Drainage Ditches Research Articles

Event-based analysis of wetland hydrologic response in the Prairie Pothole Region

Previous studies in the Prairie Pothole Region mainly assessed wetland hydrologic function at seasonal, annual and decadal scales. While many studies have looked at water balance dynamics and local flow generation processes in wetlands, no study looked at hydrological dynamics in response to individual rainfall events in prairie pothole wetlands (here after referred as wetlands) across a gradient of alteration. The present study aimed to investigate: (1) the most important metrics needed to characterize the spatial variability of wetland hydrologic response to rainfall-runoff events; (2)the temporal variability of individual wetland hydrologic response; (3) the spatial and temporal variability of wetland-stream interaction; and (4) the temporal persistence of various spatial controls on individual wetland hydrologic response characteristics. High-frequency water level data was collected over two years for ten intact, three consolidated, and seven drainage ditches associated with fully drained wetland(s), as well as a creek located in southwestern Manitoba, Canada. The hydrologic response of the studied wetlands to individual rainfall-runoff events was characterized using a range of metrics. Several data analysis methods were used, including principal component analysis, graphical assessments of wetland-stream hysteresis dynamics, and correlations analyses between wetland response metrics and spatial characteristics. Results suggested that wetland alteration status (i.e., drained versus intact, open-water wetlands) plays an important role in explaining differences in the event-scale hydrologic behaviour of wetlands. Climatic and antecedent storage conditions (i.e., surface and subsurface storage in wetland basin) also had a strong influence on the hydrologic responses of wetlands during individual rainfall-runoff events and appeared to override the influence of spatial controls such as wetland area, volume or catchment area. Antecedent storage also seemed to be the driving factor of wetland-stream interactions. A lack of persistent correlations between wetland spatial characteristics and response metrics was observed and suggested nonstationary wetland hydrological behaviours and controls, a conclusion that has significant implications for wetland classification and modelling.

Millennial-Scale Carbon Storage in Natural Pine Forests of the North Carolina Lower Coastal Plain: Effects of Artificial Drainage in a Time of Rapid Sea Level Rise

Coastal forested wetlands provide important ecosystem services along the southeastern region of the United States, but are threatened by anthropogenic and natural disturbances. Here, we examined the species composition, mortality, aboveground biomass, and carbon content of vegetation and soils in natural pine forests of the lower coastal plain in eastern North Carolina, USA. We compared a forest clearly in decline (termed “ghost forest”) adjacent to a roadside canal that had been installed as drainage for a road next to an adjacent forest subject to “natural” hydrology, unaltered by human modification (termed “healthy forest”). We also assessed how soil organic carbon (SOC) accumulation changed over time using 14C radiocarbon dating of wood sampled at different depths within the peat profile. Our results showed that the ghost forest had a higher tree density at 687 trees ha−1, and was dominated by swamp bays (Persea palustric), compared to the healthy forest, which had 265 trees ha−1 dominated by pond pine (Pinus serotina Michx). Overstory tree mortality of the ghost forest was nearly ten times greater than the healthy forest (p < 0.05), which actually contributed to higher total aboveground biomass (55.9 ± 12.6 Mg C ha−1 vs. 27.9 ± 8.7 Mg ha−1 in healthy forest), as the dead standing tree biomass (snags) added to that of an encroaching woody shrub layer during ecosystem transition. Therefore, the total aboveground C content of the ghost forest, 33.98 ± 14.8 Mg C ha−1, was higher than the healthy forest, 24.7 ± 5.2 Mg C ha−1 (p < 0.05). The total SOC stock down to a 2.3 m depth in the ghost forest was 824.1 ± 46.2 Mg C ha−1, while that of the healthy forest was 749.0 ± 170.5 Mg C ha−1 (p > 0.05). Carbon dating of organic sediments indicated that, as the sample age approaches modern times (surface layer year 2015), the organic soil accumulation rate (1.11 to 1.13 mm year−1) is unable to keep pace with the estimated rate of recent sea level rise (2.1 to 2.4 mm year−1), suggesting a causative relationship with the ecosystem transition occurring at the site. Increasing hydrologic stress over recent decades appears to have been a major driver of ecosystem transition, that is, ghost forest formation and woody shrub encroachment, as indicated by the far higher overstory tree mortality adjacent to the drainage ditch, which allows the inland propagation of hydrologic/salinity forcing due to SLR and extreme storms. Our study documents C accumulation in a coastal wetland over the past two millennia, which is now threatened due to the recent increase in the rate of SLR exceeding the natural peat accumulation rate, causing an ecosystem transition with unknown consequences for the stored C; however, much of it will eventually be returned to the atmosphere. More studies are needed to determine the causes and consequences of coastal ecosystem transition to inform the modeling of future coastal wetland responses to environmental change and the estimation of regional terrestrial C stocks and flux.

