Basin Area Research Articles

Driving Mechanisms of Ecological Suitability Index in the Yellow River Basin from 1990 to 2020

Ecological security is of central significance for maintaining the integrity and stability of regional ecosystems. Nevertheless, current academic research systematically studying the complex driving mechanisms behind ecological security is deficient. Therefore, this study utilised ecological sources (ESs) and ecological resistance surfaces (ERSs) to calculate and obtain the Ecological Suitability Index (ESI), thereby reflecting the ecological security status. The drivers of ESI in different areas of the Yellow River Basin (YRB) from 1990 to 2020 were explored using the random forest (RF) model and GeoDetector. The results of the study show that: (1) according to the results of the RF model, LANDUSE, NDVI, and PRE are the most important driving factors of the ESI in the upper (UYR), middle (MYR), and lower (LYR) reaches of the YRB; (2) according to the results of GeoDetector factor detection, in the UYR and MYR, the ESI is primarily influenced by natural factors such as NDVI and PRE, showing particularly significant impacts in 2010 and 2020; (3) in the LYR, the ESI is mainly influenced by NDVI, but the degree of influence from socioeconomic factors has significantly strengthened. This study provides a decision-making direction for ecological protection and coordinated development in the YRB.

Invisible Threads: Emerging Water Governance in the Multi‐Actor Dynamics of the Mira‐Mataje Transboundary River Basin

ABSTRACTIn recent years, scholarly interest has surged in exploring the emergence of new governance regimes that redefine the self‐governing capacities of local communities in water management, navigating security challenges to ensure compliance to central government water laws and regulations. Embracing polycentric governance across various levels of political interaction provides insights into the factors driving the establishment of these regimes, particularly in regions with limited state presence, and where the threat of climate impact has become visible by climate extreme events as drought. This approach emphasizes the importance of decentralized, collaborative systems for effectively and sustainably managing water resources. Such systems promote equitable water use, regional stability, and resilience to drought through innovative, community‐driven solutions aimed at addressing water scarcity challenges. While the former, polycentric governance, involves multiple centers of authority making decisions collaboratively, the latter, decentralized governance, refers to communities independently managing their affairs. To understand evidence related to these dynamics, we focus on actors' interactions around the downstream area of the transboundary Mira River Basin, between Ecuador and Colombia. Employing mixed method approaches such as qualitative interviews, policy analysis, and participatory observation provides comprehensive insights into the complex interactions shaping transboundary water governance and community responses. These methods facilitate a thorough understanding of how institutional arrangements and governance structures evolve and adapt in diverse sociopolitical contexts, offering valuable lessons for sustainable water management strategies on (local) scale or on (cross‐border) collaboration. This is particularly crucial in addressing the challenges posed by drought scenarios, ensuring resilience and adaptability in water governance worldwide.

Siliciclastic reservoir characterisation and geometric trend modelling for hydrocarbon quantification and uncertainty analysis: a case study of Doma field, Niger Delta basin, Nigeria

ABSTRACT Reservoir architecture delineation and understanding of heterogeneity in geological reservoir models are crucial for accurately estimating hydrocarbon reserves, production forecast, and recovery in an effective economic scenario. This work demonstrates the combination of statistical tools and geometric trend models for hydrocarbon quantification and uncertainty analysis in the Doma Field development. 3D seismic cube and five (5) well data were integrated to build structure, facies, and petrophysical models (total and effective porosity, water saturation, net-to-gross, and permeability). Eleven (11) hydrocarbon-bearing reservoirs were identified and modelled out of twenty-two (22) reservoirs (sand 1–1B2–5-IB1) delineated and correlated from the logs. The saturation height function (SHF) was generated to populate the water saturation model to mitigate capillary pressure build-up. The structural model shows that fault-dependent three-way closure dominated the field. The results of petrophysical analysis and modelling biased to the litho-facies models indicated an average effective porosity value between 20 and 37% and water saturation ranging from 0.1 to 0.5. The permeability model showed that the permeability value was greater than 100 mD. Based on uncertainty analysis, the low case, base case, and high case cumulative volumetric for oil is 43.63MMSTB, 56.72MMSTB, and 71.34MMSTB and for gas is 73.65BSCF, 96.3BSCF, and 120.59BSCF, respectively. The coefficient of variation computed from log-derived porosity varies from 0.14 in reservoir 1-IB1 to 0.44 in reservoir 14-IB2. Also, the coefficient of variation computed from the 3D model porosity varies from 0.21 in reservoir 2-IB1 to 0.45 in reservoir 14-IB2. Thus, the research study has created a bridge between statistical tools in quantifying reservoir model heterogeneity and established a reference model for siliciclastic reservoir heterogeneity classification and prediction in the area and development of reservoir parameters in the adjacent areas of the Niger Delta basin.

