Search Results (23)

The Pearl River Mouth Basin is a significant hydrocarbon basin in the northern part of the South China Sea, where deep hydrocarbon exploration has become increasingly important research in recent years. However, the current understanding of the source-to-sink and depositional systems of the Paleogene Zhuhai Formation is still limited, which restricts the exploration and discovery of large-scale sand bodies. Based on core observation, heavy mineral analysis, and well-seismic integrated analysis, this paper clarifies the development of a fan delta-tidal flat depositional and the source-to-sink systems of the Zhuhai Formation. The bedrock in the source region primarily consists of granite, Mesozoic sandstone, and tuff. The source region is divided into five parts (A1–A5), with seven main valleys (V1–V7) developed, supplying sediments to five depositional areas (S1–S5). Additionally, a fault-slope type coupled valley–fan depositional model is established for the study area, revealing the spatiotemporal distribution and main controlling factors of the fan delta system in a steeply dipping boundary fault environment. Catchment area, valley length, and cross-sectional area show a strong positive correlation with sedimentary system scale. Increased elevation difference enhances sediment transport potential energy, while reduced width-to-depth ratio strengthens hydrodynamic forces, promoting sedimentary sand body development and sedimentary system expansion. Full article

Coastal climate processes that affect landscape hydrology and beach dynamics are studied using local and remote data sets near Cape Vidal (28.12° S, 32.55° E). The sporadic intra-seasonal pulsing of coastal runoff, vegetation, and winds is analyzed to understand sediment inputs and transport by near-shore wind-waves and currents. River-borne sediments, eroded coral substrates, and reworked beach sand are mobilized by frequent storms. Surf-zone currents ~0.4 m/s instill the northward transport of ~6 10⁵ kg/yr/m. An analysis of the mean annual cycle over the period of 1997–2024 indicates a crest of rainfall over the Umfolozi catchment during summer (Oct–Mar), whereas coastal suspended sediment, based on satellite red-band reflectivity, rises in winter (Apr–Sep) due to a deeper mixed layer and larger northward wave heights. Sediment input to the beaches near Cape Vidal exhibit a 3–6-year cycle of southeasterly waves and rainy weather associated with cool La Nina tropical sea temperatures. Beachfront sand dunes are wind-swept and release sediment at ~10³ m³/yr/m, which builds tall back-dunes and helps replenish the shoreline, especially during anticyclonic dry spells. A wind event in Nov 2018 is analyzed to quantify aeolian transport, and a flood in Jan–Feb 2025 is studied for river plumes that meet with stormy seas. Management efforts to limit development and recreational access have contributed to a sustainable coastal environment despite rising tides and inland temperatures. Full article

Understanding the impact of climate change on agricultural nonpoint source (NPS) pollution is crucial for developing effective adaptation strategies and reducing vulnerabilities where such challenges exist. This study evaluated the impact of precipitation and temperature variations on Total Inorganic Nitrogen (TIN), Total Inorganic Phosphorus (TIP), and sediment loads in the Sand River Catchment (SRC) using the Soil and Water Assessment Tool plus (SWAT+). One-way analysis of variance (ANOVA) was used to determine the significance (p < 0.05) of the relationships (R²) between precipitation and temperature on sediment, TIN, and TIP loads in the SRC. SWAT+ calibration and validation demonstrated that the statistical indices (NSE and R² ≥ 0.72; −17.30 ≤ PBIAS ≤ 14.74) fell within an acceptable range. Results indicated a significant influence of average monthly precipitation (p < 0.0001) and temperature (p ≤ 0.004) on sediment, TIN, and TIP loads. In addition, a decrease in average annual precipitation led to a decline in sediment, TIN, and TIP loads (R² ≥ 0.55), with the average annual temperature increasing in the same period (R² ≤ 0.23). This study confirms that climate change contributes to agricultural NPS pollution in the SRC and highlights the need to employ suitable adaptation strategies for pollution control in the catchment. Full article

