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Understanding temporal variation in mechanisms and factors shaping metacommunity is an important issue of community ecology. The relative importance of different assembly mechanisms, such as dispersal and environmental filtering, can vary through time in dynamic systems, whereas it is still unclear how different dispersal modes affect temporal patterns of the variation. We investigated metacommunity structures of fish and aquatic insects with flying adults in spring, summer, and autumn in drainage ditches of paddy fields in the Kita River basin, Japan, where agricultural water management and flood events cause seasonal flow changes. Using redundancy analysis and variation partitioning, we examined how the variation of these metacommunity structures was explained by local environmental factors and two types of spatial factors (overland based and watercourse based). Fish metacommunities were mainly influenced by local environmental factors (e.g., water depth) in summer, and by watercourse‐based spatial factors (e.g., distance to downstream rivers) in spring and autumn. As fishes are obligate aquatic dispersers, increased hydrological connectivity among habitats in summer weakens the dispersal limitation from downstream rivers and enables species to track environmentally preferred habitats. In contrast, only overland‐based spatial factors (e.g., spatial patterns based on overland distance) significantly affected aquatic insect metacommunities in summer and autumn. These results suggest that regional and landscape variables can influence their metacommunity patterns more than the local environment. We conclude that the dynamic nature of the environment and dispersal modes can interactively influence metacommunity structures in temporally connecting habitats. [ABSTRACT FROM AUTHOR]

Copyright of Vadose Zone Journal is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Bylye Gody is the property of Cherkas Global University Press and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Draining and extracting peat alters a peatland's control of CO2 and CH4 emissions. Carbon (C) emissions from peatlands undergoing extraction are not well constrained due to a lack of measurements. We determine the effect that production duration (years of extraction) has on the CO2 and CH4 emissions from an actively extracted peatland over three years of measurements (2018-2020). We studied five sectors identified by the year when extraction began (1987, 2007, 2010, 2013, 2016). Higher average CO2 and CH4 emissions were measured from the drainage ditches (CO2: 2.05 ± 0.12 g C m-2 d-1; CH4: 72.0 ± 18.0 mg C m-2 d-1) compared to the field surface (CO2: 0.9 ± 0.06 g C m-2 d-1; CH4: 9.2 ± 4.0 mg C m-2 d-1 regardless of sector. For peat fields, CO2 fluxes were highest in the youngest sector, which opened in 2016 (1.5 ± 0.2 g C m-2 d-1). The four older sectors all had similar mean CO2 fluxes (~0.65 g C m-2 d-1) that were statistically different from the mean 2016 CO2 flux. A spatial effect on CO2 fluxes was observed solely within the 2016 sector, where CO2 emissions were highest from the centre of the peat field and declined towards the drainage ditches. These observations occur due to operators' surface contouring to facilitate drainage. The domed shape and subsequent peat removal resulted in a difference in surface peat age hence different humification and lability. 14C dating confirmed that the remaining peat contained within the 2016 sector was younger than peat within the 2007 sector and that peat age is younger toward the centre of the field in both sectors. Humification indices derived from mid-infrared spectrometry (MIRS) (1630/1090 cm-1) indicated that peat humification increases with increasing years of extraction. Laboratory incubation experiments showed that CO2 production potentials of surface peat samples from the 2016 sector increased toward the centre of the field and were higher than for samples taken from the 1987 and 2007 sectors. Our results indicate that peatlands under extraction are a net source of C where emissions are high in the first few years after opening a field for extraction and then decline to about half the initial value and remain at this level for several decades, and the ditches remain a 2 to 3 times greater source than the fields, but represent < 7% of the total area of a field. [ABSTRACT FROM AUTHOR]

One of the major current ecological challenges is to understand how to reconcile human activities with biodiversity conservation concerns. This issue is particularly relevant in freshwater ecosystems where biodiversity is globally under severe threat. Artificial waterbodies, such as ditch networks, are part of the few remaining wetlands in agricultural landscapes and hence play a crucial role in maintaining aquatic biodiversity in these landscapes.We investigated the responses of adult Odonata assemblages at different spatial scales in a marshland crossed by ditches to two factors expected to be pivotal influences on assemblages. At the local scale, this was mainly the water regime in ditches and, at a broader scale, the composition of the landscape. Both taxonomic alpha and beta diversity, and functional trait composition were considered as response variables.Significant differences were found between the responses of the two Odonata suborders. We showed that Zygoptera species richness decreased and species turnover increased with the duration of drying episodes in ditches. Geographical distances between local assemblages as well as landscape characteristics, notably woodland cover, meadow cover and ditch network length, also significantly shaped the distribution of Zygoptera. For Anisoptera, species richness was not explained by environmental variables and beta diversity was associated only with local conditions; it increased with increasing dissimilarity in water quality and riparian vegetation. We also found evidence of functional trait syndromes (combinations of correlated traits) in Odonata assemblages, but without clear relationships to environmental gradients.This study reveals the structuring role of water regime for Odonata in ditch networks and demonstrates the need to jointly consider environmental variables at different spatial scales to properly understand the distribution of Odonata.Our findings have important conservation implications as the water regime is heavily managed in such ecosystems. Even though the relationship between functional composition and environmental gradients was found to be of limited extent in this study, we discuss how it might provide new insights for Odonata assemblage structure and be useful, locally, for stakeholders and managers. Lastly, we call for further multiscale investigations considering both the taxonomic and functional responses of Odonata assemblages (functional analyses with multiple traits and several species being scarce in this taxonomic group) in other anthropogenic freshwater ecosystems to gather more lessons for their conservation. [ABSTRACT FROM AUTHOR]

