Search Results (37)

Urbanization, escalating agriculture, tourism, and industrial development in the Chiang Mai–Lamphun groundwater basin in northern Thailand have increased water demand, causing widespread groundwater extraction. Over the past few decades, there has been a rapid, unrecoverable steady drop in groundwater levels in several areas in Chiang Mai and Lamphun provinces. This study employed hydrogeological investigations, hydrometeorological data analyses, stable isotopic analysis (δ¹⁸O and δ²H), and groundwater flow modeling using a 3D groundwater flow model (MODFLOW) to quantify groundwater recharge and delineate important groundwater recharge zones within the basin. The results showed that floodplain deposits exhibited the highest recharge rate, 104.4 mm/y, due to their proximity to rivers and high infiltration capacity. In contrast, younger terrain deposits, covering the largest area of 1314 km², contributed the most to total recharge volume with an average recharge rate of 99.8 mm/y. Seven significant recharge zones within the basin, where annual recharge rates exceeded 105 mm/y (average recharge of the entire basin), were also delineated. Zone 4, covering parts of densely populated Muaeng Lamphun, Ban Thi, and Saraphi districts, had the largest area of 330 km² and a recharge rate of 130.2 mm/y. Zone 6, encompassing Wiang Nong Long, Bai Hong, and Pa Sang districts, exhibited the highest recharge rate of 134.6 mm/y but covered a smaller area of 67 km². Stable isotopic data verified that recent precipitation predominantly recharged shallow groundwater, with minimal evaporation or isotopic exchange. The basin-wide average recharge rate was 104 mm/y, reflecting the combined influence of geology, permeability, and spatial distribution. These findings provide critical insights for sustainable groundwater management in the region, particularly in the context of climate change and increasing water demand. Full article

This study explores flood forecasting in the Pa River basin, a major tributary of the Beijiang River in South China, by integrating the Xin’anjiang hydrological model with the Shuffled Complex Evolution-University of Arizona (SCE-UA) algorithm for parameter calibration. Fifteen observed flood events from April to August 2024 were employed in this study, with twelve events used for model calibration and the remaining three for validation. Additionally, to assess model performance under extreme conditions, a 50-year return period flood event from June 2020 was incorporated as a supplementary validation case. The calibrated model reproduced flood hydrographs with high accuracy, achieving Nash–Sutcliffe Efficiency (NSE) values of up to 0.98, relative peak discharge errors generally within ±10%, and peak timing deviations under 3 h. The validation results demonstrated consistent performance across both typical and extreme events, indicating that the proposed framework provides a feasible and physically interpretable approach for flood forecasting in data-limited catchments. Full article

Examining the effects of climate change (CC) and anthropogenic activities (AAs) on vegetation dynamics is essential for ecosystem management. However, the time lag and accumulation effects of climate change on plant growth are often overlooked, resulting in an underestimation of CC impacts. Combined with the kernel normalized difference vegetation index (kNDVI), climate data during the growing season from 2000 to 2023 in the Three Rivers Source Region (TRSR) and trend and correlation analyses were employed to assess kNDVI dynamics. Furthermore, time lag and accumulation effect analyses and an upgraded residual analysis were applied to explore how climatic and human drivers jointly influence vegetation. The results show the following: (1) The kNDVI showed a fluctuating but overall increasing trend, indicating an overall improvement in vegetation growth. Although future vegetation is likely to continue improving, certain areas—such as the east of the western Yangtze River basin, south of the Yellow River basin, and parts of the Lancang River basin—will remain at risk of deterioration. (2) Overall, both precipitation and temperature were positively correlated with the kNDVI, with temperature acting as the dominant factor affecting plant growth. The predominant temporal effects of precipitation on the kNDVI were a 0-month lag and a 1-month accumulation, while temperature primarily showed a 2–3-month lag and a 0–1-month accumulation. The main category of the overall climatic temporal effects were precipitation accumulation and temperature time lag effects (PA_TL), which accounted for 70.93% of the TRSR. (3) Together, CC and AA drove vegetation dynamics, with contributions of 35.73% and 64.27%, respectively, indicating that AA played a dominant role. Furthermore, incorporating combined time lag and accumulation effects enhanced the explanatory ability of climatic factors for vegetation growth. Full article