Rate of Fen-Peat Soil Subsidence Near Drainage Ditches (Central Poland)

This study analyzed design depths (to), post-subsidence depths (t), shallowing magnitudes (d = to − t) and ratio values (d/t) of 12 drainage ditches in a fragment of the drained Solec fen-peat (central Poland) over a period of 47 years between 1967 and 2014. A significant decrease of the designed depth of the ditches to was shown, from the average designed value of 0.97 m to their average depth after subsidence, t = 0.71 m. The ratio (d/t) of 0.41, which is associated with the degree of organic matter decomposition, indicated medium degree of peat decomposition. The average values of bank and bottom subsidence of the ditches during the analyzed period, 1967–2014, were 0.43 m and 0.17 m, respectively. The values of the average annual rate of land surface subsidence in the vicinity of the ditches were varied and within the range of 0.09 cm year−1 to 1.70 cm year−1, with an average of 0.92 cm year−1. Two linear empirical equations were proposed to calculate the amount of subsidence and the average annual rate of subsidence of peat soil surface near the drainage ditch route, based on the knowledge of the initial thickness of the peat deposit. The results of calculations using the equations proposed by the authors were compared with calculations of the same parameters using 10 equations published in the literature. The results obtained using the proposed equations were mostly larger than those calculated with literature-published equations.

Determinants of Pathogen Contamination of the Environment in the Greater Yangon Area, Myanmar.

Recent results from water, sanitation, and hygiene interventions highlight the need to better understand environmental influences on enteropathogen transmission. We quantified a range of viral, bacterial, and protozoal pathogens and one indicator, Enterococcus faecalis in soil and water from urban and rural sites in and around Yangon, Myanmar. We found that environmental characteristics associated with contamination differed by pathogens and substrates. In soil, bacterial pathogen gene counts were associated with elevation and drainage ditches (compared to stagnant water) (RR = 0.96, 95% CI 0.93, 0.99 and RR = 1.70, 95% CI 1.18, 2.45, respectively), while viral gene counts were associated with the presence of sanitation facilities within 50 m of the collection point (RR = 3.99, 95% CI 1.12, 14.24). In water, E. faecalis, total pathogen, and bacterial pathogen gene counts were associated with drainage ditches (RR = 1.86, 95% CI 1.27, 2.72, RR = 1.38 95% CI 1.09, 1.74, and RR = 1.38 95% CI 1.07, 1.77, respectively). E. faecalis, total pathogen, bacterial pathogen, and viral gene counts were associated with the presence of uncollected garbage within 50 m of the collection point (RR = 1.57, 95% CI 1.00, 2.47, RR = 1.52, 95% CI 1.16, 2.00, RR = 1.52, 95% CI 1.13, 2.06, and RR = 1.75, 95% CI 1.17, 2.61 respectively). Measuring the environment provides added specificity toward identifying important environmental pathways that require mitigation.

Comparative Microbial Communities of Anode Associated Soils in Sediment Microbial Fuel Cells of Rice Field and Drainage Ditch Soils

Comparative Microbial Communities of Anode Associated Soils in Sediment Microbial Fuel Cells of Rice Field and Drainage Ditch Soils

Evaluating soil erosion and factors determining farmers’ adoption and management of physical soil and water conservation measures in Bachire watershed, southwest Ethiopia

