Man-made Ditches Research Articles

Metabolic processes control carbon dioxide dynamics in a boreal forest ditch affected by clear-cut forestry

Boreal watercourses are large emitters of carbon dioxide (CO2) to the atmosphere. For forestry intensive areas of the Nordic and Baltic countries, a high share of these watercourses are man-made ditches, created to improve drainage and increase forest productivity. Previous studies have suggested that terrestrial sources sustain the CO2 in these ditches and variability in hydrology is the main temporal control. However, few studies have explored ditch CO2 dynamics and its associated controls in catchments being exposed to forest harvest. An altered hydrology, increased nutrient export and light availability following forest harvest are all factors that potentially can change both levels, dynamics, and source controls of ditch CO2. Here, high-frequency (30 min) CO2 concentration dynamics together with other hydrochemical variables were studied in a forest ditch draining a fully harvested catchment in the Trollberget Experimental Area, northern Sweden. We collected data during the snow-free season from May to October. Ditch CO2 concentrations displayed a clear seasonal pattern with higher CO2 concentrations during summer than in spring and autumn. Concentrations ranged from 1.8 to 3.5 mg C L−1 (median: 2.4 mg C L−1, IQR = 0.5 mg C L−1). Strong diel cycles in CO2 developed during early summer, with daily amplitudes in CO2 reaching up to 1.1 mg C L−1. These pronounced daily cycles in CO2 were closely related to the daily sum of shortwave radiation and water temperature. Variations in hydrology had generally a low impact on the CO2 dynamics but did vary among seasons and between individual hydrological events. It was evident from our study that growing season CO2 concentrations in a forest ditch affected by clear-cut harvest were highly variable and mainly controlled by light and temperature induced metabolism. These high dynamics and the associated controls need to be considered when scaling up ditch CO2 emissions across boreal landscapes affected by intensive forestry.

Evaluating the effect of natural-artificial linear landscape elements on flow and sediment connectivity in a typical agricultural terraced catchment, China

Linear landscape elements, such as man-made ditches and road networks, play a pivotal role in the transport of water and eroded sediments. Yet very few studies have focused on the variations in drainage flow paths disturbed by artificial linear landscapes and their contribution to flow and sediment connectivity (FSC). This study utilized the index of connectivity (IC) to examine and distinguish the impact of natural and artificial linear landscape elements (i.e., natural streams, man-made ditches, and road networks) on the spatial distribution of FSC. The method was employed in a typical agricultural terraced catchment of the Honghe Hani Rice Terraces World Heritage Site of China, based on two weight factors - roughness index (RI) and Rndvic factor. The results indicate that the incorporation of the linear landscape elements for the IC calculation remarkably affected the spatial distribution of FSC. Specifically, FSC values notably increased by closing the distance to linear landscape elements within a specific threshold. Moreover, in the confluence between natural and artificial linear landscape elements, the mean value of FSC was higher compared to scenarios without any or only one linear landscape element. In comparison, the presence of road networks only improved lateral connectivity by modifying the surface flow along east-west directions, while man-made ditches significantly influenced both longitudinal and lateral connectivity to a larger degree, especially in the terraced area. This finding underscores the effectiveness of ditch constructions as management practices for the regulation of water resources and facilitating the downstream transfer of sediment. Field observations and validation confirmed that Rndvic, which incorporates vegetation variable as a weight factor in the calculation of IC, yields more accurate and reliable maps of FSC than that of RI. This study holds far-reaching significance for water resources management and landscape sustainability within terrace-protected areas, providing invaluable insights for decision-makers.

An Early Iron Age Moat in Jerusalem between the Ophel and the Southeastern Ridge/City of David

Excavations on Jerusalem’s Southeastern Ridge, in the GivꜤati Parking Lot excavations, have exposed a man-made ditch, some 30 m wide and at least 6 m in depth, close to the hill’s summit. This paper presents the technical features of the ditch, including the rock scarps that delineate it from the north and south, as well as an enigmatic installation composed of a series of intertwined channels. Through comparison with data from previous excavations farther east, it is clear that this ditch traversed the entire width of the ridge, creating a disconnect between the Southeastern Ridge and the Ophel. Although the initial cutting of the ditch cannot be determined, it is clear that by the Late Iron IIA, the ditch served as a moat between the acropolis—possibly including the Temple Mount—and the city. This continued until the Late Hellenistic period, when construction activities backfilled the ditch, leading to its disappearance from the cityscape.