To achieve resourceful utilization of dredged sludge, lightweight treatment was performed on sludge from Xunsi River in Wuhan using fly ash, cement, and expanded polystyrene (EPS) particles. Density tests and unconfined compressive strength (UCS) tests were conducted on the composite stabilized sludge lightweight soil to determine the optimal mix ratio for high-quality roadbed fill material with low self-weight and high strength. Subsequently, microstructural tests, including X-ray diffraction (XRD) and scanning electron microscopy (SEM), were conducted. The Particle (Pore) and Crack Analysis System (PCAS) was used to analyze the SEM images, investigating the cement–fly ash composite stabilization mechanism. The experimental results showed that the optimal lightweight treatment was achieved with an EPS content of 80% (by volume ratio to dry soil), cement content of 7.5% (by mass ratio to dry soil), and fly ash content of 5% (by mass ratio to dry soil). The density of the optimized lightweight soil was 1.04 g/cm³, a reduction of 28.27% compared to the density of raw sludge soil (1.45 g/cm³). The UCS increased significantly from 110 kPa for raw sludge soil to 551 kPa. The addition of fly ash enhanced the hydration and secondary hydration reactions between cement and sludge, generating more calcium silicate hydrate (C-S-H) gel, which filled the larger pores between the EPS particles and soil particles, as well as those between the soil particles themselves, making the structure denser. Compared to single cement stabilization, composite stabilization resulted in a lower content of expansive ettringite crystals, a more uniform pore distribution, fewer pores, and a lower surface porosity ratio. These research findings can provide theoretical support and practical references for the lightweight treatment of dredged sludge in the Yangtze River Basin of Central China. Full article

The hydrosphere is an element of the climate system and changes in the latter are reasonably projected over the river outflow. Climatic changes, however, are unevenly distributed over the Earth, and understanding their regional imprint on the hydrosphere is of great importance. In this study, we have conducted a statistical analysis of the monthly maximum and minimum river discharge recorded in 22 hydrological stations located on 19 of the Bulgarian rivers during the period 1993–2022. We have found that in half of the river basins, the trend of the spring maximum discharge is significantly positive (α = 0.05). In the other half of the stations, the trend is neutral. The stations with a positive trend are not randomly distributed but grouped, forming a pattern crossing the country from northwest to southeast. This pattern of trend distribution raises questions about the causes of the irregular hydrological response to the rising global near-surface temperatures. A comparison of hydrological data with some climatic variables (i.e., temperature, precipitation, and ozone at 70 hPa), combined with neural network analysis results, suggests ozone as a possible reason for the heterogeneous hydrological response. Its effect could be explained by an imposed episodic warming of the near-surface temperature due to fluctuations in the ozone density near the tropopause, which in turn favours the faster melting of ice and snow in the corresponding river basins. Full article

The riparian vegetation buffer zone is an important component of riverbank ecosystems, playing a crucial role in soil consolidation and slope protection. In this study, the riparian vegetation buffer zones in the Tongnan section of the Fujiang River Basin were selected as the research object. Surveys and experiments were conducted to assess the species composition and the soil and water conservation effectiveness of the riparian vegetation buffer zone. There are a total of 35 species, mainly comprising angiosperms and ferns. The dominant species include Cynodon dactylon, Setaria viridis, Phragmites australis, Erigeron canadensis, and Melilotus officinalis. The Patrick richness index (R) and Shannon–Wiener diversity index (H) are more significantly influenced by the types of land use in the surrounding area, whereas the impact on the Simpson diversity index (D) and Pielou uniformity index (E) is comparatively less pronounced. When the root diameter is less than 0.2 mm, the tensile strength of Cynodon dactylon roots is the highest. For root diameters larger than 0.2 mm, Melilotus officinalis roots exhibit the highest tensile strength. The presence of plant root systems significantly reduces erosion, delaying the time to reach maximum erosion depth by 1–4 min, decreasing erosion depth by 9–38 mm, and reducing the total amount of erosion by 20.17–58.90%. The anti-scouribility effect of Cynodon dactylon is significantly better than that of Setaria viridis. The root system notably enhances soil shear strength, delaying the shear peak by 0.26–4.8 cm, increasing the shear peak by 4.76–11.37 kPa, and raising energy consumption by 23.76–46.11%. Phragmites australis has the best resistance to shear, followed by Erigeron canadensis, with Melilotus officinalis being the least resistant. Therefore, to balance the anti-scouribility effect and shear resistance of plant roots, it is recommended to use a combination of Cynodon dactylon and Phragmites australis for shallow-rooted and deep-rooted planting. This approach enhances the water and soil conservation capacity of riverbanks. Full article

