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Abstract Background Altering the natural flow regime, an essential component of healthy fluvial systems, through hydropower operations has the potential to negatively impact freshwater fish populations. Establishing improved management of flow regimes requires better understanding of how fish respond to altered flow components, such as flow magnitude. Based on the results of a recent systematic map on the impacts of flow regime changes on direct outcomes of freshwater or estuarine fish productivity, evidence clusters on fish abundance and biomass responses were identified for full systematic review. The primary goal of this systematic review is to address one of those evidence clusters, with the following research question: how do changes in flow magnitude due to hydropower operations affect fish abundance and biomass? Methods This review follows the guidelines of the Collaboration for Environmental Evidence. It examined commercially published and grey literature originally identified during the systematic map process and a systematic search update. All articles were screened using an a priori eligibility criteria at two stages (title and abstract, and full-text) and consistency checks were performed at all stages. All eligible articles were assessed for study validity and specifically designed data extraction and study validity tools were used. A narrative synthesis included all available evidence and meta-analysis using the standardized mean difference (Hedges’ g) was conducted where appropriate. Review findings A total of 133 studies from 103 articles were included in this systematic review for data extraction and critical appraisal. Most studies were from North America (60%) and were conducted at 146 different hydropower dams/facilities. Meta-analysis included 268 datasets from 58 studies, separated into three analyses based on replication type [temporal (within or between year replication) or spatial]. Fish abundance (226 datasets) and biomass (30 datasets) had variable responses to changes in flow magnitude with estimated overall mean effect sizes ranging from positive to negative and varying by study design and taxa. In studies with temporal replication, we found a detectable effect of alterations to the direction of flow magnitude, the presence of other flow components, sampling methods, season, and fish life stage. However, we found no detectable effect of these moderators for studies with spatial replication. Taxonomic analyses indicated variable responses to changes in flow magnitude and a bias towards salmonid species. Conclusions This synthesis did not find consistent patterns in fish abundance or biomass responses to alterations or changes in flow magnitude. Fish responses to flow magnitude alterations or changes were highly variable and context dependent. Our synthesis suggests that biotic responses may not be generalizable across systems impacted by hydroelectric power production and operations, where specific features of the system may be highly influential. Site-specific and adaptive management may be necessary. To improve study validity and interpretability, studies with long-term continuous monitoring, and both temporal and spatial replication are needed. When this gold standard is unfeasible, studies should strive, at minimum, to maximize replication within both intervention and comparator groups for either temporal or spatial designs. To further address knowledge gaps, studies are needed that focus on non-salmonids, multiple seasons, and systems outside of North America.

North Sulawesi has one large dam located in Pindol Village, Lolak District. The research objective was to determine the lithology of the bedrock of dam foundation, rock class, and subsurface permeability of the dam. The method used in this research is core logging analysis and water pressure test. The bedrock foundations of the dam consist of andesite units, shale units, sandstone units which are included in the Sedimentary Facies Tinombo Formation and Volcanic Tinombo Formation. The formations are included in the Eocene to Early Oligocene Eocene and deposited in the deep marine environment. The foundation rock class is predominantly CM class (rather soft and fairly weathered rock), the rock quality of design is poor-medium characterized by the presence of broken cores and easily crushed in some parts. Lolak Dam has 6 permeability zones, namely very high, high, medium, moderate, low, and very low permeability with an average lugeon value of 4.43 liters/minute. The standard of lugeon value for the dam foundation is Lu3, so it is necessary to repair the drill points on the pilot hole which has a lugeon value of 3 (low, moderate, medium, high, and very high permeability zones) to increase the capacity foundation rock.

The hydropower sector is currently experiencing several technological developments. New technologies and practices are emerging to make hydropower more flexible and more sustainable. Novel materials have also been recently developed to increase performance, durability, and reliability; however, no systematic discussions can be found in the literature. Therefore, in this paper, novel materials for hydropower applications are presented, and their performance, advantages, and limitations are discussed. For example, composites can reduce the weight of steel equipment by 50% to 80%, polymers and superhydrophobic materials can reduce head losses by 4% to 20%, and novel bearing materials can reduce bearing wear by 6%. These improvements determine higher efficiencies, longer life span, waste reduction, and maintenance needs, although the initial cost of some materials is not yet competitive with respect to the costs of traditional materials. The novel materials are described here based on the following categories: novel materials for turbines, dams and waterways, bearings, seals, and ocean hydropower.

Dams are important water conservation hubs; however, dam locations provided by open datasets are often unreliable. The aim of this article is to provide a single, geographic location-reliable dataset of dams for the scientific community by fusing existing dam datasets and verifying these locations. Using Southeast Asia as the case study, we propose an efficient and automatic method to verify dam locations and developed a process framework. First, the possible location of a dam was obtained by analyzing its geographic location characteristics. Then, the deep learning method was used to detect dams. Finally, a variety of geographic knowledge was applied to comprehensively verify the detection results to obtain accurate and reliable dam location information. The fused dam dataset we produced includes the locations of 4493 dams in Southeast Asia, which were verified using the proposed framework. The verification results were then evaluated via manual visual inspection. The verification accuracy of the framework was 86.7%. The experimental results show that the proposed framework can quickly and reliably verify dam spatial locations and provide solutions for the spatial location verification of other remote sensing objects.