Soil degradation due to erosion, which emanates from improper land management, has been one of major challenges affecting agricultural production and food security. To control soil erosion, soil and water conservation (SWC) measures including soil and stone bunds have been developed and adopted. However, little is known on the impacts of SWC techniques in Africa. Objective of this study was to assess soil erosion and analyze effect of physical SWC measures on cropland productivity. Data were collected using focus group discussion, key informant interview and survey of 169 farm households (122 adopters and 47 non-adopters of physical SWC). Farmers were responded on soil erosion (rill and gully) and its impacts, long existed indigenous erosion mitigation measures as well as effects of introduced physical SWC techniques such as soil and stone bunds. Descriptive statistics and binary logistic regression model were used to analyze data. Based on visible erosion features such as rills and gullies, about 92% of respondents indicated that soil erosion is a major problem on cultivated land, where 64% of the farmers abandoned part of their plot due to exhausted soil fertility and gully development. About 97% of the farmers perceived that soil erosion reduces crop production. Traditional drainage ditch, grass strip and contour furrow are common indigenous SWC measures. More than 86% of the respondents believe that the introduced physical SWC measures (e.g., bunds) reduce erosion and improve crop production. Family size, participation in technical training, access to extension service, the perceived land tenure security, slope of the plot, and perceived severity of erosion had significant (p < 0.05) and a positive association with adoption of introduced physical SWC measures, while farm size had significant (p < 0.05) negative relationship. Increasing knowledge and skill of farmers, providing technical and resource supports and implementing appropriate policy could help sustainable land management that ensure environmental quality and food security in the study area as well as in the other areas having related biophysical and socioeconomic settings.

A common agricultural soil test can identify legacy P hotspots in a drainage ditch network

Agricultural soils have accumulated considerable phosphorus (P) reserves along the transport pathways within land-water continuum. Where P concentrations are excessive compared to the soil P sorption capacity, dissolved soluble P can leach to waterbodies. A phosphorus saturation ratio (PSR = P/(Fe + Al)) can be used to classify high and low risk soils based on a commonly applied Mehlich-3 soil test. PSR has been used for acid mineral soils, but in this study it was applied to sediments and drainage ditch bankside samples. Previous published data was converted to PSR and compared to P availability measurements. The results confirmed earlier findings, that a PSR threshold of 0.1 can delineate high and low P risk sites. By quantifying the amount of P in excess to the threshold, legacy P hotspots could be located in the network which would act as an additional source of P inputs to waters. In the study site, two soils contained over 80% of the excess legacy P, presenting a localized long-term risk to water quality. The findings support using the cost effective Mehlich-3 extraction to identify hotspots with most susceptible soil-P to losses and quantify the amount of potentially leachable legacy P.

“We’re Still Here”: An Abolition Ecology Blockade of Double Dispossession of Gullah/Geechee Land

Narratives of resilience to sea-level rise too often perpetuate social violence. An abolitionist climate justice praxis necessitates seeing beyond physical inundation to sea-level rise as the sole issue. We argue that sea-level rise is environmental racism, if not always in its racialized outcomes of disproportionate harms, then always in its racialized production of differential value. More than mitigating flood risk when developing Black land futures strategies, to mitigate coastal land loss in the face of rising seas necessitates dismantling “racial regimes of ownership” that are imbued in property relations. Recognizing such, we argue that land futures strategies in the face of rising seas must account for multiple capitalist modes of accumulation but specifically the primitive accumulation process connected to heirs’ property. Here, we argue that racial coastal formations are still underway in how sea-level rise and gentrification are leading to a double dispossession of land and displacing Gullah/Geechee people on Sapelo Island. Although such displacement precipitates loss through harm and violence, in this article we share strategies from abolition ecology praxis to “blockade” these double dispossession processes and, to a degree, even the narrative of loss. To situate the double dispossession narrative within a broader praxis that imagines alternative futures, we till the soil, trace the archives, and tread the marsh and drainage ditches with each other, and in solidarity with other residents, to work toward achieving agricultural revival, property retention, and flood risk mitigation.