The Pisha sandstone area in the Yellow River Basin is one of the regions with the most severe soil erosion in China and globally, and its erosion is particularly challenging to control. W-OH, a hydrophilic polyurethane material, possesses controllable degradation properties. It can react with water to achieve soil stabilization and erosion resistance during the curing process. The material has been successfully utilized in erosion control in Pisha sandstone areas. This study aims to investigate the impact of W-OH material on water/fertilizer retention and plant growth through experiments on soil hardness, permeability, soil evaporation, soil column leaching, pot tests, and a small-scale demonstration in practical engineering applications. The results indicate that different concentrations of W-OH solution can effectively permeate Pisha sandstone, solidifying the particles to create a flexible and porous consolidation layer on the surface with a specific depth. As the W-OH concentration (3%, 4%, and 5%) increases, the harnesses of the consolidation layer also increase but remain below 1.5 kPa, which does not impede plant root growth. The soil evaporation rate decreased by approximately 45.2%, 45.8%, and 50.3% compared to the control group. The reduction rates of cumulative total nitrogen (TN) content are around 43.57%, 48.14%, and 63.99%, and, for cumulative total phosphorus (TP), are approximately 27.96%, 45.70%, and 61.17% under the 3%, 4%, and 5% concentrations of W-OH solution, respectively. In the pot tests, concentrations of W-OH solution below 5% are suitable for germination and growth of monocotyledons, while the optimal concentration for dicotyledons is around 3%. In the demonstration, the vegetation coverage of the treated gully increases by approximately 11.35%. This research offers a promising and effective approach to enhance ecological restoration in Pisha sandstone areas. Full article

Stable isotopes of precipitation play an important role in understanding hydrological and climatic processes of arid inland river basins. In order to better understand the difference of regional water cycle and precipitation patterns, precipitation samples were collected in Shiyang River Basin from June 2018 to May 2020, and spatial and temporal variation characteristics of stable isotopes in precipitation and their relationships with meteorological factors were discussed. The results showed that stable isotopes in precipitation showed seasonal variation characteristics, that δ²H and δ¹⁸O values were higher in summer and autumn and lower in winter and spring, and d-excess values were higher in spring and autumn and lower in winter and summer. Slopes and intercepts of the local meteoric water lines gradually increased with elevation increasing. δ¹⁸O significantly showed a positive correlation with temperature but a negative correlation with precipitation in summer. Contrary to below 15 hPa, δ¹⁸O significantly showed a negative correlation with water vapor pressure above 15 hPa. Due to the influence of meteorological factors, there are significant differences in stable isotopes of precipitation in arid inland river basins, which were more influenced by local moisture recycling in upstream area but by below-cloud secondary evaporation in mid-downstream area. Full article

High-elevation tropical streams are under increasing threat from human activities and climate change. Specifically, Ecuadorian Andean streams require priority actions such as bioassessment (e.g., biodiversity and functional ecology of macroinvertebrates) in order to generate adequate environmental management policies. Therefore, we investigated the distribution and composition of the macroinvertebrate taxa and their functional feeding groups in relation to the environmental variables in the Antisana river basin (Andean–Ecuadorian Region). We sampled macroinvertebrates from 15 locations to assess ecological conditions (ECs), expressed as the Biological Monitoring Working Party Colombia (BMWP-Col) classes, the Andean Biotic Index (ABI) and the Andean–Amazon Biotic Index (AAMBI). Results indicate that dissolved oxygen saturation, elevation, nutrient concentration and conductivity contributed significantly to the composition of the taxa and functional feeding groups (FFGs). Taxa diversity and FFGs were more abundant in the best EC sites. Shredders (SH) were, overall, dominant and abundant at sites with medium-high ECs. Scrapers constituted the second most prevalent assemblage, exerting dominance at moderate ecological conditions (high altitude and high oxygen saturation). Collector–gathers (CGs) are less sensitive to contamination than the previous two groups but were equally abundant at medium-high EC sites. Collector–filterers (CFs) and parasites (PAs) were less abundant, although the presence of the former was slightly related to better environmental conditions. Predators (PRs) were almost absent throughout the study, but they were collected from poor EC sites. CGs, PAs and PRs showed more tolerance to the presence of human disturbances (e.g., hydraulic constructions or slope erosion). The BMWP-Col index seems to be the best fit for this ecosystem, showing a significant difference in FFG between the index classes, compared to the other indices evaluated. The results of this investigation may be regarded as a fundamental starting point and used in future bioassessment work in other similar ecosystems, particularly high-altitude tropical Ecuadorian streams. Full article