Copyright of Geopolitica(s): Revista de Estudios Sobre Espacio y Poder is the property of Universidad Complutense de Madrid and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Large‐scale, intensive agriculture is a critical activity supporting global food production, yet it has taken a significant toll on the equally critical ecosystem services supplied by global biodiversity. This is particularly true for the planet's most threatened ecosystems: freshwaters. As one of the world's largest agricultural producers, Canada is also home to much of the world's freshwater. As Canada's agricultural capacity expands under climate warming into more northerly latitudes—and in some cases regions with large carbon sinks—it is imperative that this sectoral shift is accompanied by careful management to avoid exacerbating ecosystem service losses. Across Canada, agricultural practices vary in terms of their impact on freshwater ecosystems. Agricultural water extraction, storage behind dams, diversions, dredging and clearing of riparian vegetation can impact more naturalized flow regimes. This review explores the influence of managed low flows on ecosystem functioning in man‐made drainage/irrigation ditch systems. We examine how low flows in these systems can impact ecosystem functions in agricultural watersheds with fragmented natural capital. We provide management options to protect ecosystem functions under a changing climate, recognizing that in agro‐ecosystems, drainage/irrigation ditch systems provide a critical remnant habitat to support biodiversity in otherwise depauperate landscapes. [ABSTRACT FROM AUTHOR]

Crystal blockages of tunnel drainage systems severely undermine the tunnel lining structure and operation safety. In order to reduce the risk of crystal blockages of tunnel drainage systems, the distribution of highway tunnel defects was identified through a field survey, indoor test, and literature analysis, and an optimization method of tunnel drainage structures was proposed. The research suggested the following: (1) Lining water leakage and construction joint water leakage were the most common defects in the tunnel drainage system of Renhua–Xinfeng Expressway and Yingde–Huaiji Expressway in Guangdong Province, accounting for 60% and 32% of total defects, respectively. The number of defects that occurred in the drainage system of the tunnel was larger in the granite formation, with the number of road seepage and inspection chamber crystallization incidents reaching 2.5/km and 2.8/km, respectively. (2) The groundwater was mainly alkaline with a pH value of 8~12, Ca2+ (107 mg/L) was the cation with the largest ion concentration, and HCO3− (165 mg/L) was the anion with the largest ion concentration. The crystals in the tunnel drainage system were predominantly square, spindle, and rhombic calcite and aragonite composed of CaCO3, mixed with a small amount of sediment. (3) To reduce the risk of crystal blockages of the tunnel drainage system and ensure tunnel lining structure safety, a threefold optimization measure was proposed, namely, setting one-directional drainage pipes between the cable trench and the roadside blind drainage ditch, applying "π" type anti-crystallization drainage water-stop belts at the circular construction joints in the secondary lining, and both increasing the slope of the transverse drainage pipe and using an anti-crystallization drainage pipe. The research results will play an important role in guiding the design, construction, and maintenance of highway tunnel drainage systems in China. [ABSTRACT FROM AUTHOR]

Anurans are a diverse group of vertebrates that occur in several different habitats. Male anurans regularly clasp their conspecific females in their habitats and on different substrates. [Extracted from the article]

This paper presents the steps performed for the execution of hydrographic works on the Danube - Black Sea Canal (CDMN) and the White Gate - Midia Năvodari Canal (CPAMN), next to Constanţa harbour. These landmarks represent the elemental key of navigation on the Danube River. The general condition of the navigable channels has not been affected since they were put into use, there are a number of problems related to the stability and local integrity of the banks that can endanger the safety of navigation. The purpose of hydrographic studies is to collect, through systematic surveys in navigable areas, georeferenced data related to: bathymetry in the area of interest; classification and precise positioning of underwater contacts; the profile and characteristics of the submerged relief; the volume of alluvium deposited in the canal ditch and their nature; currents and water levels or the physical properties of the water column. [ABSTRACT FROM AUTHOR]

The Baligówka peat bog is one of the peat bogs of the Orawa-Nowy Targ Basin—the largest complex of wetlands in the Polish Carpathians. Its area has declined in the past as a result of drainage and peat exploitation, which caused a bad hydrological condition and it is gradually overgrown by non-peat bog medium and high vegetation. The research uses models derived from airborne laser scanning (ALS) and an orthophotomap to delimit the bog and divide it into parts and assess the range of drainage ditches and vegetation. The area of the peat dome along with 3 sites of peat exploitation is currently 159.6 ha, while the ecotone zone is 105.9 ha. Both sections are separated by a steep post-mining slope. The medium and high vegetation areas cover 44% of the peat bog; its location is related to the dense drainage system in the southern part of the dome. The parameters of the Baligówka peat bog: area, size and extent of drainage system, and the degree of overgrowth by high vegetation, are the subject of research towards the protection under the Natura 2000 network (PLH120016) and the establishment of a plan for restoration activities. [ABSTRACT FROM AUTHOR]

