrusion can mask the effects of salinity regional groundwater flows, connate waters mobilization or contaminant process. Therefore, to discriminate between all the processes that have taken place in the coastal aquifer, is a complex task. Normally, traditional hydrogeochemical methods (e.g., Piper and Durov) together with statistical multivariate techniques (e.g., cluster and factorial analysis) and other methods (e.g., ionic deltas and isotopic studies) have been used to understand the hydrogeochemistry of aquifers and to confirm previous hypothesis. This paper presents a characterization of the salinization process in coastal aquifers, by means a fuzzy logic and data mining based methodology, which has not been used before for this purpose in a coastal aquifer. The proposed fuzzy methodology is based on the use of the data mining computer tool Predictive Fuzzy Rules Generator (PreFuRGe). The results have been obtained by processing groundwater samples analyses with PreFuRGe. The parameters used for the experimentation have been: temperature, electric conductivity, redox potential, total dissolved solids, silicon dioxide, oxidability, major ions (chloride, sulphate, bicarbonate, nitrate, calcium, magnesium, sodium and potassium), and minor ions (arsenic, bromide, lithium, boron, strontium, chromium and fluoride). The application of this method has made it possible to differentiate several overlapping hydrogeochemical processes, such as seawater intrusion, the entry of high salinity regional groundwater flows with high concentrations of strontium, magnesium, lithium and sulphates, and the effect of contamination from agricultural activities, with the presence of nitrates. The qualitative obtained results in this paper have been compared to previous research carried out in the same coastal aquifer, and it is proved that the used fuzzy methodology is a powerful tool for discriminating between overlapping geogenic and anthropogenic processes in coastal aquifers.

The growing demands for critical raw materials like copper, lithium, lead–zinc and iron ore which are essential commodities that will drive the global sustainable energy development has reignited the interest of the Nigerian government to reinvigorate the mining sector of the economy. Sparse availability of detailed structural and mineral data that will guide future exploration programs in most parts of the country emphasizes the need for a regional geophysical study to identify new mining sites in potential prospective areas within the mineralization-prone basement setting of northcentral Nigeria, like the Minna area and environs. Hence, the main goal of this study was to map subsurface features controlling hydrothermal mineralization occurrences in the Minna area of Nigeria, based on integrated interpretation of aeromagnetic and airborne radiometric data. The aeromagnetic data were subjected to various processing techniques using filtering algorithms including reduction to the equator, regional–residual separation (employing the polynomial fitting method), first vertical derivative, analytical signal, source parameter imaging, and spectral analysis, to detect the boundaries and depths of occurrences of linear geologic features. The airborne radiometric data were gridded to generate color composite, ternary, and ratio maps of potassium (K), thorium (eTh), uranium (eU), and K/eTh, in order to identify the various lithological components, as well as potential hydrothermally altered zones in the area. The results revealed potential prospective hydrothermal alteration zones that are characterized by long lineaments length and high lineaments density. The lineaments showed major orientations in the ENE–WSW, NE–SW, WNW–ESE, and E–W directions, synonymous to the Pan-African and earlier tectonic cycles that impacted the Precambrian Basement rocks of Nigeria. These geological features may have enhanced the formation of hydrothermal mineralization in the area by acting as pathways for the migration of hot mineralized fluids from depths, thereby creating room for the chemical activities responsible for wall rock alteration. The integrated approach adopted in this study can serve as guide for mineral exploration campaign in Nigeria, and other parts of the world with similar geological disposition.