The Schuylkill River Watershed in southeastern PA provides essential ecosystem services, including drinking water, power generation, recreation, transportation, irrigation, and habitats for aquatic life. The impact of changing climate and land use on these resources could negatively affect the ability of the watershed to continually provide these services. This study applies a hydrologic model to assess the impact of climate and land use change on water resources in the Schuylkill River Basin. A hydrologic model was created within the Structural Thinking Experiential Learning Laboratory with Animation (STELLA) modeling environment. Downscaled future climate change scenarios were generated using Localized Constructed Analogs (LOCA) from 2020 to 2040 for Representative Concentration Pathways (RCP) 4.5 and RCP 8.5 emission scenarios. Three regional land use change scenarios were developed based on historical land use and land cover change trends. The calibrated model was then run under projected climate and land use scenarios to simulate daily streamflow, reservoir water levels, and investigate the availability of water resources in the basin. Historically, the streamflow objective for the Schuylkill was met 89.8% of the time. However, the model forecasts that this will drop to 67.2–76.9% of the time, depending on the climate models used. Streamflow forecasts varied little with changes in land use. The two greenhouse gas emission scenarios considered (high and medium emissions) also produced similar predictions for the frequency with which the streamflow target is met. Barring substantial changes in global greenhouse gas emissions, the region should prepare for substantially greater frequency of low flow conditions in the Schuylkill River. Full article

Forest ecological products are closely related to ecological balance, and an in-depth understanding of the development dynamics of these products is crucial to the realization of sustainable development that integrates ecological, economic, and social benefits. Based on the Web of Science (WOS) and China National Knowledge Infrastructure (CNKI) databases, this study conducted a comprehensive econometric analysis of the number of articles, journals, research institutions, author collaborations, research hotspots, and research trends of forest ecological products globally during the period of 2003–2023 with the help of CiteSpace software (Philadelphia, PA, USA). The study’s results revealed the following insights: (1) The research on forest ecological products in recent years showed a general upward trend, but the research interest in foreign countries was higher than that in China. (2) The literature within the WOS database primarily focused on the field of ecology, whereas the literature in the CNKI database predominantly emphasized the field of forestry. (3) In both databases, the Chinese Academy of Sciences was the organization with the highest number of articles. Globally, Chinese institutions had the largest proportion of articles issued. The high percentage of articles issued by specialized agricultural and forestry schools in China showed clear domain relevance. (4) In both databases, author collaborations were relatively decentralized, and no significant core group of authors had been formed. (5) The research hotspots in foreign countries focused on the ecological regulation of forest ecological products, while the research hotspots in China focused on the realization of the economic value of forest ecological products. (6) “Machine learning”, “river basin”, and “health” are the future research frontiers in foreign countries, while “ecological function” and “forest ecosystem service” are the future research frontiers in China. The results of both databases indicate that the sustainability of forest ecological products is a research trend for the coming period. Finally, the outlook for future research on forest eco-products is presented in four aspects: promoting the establishment of a unified international standard certification system for forest eco-products, developing diversified products, strengthening the function of policy support and guidance, and establishing national partnerships. Full article

The degree of success of river water diversion planning decisions is affected by uncertain environmental conditions. The adaptive water management framework incorporates this uncertainty at all stages of management. While the most effective form of adaptive management requires experimental comparison of practices, the use of optimization modeling is convenient for conducting exploratory simulations to evaluate the spatiotemporal implications of current water diversion management decisions under future environmental changes. We demonstrate such an explorative modeling approach by assessing river water availability for diversion in a river basin in Northern Spain under two future environmental scenarios that combine climate and land use change. An evolutionary optimization method is applied to identify and reduce trade-offs with Supporting Ecosystem Services linked to environmental flow requirements for relevant local freshwater species. The results show that seasonal shifts and spatial heterogeneity of diversion volumes are the main challenges for the future diversion management of the Pas River. Basin-scale diversion management should take into account the seasonal planning horizon and the setting of tailored diversion targets at the local-level to promote the implementation of adaptive management. The presented assessment can help with strategic placement of diversion points and timing of withdrawals, but it also provides deeper insight into how optimisation can support decision-making in managing water diversion under uncertain future environmental conditions. Full article