Mosquito larval surveys were conducted in two urban neigbourhoods, Surulere and Apapa, in Lagos State, Nigeria from July to October 2021. The aim was to investigate mosquito species composition and habitats utilized by these species with the overall goal of generating useful information to guide mosquito surveillance and control activities targeting vector species. Immature mosquitoes (larva and pupa) found were collected using dipping technique and emerged adults were identified using standard morphological keys. Mosquito abundance, diversity and habitat types were also assessed. A total of 2,696 immature mosquitoes were collected from both areas with 90.3% (2,434) collected from Surulere. Three species of mosquitoes; Aedes aegypti, Culex pipiens complex and Anopheles gambiae complex were found in both Surulere and Apapa. One species identified as Lutzia tigripes was found only in Apapa. In Surulere, Cx. pipiens complex had significantly (p < 0.05) the highest relative abundance (59.8%) while An. gambiae complex had the lowest (2.2%). In Apapa, Ae. aegypti had the highest abundance (68.7%) while Lt. tigripes had the lowest (6.9%) but there was no significant difference. Habitat types encountered in both areas included gutters (roadside ditches), ground pools and man-made containers especially used tyres. Larval densities varied significantly (p < 0.05) among species, and habitat types in Surulere but not in Apapa. The observed variations in species composition and abundance between the two urban neigbourhoods suggest different risk for specific mosquito-borne diseases. Integrated vector management tactics such as source reduction through larval habitat elimination and larviciding are recommended. [ABSTRACT FROM AUTHOR]

Malaria is a widespread vector-borne disease in the tropics and subtropics causing nearly half a million deaths every year. Malaria vector control intervention mainly rely on the control of adults using Indoor residual sprayings (IRS) and long lasting insecticidal nets (LLINs). The purpose of this study was to assess the species composition of Anopheles mosquitoes and determine the environmental and physicochemical parameters of their breeding habitats in Bambasi district, Benshangul Gumuz regional state, northwestern Ethiopia. Three major Anopheles breeding habitats were identified in three Kebeles namely; drainage ditch (Keshmando), swamp (Amba 46), and stagnant water (Amba 47). Anopheles mosquito larvae were sampled twice a month from September 2020 to November 2020. A total of 2185 Anopheles mosquito larvae were collected. Of those collected larvae three Anopheles species (Anopheles gambiae s.l. An. funestus and An. coustani complex) were identified. Anopheles gambiae s.l was the most abundant whereas An. funestus and An. coustani were the least in all the study kebeles. Of the three kebeles, Amba 47 was found the most productive for Anopheles followed by Amba 46 and Keshmando. The highest mean density of larvae per dip was sampled in September in all the study sites. The three sampling sites varied in physicochemical characteristics. The findings of this study showed that dissolved oxygen (DO) was highest (7.07 ± 0.55 mg/L) in the swamps and lowest (0.32 ± 0.04 mg/L) in the drainage ditches. Conductivity across different habitats showed wide variations. There were slight variations in temperature between different habitats. Higher total dissolved solids (TDS) 12.19 ± 0.26 mg/L was recorded from the drainage ditches; whereas TDS 9.49 ± 1.62 mg/L was recorded from the swamp. Salinity in the drainage ditches and stagnant water was 5.54 ± 1.00PSU and 3.30 ± 0.97 PSU respectively. There were negative strong correlation between the larval density with temperature and EC but positive correlation between larval density with salinity. However, there was no significant correlation between Anopheles larval density with TDS and DO. In conclusion this study suggested that environmental and physicochemical factors could play an important role in the development of mosquito larvae. Therefore, characterizing mosquito larval habitats is important for targeted control of malaria vectors in Ethiopia. [ABSTRACT FROM AUTHOR]

Middle Neolithic circular enclosures, known as Kreisgrabenanlage (KGA), are the oldest known monumental sites in Central Europe, dating roughly to 4850–4600/4500 BC. These large prehistoric monuments are mainly discovered by aerial archaeology and have been investigated by geophysical prospection and archaeological excavations since the 1960s. The site of Velm (Lower Austria) was discovered by aerial photographs in 2001. Due to its unusual location on a flat gravel plateau, the enclosure has become the object of intensive interdisciplinary research in recent years. In 2016, two motorized ground-penetrating radar (GPR) surveys were conducted, resulting in a detailed three-dimensional dataset visualizing the circular ditches, palisades and dwellings of an adjacent settlement. The high contrast between the gravel sediments and the humic earthen backfill of the ditches, palisades and individual postholes resulted in a highly detailed visualization of the Middle Neolithic monument. Based on this survey, selected structures were investigated by targeted archaeological excavations to evaluate the GPR results and to take samples for radiocarbon dating. This paper presents a synopsis of all the methods used. An integrated interpretation of aerial photo information, magnetometry and GPR is conducted, and it is shown to what extent these could be verified by the targeted archaeological excavation. By a detailed analysis of all applied archaeological prospection methods, it is now possible to interpret the monument in its entirety and confirm its dating to the Middle Neolithic Lengyel cultural complex. [ABSTRACT FROM AUTHOR]