Dam installation on a deep hydrologically open lake provides the experimental framework necessary to study the influence of outlet engineering and changing base levels on limnogeological processes. Here, high-resolution seismic reflection profiles, sediment cores, and historical water level elevation datasets were employed to assess the recent depositional history of Jackson Lake, a dammed glacial lake located adjacent to the Teton fault in western Wyoming (USA). Prograding clinoforms imaged in the shallow stratigraphy indicate a recent lake-wide episode of delta abandonment. Submerged ∼11–12 m below the lake surface, these Gilbert-type paleo-deltas represent extensive submerged coarse-grained deposits along the axial and lateral margins of Jackson Lake that resulted from shoreline transgression following dam construction in the early 20th century. Other paleo-lake margin environments, including delta plain, shoreline, and glacial (drumlins, moraines) landforms were likewise inundated following dam installation, and now form prominent features on the lake floor. In deepwater, a detailed chronology was established using 137Cs, 210Pb, and reservoir-corrected 14C for a sediment core that spans ∼1654–2019 Common Era (CE). Dam emplacement (1908–1916 CE) correlates with a nearly five-fold acceleration in accumulation rates and a depositional shift towards carbonaceous sediments. Interbedded organic-rich black diatomaceous oozes and tan silts track changes in reservoir water level elevation, which oscillated in response to regional climate and downstream water needs between 1908 and 2019 CE. Chemostratigraphic patterns of carbon, phosphorus, and sulfur are consistent with a change in nutrient status and productivity, controlled initially by transgression-driven flooding of supralittoral soils and vegetation, and subsequently with water level changes. A thin gravity flow deposit punctuates the deepwater strata and provides a benchmark for turbidite characterization driven by hydroclimate change. Because the Teton fault is a major seismic hazard, end-member characterization of turbidites is a critical first step for accurate discrimination of mass transport deposits controlled by earthquakes in more ancient Jackson Lake strata. Results from this study illustrate the influence of dam installation on sublacustrine geomorphology and sedimentation, which has implications for lake management and ecosystem services. Further, this study demonstrates that Jackson Lake contains an expanded, untapped sedimentary archive recording environmental changes in the American West.

Project Description:  The objective is to generate 500 MW of power for 8 hour periods. This would be enough to supply 325,000 homes annually in the San Diego area. A new upper reservoir will be constructed above the existing San Vicente Reservoir and connected by an underground pipe containing a reversible pump-turbine system. Energy produced by the system will be stored during off-peak hours and sold during peak hours. Tasks Completed:  Project research and analysis, Determination of criteria for upper reservoir, Selection of candidate sites using topography, Calculation of upper reservoir volume Faculty Adviser:   Richard Trembath, Trembath Consulting, Inc.

This paper presents technological innovations based on new hydraulic insulating materials, the use of which in reservoir construction will essentially reduce construction costs by up to half. New polymer-mineral based waterproofing materials N1 and PMM can be used to construct inexpensive reservoirs. In particular, a thoroughly mixed mixture of soil taken from the bottom of a reservoir or other substrate with PMM material at a ratio of 30 grams PMM to one kg of the substrate, laid on the bottom of the reservoir with a thickness of at least 10 cm, and tamped down to a layer of 7 cm or less, will withstand at least 2.5-3 atm pressure of water column. A similar result can be obtained if a 5 cm thick layer of N1 material is laid on the reservoir bottom, together with pebbles to reduce the cost of the proposed solution.

Water management has become one of the major interests in arid and semi-arid regions. Scientists have suggested different criteria and methodologies for the identification of suitable dam sites. According to our literature review, we have used two major methodologies for the selection of suitable dam site location: geographic information system and remote sensing (GIS/RS) and multicriteria analysis (MCA) integrated with GIS/RS. The most common criteria used for the selection of suitable dam sites were slope, rainfall, land use land cover, soil type, lithology, lineament density, and hydrographic typology. All the factors were superimposed to prepare the synthesis map of water-harvesting structures, each thematic layer’s weight was determined, and storage water potential indices were calculated using water accumulation conditions. According to the water-harvesting location map, where the spatial distribution of the excellent (5%), very good (9%), and good (17%) aptitude classes is established in the northeast and central parts of the westward zone, the average located in the center of the zone. Study and weak are located south of the map; the area of moderate (25%) to poor (44%) suitability is situated in the south and southwest zone. The MCA was validated using an existing dam across the study area, where the MCA provides for the dam located in the good and moderate zones. The approach adopted in this study can be applied for any other location globally to identify potential dam-construction sites. From the point of view of the literature of multicriteria analyses of water recovery, areas unsuitable for surface water harvesting and dam projects are suitable for groundwater recharge.

153 reservoirs have been created in the Republic of Belarus. During the period of passing catastrophic floods and high waters along the river, there is a risk of overflowing reservoirs, overflow of water masses through the crest of an earthen dam and flooding of significantly large areas. The destruction of the dam is accompanied by the formation of a breach and the outflow through it of an unsteady flow of water in the form of a breakthrough wave into the downstream. A breakthrough wave and catastrophic flooding of the area are the main destructive factors of hydrodynamic accidents. Calculations to determine parameters of the wave and to assess the possible consequences of flooding are necessary when drawing up operational-and-tactical plans for the prevention and elimination of emergencies in case of accidents at retaining structures, determining the probable damage from flooding of the territory in the downstream of a hydraulic structure as a result of the passage of a breakthrough wave. It is necessary to assess the flooding zone and the hydrodynamic parameters of the flow, viz. the maximum values of the depth and velocity of the flow in the zone of catastrophic flooding, the time from the beginning of the accident to the arrival of a breakthrough wave at the particular point of the terrain, the duration of flooding, the boundaries of the zone of catastrophic flooding, the hydrographic flow rate in the section of the eroded dam and the graph of the fall headwater level. The degree of reliability of predictive calculations is determined by the accuracy of the two applied mathematical models, viz.: 1) erosion of the dam; 2) the movement of the breakout wave. The analysis of the applied mathematical models shows that in all cases the hydrodynamic models based on the oneand two-dimensional equations of Boussinesq – Saint-Venant are used to calculate the movement of the breakthrough wave. Wave parameters, i. e. wave height and speed of its propagation, completely depend on the hydrograph of the discharge in the section of the eroded dam, which, in its turn, is determined by the dynamics of its erosion. The aim of the work is to develop a methodology for calculating the flooding of the downstream as a result of the destruction of a soil dam.