Virtual landscape-scale restoration of altered channels helps us understand the extent of impacts to guide future ecosystem management

Human modification of hydrological connectivity of landscapes has had significant consequences on ecosystem functioning. Artificial drainage practices have fundamentally altered northern landscapes, yet these man made channels are rarely considered in ecosystem management. To better understand the effects of drainage ditches, we conducted a landscape-scale analysis across eleven selected study regions in Sweden. We implemented a unique approach by backfilling ditches in the current digital elevation model to recreate the prehistoric landscape, thus quantifying and characterizing the channel networks of prehistoric (natural) and current (drained) landscapes. Our analysis detected that 58% of the prehistoric natural channels had been converted to ditches. Even more striking was that the average channel density increased from 1.33 km km−2 in the prehistoric landscape to 4.66 km km−2 in the current landscape, indicating the extent of ditching activities in the northern regions. These results highlight that man-made ditches should be accurately mapped across northern landscapes to enable more informed decisions in ecosystem management.

Assessing conservation practices in Amalacaxco Gorge (Izta-Popo National Park, Central Mexico) using fallout 137CS and Optically Stimulated Luminescence (OSL)

This study aims to assess conservation practices in Izta-Popo National Park (Central Mexico) by evaluating the mechanisms of sediment transfer. We applied a methodology based on fallout 137Cs and optically stimulated luminescence (OSL) analysis. This was tested in the upper catchment of Amalacaxco Gorge, selected for being one of the sectors of the park in which man-made actions have been implemented in last decades to favor forest growth in the alpine grassland and to reduce the effect of water runoff. We quantified the 137Cs activity using gamma and beta spectrometry of fine sediment grains extracted from the surface of parcels of 0.4 m2 in areas of natural forest, natural alpine grassland, alpine grassland with conservation practices, ravines and trails. In general, 137Cs values increases as local slope decreases as it was expected. The natural forest is the most stable area in terms of soil erosion and sediment accumulation and, mean 137Cs activity was taken as reference to assess cumulative zones, with higher 137Cs values and erosive, with lower. We found that trails are accumulative surfaces but in other areas, erosion predominates. Man-made ditches, trenches and afforestation in the alpine grassland have higher 137Cs values than the natural grassland, which indicates that conservation practices are limiting the sediment transfer from hillslopes to channels, however, soil retention is less than in the natural grassland. Additionally, we evaluated the luminescence (OSL) values obtained from samples extracted from the sediment transported in ravines that are cutting into different sectors of the study area to assess the grade of resetting of fluvial materials. These luminescence results indicated that the sediment transported in ravines that are cutting into the natural forest and alpine grassland is bleached more efficiently than the sediment transported in the alpine grassland with conservation practices. Results of fallout 137Cs and luminescence strongly suggest that man-made actions in this part of the Izta-Popo National Park are dramatically modifying the natural mechanisms of sediment transfer and favoring soil erosion. We conclude that made ditches, trenches and afforestation are not an effective conservation practice in Amalacaxco Gorge because they are promoting soil erosion instead of reducing it.

Analysis of zooplankton assemblages from man-made ditches in relation to current velocity

Abstract Because of the slow current velocity, man-made ditches may create distinct physical and ecological conditions that are suitable for the growth of zooplankton populations. However, the influence of drainage ditches on zooplankton communities has not been studied yet. This study aims to answer the following questions: i) Are man-made ditches a rich source of zooplankton? ii) What current velocity value leads to abundant zooplankton in man-made ditches? iii) Do zooplankton communities differ between man-made ditches and connected natural streams? In man-made drainage ditches with a water current lower than 0.1 m s-1, the abundance of zooplankton was greater than in the majority of streams. Sometimes this level of abundance was equivalent to the densities of zooplankton in lakes or dammed reservoirs. The presence of zooplankton in man-made ditches may be of great importance to the establishment of food webs, particularly during periods of high water levels or heavy rainfall, both of which may accelerate the water current, causing the dispersion of zooplankton along the ditches and into natural streams.