A study was conducted concerning the perceptions of a future reservoir (4.7–8.9 square kilometres, 42.2 million cubic metres) by residents, tourists, and visitors; the location in question was the former Kotlarnia sand pit in the catchment area of the Bierawka River (tributary of the Oder River in southern Poland). Divergent concepts for the reclamation and development of the former sand pit emerged; the construction of a reservoir was initially the dominant option but was eventually abandoned despite it having the greatest acceptance among the respondents (out of the 134 respondents, 43.3% favoured the creation of a water reservoir, 29.9% favoured introducing nature protection arrangements in the area to enable spontaneous nature regeneration, and 16.4% favoured reforestation). A clear discrepancy arose between the public’s expectations related to the reclamation and development of the former sand pit in order to create a reservoir and the official position of the land user and administrator of the potential reservoir, which indicated that it no longer intended to create such a reservoir. This study indicates that in the process of developing concepts related to the reclamation and development of former mineral workings, it is essential to obtain the results of public consultation based on a diagnostic survey conducted among representatives of the local community. This is an effective tool for predicting the optimal use of sites regenerated after the damage caused by open-pit mining provided that all technical considerations related to the planned project are taken into account in advance. Full article

A geochemical mapping of regional modern river-sand is performed to clarify geological information in the study area of Timor-Leste. Several areas of Timor-Leste including the study area in particular have limited geological information due to limited accessibility and dense vegetation coverage, and deformed, weathered, and erosion-covered materials. A total of 53 modern river sand samples were collected and analyzed. Ten major elements were determined by using wavelength-dispersive X-ray fluorescence. Areas characterized by clastic sedimentary rocks are recognized clearly by elevated concentrations of SiO₂, Al₂O₃, and K₂O. Meanwhile, areas covered by carbonate sedimentary rocks are detected by significant concentrations of CaO and MnO. The occurrences of the altered clastic and carbonate sedimentary rocks of the Wailuli and Aitutu Formations due to metamorphic, silicification and other alteration processes were responsible for the elevated concentrations and positive correlation between SiO₂, CaO, K₂O, and MnO, and CaO, TiO₂, and MnO in the midstream and near the downstream areas of the Clerec and Sahe River catchments. The positive correlation observed between TiO₂, CaO and MnO may be ascribed to the presence of carbonate components associated with secondary Ti-bearing minerals, which are potentially formed through hydrothermal alteration processes. Full article

The 2021 Navalacruz wildfire occurred in a mountainous area in the Sistema Central (Spain). Despite having an average low severity index (dNBR), the loss of vegetation cover associated with the fire was responsible for a high rate of sedimentation in the rivers and streams. Additionally, the burned area affected up to 60 cultural heritage sites, including archaeological and ethnological sites, and damage ranged from burnt pieces of wood to the burial of archaeological sites. In the present work, we document and analyze the post-fire evolution in several rivers and streams. This is based on a field survey of infiltration rates, hydrodynamic modeling, and the study of channel morphological changes. Our analysis revealed how the first post-fire rains caused the mobilization and transport of ashes. This created hydrophobicity in the soils, resulting in large amounts of materials being transported to rivers and streams by subsequent medium- and low-magnitude storms. A hydrological and hydraulic model of the study catchments under pre- and post-fire conditions suggests that these trends are a consequence of a post-fire increase in flow rates for similar rainfall scenarios. In this respect, our estimates point at a significant increase in sediment transport capacities associated with this post-fire increase in flow rates. The combination of locally steep slopes with high-severity fire patches, and a considerable regolith (derived from pre-fire weathering), resulted in a series of cascading responses, such as an exacerbated supply of sand to the drainage network and the triggering of debris flows, followed by erosion and entrenchment. Full article

Artisanal and Small-scale river sand mining is one of the upcoming activities associated with the environmental crisis concerning the water ecosystem. However, the determination of the duration in which illegal sand mining has occurred, and the future prediction on the extent of river sand mining is not well-established in most of the world. This study aimed to assess the extent of river sand mining activities across some of the catchments in Limpopo province, South Africa and understand the sustainable extraction of sand resources. This was followed by the determination of when sand mining activities commenced in each of the individual catchments. Thus, remote sensing was applied to predict the extent of river sand mining from the year 1992 to 2022, and statistical prediction models were utilised to predict the extent of sand mining for the next 10 years. The results of the study suggest that most of the catchments started to experience illegal sand mining activities from the year 1992, though the extraction was relatively low. Equally, a decrease in vegetation coverage across the river system has been evidenced, which also suggests that the extraction of sand and gravel has been elevated from the year 2010. In terms of the prediction model, the Turfloop River system was predicted to experience a large extraction ratio in the coming 10 years, with about 92.415 ha of land expected to be affected. Meanwhile, the Molototsi River system was denoted to be the least affected river system, with a reduced extraction ratio of about 6.57 ha expected in the next 10 years’ time. Full article