ABSTRACT Many mechanisms have been proposed to be involved in the formation of bacterial persister cells. In this study, we investigated the impact of dam encoding DNA methylation on persister cell formation in Acinetobacter. We constructed plasmids overexpressing dam encoding DNA-(adenine N6)-methyltransferase and four genes as possibly involved in persistence and introduced them into three A. baumannii strains. For persister cell formation assays, bacteria were exposed to ciprofloxacin, imipenem, cefotaxime, and rifampin, and the transcription levels of the genes were measured by qRT-PCR. In addition, growth curves of strains were determined. We found that all five genes were upregulated following antibiotic exposure. Dam overexpression increased persister cell formation rates and activated the four persister cell-involved genes. Among the four persister cell-involved genes, only RecC overexpression increase persister cell formation rates. While recC-overexpressing strains showed higher growth rates, dam-overexpressing strains showed decreased growth rates. In this study, we revealed that a DNA methyltransferase may regulate persister cell formation in A. baumannii, while RecC seems to mediate epigenetic regulation of persister cell formation. However, Dam and RecC may act at different persister cell formation states. IMPORTANCE Bacterial persister cells are not killed by high concentration of antibiotics, despite its antibiotic susceptibility. It has been known that they may cause antibiotic treatment failure and contribute to the evolution of antibiotic resistance. Although many mechanisms have been suggested and verified for persister cell formation, many remains to be uncovered. In this study, we report that DNA methyltransferase leads to an increase in persister cell formation, through transcriptional activation of several regulatory genes. Our results suggest that DNA methyltransferases could be target proteins to prevent formation of persister cells.

Excessive nutrient inputs are generally perceived to be responsible for the eutrophication of estuarine and coastal systems. Here, we show that the alteration of estuarine water circulation may be a very critical driver in the case of macrotidal systems. For this study, we intensively sampled the upstream part of the Ria Penfeld in June 2021, in a period of maximum irradiance and after a period of ~7 days of closure of the Kervallon dam gate. We observed that the physico-chemical structure of the Ria Penfeld reservoir (RPR), with very high biomass (chl-a values up to 120 µg L−1) and anoxic conditions in the bottom, was radically different from what is usually observed in the other estuaries of the region. The very high net primary production (~1700 mg C m−2 d−1) in the RPR was associated with an important removal of nutrients, especially phosphate, resulting in a strong nutritional imbalance (molar N:Si:P ratio of 2100:1500:1) for the water exported to the downstream estuary.

This paper examines whether lime can be used for the drainage of cohesive soils built into hydraulic engineering embankments. It is a common practice, as early as the planning stage, to seek to reduce costs and accelerate work while maintaining the quality of work. Although lime stabilisation is not currently a widely used solution in the hydraulic engineering sector, it can play an important role in the future. Lime stabilisation can be considered an optimal solution as it shortens the embankment construction by eliminating the need to replace the soil when it is over-wet. This paper investigates whether it is possible to apply lime treatment in the forming of hydraulic engineering embankments as well as analyses the efficiency of mechanical soil drainage and compares it against chemical drainage (lime stabilisation) based on the example of the construction of the Szalejów Górny dry flood control reservoir located in south-western Poland. It presents the results of geotechnical investigations carried out during the construction phase and compares them with cases reported in the literature. The observation of the construction process reveals a high efficiency and effectiveness of quicklime (CaO) as a stabiliser in the soil used for reservoir dams. Adoption of this technology made it possible to achieve significantly higher embankment formation rates (max. approx. 14,000 m3/week) than when mechanical drainage was used (max. approx. 11,000 m3/week). It was also noted that the lime stabilisation process was significantly independent of unfavourable weather conditions, resulting in frequent high weekly efficiencies. Geotechnical tests on samples of the lime-stabilised soil built into the dam body confirmed the possibility of obtaining favourable strength parameters, particularly with regard to the angle of internal friction, cohesion and degree of plasticity. Therefore, it can be expected that lime will be used more widely in the formation of hydraulic engineering embankments and that soil stabilisation technology will be applied more frequently. [ABSTRACT FROM AUTHOR]

A current trend is to implement dam risk management. Dam risk analysis is the premise of dam risk management. Methods such as PRA, FMEA/FMECA, FTA, ETA, and group dam risk analysis have been proposed in studies at home and abroad. In practice, it is found that dam breaks or accidents occur even though the dam risk calculated by the existing methods meets the acceptable risk standard, and that many occurred accidents are at variance with dam risk analysis. This indicates that the existing methods have systematic defects, and the dam risk calculated based on such methods is only a part of the actual risk. This paper reviews the dam risk analysis theory and technical research and practice, discusses and analyzes the applicability and existing defects of the dam risk analysis theory, and proposes the future development direction of the dam risk analysis theory. It is concluded that the current dam risk assessment theories are tantamount to the traditional safety factor method coupled with probability analysis. The correlation among influencing factors of dam system risk, as well as the uncertainties of the said factors are not fully considered. Difficulties and opportunities coexist in China to link the existing dam safety standard system with the dam risk management system. The next step is to use system theory to carry out theoretical research on dam operation risk assessment, strengthen the connection between dam risk theory and management status, and formulate risk prevention regulations and technical standards. [ABSTRACT FROM AUTHOR]