Seasonal variation in home range size of evening bats (Nycticeius humeralis) in an urban environment

Abstract Despite the negative impacts of urbanization on bats, green spaces in urban environments, such as parks, cemeteries, and golf courses, have the potential to provide resources necessary for these animals. Water resources in these areas include natural or semi-natural ponds, streams, and drainage ditches. Such water resources, however, are frequently ephemeral when subject to prolonged periods of high temperatures and low precipitation. We hypothesized that home ranges of evening bats (Nycticeius humeralis) would increase in size or shift from urban green spaces into surrounding neighborhoods to access alternative resources, such as residential swimming pools, when water resources in green spaces are scarce. To explore whether seasonal variations in bat home ranges occurred, we radio-tracked resident evening bats in a local park system during their summer activity period 2017–2019 in Fort Worth, Texas, USA. We used Local Convex Hulls created by associating point locations with their nearest neighbor to estimate home range size, location, and the percentage area that fell within the surrounding neighborhood. We compared these variables to temperature and precipitation using various regression models. We successfully tracked 30 bats over the 3-year period and found a positive correlation between home range size and temperature. Home range sizes increased 6-fold when temperatures exceeded 30°C. Our study indicates the importance of urban neighborhoods surrounding green spaces in providing alternative resources, such as water, for bats. If managed appropriately, these urban areas have the potential to act as oases for bat populations.

Drainage increases species richness and density of soil macro-invertebrates in the Zoige peatland of eastern Tibetan Plateau

Soil macro-invertebrates play an important role in the decomposition process of soil organic matter. As the world’s largest alpine peatland, the Zoige peatland on the eastern Tibetan Plateau is experiencing the decline in water table level primarily because of historic drainage. However, little is known about the responses of soil macro-invertebrate communities to water table decline. To address this issue, we established a field drainage experimental platform in 2013, which consists of low (50 cm deep drainage ditch) and intermediate (20 cm deep drainage ditch) water table level treatments, and the ambient (no drainage ditch) plots. In July (warm season) and November (cold season) of 2019, we examined the species composition, richness, densities and the vertical distribution of soil macro-invertebrates. Results showed that the species composition differed significantly among treatments. Species richness and densities of overall and different trophic groups (i.e., detritivores, herbivores and predators) of soil macro-invertebrates were significantly higher in the drained treatments compared to the ambient plots. Moreover, soil macro-invertebrates moved down to deeper soil layers in the low water table treatments compared to the ambient plots. In addition, sampling season (warm vs. cold) did not affect the responses of soil macro-invertebrates to water table decline. These results indicate that soil macro-invertebrate community is sensitive to water table decline in the Zoige peatland. Given the recognized importance of soil fauna to ecosystem functioning, more attention should be paid to the conservation of peatlands.

Significant Emissions From Forest Drainage Ditches—An Unaccounted Term in Anthropogenic Greenhouse Gas Inventories?

AbstractForestry is a natural climate solution for removing atmospheric carbon dioxide (CO2) and reaching net zero emissions. Managed boreal forests typically have extensive drainage ditch networks, and these can be hotspots of anthropogenic greenhouse gas (GHG) emissions, potentially offsetting the terrestrial carbon gain. However, there is a lack of data detailing GHG emissions from ditches on mineral soils, where most boreal forestry occurs. Here, we address this knowledge gap using two approaches. First, we conducted a synoptic campaign to measure summer GHG fluxes from 109 boreal forest ditches draining mineral soils within one local region. We found a clear control of ditch water level on methane (CH4), with zero emissions from dry ditches and variable, but often high, emissions from water‐filled ditches. Almost all ditches acted as sources of CO2, regardless of water status. Second, we reanalyzed a published data set of boreal forest ditches and streams across three regions where GHG concentrations had been repeatedly measured and detailed catchment information was available. Within this data set we categorized 76 ditches into mineral and peatland catchments and detected no difference in mean CH4 and CO2 concentrations between the two soil types. GHG emissions from ditches draining mineral forest soils can be as large as those from peatland forest ditches. Using literature values for forest GHG uptake we demonstrate that ditch CH4 emissions are particularly important and can offset the terrestrial CH4 uptake. Ignoring ditch emissions, which are anthropogenic in origin, will lead to incorrect estimates of the landscape‐scale forest GHG budget.