Organic geochemical characteristics of Jurassic Yan ’an Formation source rock in Pengyang area of southwestern Ordos basin

The Jurassic Yan ’an Formation in the southwestern margin of Ordos Basin has developed many sets of coal-associated and non-associated mudstone as well as oil shale. Different analytical methods including total organic carbon (TOC), Rock-Eval pyrolysis, and conventional biomarker analyses were applied on the mudstone, the coal and the oil shale extracts to unravel their organic geochemical characteristics and the paleo depositional environment. Results reveal that all the source rock samples are immature to mature with good petroleum generation potentials. The redox environment is generally reducing. The organic matter input is mainly terrestrial higher plants. The low Ga/C30 hopane ratio of all the samples indicate the low salinity of the paleo-water column. The oil shale samples show much higher thermal maturity than the coals and mudstones as indicated by the higher C31 homohopane isomerization indexes, C32 homohopane isomerization indexes and the C29 sterane ααα20S/(S + R) ratios. The depositional environment of the oil shale is more reduced compared to the coals and mudstones as can be reflected by the low oxygen index and the higher C35 hopane/(C31-C35 homohopanes) ratios. Thus, the oil shale layers should be the target of the next exploration and development. And the Oil shale and coal can be exploited simultaneously in Pengyang area.

Study on the Spatiotemporal Changes and Driving Factors of Habitat Quality in the Yarlung Zangbo River From 2000 to 2020.

The Yarlung Zangbo River (YLZB), the world's highest plateau river, possesses a particularly fragile ecosystem, making it highly vulnerable to global climate change. Understanding changes in YLZB habitat quality and their driving mechanisms is crucial for ecological protection and sustainable development in the region. Based on land use data from 2000 to 2020, we conducted a quantitative study on the spatiotemporal changes and driving mechanisms of habitat quality in the YLZB. This study employed habitat quality model, Land Use Transition Matrix, optimal parameter geographical detector, and partial least squares structural equation model (PLS-SEM). The results show that: (1) Forests, grasslands, and unused land account for 94.14% of the basin area. The areas of unused land, forest land, and water bodies have continuously increased, while the areas of grasslands, permanent glaciers, and snowfields have continuously decreased. The decline was most pronounced from 2005 to 2010. (2) The habitat quality in the study area is higher in the southeast and lower in the west. The area of degraded habitats is significantly larger than that of improved habitats. (3) NDVI, elevation, and annual average temperature are key factors affecting changes in habitat quality. Elevation indirectly affects NDVI by influencing climate conditions, leading to a decline in habitat quality. This study provides a scientific basis for understanding ecological trends in YLZB habitat quality, it provides new insights into the intrinsic driving mechanisms in high-altitude regions, and it offers theoretical support for relevant departments to implement sustainable management and conservation efforts.

Lithological controls on chemical weathering signatures in the semi-arid climatic regime: Study based on tropical small scale catchments

Lithological controls on chemical weathering can be better constrained by studying catchments having different lithologic settings in similar climatic conditions. This study compares the weathering fluxes in two small catchments having different lithology in semi-arid region (500–800 mm/year rainfall) in western India: The West Banas River (2100 km2, 372 m relief) on granitic/gneissic rocks and the Berach River (610 km2 area; 542 m basin relief) on shale. Sample collected in the year 2016 and 2017, were analysed for chemical composition to evaluate chemical weathering fluxes. Inverse model analysis and Soil and Water Assessment tool (SWAT) simulated runoff were combined to estimate the annual weathering fluxes. Total dissolved loads (TDS) in the West Banas ranged from 71 to 428 mgL−1(avg. 227 mgL−1), while the Berach River showed TDS of 190–712 mgL−1(avg. 370 mgL−1), with some higher values of due to anthropogenic sources. Silicate weathering rate (SilWR) derived as 7.7 ± 1.7 tonkm−2y−1 for the granitic West Banas catchment whereas 5.7 ± 1.2 tonkm−2y−1 for the shale lithology in Berach River. The weathering susceptibility ratio of shale to granite was derived as 2:3. The weathering intensity is highly controlled by the susceptible minerals present in these rocks. The posteriori results of elemental ratios of the silicate endmember in shale lithology basin (Berach River) shows strong indication of incongruent weathering in the basin. This weathering signatures in shale (sedimentary) lithology happened as their constituting minerals has already gone through at least one cycle of chemical weathering during their formation. Saline-alkaline soils (SAS) contribute significantly to dissolved loads, especially in the Berach (38 ± 12 %), compared to the West Banas (26 ± 7 %). The cations derived from different lithologic sources have a dependency on the drainage basin area. However, other topographical factors showed minor control on chemical weathering.