The embankment dam on Lake Boyuk-Shor is designed for a highway and divides the lake into two parts. Engineering and geological studies have revealed a complex structure of the soil base of the dam and high seismicity. Studies of the stability of the dam slopes under the PLAXIS 2D program have shown their reliable stability. Studies of the sediment of the body of the dam and its soil base according to the PLAXIS 2D program have shown that the sediment of both the dam and its soil base is acceptable for this class of structures. [ABSTRACT FROM AUTHOR]

Floods control equipment in large dams is one of the most important requirements in hydraulic structures. Howell–Bunger valves and butterfly valves are two of these types of flow controls that are commonly used in bottom outlet dams. The optimal longitudinal distance (L) between the two Howell–Bunger and butterfly valves is such that the turbulence of the outlet flow from the butterfly valve should be dissipated before entering the outlet valve. Subsequently, the flow passing through the butterfly valves must have a fully developed flow state before reaching the Howell–Bunger valve. Therefore, the purpose of this study was to evaluate the optimal longitudinal distance between the Howell–Bunger and butterfly valves. For this purpose, different longitudinal distances were investigated using the Flow-3D numerical model. The ideal longitudinal distance obtained from the numerical model in the physical model was considered and tested. Based on the numerical study, the parameters of flow patterns, velocity profiles and vectors, turbulence kinetic energy, and formation of flow vorticity were investigated as criteria to determine the appropriate longitudinal distance. In addition, the most appropriate distance between the butterfly valve and the Howell–Bunger valve was determined, and the physical model was evaluated based on the optimal distance extracted from the numerical simulation. A comparison of the results from the numerical and the laboratory models showed that the minimum distance required in Howell–Bunger valves and butterfly valves should be equal to four times the diameter of the pipe ( L = 4 D ) so as not to adversely affect the performance of the bottom outlet system. [ABSTRACT FROM AUTHOR]

Extensive studies have been performed on water and sediment transport of the Yangtze River in recent decades, but very few studies were focused on seasonal and daily variations. After the construction of Three Gorges Dam (TGD) in 2003, several key cascade dams were built on the Yangtze upstream. Annual, monthly, and daily data were used to study the seasonality change on water level, water discharge, and sediment load in response to multiple reservoir impoundments. TGD impacted the water level inside the reservoir greatly by shifting the peak water level from summer to winter and made the hydrograph more asymmetrical. In contrast, minor changes in water levels (<2 m) occurred at stations downstream of the TGD mainly due to channel incision. Downstream of TGD at Yichang station, annual hydrograph was flattened slightly: water discharge in the dry season increased 49% whereas that of flood season decreased 14% from 1956–2002 to 2013–2017. Mean annual water discharge downstream of the TGD was slightly impacted because the impounded water was <5% of annual inflow of the reservoir. Comparing with the Yangtze, the annual hydrographs of other intensively managed rivers like the Yellow, Missouri, and Colorado have been flattened more effectively by reservoir impoundments. The sediment rating curves at Yichang and Hankou changed from an oval‐like shape before 2013 to two overlapping and flattened lines in 2013–2017. This shift indicates that the rising and falling limbs of the hydrograph experienced similar sediment concentrations in 2013–2017 and suggests a less obvious hysteresis effect. Over 50% of the sediment load observed at the seaward‐most Datong station was contributed by the large tributaries in the upper reach, like Jinsha and Jialing rivers, before 2003. The channel scour downstream of TGD contributed 49%–64% of the Datong sediment load after 2003. Plain Language Summary: Cascade dams were built on the Yangtze River mainstream, including the largest and key dams and reservoirs in China, like the Three Gorges Dam (TGD) in 2003. Annual, monthly, and daily data were used to study the seasonality change on water level, water discharge, and sediment load in response to multiple reservoir impoundments. The seasonality of water level in Three Gorges Reservoir does not follow the natural hydrological cycle in the river basin anymore. Rapid rising and slow falling in reservoir water level are mainly controlled by rapid impoundment and slow water release during hydropower generation. In contrast, minor changes in water levels (<2 m) occurred at stations downstream of the TGD mainly due to channel incision. Mean annual water discharge downstream of the TGD was slightly impacted because the impounded water was <5% of annual inflow of the reservoir. Comparing with the Yangtze, the annual hydrographs of other intensively managed rivers like the Yellow, Missouri, and Colorado Rivers have been more effectively flattened by reservoir impoundments. Our findings are valuable to water and sediment management of other large rivers that are experiencing increasing anthropogenic impacts. Key Points: Impoundment shifted the peak water level inside the Three Gorges Reservoir from summer to winter and changed the hydrograph to be asymmetricalRating curves of water discharge versus sediment load at Yichang and Hankou changed from an oval‐like shape before 2013 to two overlapping and flattened lines in 2013–2017Comparing with the Yangtze, the annual hydrographs of the Yellow, Missouri, and Colorado Rivers have been flattened more effectively by reservoir impoundments [ABSTRACT FROM AUTHOR]