A one‐dimensional longitudinal mixing model for an oxidation ditch with a moving symmetrical boundary and a series model for a symmetric aeration mixing unit of an aeration tank were developed in this study to analyze their mixing processes. The analysis of these models showed that the mixing process in the oxidation ditch tended to that of a continuous stirred tank reactor (CSTR) in a mode of circulation flow and dispersion; however, the mixing in the aeration tank tended to that of a CSTR in a mode of dispersion. The tracer output patterns and complete mixing times of the oxidation ditch and aeration tank with treatment capacities of 1000–50,000 m3/d and hydraulic retention time 12.0 h were evaluated. The complete mixing time increased from 7.5 min to 128.5 min for the aeration tank with an increase in volume; and the oxidation ditch with same complete mixing time as that of the aeration tank was obtained. The complete mixing time for the oxidation ditch can be changed in a wider range, for matching the time scale of biochemical degradation of organic pollutants. Practitioner Points: Mixing model of an oxidation ditch and an aeration tank were built.Mixing in oxidation ditch tends to that of CSTR in a mode of circulation flow and dispersion.Mixing in an aeration tank is in accordance with advection diffusion and tends to that of CSTR as its Peclet number is large.Complete mixing time for an oxidation ditch can be changed in a wider range. [ABSTRACT FROM AUTHOR]

While many communications media, such as wireless and certain classes of wireline channels, typically lead to bursty errors, most decoders are designed assuming memoryless channels. Consequently, communication systems generally rely on interleaving over tens of thousands of bits to match decoder assumptions. Even for short high rate codes, awaiting sufficient data in interleaving and de-interleaving is a significant source of unwanted latency. We construct an extension to the recently proposed Guessing Random Additive Noise Decoding (GRAND) algorithm, which we call GRAND-MO for GRAND Markov Order. By foregoing interleaving and instead making use of the bursty nature of noise, low-latency communication is possible with block error rates outperforming their interleaved counterparts by a substantial margin. We establish that certain well-known binary codes with structured code-word patterns are ill-suited for use in bursty channels, but Random Linear Codes (RLCs) prove robust to correlated noise. We further demonstrate that by operating directly on modulated symbols rather than de-mapped bits, GRAND-MO achieves further performance and complexity gains by exploiting information that is lost in demodulation. As a result, GRAND-MO provides one potential solution for applications that require ultra-reliable low latency communication. [ABSTRACT FROM AUTHOR]

Nitrogen loss with the farmland drainage from the rice irrigation areas has been a great threat to the aquatic environment of the receiving water in southern China. In this present study, a systematic investigation was made to clarify the effect of different irrigation and drainage control strategies at the field level on ammonia nitrogen (NH3-N) reduction. The potential of pollutant reduction with the ditches and ponds was also proposed to meet the requirements of water quality in small agricultural watersheds. A case study was set in the Yanyun Irrigation Area along the Grand Canal in Yangzhou City, Jiangsu Province, China. A field experiment was performed on rice irrigation and drainage in two rice growing seasons. Some parameters were measured, including the soil properties, groundwater depth, and nitrogen concentrations of drainage flow in the field. The field hydrological model-DRAINMOD was used to simulate the different water management scenarios. A conceptual model was developed to predict the nitrogen reduction in the ditches and ponds under different irrigation and drainage management scenarios. The results showed that the annual drainage depth was as high as 1 162 mm, accounting for 59% of the total irrigation and rainfall depth under the current irrigation and drainage practice. The surface runoff depth accounted for 51% of the total drainage, including a 20% uncontrollable portion caused by storm events. A controlled irrigation strategy (or irrigating only when the field water level drops to -25 cm and no significant rainfall was forecasted) was significantly adopted to reduce the drainage and nitrogen losses: 55% reduction in the drainage and 59% reduction in the NH3-N, compared with the conventional practice. However, the controlled drainage presented a relatively low effect on drainage reduction and surface runoff. The total drainage remained nearly constant for the controlled drainage with the fixed irrigation volume under the current irrigation practice, indicating an increase in the surface runoff from 51% to 75%. The total drainage was reduced from 519 mm to 435 mm (16% reduction), whereas, the surface runoff increased from 35% to 56% under the controlled irrigation practice. The NH3-N concentration in the surface runoff (2.85 mg/L) was higher than that in the subsurface drainage (1.80 mg/L), indicating the significant increase of NH3-N losses with the increased surface runoff. Therefore, there were much higher volumes of irrigation and drainage water in the nitrogen reduction, in terms of the ditches and ponds distribution in the small agricultural watershed of the study area. Only when the drainage volume was significantly reduced using the controlled irrigation and drainage practice, the current ditches and ponds (15% of the farmland area) can be expected to gain lower ammonia nitrogen concentration level for the national water quality standards of Class V for surface water. Nevertheless, there is also an adverse impact on the NH3-N for the shallow depth (60 cm) of the drainage ditches, due to the increase in the surface runoff in the study area. In conclusion, the controlled irrigation of paddy fields can be more effective to reduce drainage and nitrogen losses. Consequently, the reduced amount of drainage water and the integrated management or optimization of the existing wetlands of ditches and ponds can greatly contribute to the water quality of rice irrigation areas in small agricultural watersheds. [ABSTRACT FROM AUTHOR]