Study on subsidence evolution induced by coal mining under highway based on finite element simulation

Accurate estimation of overlying strata subsidence and surface deformation caused by coal extraction is crucial for assessing the impact of mining activities on surface infrastructure. In this study, we investigated the subsidence evolution of overlying strata and ground surface induced by underground mining using finite element simulation and focus on a mining district in the Yu-Heng mining area of the central Ordos Basin and then, the influence of underground longwall mining on the surface roads was evaluated. A three-dimensional geological model of the mining district was constructed, considering the actual stratum structures and the deterioration effect of water on rock mechanical properties. The whole coal mining process was simulated to predict the evolution of the subsidence basin at different mining stages, and the surface deformation characteristics caused by coal mining were calculated. Results showed that the subsidence characteristics by numerical simulation were highly consistent with the records of surface subsidence in the adjacent areas, indicating that the constructed geological model can accurately reflect the actual geological conditions and the deformation behaviors of overlying strata. A comparative study revealed that the mechanical properties of the generalized layers determined by processing the mechanical parameters of dry core samples will be much higher than those of the natural strata under the in situ water-saturated condition, and then the subsidence caused by coal mining will be significantly underestimated. Thus, the water-induced mechanical property deterioration of overlying strata must be fully considered when constructing geological models.

Evaluating the influence of meteorological drought on river flow in the transboundary Sunkoshi basin, Nepal

ABSTRACT The transboundary Sun-Koshi River basin, characterized by intricate topography and geo-climatic diversity, has encountered distinct periods of droughts significantly impacting downstream river discharge. This study focuses on assessing temporal and spatial patterns of meteorological drought using SPI and SPEI indices, gauging their influence on river discharge through hydro-meteorological station data and the HEC–HMS model. Severe drought episodes were notably observed in 2010 and 2015. In 2010, prominent drought occurrences extended beyond Nepal's border into China. Conversely, in 2015, Jiri, Okhaldhunga, and Salleri experienced heightened drought conditions. Spatially, over 99% of the basin area experienced drought, varying from moderate to extreme magnitudes during 2010 and 2015. The estimated annual rainfall and basin outlet discharge were 1,800 mm, 1,907 mm, and 1,899 m3/s, 1,086 m3/s in 2010, and 2015, respectively. During drought periods, the stations indicated significantly reduced discharge, indicating a marked departure from normal conditions across the basin. Ultimately, station data performance and the HEC–HMS SCS curve number model showed that discharge in the Sunkoshi River basin is profoundly impacted by drought, notably influencing rainfall intensity on monthly, seasonal, and annual scales. The smaller basins discharge more accurate results compared to the larger outlet basins.

Impact of Alternate Wetting and Drying Irrigation (AWDI) on Water Saving and Yield of Transplanted Rice

A large-scale demonstrations was conducted on Alternate Wetting and Drying Irrigation (AWDI) on water saving and yield of Transplanted Rice in Mettur-Noyyal confluence sub basin areas of Tamil Nadu, India, by the Tapioca and castor Research station, Yethapur from the year 2019 to 2023. For adopting the safe AWDI, the depth of ponded water on the field is monitored using a ‘Field Water Tube’ which is made of 40-cm long plastic pipe having a diameter of 15 cm which is perforated with holes on all sides. The AWDI technology consumed ranges between 871 mm to 950 mm of irrigation water, higher water use efficiency (6.22 to 7.53 kg ha-1 mm-1) and number of irrigations were recorded between 22 to 30. Adopting AWDI in rice resulted in the highest yield of 7045 kg ha-1 compared to the conventional method, which produced 5927 kg ha-1 across all experiments. The highest gross returns (Rs. 131927 ha-1), net return (Rs. 77438 ha-1) and BCR (2.99) were observed in adoption of AWDI. The AWDI will be an appropriate technology for water saving in rice. This technology saves up to 49 per cent of irrigation water without reducing yield, and it reduces the number of irrigations by 12 compared to farmers.