A large number of long hydraulic and civil structures have been built around the world. Over time, most ground and concrete structures naturally have several problems associated with material aging and changes in operating and natural conditions. The occurrence of these problems necessitates the monitoring of their evolution and assessment of the corresponding risks to the integrity of structures. However, the monitoring of such structures is complicated owing to their considerable length. The optimal solution to this problem is the use of distributed fiber-optic sensors, which have many undoubted advantages over their point-based counterparts. This article discusses the experience of using this technology in other countries, identifies the fields of its use, and presents recommendations on the use of distributed sensors on long structures in the Russian Federation. [ABSTRACT FROM AUTHOR]

There are approximately 2.5 million small rivers in the Russian Federation, whose energy potential is estimated at 382 billion kWh. In the middle of the 20th century, the creation of large hydropower plants (HPPs) became a priority in the Russian energy sector. As a result, the maintenance and operation of a significant part of small HPPs (SHPPs) were suspended. Currently, about 10% of previously built SHPPs remain in operation. This article discusses the development history, existing problems, and future prospects for SHPPs. [ABSTRACT FROM AUTHOR]

Label-free quantitative proteomic (LFQ) and widely targeted metabolomic analyses were applied in the safety evaluation of three genetically modified (GM) maize varieties, BBL, BFL-1, and BFL-2, in addition to their corresponding non-GM parent maize. A total of 76, 40, and 25 differentially expressed proteins (DEPs) were screened out in BBL, BFL-1, and BFL-2, respectively, and their abundance compared was with that in their non-GM parents. Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis showed that most of the DEPs participate in biosynthesis of secondary metabolites, biosynthesis of amino acids, and metabolic pathways. Metabolomic analyses revealed 145, 178, and 88 differentially accumulated metabolites (DAMs) in the BBL/ZH58, BFL-1/ZH58, and BFL-2/ZH58×CH72 comparisons, respectively. KEGG pathway enrichment analysis showed that most of the DAMs are involved in biosynthesis of amino acids, and in arginine and proline metabolism. Three co-DEPs and 11 co-DAMs were identified in the seeds of these GM maize lines. The proteomic profiling of seeds showed that the GM maize varieties were not dramatically different from their non-GM control. Similarly, the metabolomic profiling of seeds showed no dramatic changes in the GM/non-GM maize varieties compared with the GM/GM and non-GM/non-GM maize varieties. The genetic background of the transgenic maize was found to have some influence on its proteomic and metabolomic profiles. [ABSTRACT FROM AUTHOR]

We present a detailed survey on the ongoing destabilization process of the Mosul dam. The dam is located on the Tigris river and is the biggest hydraulic structure in Iraq. From a geological point of view the dam foundation is unstable due to the underlying geology that is formed by alternate and variable strata of highly soluble materials such as gypsum, anhydrite, marl and limestone. Here we present the first comprehensive multi-sensor cumulative deformation map for the dam generated from space-based synthetic aperture radar (SAR) measurements from the Italian constellation COSMO-SkyMed and the European Sentinel-1a satellite. We compared 2014-2016 data to an historic dataset spanning 2004-2010 acquired with the Envisat ASAR sensor. We found that deformation was rapid during 2004-2010, slowed down in 2012-2014, and restarted in August 2014 when grouting operations stopped due to the temporary capture of the dam by the self proclaimed Islamic State in Iraq and Syria (ISIS). We took advantage of the availability of data from multiple SAR satellites to infer the deformation at the dam in great spatial and temporal detail and shed new light on the processes of the ongoing destabilization. This study highlights how new constellations of SAR sensors together with the availability of historical datasets are leading to important advances in deformation monitoring of small scale geologic and manmade features.

This paper presents the results of laboratory and field compaction of coarse soil. For laboratory compaction, a vibrating installation with a diameter of 300 mm was used; for field conditions, compaction was performed with a smooth roller weighing 27 tons of sany type, Laboratory experiments were carried out with model mixtures using device for standard soil compaction. To determine the maximum density and optimal moisture content in the laboratory, a graph of the dependence of the density of dry soil on moisture is built and the maximum obtained dependence is found corresponding to the values of the maximum density and optimal moisture content. In the field at layer thickness 50 cm soil compaction with a 27 ton roller in four six passes ρd=2.25 t/m³ with a thickness of 70 cm density ρd=2.10 t/m³ and with a layer thickness of 80 cm, the density ρd=2.04 t/m³ . In addition, it is shown about the effectiveness of the applied method of drilling and blasting operations in a quarry to obtain stone material of the required grain size composition. [ABSTRACT FROM AUTHOR]

The dam bedrock of Daxigou Reservoir has developed inlaid and fractured structures, and abnormal hydrogen sulfide gas appears during the excavation of the dam foundation, which is corrosive to the dam foundation concrete. After analysis, the dam foundation inlaid and fractured structure, the low temperature of the bedrock groundwater, fast seepage velocity, dissolved hydrogen sulfide gas and sulfate ions and other factors caused the poor quality of the experimental grouting. In view of this, mixed grout and silica sol grout were selected as curtain grouting materials. According to the difference of geological conditions along the axis, the curtain grouting area was divided, and different grouting material combinations were adopted for each partition, and appropriate construction methods were adopted to prevent the rock mass disturbance and splitting. In addition, the seepage problem of the surface bedrock was solved by adding concrete seepage troughs, adding concrete cover plates, and filling in anti-filter materials. The continuous seepage monitoring results during the storage operation period of the reservoir shows that the dam foundation treatment measures work well and the groundwater seepage is normal. [ABSTRACT FROM AUTHOR]