Copyright of Railway Signalling & Communication Engineering is the property of Railway Signalling & Communication Engineering and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Coal Science & Technology (0253-2336) is the property of Coal Science & Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Ditch cleaning (DC) is increasingly applied to facilitate forest regeneration following clear-cutting in Fennoscandinavia. However, its impact on the ecosystem carbon and greenhouse gas (GHG) balances is poorly understood. We conducted chamber measurements to assess the initial DC effects on carbon dioxide (CO2) and methane (CH4) fluxes in a recent forest clear-cut on wet mineral soil in boreal Sweden. Measurements were conducted in two adjacent areas over two pre-treatments (2018/19) and two years (2020/21) after conducting DC in one area. We further assessed the spatial variation of fluxes at three distances (4, 20, 40 m) from ditches. We found that DC lowered the water table level by 12 ± 2 cm (mean ± standard error) and topsoil moisture by 0.12 ± 0.01 m3 m−3. DC had a limited initial effect on the net CO2 exchange and its component fluxes. CH4 emissions were low during the dry pre-treatment years but increased particularly in the control area during the wet years of 2020/21. Distance to ditch had no consistent effects on CO2 and CH4 fluxes. Model extrapolations suggest that annual carbon emissions decreased over the four years from 6.7 ± 1.4 to 1.6 ± 1.6 t-C ha−1 year−1, without treatment differences. Annual CH4 emissions contributed <2.5% to the carbon balance but constituted 39% of the GHG balance in the control area during 2021. Overall, our study suggests that DC modified the internal carbon cycling but without significant impact on the carbon and GHG balances. [ABSTRACT FROM AUTHOR]

It is difficult to build roads in the desert areas with wind-blown sands because the prevailing harsh environment and the characteristics of the aeolian sands inhibit strategies and measures for road damage prevention and control that are typically effective in other settings. Typically, the rainfall period in aeolian sand areas worldwide is concentrated and the rainfall volume is relatively large, which combined with small and unstable nature and the aeolian sand particles means roads built in these areas can be easily washed away and are vulnerable to water damage. Given geological conditions, topographic features and hydrometeorological conditions differ depending on the region, basic research into water damage in highway roadbed slopes in aeolian sand areas is necessary to formulate treatment measures that are versatile and applicable in different regions. Towards that end, this study strengthens the evaluation of roadbed and pavement drainage and protective measures given aeolian sand erosion caused by rainwater infiltration in certain longitudinal length sections of the Expressway K165 + 250 mileage pile section, and includes verification of the design scheme. The effects of rainwater drainage, storage, and subgrade reinforcement on the seepage and stability of drainage in a long longitudinal slope in the desert hinterland were quantitatively analyzed using numerical analysis. Additionally taking into account the regional climate environment characteristics that locally prevail, the necessity and applicability of geotechnical reinforcement in practical engineering applications is demonstrated. The research found the stability of the subgrade slope given potential for rainfall erosion due to concentrated-rainfall periods in an aeolian sand region is promoted through measures including slope drainage on the highway combined with side ditch drainage, strengthening of the box culvert under embankment ditches, and local protection by laying geogrid in the embankment to produce a significant lateral diffusion effect. [ABSTRACT FROM AUTHOR]

Dredged soil has a high potential resource utilization for agricultural land, but the dredged soil is difficult to be directly used because of its high moisture content and poor engineering properties, therefore, it needs to be dehydrated and solidified. Relying on a dredging project, taking newly dredged soil as the research object, the solidification of surface dredged soil by plant combined with engineering drainage measures was explored, and the solidification effect was studied. The results showed that the excavation of drainage ditches every 30 m on the cofferdam in the soil storage area and laying rice straw in the ditches can quickly drain the surface soil moisture and purify the SS in the water, with an average removal rate of 52.5% . Planting pennisetum hydridum can accelerate the water loss and solidification of shallow surface dredged soil, especially in the depth range of 50 to 100 cm. About 5 months after planting, the maximum bearing capacity reached 90.7 kPa, while that of blank control was only 53.6 kPa. The solidification effect of 0.5 m planting spacing is better than that of 1 m planting spacing. In conclusion, the way of planting combined with engineering drainage measures can effectively solidify the shallow surface dredged soil, which is an ecological and environmentally protection method for the solidification of dredged soil. [ABSTRACT FROM AUTHOR]