Hydro-geodetic approach for predicting river runoff in ungauged basins using gravity and altimetry satellite data

A novel satellite-based approach is proposed for predicting river runoff in ungauged basins using gravity and altimetry data. This hydro-geodetic approach integrates the Gravity Recovery And Climate Experiment (GRACE) observations in the global monthly hydrological model, as an alternative input data to in-situ runoff. By combination with water-budget equation and by using an efficient innovative multi-objective-optimization algorithm, the problem is solved and validated by three strategies, considering various basins. The results have outlined a 3-months time-shift to be considered for Amazon basin for transiting from storage to runoff, while other basins as Cheliff, Congo and Daly require runoff bias correction. Basin area and climatic characteristics have demonstrated its effect on parameter calibration performance, while the relationship between runoff and space-based river-level needs an appropriate mathematical model to each basin. An agreement was found between the predicted runoff and those reported elsewhere, highlighting the effectiveness and feasibility of the proposed approach.

A Comparative Spatiotemporal Analysis for Long-Term Trends of Hydrometeorological Variables in Maritsa River Basin

Revealing long-term trends in hydrometeorological variables plays a critical role in the sustainable management and planning of water resources. These analyses are necessary to understand climate change impacts, taking precautions for natural disasters, plan agricultural activities, and develop water management strategies. The aim of this study is to examine the changes in monthly and annual total precipitation and evapotranspiration values in the Maritsa River Basin, a transboundary water basin between Bulgaria, Greece, and Türkiye. For this, precipitation values for the 1982-2023 water years were taken from the Climate Hazards Group InfraRed Precipitation with Stations (CHIRPS) data set, and evapotranspiration values for the 1982-2023 water years were taken from the European Reanalysis 5th Generation-Land (ERA5-Land) data set. The Mann-Kendall, Sen's slope estimator, and Innovative Trend Analysis (ITA) methods were used to determine trends. According to the test results, there is a statistically significant increase in annual total precipitation values within the 95% confidence interval and in annual total evapotranspiration values within the 99% confidence interval. Specifically with all three methods positive and statistically significant trends are observed in precipitation in October, January, May and June. In the monthly evapotranspiration trend analysis, a statistically significant increase is observed except for November, December, June and July. Trend increases were visualized using the graphical method ITA. Significant increasing trends in both monthly and annual precipitation and evapotranspiration reveal changes in the hydrological cycle of the basin. The test results can be used in planning and solving problems related to the basin area.

The Small Mobile Ozone Lidar (SMOL): instrument description and first results

Abstract. Ozone profile measurements at high temporal and vertical resolution are needed to better understand physical and chemical processes driving tropospheric ozone variability and to validate the tropospheric ozone measurements from spaceborne missions such as TEMPO (Tropospheric Emissions: Monitoring Pollution). As part of the Tropospheric Ozone Lidar Network (TOLNet) efforts allocated to provide such measurements and leveraging on the experience of more than 20 years of ozone lidar measurements at Table Mountain Facility, the JPL lidar group developed the SMOL (Small Mobile Ozone Lidar), an affordable differential absorption lidar (DIAL) system covering all altitudes from 200 to 10 km above ground level (a.g.l.). The transmitter is based on a quadrupled Nd:YAG laser, which is further converted into a 289/299 nm wavelength pair using Raman shifting cells, and the receiver consists of three ozone DIAL pairs, including one that is 266/289 nm and two that are 289/299 nm. Two units were deployed in the Los Angeles basin area during the Synergistic TEMPO Air Quality Science (STAQS) and Atmospheric Emissions and Reactions Observed from Megacities to Marine Areas (AEROMMA) campaigns in summer 2023. The comparison with airborne in situ and lidar measurements shows very good agreement, with systematic differences below 10 % throughout most of the measurement range. An additional comparison with nearby surface ozone measuring instruments indicates unbiased measurements by the SMOL lidars down to 200 m a.g.l. Further comparison with the Goddard Earth Observing System Composition Forecast (GEOS-CF) model suggests that such lidars are a critical tool to perform model validation and can potentially be used for assimilation to air quality forecasts.