In bacteria, DNA-methyltransferase are responsible for DNA methylation of specific motifs in the genome. This methylation usually occurs at a very high rate. In the present study, we studied the MTases encoding genes found in the entomopathogenic bacteria Xenorhabdus. Only one persistent MTase was identified in the various species of this genus. This MTase, also broadly conserved in numerous Gram-negative bacteria, is called Dam: DNA-adenine MTase. Methylome analysis confirmed that the GATC motifs recognized by Dam were methylated at a rate of >99% in the studied strains. The observed enrichment of unmethylated motifs in putative promoter regions of the X. nematophila F1 strain suggests the possibility of epigenetic regulations. The overexpression of the Dam MTase responsible for additional motifs to be methylated was associated with impairment of two major phenotypes: motility, caused by a downregulation of flagellar genes, and hemolysis. However, our results suggest that dam overexpression did not modify the virulence properties of X. nematophila. This study increases the knowledge on the diverse roles played by MTases in bacteria. [ABSTRACT FROM AUTHOR]

Information about species diversity, integration of local data, and the dynamics of regional diversity is essential for understanding the mechanisms that maintain diversity in biological communities, especially in aquatic environments, which have extensive connectivity. Here, we used phytoplankton community data from two subtropical reservoirs and evaluated the site contributions to phytoplankton beta diversity. We partitioned beta diversity into two mechanisms, replacement and differences in species richness and abundance, and we related to environmental heterogeneity. We tested whether there is a predominance of replacement or differences in richness and abundance in beta diversity, and whether environmental heterogeneity predicts beta diversity and its components. Our results indicated the temporal and spatial variation of the environmental conditions of the reservoirs. The species replacement was prevalent in lentic sites, while differences in richness and abundance contributed to lotic sites. Dissolved oxygen, total phosphorus, euphotic zone light availability, orthophosphate, water flow, and total dissolved solids were predictors of beta diversity and its components. Thus, studies that consider the local and regional variability of species in the function of environmental heterogeneity are essential in understanding ecological determinants and should be considered for the conservation of aquatic biodiversity and the maintenance of ecosystem services in reservoirs. [ABSTRACT FROM AUTHOR]

Global river systems are experiencing rapid changes in sediment transport under growing anthropogenic and climatic stresses. However, the response of sediment discharge to the coupled influence of anthropogenic and natural factors and the associated impacts on the fluvial geomorphology in the Yangtze and Mekong rivers are not comprehensively assessed. Here, we recalibrated a seamless retrieval algorithm of the total suspended sediment (TSS) concentrations using in situ data and concurrent satellite data sets to analyze spatiotemporal patterns of the TSS concentrations in the lower Yangtze and Mekong rivers. Combined with soil erosion rates estimated by the Revised Universal Soil Loss Equation for the past 20 years, we examined the contributions of different factors to TSS trends. The results show that TSS concentrations in the Yangtze River decreased from 0.47 g L−1 in 2000 to 0.23 g L−1 in 2018 due to the construction of the Three Gorges Dam (TGD), especially in the Jingjiang reach, with a declining magnitude of 0.3 g L−1 (∼56%) since the TGD began operating. The Mekong River experienced increasing TSS concentration trends upstream and decreasing trends downstream from 2000 to 2018, possibly attributed to increased upstream soil erosion and decreased downstream water discharge. Declining TSS concentrations in both rivers have driven varying degrees of river channel erosion over the past two decades. This study investigated long‐term changes in the TSS concentrations and soil erosion in the Yangtze and Mekong rivers, and the results provide baseline information for the sustainable development of river sediment delivery. Plain Language Summary: Growing anthropogenic and climatic stresses have driven rapid changes in sediment transport for river systems globally. However, poorly available studies about the response of sediment discharge to coupled human and natural forces over the Yangtze and Mekong rivers limit the assessments of their impacts on river channel morphology. In this study, we estimated the spatiotemporal patterns of total suspended sediment (TSS) concentration in river channels of these two rivers and examined the contributions of driving factors to its temporal trends for the past 20 years. Three Gorges Dams caused TSS decrease of over 50% from 2000 to 2018 in the Yangtze River. In the Mekong River, soil erosion drove TSS increase in the upstream, while downstream TSS concentration decreased under declining water discharge during 2000–2018. Declining TSS concentrations enhanced river channel erosion in the Yangtze and Mekong rivers. We anticipate that the data sets here could serve as important information to assess the trade‐offs of future dam strategies and sustainable developments of river systems under human and climatic impacts. Key Points: Developed a seamless total suspended sediment (TSS) algorithm to determine the spatiotemporal patterns of the TSS concentration in channels of the Yangtze and Mekong riversExamined the contributions of dams and soil erosion to the TSS trendsExplored the impacts of declining TSS concentrations on river width dynamics [ABSTRACT FROM AUTHOR]