Amphibians are the most threatened vertebrate group on earth, and one of the reasons for their decline is habitat loss. While some populations have persisted in agricultural wetlands such as rice paddies, the current anthropisation of landscapes is dealing a new blow to the survival of these species. In rice paddies, the new threats are especially visible through the increased channelization of water bodies with increasingly efficient drainage ditches, which become deadly traps. We first conducted surveys over three years to determine the use of ditches by frog species for natural versus concrete ditches, and thus relate to habitat adequacy as well as the probability of becoming trapped in concrete ditches. We then set up four types of experimental arena for escape trials. Experiments were replicated for the Black-spotted pond frog (Pelophylax nigromaculatus), as a proxy for other species abundant in rice paddies in the Republic of Korea. We determined that a slope of at least 70 degrees, with engraved patterns, was the only set-up from which frogs managed to escape. We recommend the implementation of this type of device in areas where a high concentration of animals is trapped, before phasing out the ancient design and relying on amphibian-friendly drainage ditches as they also support higher amphibian biodiversity. [ABSTRACT FROM AUTHOR]

Copyright of Railway Standard Design is the property of Railway Standard Design Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

We performed geophysical and geoarchaeological investigations in the Wadden Sea off North Frisia (Schleswig-Holstein, Germany) to map the remains and to determine the state of preservation of the medieval settlement of Rungholt, especially its southern dyke segment, called the Niedam dyke. Based on archaeological finds and historical maps, Rungholt is assumed to be located in the wadden sea area around the island Hallig Südfall. During medieval and early modern times, extreme storm events caused major land losses, turning cultivated marshland into tidal flats. Especially the 1st Grote Mandrenke (or St. Marcellus' flood), an extreme storm surge event in 1362 AD, is addressed as the major event that flooded and destroyed most of the Rungholt cultural landscape. Cultural traces like remains of dykes, drainage ditches, tidal gates, dwelling mounds or even plough marks were randomly surveyed and mapped in the tidal flats by several authors at the beginning of the 20th century. Due to the tidal flat dynamics with frequently shifting tidal creeks and sand bars, the distribution of cultural remains visible at the surface is rapidly changing, making it hard to create a comprehensive map of the cultural landscape by surveying. Today, the Niedam dyke area is fully covered by tidal flat sediments, depriving any remains from further archaeological investigation. Since little is known about the precise location or state of preservation of these remains, our investigation aimed at the rediscovery of the medieval dyke system and associated structure with modern and accurate geophysical, geodetical and geoarchaeological methods. Magnetic gradiometry revealed a large part of the medieval dyke, confirming two tidal gates and several terps connected inland with the dyke, providing a detailed example of a Frisian medieval dyke system. Based on our results, the so far inaccurate and incomplete maps of this part of Rungholt can now be specified and completed. Beyond that, seismic reflection profiles give a first depth resolving insight in the remains of the dyke system, revealing a severe threat to the medieval remains by erosion. The site is exemplary for the entire North Frisian coast, that was influenced by multiple flood events in the middle ages to modern times. [ABSTRACT FROM AUTHOR]

Due to their burrowing lifestyles that make them difficult to sample, the distributions and habitat associations of most burrowing crayfishes are poorly understood. A distributional study was conducted in south-western Pennsylvania to better understand the range and habitat associations of the primary burrowing crayfish Cambarus dubius within the state. A total of 790 new sites and six previously surveyed sites were sampled between the Chestnut Ridge and Allegheny Mountains, with the majority of these localities being roadside ditches. Crayfish were collected using a combination of burrow excavation, baited lines, and by hand. We utilised permutation-based t-tests to determine differences in habitat variables between sites with and without C. dubius and sites with and without any burrowing crayfish species. Cambarus dubius was collected from 61 total sites, and active crayfish burrows were observed at 137 additional sites. Cambarus carinirostris was collected from 13 sites, Lacunicambarus thomai was collected from six sites, and an exuvia of Procambarus acutus was collected from a stream at one site. New behavioural observations for C. dubius juveniles were observed while collecting specimens with baited lines. Sites with C. dubius had significantly more canopy cover and deciduous forest land cover and significantly less pasture-hay land cover than sites without C. dubius. Sites with burrowing crayfishes (all species) had significantly more canopy cover and deciduous forest land cover and significantly lower elevation, depth to the water table, percent sand substrate and pasture-hay land cover than sites without burrowing crayfish. In Pennsylvania, Cambarus dubius has not expanded its range in comparison to its historical range, and populations appear to be concentrated primarily in the southern valleys of the Chestnut Ridge and Allegheny Mountains. [ABSTRACT FROM AUTHOR]

This paper investigated the hydraulic characteristics of the triangular central baffle (TCB) flume. Laboratory tests were carried out to determine the flume dimensions. The field applicability of the proposed portable device was examined by on-farm installation. According to the laboratory tests, when the contraction ratio, r, was less than 0.39, the flow capacity was not affected by the ratio between the flume's floor height and the throat width. The laboratory analysis also showed that there was no significant effect of installing an entrance ramp on the stage-discharge relationship for r<0.39, while the entrance ramp increased the discharge capacity for r>0.39. The stage-discharge curve obtained based on the laboratory tests was verified using field data. The results revealed that the proposed portable flume could be used accurately to determine the flow through an unlined ditch. Practical suggestions were proposed to determine the distinguishing condition curve. [ABSTRACT FROM AUTHOR]