In situ measurements of shear stress, erosion and deposition in man-made tidal channels within a tidal saltmarsh

A field study was conducted in man-made ditches in a tidal saltmarsh in Lewes, Delaware, USA. Ditches are prevalent throughout tidal marshes along the Atlantic US coast, and influence hydrodynamics and sediment transport. The field study focused on measuring near-bed velocity, shear stress, sediment concentration, and bed level variability at 5 stations over a 3-week period. Velocities in the ditch (2–5 m wide, 1 m deep) peaked between 0.4 and 0.6 m/s and were slightly ebb dominated. Velocity and shear stress were maximum during a storm event, with peak shear stresses of 2 N/m2. Bed levels were estimated from acoustic amplitude return of a downward-looking velocity profiler. The bed level in the ditch at the landward locations increased ∼ 0.03 m over 3 weeks, while there was ∼ 0.01 m bed level decrease at the most seaward site suggesting a net import of sediment into the channel. At all sites, erosion (∼ 0.005–0.015 m) occurred during the accelerating phase of the flood tide, and accretion of a similar magnitude occurred during the decelerating phase of the ebb tide. This erosion-deposition sequence resulted in small net changes in bed level at the end of each tidal cycle. The intratidal behavior of the bed level was simulated using erosion and deposition flux equations based on shear stress, critical shear stress, and suspended sediment concentration. Erosion was predicted well with RMS errors on the order of 2⋅10−3 m. The bed level during the deposition phase could not be reproduced using the simple approach. Model inaccuracies for deposition were attributed to advection and variations in fall velocity due to flocculation that were not modeled due to lack of ground-truth observations.

On the use of historical archive of aerial photographs for the discovery and interpretation of ancient hidden linear cultural relics in the alluvial plain of eastern Henan, China

Abstract Hidden linear ancient cultural relics were discovered in the alluvial plain of Eastern Henan province (China) using historical archive of aerial photographs and further confirmed by regional features, historical documents and recent archaeological progress. The discovered relics included large-scale man-made ditches, canals and dock relics in Shangqiu and circular moat relics in Luyi. According to historical documents and archaeological researches, we discussed the cultural types and natures of the relics discovered by remote sensing images. On this basis, more pertinent and operable interpretation marks were proposed focusing on hidden linear ancient cultural relics in the alluvial plain. To improve the interpretation of the traditional crop, soil and shadow marks, we also included indexes of scale, continuity, shape and clustering. Our research highlights the macroscopic and spectrographic observation capability of remote sensing in discovering large-scale, massive, surface distribution of ancient cultural relics. In the test area, the solution of image interpretation was proposed through a combined feature identification of scale, continuity, shape and clustering. The derived thematic map demonstrated that the proposed solution is effective for discovering ancient remains in the alluvial plain of eastern Henan, China.

Distribution and risk assessment of metals and arsenic contamination in man-made ditch sediments with different land use types.

Ditches are subjected to a large input of nutrients, trace metals, and arsenic and the enhancement of sedimentation due to human activities. However, the influence of different types of land uses on the distribution and associated environmental risk of metals and arsenic in the Red purple Sichuan Basin remains largely unclear, which is needed for water management. This study was carried out to characterize metal/metalloid status in ditch sediments from different land uses. A total of 68 surface sediment samples (0-5cm) were collected from open ditches distributed in different land use types, i.e., cultivated ditches (CD), barren land ditches (BLD), roadside ditches (RSD), and residential ditches (RD), within the Sichuan Basin. Mean concentrations of Cr, Ni, Cu, Zn, Cd, Pb, and Mn in both RD and RSD were above the soil background values of Sichuan Basin, but Cd in ditch sediments of the basin posed considerable ecological risk to the environment. Overall, metals/metalloid (except Pb) decreased in the following order of RD>RSD>BLD>CD. Of the different land use types in the hilly region, residential and roadside land uses were likely to adverse effects on aquatic life. Multivariate statistical analysis showed that Mn, As, Cu, Ni, Zn, Fe, and Al were mainly influenced by natural weathering (erosion), while Pb might come from heavy vehicular traffic. The degree of contamination (Md), enrichment factor (EF), and the geo-accumulation index (Igeo) showed that Cd causes strong sediment pollution in the basin. Sediment quality guidelines SQG-Q values displayed that metals and arsenic created medium-low potential of adverse biological effects. These results provide baseline information on the metals and arsenic pollution in the Sichuan Basin. Awareness of land use type contributions to metals and arsenic requires that these man-made ditches be considered for their mitigation of pollutants in this region.