Evaluation of ecological geological environment carrying capacity and analysis of driving mechanisms based on normal cloud model and geodetector model

The Luoyang area of the Yellow River Basin, as a typical resource-based city, its special industrial structure and complex geological structure make the ecological and geological environment of the area extremely fragile. In order to realize the sustainable development of the region in this fragile ecological-geological environment, it is necessary to study its Ecological Geological Environmental Carrying Capacity (EGECC) to better serve the regional ecological-geological environment restoration and management work. This study constructs an indicator system encompassing three subsystems: Geological Environment (GE), Social Environment (SE), and Ecological Environment (EE). Based on game theory combination weighting (G1-IEW-GT) and the Normal Cloud model, the EGECC of Luoyang City from 2000 to 2022 was evaluated on a grid scale. Concurrently, a coupled model of geographic detectors and geographically weighted regression was established to recognize the spatial heterogeneity and driving mechanisms of the ecological geological environment system. The findings demonstrate that: (1) The overall EGECC in the Luoyang region of the YRB fluctuates upward, with the eastern area displaying more favorable conditions compared to the western region. (2) Over these twenty-two years, the geological environment system experienced initial deterioration followed by improvement, the ecological environment system remained relatively stable, and social and economic development continuously strengthened. (3) Landform types, elevation, human activity impact index, population density, and geological disaster susceptibility are the main driving elements for the assessment of the ecological geological environment system. Any pair of the 18 variables show varying degrees of enhancement effects on the EGECC. (4) The regression coefficients of the five major driving factors exhibit significant agglomeration characteristics in spatial distribution. Among them, geological disaster susceptibility has a negative driving effect on the EGECC, while landform, human activity impact index, and population density all display bidirectional effects. Overall, this study provides essential guidance for formulating ecological protection and restoration plans for the national territorial space in the Luoyang area of the YRB. Additionally, the evaluation methods established in this study have promotional value and can serve as a reference for the ecological geological spatial management of other resource-based cities.

Geophysical characterization of dissolution features and deformation in bedded salt formations in NE Delaware Basin

Salt formations have resource potential for energy storage, nuclear waste repositories, brine production; but their mineralogical heterogeneity and complex structures present significant challenges for characterization. This geophysical analysis uses 3-D seismic reflection and petrophysical data to explore the intricate characteristics of the Lopingian bedded salt formations in the Delaware Basin located within the Greater Permian Basin Area in the United States. The study focuses on the Castile and Salado formations and reveals an area of deformed strata linked to an intrasalt fold-thrust belt in the southwestern portion of the 215 mi2 (557 km2) seismic volume within the bedded salt interval. The proposed mechanism for the deformation involves gravitational gliding initiated during the Lopingian, influenced by a northeasternward tilt of the décollement towards the shelf. Adjacent to the fold-thrust belt, there is a geophysically distinct area we term the buffer zone. The Castile Formation within the buffer zone differs from its expected cyclical anhydrite-halite members and is only composed of anhydrite. The buffer zone’s unique composition prompts a reevaluation of halite absence, suggesting gypsum deposition, followed by conversion to anhydrite, instead of a dissolutional mechanism, as previously postulated. The overlying Salado Formation exhibits heterogeneity and karst features (i.e. sags, suffusion, and collapse features), indicating potential complications and geohazards. The findings underscore the importance of multidisciplinary approaches and extensive data sets for accurate mapping, geohazard assessments, strategic placement of salt caverns in underground storage, and for assessment of evaporitic sequences as effective seals for underlying petroleum systems and water resources.

The Impact of Land Use Changes on The Service Life of Wlingi Reservoir

One of the factors that can affect changes in the capacity of a reservoir is the amount of sedimentation that settles at the bottom of the reservoir. Several reservoirs in Indonesia have experienced shallowing due to sedimentation. The increase in sedimentation rate is caused by high land erosion. Land erosion comes from changes in land use in a River Basin Area. The benefits of the Wlingi Reservoir are as a flood controller of 2.37 m3/s, irrigation supply of 13,600 hectares, as a power plant that can drive the turbine of a PLTA unit with a power of 2 x 27 MW. In this study, land use data comes from ESRI satellite imagery, which differs from previous studies. This study aimed to obtain sediment yield from land use changes in the Brantas Hulu Watershed with Wlingi Reservoir outlet point from 2018 to 2023 and to predict remaining service life of the reservoir. The method used to calculate the erosion rate is USLE, which uses GIS (Geographic Information System) software. The results showed that undisturbed forests dominated land use, and land use changes for 6 years were volatile. The average sediment rate for 6 (six) years was 0.011 mm/year. The predicted service life is that Wlingi Reservoir can only serve for 91 years. These findings highlight the urgency of implementing effective sediment management strategies. Without intervention, sedimentation will reduce the reservoir's capacity to support irrigation and hydropower, impacting regional water management and food security and limiting flood mitigation capabilities in East Java.