The article presents the impact of Zn and Pb ore mining and land use on ecohydrological changes in the area of the Biała Przemsza valley in the historical aspect, with particular emphasis on the period 1941–2021. GIS was used to analyse the maps to identify spatial and temporal changes in land use. The following trends could be observed in the spatial development of the Biała Przemsza valley: rapid urbanisation and industrialisation in the 21st century, marked reduction in the surface area of arable land and sands, and dynamics of the increase in the surface area occupied by forests. Notable changes occurred in the plant ecosystems between 1941 and 2021 due to land management. Groundwater level lowering due to mining activity resulted in the change from wet meadows to fresh or dry xerothermic grasslands, while forest cover increased by 4% within the catchment area. The hydrographic network evolved. After the commissioning of the Zn-Pb ore mines Olkusz and Pomorzany in the 1960s and 1970s, a regional depression cone with an area of 400 km² was formed, while the maximum groundwater inflows to the mines reached 360 m³/min. Changes in the hydrodynamic conditions have resulted in changes in the hydrogeochemical regime of the Triassic aquifer manifested by increased levels of, e.g., SO₄ and Cl. Wastewater with lignosulphonate compounds from the paper factory caused periodic degradation of some of the water flowing into the Pomorzany mine. As a result of mining activity, the character of some sections of the Biała Przemsza river changed to an infiltrating one, the quantitative depletion of groundwater resources within the range of the mine drainage cone occurred, river springs disappeared, and the flow in the river decreased. At the same time, mine water was discharged to the tributaries of the Biała Przemsza. A radical reduction in the flow of the Biała Przemsza and its tributaries occurred after the decommissioning of the Zn-Pb ore mines at the turn of 2021 and 2022. Full article

Pollution of water sources is a global issue that primarily affects rural communities that rely on these water sources for domestic purposes on a daily basis. The study’s goal was to determine if the effluent from the Bushbuckridge Municipality’s Waste Water Treatment Works (WWTWs) contributes to the pollution of the Sand River Catchment. The investigation was conducted at two WWTWs, Dwarsloop and Thulamahashe. A questionnaire was used to collect information from participants. Water samples were collected monthly from the treatment plant and Sand River for the determination of physico-chemical parameters and coliform counts. The study found that the WWTWs were the main sources of the pollution of the Sand River Catchment. The WWTWs are confronting unprecedented mechanical and technical challenges. The WWTWs have experienced numerous system failures due to aging systems and pressure on deteriorating facilities, resulting in raw wastewater discharges into catchments. Furthermore, the study revealed that factors such as population growth, poor operation and maintenance of WWTWs, poor budgeting, and a lack of well-trained personnel contributed to WWTW failure. The effluent quality in both WWTWs met the National Water Act of South Africa’s effluent discharge standards for pH (ranged from 6.90 to 9.30), EC (ranged from 20.80 to 87.50 mS/m), ammonia (ranged from 7.22 to 86.80 mg/L as N), nitrate/nitrite (ranged from 0.10 to 0.73 mg/L as N), and ortho-phosphate (ranged from 0.01 to 6.50 mg/L as P). While COD levels in both WWTWs (ranging from 25.00 to 149.00 mg/L) were over the limit during some months of the study period. The study also discovered that E. coli counts were low upstream but high in both the WWTWs point of discharge and downstream for both catchments. The study, therefore, established a connection between wastewater treatment plants and water quality parameters as well as poor water quality linked to the condition of the WWTWs. The study recommends that effective measures be implemented to address the challenges. Full article

Erosion and sediment delivery have been undergoing considerable variations in many catchments worldwide owing to climate change and human interference. Monitoring on-site erosion and sediment deposition is crucial for understanding the processes and mechanisms of changes in sediment yield from the catchments. The Ten Kongduis (kongdui is the transliteration of ephemeral creeks in Mongolian) are 10 tributaries of the upper Yellow River. Severe erosion in the upstream hills and gullies and huge aeolian sand input in the middle reaches had made the 10 tributaries one of the main sediment sources of the Yellow River, but the gauged sediment discharge of the tributaries has decreased obviously in recent years. In order to find out the mechanisms of changes in the sediment load of the tributaries, topographic surveys of four typical gullies in 3 of the 10 tributaries were made repeatedly in the field with the terrestrial laser scanning (TLS) technique. The results show that all the monitored gullies were silted with a mean net rate of 587–800 g/m² from November 2014 to June 2015 and eroded by a mean net rate of 185–24,800 g/m² from June to November 2015. The monitoring data suggest that the mechanism of interseasonal and interannual sediment storage and release existed in the processes of sediment delivery in the kongduis. The contrast of the low gauged sediment load of the kongduis in recent years against the high surveyed gully erosion indicates the reduction in their sediment delivery efficiency, which can be attributed to the diminution in hyperconcentrated flows caused mainly by the increase in vegetation coverage on slopes and partly by construction of sediment-trapping dams in gullies. Full article