Dams are one of the most important engineering works of the current human society, and it is crucial to monitor and obtain analytical data to log their conditions, predict their behavior and, eventually, receive early warnings for planning interventions and maintenance activities. In this context, GNSS-based point displacement monitoring is nowadays a consolidated technique that is able to provide daily millimeter level accuracy, even with less sophisticated and less expensive single-frequency equipment. If properly designed, daily records of such monitoring systems produce time series that, when long enough, allow for an accurate reconstruction of the geometrical deformation of the structure, thus guiding semi-automatic early warning systems. This paper focuses on the procedure for the GNSS time series processing with a statistical approach. In particular, real-world times series collected from a dam monitoring test case are processed as an example of data filtering. A remove–restore technique based on a collocation approach is applied here. Basically, it consists of an initial deterministic modeling by polynomials and periodical components through least squares adjustment and Fourier transform, respectively, followed by a stochastic modeling based on empirical covariance estimation and a collocation approach. Filtered time series are interpreted by autoregressive models based on environmental factors such as air or water temperature and reservoir water level. Spatial analysis is finally performed by computing correlations between displacements of the monitored points, as well as by visualizing the overall structure deformation in time. Results positively validate the proposed data processing workflow, providing useful hints for the implementation of automatic early warning systems in the framework of structural monitoring based on continuous displacement measurements. [ABSTRACT FROM AUTHOR]

The Krasna River (length 28 km), left-side tributary of the Czarna Konecka River, is located in the northern part of the Świętokrzyskie Province in the Polish Uplands. The basin area (121 km2) was located in the Old Polish Industrial District (OPID). The metallurgical centres that were common in the OPID area in the past did not survive in their original form until today. One such centre is the former metallurgical plant at Duraczów, situated in the Krasna River valley. The main aim of this study was to reconstruct the functioning of a non-existent metallurgical centre. In the first stage, an analysis of historical literature and archival maps was carried out. Then, during the field prospectus, the forms of relief were identified and exposures of sediments were made. Material for laboratory tests, radiocarbon dating and palaeobotanical analyses were taken. The metallurgical centre in Duraczów was already functioning in 1577. The metallurgical settlement was located directly at the bottom of the Krasna valley. There are traces of iron production in the form of slag fragments on the surface of the ground. The smelter pond certainly existed from the early 19th century until the 1940s. It was created by damming up the waters with a dam of the original length of about 250 metres, width of 40 metres and height of about 2 metres. The dam was made of the Jurassic sandstone and slate. Below the dam, traces of an anthropogenic anastomosis are preserved in the relief. Numerous charcoal hearth remains (CHRs) were identified, in which charcoal from Scots pine wood was burned. They are 13-16 m in diameter and date from the period of prosperity (18th-19th c.) of metallurgical activity in the Krasna basin. [ABSTRACT FROM AUTHOR]

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The progressing development of civilisation and climate change require access to an appropriate quantity of environmental resources. One of the key resources is water. Both its deficit and excess evidently affect human life. Control over water circulation is possible owing to water management, largely involving introduction of hydraulic structures. The paper analyses the effect of the Jeziorsko dam reservoir on the flows of the Warta River, the third largest river in Poland. It analyses water flows in the Warta River in the years 1993–2020 for hydrological stations above and below the reservoir. The conducted research showed that the construction of the Jeziorsko reservoir also substantially contributed to an increase in minimum flows and a decrease in maximum flows. Moreover, the simulation showed that in the case of abscence of the reservoir, the flows of the Warta River would be higher in the period from January to June, and in the period from July to October the opposite situation would occur. In November and December, the flows would be at a similar level. Results obtained in the study, show that hydraulic structures are an effective solution in the context of stabilisation of the hydrological situation in a given region, particularly in terms of hydrological lows occurring with increasing intensity mitigated on sections of rivers below the reservoirs. [ABSTRACT FROM AUTHOR]

Although previous studies demonstrate declines in many large bodied species following hydropower dam installation, others suggest that some species, including the giant otter (Pteronura brasiliensis) may return to newly created reservoir habitats. Yet, there is a lack of evidence to support such theories. Here, we analyzed the effects of a hydropower dam on giant otters using a before-after control-impact study design in the eastern Brazilian Amazon. We collected data 3 years before (2011-2012 and 2015) and after (2017-2019) dam construction, totaling 6,459 km of surveys along rivers with 43 direct sightings of giant otters. Contrary to expectations, our results revealed that giant otters did not remain nor did they return to the dam reservoir. Beyond the zone directly impacted by the dam giant otter occurrence and relative abundance declined next to sustainable-use reserves where the river was more intensely used by people. Our study showed that in the absence of active management sustainable-use reserves and low human density were not sufficient to maintain this apex-predator. Our findings suggest a need to proactively create and maintain areas with low levels of anthropogenic disturbance to enable sustainable coexistence between energy demands and biodiversity across Amazonia. [ABSTRACT FROM AUTHOR]

The Sacachún commune in Ecuador currently faces a lack of water for its agricultural development; this reduces its possibilities of socio-economic development and causes migration to urban areas. This research proposes a presa colinar (hill dam) design that uses ancestral knowledge and classic engineering techniques to promote water use during the dry season in semi-arid regions. The methodology consisted of: (i) a systematic compilation of the ancestral structures used for water planting and harvesting in Ibero-American; (ii) selecting an appropriate place to build the hill dam; (iii) the dam's body design; (iv) and creating a proposal for agricultural water use. The results helped define a good location for the hill dam implementation. In addition, a 10 m high and 40 m wide earthen dam was designed, with a storage capacity of 114,341 m3, extending agriculture to 7.5 ha through a polyculture system of six different plants. The embankment has a cofferdam located downstream, which provides stability in static and pseudo-static conditions. In addition, the dam slopes have a 2:1 ratio, and a spillway channel and filter drain were dimensioned to protect the dam. [ABSTRACT FROM AUTHOR]