Water Balance and Climate of the Ipojuca River Water Basin – Pernambuco, Brazil

The objective is to carry out the analysis of the climatic water balance and make a comparison between the municipalities surrounding the Ipojuca River basin, using the applications of climatic indices and aridity. The study area is the Ipojuca River – Pernambuco river basin, made up of twenty-seven municipalities. The rainfall data were provided by the Water and Climate Agency of the State of Pernambuco and thermal data were estimated by the Estima_T software corresponding to the years 1962 to 2018. For the climatic and agricultural suitability analysis, climatic indices of aridity and water availability were applied to the vegetation. The aridity index was calculated using the UNEP formulation, the climatic classifications, using the aridity index or dry month, recommended by Gaussen. Municipalities with higher altitudes provide conditions for better natural development of vegetation followed by greater potential for the development of agricultural activities, when compared to municipalities at lower altitudes. A marked change was observed between the climatic conditions of municipalities with high and low altitudes in the basin area, with emphasis on water deficits and high temperatures. Marked disputes between climate variability in municipalities at higher and lower altitudes were recorded in water deficits and inter-municipal thermal fluctuations.

Geochemistry and Origin of Deep and Ultradeep Crude Oils from the Jurassic Qigu Formation, Yongjin Area, Central Junggar Basin, NW China.

Recently, there has been an increasing focus on deep and ultradeep oil and gas exploration and development. The Upper Jurassic Qigu Formation (Fm.) in the Yongjin region, located in the central area of the petroleum-bearing Junggar Basin, develops typically deep and ultradeep hydrocarbon reservoirs, but there is currently limited knowledge of the geochemical characteristics and origins of the oils in the reservoirs. A comprehensive analysis of the molecular characteristics and carbon isotopes of the oil and extractable organic matter (OM) samples from the Qigu reservoirs, as well as source rocks from the Middle Permian lower Wuerhe and Lower Permian Fengcheng Fm., was carried out to elucidate the thermal maturity, biological sources, and biodegradation scale of the OM, as well as the depositional environment of the related source rocks. The results suggest that the Qigu oils originated primarily from source rocks formed in a hypersaline lacustrine environment with paleoredox conditions of bottom water ranging from reducing to suboxic conditions. Furthermore, the biological sources of oils predominantly originated from bacteria, followed by algae. The degradation scales range between 3 and 4, and the thermal maturity is in the oil window for the samples examined. The OM of the Permian source rocks in the Yongjin region are in the high thermal maturity stage due to their ultradeep burial, thereby providing limited information to oil and source correlation. By combining more than 1000 published data from the entire basin, significant differences between the Jurassic and Permian source rocks, as well as minor differences between the lower Wuerhe (i.e., the ratios of Pr/n-C17 of <0.5, Ph/n-C18 of <0.5, Pr/Ph of >1.5, C27/C29 sterane of >0.4, and hopanoids/steranes of >1 as well as the higher C20/C23 Tri ratios) and Fengcheng source rocks (i.e., β-carotane/n-C max ratios of >0.1 and some samples with C28 steranes concentrations of <10% in the normalized concentrations of C27, C28, and C29 steranes), were observed, and the origins of the oils were determined. The oil-source correlation suggests that the oils most likely originated from the lower Wuerhe Fm. without strictly excluding the possibility of a contribution from the Fengcheng Fm.