High-resolution reanalysis data are an effective way to evaluate cloud water resources (CWRs). Based on ERA5 reanalysis data and gridded observed precipitation data, combined with the diagnostic quantification method of cloud water resource (CWR-DQ), we analyze and evaluate the CWRs and their distribution characteristics in the Huaihe River Basin from 2011 to 2021. Moreover, we compare and evaluate the CWRs of two typical precipitation processes in summer and winter. The results show that the annual total amount of atmospheric hydrometeor (GM_h) in the Huaihe River Basin is approximately 1537.3 mm. The precipitation (P_s) is 963.5 mm, the cloud water resource (CWR) is 573.8 mm, and the precipitation efficiency of hydrometeor (PE_h) is 62.4%. The CWR in the Huaihe River Basin shows a slow increasing trend from 2011 to 2021.The monthly variations in P_s, CWR, and PE_h show a single peak distribution. The spatial horizontal distributions of the gross mass of water vapor (GM_v), GM_h, and P_s in the Huaihe River Basin are zonal, and the values decrease with increasing latitude. In summer, the hydrometeors are mainly distributed in the middle layer (between 600 and 350 hPa). The hydrometeors in spring, autumn, and winter are mainly below 500 hPa. Two cases reveal that GM_v, the condensation from water vapor to hydrometeors (C_vh), GM_h, P_s, and PE_h in the summer case are significantly higher compared to those in the winter case, while the CWRs are similar. The results are helpful for proposing rational suggestions for the Huaihe River Basin and to provide some beneficial reference for the development of CWRs. Full article

The Chesapeake logperch, Percina bimaculata (Halderman) has a disjunct distribution when compared to other species in the subgenus Percina. Members of this subgenus in Pennsylvania include Percina caprodes caprodes (Rafinesque), Percina caprodes semifasciata (DeKay), and P. bimaculata. Historically the Chesapeake logperch was known only from the Susquehanna River and Potomac River basins. Its range is now restricted to the Susquehanna River below Holtwood Dam and upper Chesapeake Bay. It has been extirpated from the Potomac River and the type locality near Columbia, PA. Attempts are being made to reintroduce it into tributaries of the Susquehanna River near Columbia, PA. We postulate that P. bimaculata diverged from a population of Percina caprodes semifasciata. A naked nape and the fact that both of these species do not occur above the fall line in Pennsylvania support such a relationship. Full article

An integrated study of sediments was conducted to examine the facies architecture and depositional environment of the Cretaceous Pab Formation, Rakhi Gorge, and Suleiman Ranges, Pakistan. This research focused on analyzing architectural elements and facies, which are not commonly studied in sedimentary basins in Pakistan. To identify lithofacies, outcrop analysis and section measurement were performed. The identified lithofacies were then categorized based on their depositional characteristics and facies associations, with a total of nine types identified within a stratigraphic thickness of approximately 480 m. These facies were mainly indicative of high-energy environments, although the specifics varied by location. Sedimentary structures such as planar and trough crossbedding, lamination, nodularity, load-casts, and fossil traces were found within these facies, indicating high-energy environments with a few exceptions in calm environments. The identified facies were grouped into seven architectural elements according to their depositional environments: delta-dominated elements, including laminated shale sheet elements (LS), fine sandstone elements (SF), planar cross-bedded sandstone elements (SCp), trace sandstone elements (ST), and paleosol elements (Pa); and river-dominated elements, including trough cross-bedded sandstone elements (SCt), channel deposit elements (CH), and paleosol elements (Pa). These architectural elements, along with their vertical and lateral relationships, indicate a transitional fluvio-deltaic environment within the Pab Formation. In conclusion, by interpreting facies and architectural elements, it is possible to gain a better understanding of the depositional history of the formation and the distribution of reservoir units. Full article