PLC Based Automated Irrigation System

Abstract: In a developing country like India, automation plays an important role in the development and advancement of the country. In the field of irrigation, proper method of irrigation is important . At the present era, the gardeners have been using irrigation technique in India through the manual control in which the gardeners irrigate at the regular intervals. This process sometimes consumes more water or sometimes the water reaches late due to which the grass and plants get dried. Over-irrigation can increase energy consumption and water cost as well as leaching of fertilizers below the root zone, erosion, and transport of soil and chemical particles to the drainage ditches. Irrigators who monitor soil moisture levels in the field greatly increase their ability to conserve water and energy and avoid soil erosion and water pollution. The objective of this paper is to develop sensor based automated gardening system to reduce water requirement and balanced gardening in smart city projects in India. Manpower isn`t required in this system and moisture content of soil will be balanced all the time.

Modeling Tidal Characteristics in a Creek-Marsh Drainage System: Implications for Stormwater Management

The traditional goal of stormwater management is to reduce the threat of flooding to life and property, and so most landscapes are engineered to maximize the speed at which the unwanted water leaves the watershed. This has been effective in landscapes with some topographic gradient. This often involves the installation of drainage ditches that disperse runoff from urban areas to receiving water bodies; in coastal areas this means a tidal creek, estuary, bay, sounds, or the coastal ocean. This practice reduces flood hazards in some cases but results in unintended effects on the natural hydrology in the watershed and downstream tidal dynamics. For low-gradient watersheds in humid climates, ditch systems also lower the water table of an area, increasing infiltration to recharge and groundwater discharge to streams (baseflow), and larger volume of freshwater delivered downstream yearround. Ditches also create unintentional avenues for the incoming tide from a tidal creek or tidally-influenced waterway to reach further inland, thus reducing the hydraulic gradient between the inland areas and the receiving water body. The combination of these effects can exacerbate compound flooding events, increasing the flood probability if high tide and storm events coincide. Additionally, coastal communities face the challenge of mitigating more complicated flood hazards while land development increases to meet the needs of a growing population. This study analyzed the tidal influence within an inland drainage ditch in the central coast of South Carolina USA that is representative of thousands of artificially-drained coastal watersheds. The ditch-creek system investigated here is 12 km long in a 753-hectare (1860-acre) watershed of Church Flats Creek, a first-order tidal system. We monitored for 13 months a 0.75-km reach of the lower ditch portion of the system, just above the relatively undisturbed tidal creek and marsh. Prior to ditching in the 1960s this system had a wetland-rich floodplain but is now partially tidal. Field data collected were stream stage (depth), discharge, tidal range, tidal volume, incoming (flood) and outgoing (ebb) tidal durations, and water table hydrograph at a location about 50 m of mid-reach of the ditch. Multiple linear regressions were performed to best predict the flood and ebb tidal durations of the system based on tidal characteristics within the ditch. The mean values were 229 ± 2.5 and 182 ± 2.1 minutes for flood and ebb tide durations, respectively and the models explained 84% (residual standard error (RSE) of 25 minutes) and 80% (RSE of 23 minutes) for the flood and ebb conditions, respectively. The models were simulated for sea levels in 1993 and 2050, and results indicate that the flood tide within the drainage ditch is predicted to increase an average of 66 minutes and the total tidal duration (flood and ebb) an average of 139 minutes by 2050. These results suggest a loss in drainage functionality as sea level rises. Increases in the duration of tidal influence will induce a lower capacity for stormwater volume than the drainage infrastructure was constructed to manage, therefore resulting in an increased frequency of compound flooding events because of the lower storage volume and decreased hydraulic gradient in the system. This study fills a knowledge gap of tidal dynamics within coastal ditch-creek systems and we urge stormwater managers to consider the unintended consequences of using traditional stormwater methods in a region that does not benefit from gravity drainage practices like in other regions.

Performance of a Bog Hydrological System Dynamics Simulation Model in an Ecological Restoration Context: Soomaa Case Study, Estonia

We describe how a bog hydrology simulation model, developed in the System Dynamics environment, predicts the changes in the groundwater levels that result from drainage ditch closure and partial thinning of the surrounding forest stand. Five plots were selected in an area that was subjected to such ecological restoration, and the observed groundwater levels were compared with the simulated ones. Across the plots, the mean difference between the observed and simulated groundwater curves varied between 0.88 and 2.63 cm, and the RMSE between 0.28 and 0.71. Although the absolute difference between the predicted vs. observed values was greater in the plots with ditch closure, the curves co-varied more closely there over time. Therefore, hydrological System Dynamics models can be particularly useful for relative comparisons and risk-mapping of novel management scenarios.