Multi-criteria analysis using AHP and GIS for identifying the most polluted sub-basin in a river basin environment

ABSTRACT This article introduces a methodology utilizing the Analytical Hierarchy Process (AHP) integrated with a Geographic Information System (GIS) to classify sub-basins within a large river basin in terms of pollution levels. The research uses data from the Haraz River basin, located in northern Iran near the Caspian Sea. The river basin under investigation comprises seven sub-basins. The primary pollution sources in this region include domestic wastewater from urban areas, effluents from fish farms, discharge from sand and gravel mines, sewage from restaurants and tourism centers, as well as land use (agriculture, forests, and rangelands). In addition to these pollution-related factors, other criteria such as basin area, river length, road network length, and slope were also considered. Using scores assigned by experts and leveraging the Expert Choice software, all sub-basins, and factors contributing to river pollution were identified. According to the findings, urban domestic wastewater was the most significant contributor to pollution in the study Basin, accounting for 42.2% of the total pollution. The sub-basins were classified according to their final weighted scores, identifying those with the highest and lowest pollution levels. The studied approach offers substantial advantages in terms of time, cost, and resource efficiency.

Evaluating major element hydrogeochemistry and fluoride occurrence in groundwater of crystalline bedrock aquifers and associated controlling factors of Eumseong basin area, South Korea.

Long-term intake of high-fluoride water can cause fluorosis in bones and teeth or damage to organs. Fluoride in groundwater is primarily derived from reactions with rocks containing fluorine-related minerals, and fluoride concentrations are elevated in groundwater that has been reacting with these rocks for a long time. The purpose of this study is to investigate the origin and distribution of fluoride in groundwater and to assess the influence of various factors, including geology, on fluoride concentrations in groundwater. The Eumseong basin and surrounding areas were selected as the study area due to the diversity of geologic factors. 139 groundwater samples and 14 rock samples were collected, with groundwater samples subjected to field water quality measurements, chemical analysis, and statistical analysis, and rock samples subjected to microscopic observation and chemical analysis. Fluoride concentration in groundwater increased with well depth, and was highest in groundwater associated with granitic rocks rich in biotite. The fluoride concentration in groundwater showed a negative correlation with the distance to the fault, suggesting that deep groundwater may preferentially flow along fault zones in certain areas. In addition, high-fluoride groundwater had depleted water-stable isotope values, which is likely to be resulted from higher degree of water-rock interaction in groundwater recharged at higher elevations. Calcite precipitation in most groundwater appears to weaken fluorite solubility control on fluoride concentration. Multivariate statistical analysis revealed that water-rock interactions generally governed fluoride and major element concentrations, with high-fluoride groundwater clearly distinguished. These findings can aid in assessing fluoride occurrence in groundwater and managing water quality in areas with similar geological characteristics.

Five Years of Natural Vegetation Recovery in Three Forests of Karst Graben Area and Its Effects on Plant Diversity and Soil Properties

In recent decades, excessive human activities have led to large-scale rocky desertification in karst areas. Vegetation restoration is one of the most important ways to control rocky desertification. In this study, vegetation surveys were conducted on three typical plantations in Jianshui County, Yunnan Province, a typical karst fault basin area, in 2016 and 2021. The plantations were Pinus massoniana forest (PM), Pinus yunnanensis forest (PY), and mixed forests of Pinus yunnanensis and Quercus variabilis (MF). Plant diversity and soil nutrients were compared during the five-year period. This paper mainly draws the following results: The plant diversity of PM, PY, and MF increased. With the increase of time, new species appeared in the tree layer, shrub layer, and herb layer of the three forests. Tree species with smaller importance values gradually withdrew from the community. In the tree layer, the Patrick index, Simpson index, and Shannon–Wiener index of the three forests increased significantly. The Pielou index changed from the highest for PM in 2016 to the highest for PY in 2021. In the shrub layer, the Pielou index of the three forests increased. The Patrick index changed from the highest for MF in 2016 to the highest for PY in 2021. There was no significant difference in species diversity index for the herb layer. With the increase of vegetation restoration time, the soil bulk density (BD) of the three forests decreased. There was no significant difference in soil total porosity (TP), soil capillary porosity (CP), and non-capillary porosity (NCP). The pH of PM increased significantly from 5.88~6.24 to 7.24~7.34. The pH of PY decreased significantly (p &lt; 0.05). The contents of total nitrogen (TN) and ammonium nitrogen (NH4+-N) in PY and MF decreased. The content of nitrate nitrogen (NO3−-N) in the three forests increased significantly (p &lt; 0.05). Total phosphorus (TP) content decreased in PM and MF. The content of available phosphorus (AP) in PM and PY increased. In general, with the increase of vegetation restoration time, plant diversity and soil physical and chemical properties have also been significantly improved. The results can provide important data support for vegetation restoration in karst areas.