The aim of this study is to develop a method for identification of the drainage ditch network, which can be used for surface runoff modeling and to increase accuracy of estimation of greenhouse gas (GHG) emissions in croplands and grasslands, using remote sensing data. The study area consists of 11 objects throughout Latvia with a total area of 145 km². Digital elevation models (DEMs) in two resolutions, which were created using three different interpolation methods, were used for the analysis. Several multi-level data filtering methods were applied to identify ditch network, including flow patterns, which can be used in surface runoff process. The method we developed correctly identified 85–89% of ditches, depending on the DEM used, in comparison to the reference data. Mapped ditches are located within 3 m range of the reference data in 89–93% of cases. The elaborated model is robust and uses openly available source data and can be used for large scale ditch mapping with sufficient accuracy necessary for hydrological modelling and GHG accounting in the national inventories. [ABSTRACT FROM AUTHOR]

In order to solve the problems of blocking the drainage ditch and reducing the soil flatness caused by soil accumulation when using compound planter with plowshare to ditch, a spiral soil separation mechanism (SSSM) is designed. The SSSM is analyzed. In order to obtain the optimal parameters of the SSSM, based on the discrete element method, the multifactor test is carried out with the embedded depth, pitch, and rotation speed of the spiral blade as the test factors and the soil separation distance and uniformity as the evaluation index. The optimal parameters are the embedded depth 49 mm, pitch 331 mm, and rotation speed of the spiral blade 318 r min−1. The field experiment is carried out with these parameters, with soil separation distance 900 mm and standard deviation of soil height 7.8 mm, which is consistent with the simulation results. No blockage of drainage ditch was found, which shows that this device can effectively solve the problem. This study can provide a reference for the design of soil separation equipment using spiral soil separation device. [ABSTRACT FROM AUTHOR]

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What factors contribute to the success of community-driven upgrading of informal settlements? The Rwandan government has adopted informal settlement upgrading and governance policies that allow citizens to participate in decision-making on issues that affect them in the Umudugudu—the smallest unit of governance. This study investigates how the government's policy has enabled community-driven informal settlement upgrading as an everyday practice, with a particular emphasis on developing and maintaining public infrastructure facilities in Kigali, the capital city of Rwanda. We conducted fieldwork, including interviews and observations, in Umudugudu of Kamwiza and Umudugudu of Mucyuranyana, located in the western part of Kigali City, from September to October 2019. We identified and mapped road pavements, drainage ditches, bridges, and communal water taps as public infrastructure facilities. We conducted semi-structured interviews with residents and committee members in charge of the resources and investigated the decision-making processes employed for their development and maintenance. We found that informal settlement upgrading and governance policies worked together to support the community-driven upgrading of public infrastructure facilities in Imidugudu. 1 1 Imidugudu is the plural form of Umudugudu in Kinyarwanda (Ansoms, 2009). This approach enabled the community to mobilize government and community resources to develop and maintain public infrastructure facilities. Government funds supplemented the development of community-driven facilities, serving as an incentive to encourage further community contributions. Importantly, both landowning and renting households shared the burden of development costs. We argue that community-driven upgrading is possible when communities, markets, and governments function together. Notably, upgrading efforts become sustainable everyday practices when informal settlements are integrated into public policy in terms of governance structures, urban and housing policy, and land ownership. This integration fosters communities characterized by residents' sense of ownership and internal investment in the area, along with stable budget allocations. • Policy integration could foster community's sense of ownership and stable budgets. • Government and community resources are required to develop and maintain facilities. • Upgrading requires collaboration between the community, market, and government. [ABSTRACT FROM AUTHOR]

Antibiotic resistance gene contamination in polluted rivers remains a widely acknowledged environmental issue. This study focused on investigating the contamination conditions of antibiotic resistance genes (ARGs) in Harbin's urban black-odor rivers, specifically Dongfeng Ditch and Hejia Ditch. The research employed a SmartChip Real-Time PCR System to explore the types, abundance, and distribution of ARGs in diverse habitats, such as surface water and sediment. Additionally, the study examined the correlation of ARGs with mobile genetic elements (MGEs) and various environmental factors. It was found that antibiotic resistance genes were prevalent in both water and sediment within the black-odor ditches. The dominant types of ARGs identified included aminoglycoside, sulfonamide, multidrug-resistant, and β-lactam ARGs. Notably, the top four ARGs, in terms of relative abundance, were sul1 , fox5 , qacEdelta1-01 and aadA1. Most categories of ARGs have significant positive connections with MGEs, indicating that the enrichment and spreading of ARGs in rivers are closely related to MGEs. Based on the correlation analysis, it is found that environmental factors such as dissolved oxygen (DO), ammonia nitrogen (NH 4 –N), and phosphate (PO 4 –P) played a substantial role in influencing the variations observed in ARGs. By employing a risk assessment framework based on the human association, host pathogenicity, and mobility of ARGs, the identification of seven high-risk ARGs was achieved. In addition, it is important to assess the environmental risk of ARGs from multiple perspectives (abundance,detection rateand mobility). This study provides a significant reference regarding the presence of ARGs contamination in urban inland black-odor rivers, essential for assessing the health risks associated with ARGs and devising strategies to mitigate the threat of antibiotic resistance. [Display omitted] • The ARG (sul1) exhibits the highest abundance in black-odor ditch. • The spread of ARGs might be mainly affected by DO and mobile genetic elements. • Nutrients promote the proliferation of ARGs within a certain concentration range. • Among 84 known ARGs in the black-odor rivers, 7 ARGs belonged to high-risk. [ABSTRACT FROM AUTHOR]