Understanding the behavior of reservoirs with flow regularization formed by hydroelectric power plants is essential for assessing water availability. The operationalization of reservoirs can be influenced both by climatic characteristics and by the consequences resulting from human actions in the basin. The objective of this study was to evaluate the existing relationships between the inflows and outflows of a reservoir, as well as with the conventional streamflow gauge stations downstream of the dam. Also evaluated were trends in the behavior of minimum, average and maximum flows, in the post-operation period, considering the characteristics of rainfall and irrigation in the region. The results indicated that reservoir operationalization is strongly related to the behavior of inflows. Moreover, a reduction was also verified in all the variables analyzed related to inflows and outflows, as well as in the stations downstream of the dam, except for the maximum flow in the station farthest from the reservoir, which showed a stationary behavior. The reductions in the flows may be related to the almost three-fold increase in the area irrigated by the center pivot in the basin; however, the same cannot be said in relation to the annual rainfall regime of the region, since it showed a stationary behavior for most of the stations evaluated. The work demonstrates the importance of trend analysis of flows over the years in order to identify possible factors responsible for their variability and assist in decision making regarding measures for the recovery and preservation of water resources. [ABSTRACT FROM AUTHOR]

Numerical modelling, a physically based method, is adopted to obtain an in-depth understanding of the mechanism of sediment-related hazards such as landslides and debris flows. With its ability to address large deformation problems, the particle flow analysis method (the particle flow code or PFC model) can simulate propagation and runout from landslides to debris flows under complex landslide material compositions with a proper rheological model. Hence, this study aims to analyse the kinematic characteristics of a landslide-generated debris flow event in Shaziba, Enshi City, that occurred on June 8, 2020, with the PFC3D numerical model and linear parallel bonding method. To determine the differences among various processes, field surveys, unmanned aerial vehicle (UAV) photography campaigns, and laboratory direct shear tests were conducted to invert the relevant parameters, such as the digital elevation model (DEM) and shear strength, corresponding to the rheological properties of landslide debris flow materials. In dynamic analysis, the velocity, displacement, and characteristics of landslide deposition were considered. The results indicate that the initial landslide stage started with overall acceleration, and the movement of gravel–silty clay materials lasted approximately 733 s with double-peak velocity curves and nonsynchronous displacement. The maximum velocity of the landslide body was 17.5 m/s, and the maximum displacement exceeded 1000 m. The volume of the landslide body was 9.31 × 105 m3. The simulation results agree with the actual landslide volume (1.5 × 106 m3) and morphology of the landslide dam observed in Qingjiang. The study provides detailed information on the recent Shaziba landslide, thereby providing a useful reference for better understanding the dynamics of gravel–silty clay landslides and preventing the potential hazard for remobilisation of the Shaziba landslide. [ABSTRACT FROM AUTHOR]

Cirata Dam is one of the dams in West Java, Indonesia, which has significant resources of endemic fish potential from adjacent rivers, as well as fish introduction from other regions or countries. Unfortunately, the production of fishing in these dams has decreased significantly every year due to unregulated fishing activities, water pollution caused by the feed from aquaculture activities, as well as domestic and industrial wastes discharged into the waters. This study analyzes the depletion of fish resources due to fishing and pollution at these sites. Methods used in this research are the bio-economic logistic standard and Gompertz model, to measure the impact of fishing on the dynamics of fish resources, and linear as well as non-linear regression to obtain the coefficient of pollution on production. The depletion of fish resources calculated by Anna model modification. The result shows that the depletion rate of Cirata's fish, varies in a year with an average depletion of 25% during the year of observation with standard model for analyzing fishing activities intervention alone. Combined with pollution, the rate of depletion is increased. The implication of the MSY or MEY management instruments is required to control the fish resources. [ABSTRACT FROM AUTHOR]

The recovery of mud is the only way to solve the problem of silting up dams. At the beginning of the 1990s, we studied the recovery of mud from a dozen dams in construction and agricultural fields. In the case where the destination of the silt is known thanks to the chemical, physical and mineralogical analyses, the desiltation is carried out in a continuous way; in this case, we speak of sustainable desilting. This is what this paper discusses for the first time. Sustainable desilting consists of equipping the dam with one or more dredges that continuously remove silt. Once the mud is discharged and then stored in basins built upstream of the dam, the water returns to the reservoir. Once dried, the mud is transported to its place of use, but preferably in the agricultural field. [ABSTRACT FROM AUTHOR]

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Flood caused by overflowing water from river has become a major issue in Southeast Asia, as it has caused economic losses and deaths. Therefore, the present work aims to propose an alternative approach for morphometric analysis of the Ciliwung River Upper Stream (CRU) without the geographic information system technique use for flood prevention strategy application. For the river network simulation, an agent‐based model having several rules in terms of agent, landscaping, and action was adopted. In addition, the river morphometric characteristics, namely, river network, river order, bifurcation ratio, length‐order ratio, fractal dimension, watershed density, and river capacity were estimated. It was found that the proposed technique was able to estimate the river morphometric characteristics of CRU. CRU has the river order, bifurcation ratio, length‐order ratio, fractal dimension, watershed density, and river capacity of 4, 1.1–2.5, 0.6–1.1, 1.84, 0.01 km km–2, and 1,404,060 L, respectively. It was also identified four suitable locations to build artificial dams for flood prevention strategy by employing the presently proposed technique. The proposed artificial dams with heights ranging from 10 m to 25 m demonstrated to have capability to prevent flood in the capital city of Jakarta, Indonesia. [ABSTRACT FROM AUTHOR]