Soil erosion is a serious environmental issue in the Gomal River catchment shared by Pakistan and Afghanistan. The river segment between the Gomal Zam dam and a diversion barrage (~40 km) brings a huge load of sediments that negatively affects the downstream irrigation system, but the sediment sources have not been explored in detail in this sub-catchment. The analysis of flow and sediment data shows that the significant sediment yield is still contributing to the diversion barrage despite the Gomal Zam dam construction. However, the sediment share at the diversion barrage from the sub-catchment is much larger than its relative size. A spatial assessment of erosion rates in the sub-catchment with the revised universal soil loss equation (RUSLE) shows that most of the sub-catchment falls into very severe and catastrophic erosion rate categories (>100 t h⁻¹y⁻¹). The sediment entry into the irrigation system can be managed both by limiting erosion in the catchment and trapping sediments into a hydraulic structure. The authors tested a scenario by improving the crop management factor in RUSLE as a catchment management option. The results show that improving the crop management factor makes little difference in reducing the erosion rates in the sub-catchment, suggesting other RUSLE factors, and perhaps slope is a more obvious reason for high erosion rates. This research also explores the efficiency of a proposed settling reservoir as a sediment load management option for the flows diverted from the barrage. The proposed settling reservoir is simulated using a computer-based sediment transport model. The modeling results suggest that a settling reservoir can reduce sediment entry into the irrigation network by trapping 95% and 25% for sand and silt particles, respectively. The findings of the study suggest that managing the sub-catchment characterizing an arid region and having steep slopes and barren mountains is a less compelling option to reduce sediment entry into the irrigation system compared to the settling reservoir at the diversion barrage. Managing the entire catchment (including upstream of Gomal Zam dam) can be a potential solution, but it would require cooperative planning due to the transboundary nature of the Gomal river catchment. The output of this research can aid policy and decision-makers to sustainably manage sedimentation issues in the irrigation network. Full article

The lower reaches of the River Ure, on the flanks of the Pennine Hills in northern England, contain sedimentary and erosional landforms that are a record of fluvial activity during deglaciation and valley-glacier retreat at the end of the last (Devensian) glacial period, and in the subsequent post-glacial Holocene. Terraces and channels, most of which are now relict features well above the altitude of the present river, attest to the impacts of massive meltwater discharge and deposition of sand and gravel outwash, and dynamic river regimes with rapid incision. Through field survey, we have created a detailed geomorphological map of these landforms and glacial and fluvioglacial surface deposits, as well as the terraces and palaeochannels that were abandoned by the river due to avulsion and incision-driven course changes. We have recorded the nature of the outwash gravels, now effectively terrace features, from exposed sections in working quarries, one of which we discuss here. The palaeochannels have accumulated sediment fills and we have examined several which lie within the range of 100 and 16 m above present sea level. The results of lithostratigraphic, palynological, and radiocarbon analyses at two main and three subsidiary sites indicate that palaeochannel ages range from almost 14,000 to approximately 4000 calibrated years ago in a clear altitudinal sequence. The oldest are probably caused by rapid incision due to deglaciation-driven isostatic uplift. The similarity in date of the three downstream sites suggests that a late Holocene combination of climatic deterioration and increased human activity in the catchment caused instability and entrenchment. Pollen data from the channel fills provide relative dating, and agree well with pollen records from other regional Lateglacial and Holocene sites. Non-pollen palynomorph (NPP) analysis at one of the sites allows reconstruction of the hydrological history of channel infill. This research shows that the application of an integrated suite of research techniques can yield a highly detailed understanding of fluvial evolution and landscape history. Full article