Extracting cross sections and water levels of vegetated ditches from LiDAR point clouds

The hydrologic response of a catchment is sensitive to the morphology of the drainage network. Dimensions of bigger channels are usually well known, however, geometrical data for man-made ditches is often missing as there are many and small. Aerial LiDAR data offers the possibility to extract these small geometrical features. Analysing the three-dimensional point clouds directly will maintain the highest degree of information. A longitudinal and cross-sectional buffer were used to extract the cross-sectional profile points from the LiDAR point cloud. The profile was represented by spline functions fitted through the minimum envelop of the extracted points. The cross-sectional ditch profiles were classified for the presence of water and vegetation based on the normalized difference water index and the spatial characteristics of the points along the profile. The normalized difference water index was created using the RGB and intensity data coupled to the LiDAR points. The mean vertical deviation of 0.14m found between the extracted and reference cross sections could mainly be attributed to the occurrence of water and partly to vegetation on the banks. In contrast to the cross-sectional area, the extracted width was not influenced by the environment (coefficient of determination R2=0.87). Water and vegetation influenced the extracted ditch characteristics, but the proposed method is still robust and therefore facilitates input data acquisition and improves accuracy of spatially explicit hydrological models.

Anthropogenic effects on bacterial diversity and function along a river-to-estuary gradient in Northwest Greece revealed by metagenomics.

Studies assessing the effects of anthropogenic inputs on the taxonomic and functional diversity of bacterioplankton communities in lotic ecosystems are limited. Here, we applied 16S rRNA gene amplicon and whole-genome shotgun sequencing to examine the microbial diversity in samples from the Kalamas River (Northwest Greece), a mid-size river that runs through agricultural and NATURA-protected areas, but also receives urban sewage from a large city through a manmade ditch. Samples from three different locations between the exit of the ditch and the estuary, during three different months showed that temporal differences of taxonomic and functional diversity were more pronounced than spatial ones, and <1% of total taxa were shared among all samples, revealing a highly dynamic ecosystem. Comparisons of gene diversity with other aquatic habitats showed that only the high flow winter samples resembled more to freshwater environments while samples during the decreased water flow months were dominated by sewage inputs and soil-related organisms. Notably, microbial human gut signals were detectable over background freshwater and soil/runoff related signals, even at tens of kilometers downstream the city. These findings revealed the significance of allochthonous inputs on the composition and dynamics of river bacterial communities, and highlighted the potential of metagenomics for source tracking purposes.

A Qualitative Evidence of the Breeding Sites of Anopheles arabiensis Patton (Diptera: Culicidae) in and Around Kassala Town, Eastern Sudan.

Anopheles arabiensis Patton (Diptera: Culicidae) is considered the most efficient malaria vector in eastern Sudan. This study aims to characterize the breeding sites of An. arabiensis throughout the year in and around Kassala town, eastern Sudan. Diverse larval habitat types were visited and characterized based on the habitat type and chemical composition. Mosquito larvae were found in many diverse habitats. During the rainy season, rain pools and water bodies created by the seasonal Gash River serve as the main breeding sites. In the dry season, irrigation canals, seepage from water pipes, neglected wells, artificial containers, and man-made ditches serve as the main breeding sites. Breeding water showed a pH of 7.9 and a low concentration of the total dissolved salts. The results of this study may be considered in planning and implementing larval control programs in the area.

The contribution of man-made ditches to the regional stream biodiversity of the new river watershed in the Florida panhandle

The role of ditches as reservoirs for or contributors to regional diversity has rarely been assessed. In this study, we aimed (1) to assess the effect of ditches on aquatic faunal assemblages of first order streams and (2) to assess the extent to which the animal communities in altered streams that are crossed by ditches resembled those found in nearby natural streams. We examined the fauna of four different aquatic habitats of the New River watershed in the Florida Panhandle: (1) natural streams, (2) altered streams, (3) ditches that cross the altered streams, and (4) ditches that do not cross the altered streams, sampling these habitats in three geographically distinct sites and visiting each location three times during a summer. Ditches did not have the same environmental features as streams and as a result their faunal community did not completely mimic those of natural streams. Streams contained 50% less aquatic vegetation and more canopy cover, while natural streams were more acidic than any other habitat. The connected altered stream and ditch habitats contained the highest biodiversity, while natural streams contained the lowest. Our ordination of taxonomic composition did not reveal any significant differences between habitats. However, natural streams were more likely to contain Hyalella spp., Oligochaetes, and Palaemonetes spp. than other sites, yet did not contain Baetidae spp., Naucorida spp., Trepobate spp., Dolomedesokefinokensis, Leptolucania ommata, or any Centrarcids. These results indicate the importance of ditches within this system as a reservoir for and contributor to regional stream biodiversity and this finding should be taken into consideration by managers for the conservation of the regional freshwater biodiversity.