Pengaruh pengelolaan agroekosistem terhadap kelimpahan kutu loncat jeruk Diaphorina citri Kuwayama (Hemiptera: Liviidae)

Asian citrus psyllid (ACP) Diaphorina citri Kuwayama is a serious problem in citrus because it transmits huanglongbing (HLB) disease. Agricultural practices without paying attention to the agroecosystem complexity often cause the agroecosystem more suitable for insect pests proliferation and less friendly to natural enemies. The research aims to study the effectiveness of agroecosystem management compared to conventional farming in the ACP control. The effects of both treatments on the diversity and abundance of ACP’s natural enemies as well as the incidence and severity of HLB were also studied. Agroecosystem management consists of preventive and responsive actions. Preventive action was carried out through a polyculture system, planting refugia and legume cover crop, providing beetle banks, applying lime, applying organic and inorganic fertilizers, citrus pruning intensively, maintaining drainage ditches, and mechanical weed control. Responsive action is short-term control when the abundance of ACP reaches the action threshold. Responsive action was carried out through biological or chemical control. Meanwhile, conventional farming is a series of conventional farming and pest control techniques commonly applied by farmers. Each treatment was applied in three orchards of Siam Orange cv. Pontianak Citrus nobilis Lour var. microcarpa Hassk. The results showed that agroecosystem management was more effective in controlling the ACP population so that its abundance was lower and less fluctuated than conventional farming. ACP’s natural enemies in agroecosystem management were also more diverse than conventional farming. The abundance of ACP’s natural enemies and the incidence and severity of HLB in the two treatments were not significantly different.

Feasibility of using Mg/Al-based layered double hydroxides as an inactivating agent to interrupt phosphorus release from contaminated agricultural drainage ditch sediments

This study aimed to evaluate the feasibility of using Mg/Al-based layered double hydroxides (Mg/Al-LDHs) treatment to prevent phosphorus release from sediments of agricultural drainage ditches. A high-resolution diffusive gradient film technique and a high-resolution peeper technique were used to measure the phosphorus and iron concentrations in the overlying water and sediment profiles at sub-millimeter vertical resolution. Results demonstrated that Mg/Al-LDHs effectively reduced the concentrations of soluble reactive P (SRP) (about 69%) in the overlying water and the concentrations of SRP (about 37.42%) and labile P (about 36.72%) in the pore water. The highly positive correlation (p < 0.01) between SRP and soluble Fe, labile P and labile Fe in the sediment profiles provided high-resolution evidence for the simultaneous release of iron and phosphorus in sediments. Furthermore, Mg/Al-LDHs inactivated mobile P (NH4Cl-P and BD-P) in the uppermost sediment (0–50 mm) and then transformed the mobile P to more stable P (NaOH-rP, HCl-P, and Res-P) (about 81% of total extractable P). An inactivation layer with low phosphorus concentrations was observed in the upper sediment. In brief, the addition of Mg/Al-LDHs to the sediment surface of agricultural drainage ditches was effective in reducing SRP concentrations in the overlying water while effectively hindering the release of sediment internal phosphorus from the pore water to the overlying water.

Radial Growth Response of Scots Pine (Pinus sylvestris L.) after Increasing the Availability of Water Resources

In the years 1998–2022, about eight thousand hydrotechnical facilities were built or planned for construction at the State Forests National Forest Holding in Poland, which could slow down the outflow of water from small forest catchments and store over 50 hm³ of water. Due to the innovative and unprecedented nature of investments retaining water resources on forest land, having a significant impact on the adaptation and mitigation of the negative effects of climate change, the literature on the subject lacks in studies describing their impact on the adjacent forest environment. The aim of the presented research is to determine the evolution of the tree-ring width of Scots pine (Pinus sylvestris L.) before and after the reconstruction of two water reservoirs and the construction of gates in drainage ditches as part of small retention projects in lowland areas. The research was carried out on the basis of core drillings collected in four forest districts and climate data provided by the Polish Institute of Meteorology and Water Management—National Research Institute. In the first stage of the work, no statistically significant influence of climatic conditions on the shaping of growths was demonstrated. In the next step, the variability of increments and their width in individual years before and after the investment was examined. Then, the distance of individual trees from reservoirs and drainage ditches was analyzed, as well as its importance in forming increments. The calculated statistical significance of differences in increments, average, minimum and maximum values, as well as standard deviation indicated the possible influence of retention reservoirs and valves on shaping the increments. The study did not confirm the importance of the distance of trees from the newly available water resources in the growth of the width of the increments.