The process of development has led to the modification of river landscapes. This has created imbalances between ecological, economic, and socio-cultural uses of ecosystem services (ESs), threatening the biotic and social integrity of rivers. Anthropogenic modifications influence river landscapes on multiple scales, which impact river-flow regimes and thus the production of river ESs. Despite progress in developing approaches for the valuation ecosystem goods and services, the ecosystem service research fails to acknowledge the biophysical structure of river landscape where ecosystem services are generated. Therefore, the purpose of this review is to synthesize the literature to develop the understanding of the biocomplexity of river landscapes and its importance in ecosystem service research. The review is limited to anthropogenic modifications from catchment to reach scale which includes inter-basin water transfer, change in land-use pattern, sub-surface modifications, groundwater abstractions, stream channelization, dams, and sand mining. Using 86 studies, the paper demonstrates that river ESs largely depend on the effective functioning of biophysical processes, which are linked with the geomorphological, ecological, and hydrological characteristics of river landscapes. Further, the ESs are linked with the economic, ecological, and socio-cultural aspect. The papers show that almost all anthropogenic modifications have positive impact on economic value of ESs. The ecological and socio-cultural values are negatively impacted by anthropogenic modifications such as dams, inter-basin water transfer, change in land-use pattern, and sand mining. The socio-cultural impact of ground-water abstraction and sub-surface modifications are not found in the literature examined here. Further, the ecological and socio-cultural aspects of ecosystem services from stakeholders’ perspective are discussed. We advocate for linking ecosystem service assessment with landscape signatures considering the socio-ecological interactions. Full article

The frozen water reserves on the Earth are not only very dynamic in their nature, but also have significant effects on hydrological response of complex and dynamic river basins. The Indus basin is one of the most complex river basins in the world and receives most of its share from the Asian Water Tower (Himalayas). In such a huge river basin with high-altitude mountains, the regular quantification of snow cover is a great challenge to researchers for the management of downstream ecosystems. In this study, Moderate Resolution Imaging Spectroradiometer (MODIS) daily (MOD09GA) and 8-day (MOD09A1) products were used for the spatiotemporal quantification of snow cover over the Indus basin and the western rivers’ catchments from 2008 to 2018. The high-resolution Landsat Enhanced Thematic Mapper Plus (ETM+) was used as a standard product with a minimum Normalized Difference Snow Index (NDSI) threshold (0.4) to delineate the snow cover for 120 scenes over the Indus basin on different days. All types of errors of commission/omission were masked out using water, sand, cloud, and forest masks at different spatiotemporal resolutions. The snow cover comparison of MODIS products with Landsat ETM+, in situ snow data and Google Earth imagery indicated that the minimum NDSI threshold of 0.34 fits well compared to the globally accepted threshold of 0.4 due to the coarser resolution of MODIS products. The intercomparison of the time series snow cover area of MODIS products indicated R² values of 0.96, 0.95, 0.97, 0.96 and 0.98, for the Chenab, Jhelum, Indus and eastern rivers’ catchments and Indus basin, respectively. A linear least squares regression analysis of the snow cover area of the Indus basin indicated a declining trend of about 3358 and 2459 km² per year for MOD09A1 and MOD09GA products, respectively. The results also revealed a decrease in snow cover area over all the parts of the Indus basin and its sub-catchments. Our results suggest that MODIS time series NDSI analysis is a useful technique to estimate snow cover over the mountainous areas of complex river basins. Full article

The impetus behind this study is to understand the sedimentological dynamics of very young fluvial systems in the Amazon River catchment and relate these to land use change and modern analogue studies of tidal rhythmites in the geologic record. Initial quartz optically stimulated luminescence (OSL) dating feasibility studies have concentrated on spit and bar deposits in the Rio Tapajós. Many of these features have an appearance of freshly deposited pristine sand, and these observations and information from anecdotal evidence and LandSat imagery suggest an apparent decadal stability. The characteristics of OSL from small (~5 cm) sub-samples from ~65 cm by ~2 cm diameter vertical cores are quite remarkable. Signals from medium-sized aliquots (5 mm diameter) exhibit very high specific luminescence sensitivity, have excellent dose recovery and recycling, essentially independent of preheat, and show minimal heat transfer even at the highest preheats. These characteristics enable measurement of very small signals with reasonable precision and, using modified single-aliquot regenerative-dose (SAR) approaches, equivalent doses as low as ~4 mGy can be obtained. Significant recuperation is observed for samples from two of the study sites and, in these instances, either the acceptance threshold was increased or growth curves were forced through the origin; recuperation is considered most likely to be a measurement artefact given the very small size of natural signals. Dose rates calculated from combined inductively coupled plasma mass spectrometry/inductively coupled plasma optical emission spectrometry (ICP-MS/ICP-OES) and high-resolution gamma spectrometry range from ~0.3 to 0.5 mGya⁻¹, and OSL ages for features so far investigated range from 13 to 34 years to several 100 years. Sampled sands are rich in quartz and yields of 212–250 μm or 250–310 μm grains indicate high-resolution sampling at 1–2 cm intervals is possible. Despite the use of medium-sized aliquots to ensure the recovery of very dim natural OSL signals, these results demonstrate the potential of OSL for studying very young active fluvial processes in these settings. Full article