Urban regions are suggested to be the main source of microplastic pollution in rivers. Thus, we investigated the spatiotemporal distribution of microplastics in the surface water of the Lanzhou section of the Yellow River in a semiarid region and the contributions of typical sources. The average concentration of microplastics in the surface water of the river was 0.98 particles (p) L−1. The daily quantity flux and mass flux were 3.63 × 109 p d−1 and 95.38 kg d−1, respectively. Most of the microplastics in the river were fibers and fragments, composed of polyethylene terephthalate, polyamide, polypropylene and polyethylene. A large quantity and mass of microplastics were found in the high-flow period of the river. The hotspots of microplastic pollution were residential and tourist reaches. The spatial distribution of microplastics was influenced by anthropogenic factors. However, the main factor influencing the temporal distribution of microplastics was precipitation seasonality. Most of the microplastics in the surface water originated from drainage ditches. The direct contribution of microplastics from atmospheric deposition was also considerable. Our results suggest that the contribution of microplastics from atmospheric deposition to urban rivers is worthy of attention. [Display omitted] • Low microplastic pollution level in Lanzhou section of the Yellow River. • Most microplastics in surface water was distributed in high-flow period. • Residential and tourist reaches were microplastic hotspots in surface water. • Rainfall runoff was the major contributor for microplastics in the river. • Direct microplastic contribution from atmospheric deposition was also crucial. [ABSTRACT FROM AUTHOR]

Agricultural intensification has a profound negative impact on farmland biodiversity worldwide. Birds closely associated with agricultural landscapes are a key indicator group for evaluating sustainability in land use. We identified key determinants of hatching success in northern lapwings (Vanellus vanellus) in agricultural landscapes of Estonia. In total, we monitored 133 nests to record the causes of nest failures on 85 field plots from three farming management types over two years. Hatching success as indicated by daily survival rate of nests was significantly lower in organic (94%) when compared to conventionally managed (98%) cultivated fields. We showed that this was mainly caused by increased nest predation by mammalian and avian predators in organic fields. Landscape elements, such as drainage ditches with tall vegetation decreased nest predation by mammalian predators. Depredation of nests by avian species was negatively related to the breeding density of lapwings, suggesting the effectiveness of their collective defense against raptors and corvids. We conclude that the hatching success for ground-breeding birds in arable fields is mainly affected by differences in nest predation. Agri-environment schemes, such as providing funding for organic farming, effectively increase the diversity and abundance of wild animals, while also increasing the number of nest predators as a side effect. The challenge is to control the abundance of mammalian and avian nest predators using different methods. Regional agricultural policy should support the retention of ditches with tall vegetation in agricultural landscapes that can effectively reduce nest predation by mammals. • Hatching success of lapwings was lower in organic than in conventionally managed fields. • Organic fields were associated with increased nest predation. • Drainage ditches with high vegetation were related to decreased nest predation by mammalian predators. • Nest predation by birds was negatively related to the breeding density of lapwings. [ABSTRACT FROM AUTHOR]

Ditch cleaning (DC) is a forestry practice commonly conducted in boreal regions that aim to lower groundwater tables (GWT) in waterlogged soils, thereby maintaining or improving forest growth. However, there is limited information on the impact of DC on water chemistry and dissolved greenhouse gases (GHG) in draining ditch networks. Based on a repeated synoptic sampling of a paired catchment design we here evaluated water chemistry and GHG data in ditch waters from 25 cleaned sites (being cleaned 1–4 years prior to sampling) and 25 non-cleaned reference sites (REF). The sampled sites were further selected to test whether there were any differences in the DC effect if the operations were conducted in forested or clear-cut areas. Across all sites, we found that DC sites exhibited higher pH, sulfate and calcium concentrations than REF sites. Also, lower dissolved carbon dioxide and higher nitrous oxide concentrations were observed in DC sites. In forested areas, DC sites exhibited significantly higher calcium and potassium concentrations, along with reduced levels of methylmercury and carbon dioxide. In clear-cuts, sulfate concentrations were significantly elevated in the DC sites. We suggest that the observed differences in water chemistry and GHG´s between DC and REF sites were induced by the DC and largely driven by lower GWT following DC, resulting in deeper groundwater flow paths through more mineral-rich soil layers, and altered redox conditions. Also, the removal of organic rich sediments and vegetation from the ditches themselves may affect water chemistry and GHG´s e.g. by decreasing the formation of methylmercury and carbon dioxide. • Cleaned and non-cleaned ditches were sampled for water chemistry and GHG's. • pH, sulfate and calcium were higher in cleaned than in non-cleaned ditches. • Cleaned ditches had lower dissolved CO 2 and higher N 2 O than non-cleaned ditches. • MeHg was elevated in cleaned ditches of clear-cuts, but not in forested areas. [ABSTRACT FROM AUTHOR]