Habitat use by Long-tailed Weasels in a Fragmented Agricultural Landscape

Long-tailed weasels (Mustela frenata) have an extensive North American geographic range and tolerate a wide range of life zones, excluding some desert ecosystems. However, little is known of their habitat use in landscapes fragmented by agriculture, despite the fact that long-tailed weasel populations may be declining in these landscapes. During late winter-spring and late summer-autumn 1998–2000, we monitored 11 long-tailed weasels (seven males, four females) via radio telemetry to examine patterns of habitat use in an Indiana landscape fragmented by agriculture. Long-tailed weasels exhibited scale-dependent patterns of habitat selection (i.e., habitat selection within a landscape and selection of habitats within home ranges). Weasels selected forest patches, fencerows, and drainage ditches, whereas agricultural fields were avoided. Forest patches and fencerows provided suitable den sites and refuge cover from other predators and exhibited an abundant and diverse prey community. Drainage ditches provided movement corridors and access to free-standing, drinking water. The resource selection patterns and limited dispersal ability of long-tailed weasels compared to other carnivores are consistent with the notion that long-tailed weasels appear sensitive to agriculturally induced fragmentation of habitat.

The streamwise velocity distribution in a two-stage channel with ice cover

Abstract The problem of agricultural non-point source pollution has become increasingly serious. How to determine the ecological drainage ditch system is one of the effective methods to solve the agricultural non-point source pollution. This research study focuses on the velocity distribution in a two-stage section ecological channel with ice cover. The results show that the two-stage section channel with ice cover can effectively reduce the flow velocity in the channel and increase the retention time of water in the channel. By comparing with the experimental data, the accuracy of the analytical solution is high, which provides a theoretical reference for the transport of sediment and pollutions in a two-stage section channel with ice cover in the future.

Evidence‐based restoration of freshwater biodiversity after mining: Experience from Central European spoil heaps

Abstract Post‐mining freshwater habitats can serve as secondary habitats for threatened species. Being globally plentiful, their efficient restoration should be based on detailed evidence, especially under the current global decline of freshwater biodiversity. Synthetic studies focusing on the effects of restoration on freshwater communities are surprisingly rare, even for the most common restoration approaches. Such a lack of evidence limits the efficiency of habitat restoration in post‐mining landscapes. We combined a landscape‐scale field study of aquatic beetles and hemipterans in 29 freshwater pools at lignite spoil heaps in Czechia with a comparative synthesis of all 14 available datasets on freshwater communities at habitats created by coal mining in Central Europe. We compared the diversity and conservation value of freshwater habitats created by the main restoration approaches, including technical reclamation, spontaneous succession and their combination. Additionally, we analysed the detailed influence of key habitat descriptors on their conservation potential. Communities of aquatic beetles and hemipterans had more species in spontaneously and semi‐spontaneously developed pools, which were also preferred by more red‐listed species of both studied groups. The reviewed studies showed the same trend for amphibians, odonates, dipterans and macrozoobenthos, although some technically created pools and drainage ditches harboured some threatened species of aquatic plants, odonates and macrozoobenthos as well. Relatively independent of the restoration approach, the conservation value of freshwater communities was related to the particular characteristics of the restored habitats. The key beneficial features were as follows: smaller area of restored water bodies, heterogeneous littoral vegetation with suppressed dominants, heterogeneous bottom substrate with low and gradually sloping banks, absence of fish, sun‐exposed water surface and some forests in the surroundings. Synthesis and applications. Efficient restoration of freshwater habitats at post‐mining landscapes can create important secondary refuges for threatened and common species. Freshwater communities of high conservation value can be supported by all main restoration approaches if heterogeneous habitats are created. A combination of technical reclamation with spontaneous succession seems to be the most efficient approach to maximise biodiversity in freshwater habitats at coal‐mining spoil heaps.