The effect of weed cutting onLuronium natans

1. Luronium natans is a rare macrophyte that seems to be disappearing from lakes and rivers throughout its distribution area. In Denmark L. natans is most often found in man-made canals and ditches, and its presence seems to be favoured by regular physical disturbance. Hence, management by cutting presents a possible method of preserving the few remaining populations of L. natans in Denmark and throughout its distribution area. 2. The objective of this study was to elucidate the effect of different weed cutting frequencies on L. natans in order to propose recommendations for management with weed cutting for future conservation of L. natans. 3. Three reaches of a river with L. natans were subjected to the following weed cutting frequencies: no cutting, twice per year, and four times per year, and the cover of L. natans and of other plants was monitored from June 2003 to October 2004. 4. L. natans developed highest cover when subjected to weed cutting four times per year, but the frequency of flowering was then very low, resulting in a reduction in sexual reproduction, which could lead to a lower genetic diversity and possibly fatal effects in the long term. At a cutting frequency of twice per year L. natans was able to maintain healthy and sexually reproducing populations. 5. Future management in canals should consist of weed cutting once or twice per year to prevent a population from being outcompeted by other species and to secure production of flowers and seeds. Alternatively, high frequencies of weed cutting could be performed in order to suppress competitive species, but should then be accompanied by a weed cutting-free zone where flowering can occur. Copyright © 2006 John Wiley & Sons, Ltd.

Recent changes in mire vegetation in Yawata, southwestern Japan

Recent changes of mire plant communities in the Yawata highland, southwestern Japan, are documented. The area and the boundary length of five important mires (range 1 to 6 ha) declined during past 24 years. Qualitative changes are primarily caused by human influences, e.g., accumulating debris from forest-harvest sites above the mires, from road construction, and increased drainage from man-made ditches. The Cirsieto-Molinietum japonicae, a characteristic mire community of temperate Japan climates, maintained its community structure and flora. However, 3 of 11 subordinate units of this community changed species composition and population structure, and 3 of them disappeared. The 28 mire plants classified as endangered in the 1950s were present in 1991.

Central Wisconsin Muskrat Study

Central Wisconsin is a typical example of footless drainage in the Lake States. Once with more than dry land, the country was ditched about twenty-five years ago in an ill-starred agricultural venture. The marshes were drained and duly planted to crops but the expected profits-except to the land speculators-failed to materialize. Farms were abandoned one by one, fires ate out most of the peat, and the job was called a failure. From the standpoint of the water-loving furbearers it was more than a failure; it was a disaster. With the marshes and swamps gone, the streams straightened, most of the stream bottom woods cut out, they had only the ditches to turn to. The federal government bought 100,000 acres of this wasteland in 1935 to make the Central Wisconsin Game Project, Necedah.* Two hundred miles of man-made ditch, sometimes wet and sometimes dry, was almost the only remaining habitat for muskrat, beaver, otter, and mink on this area. Project development plans include fur management. In 1936 and 1937 we studied the furbearers, using repeated surveys over the whole ditch systems as our study method. Five surveys were run, in two springs, two summers, and one autumn; fur sign was recorded in maps and notes. The survey technique, summary of findings for the major species, and a more detailed description of the area, have already been reported (Hamerstrom and Blake, 1939). The present muskrat situation on the Project is a matter of more than local application. It is directly comparable with conditions on many of the drained areas throughout the Lake States, and probably in much of the rest of the Middle West as well. The best muskrat water was in the rather shallow open ditches in the marsh country-alternating shallow peat, black (Dunning) sand, and scattered islands of white (Plainfield) sand. Here the ditches follow in a general way the old basins, occasionally cutting through low sand islands and ridges. As a result, high ditch bottoms are made up of sand, muck, and some shallow peat, offering a variety of growing conditions. Water varies from slightly acid to slightly alkaline; plants and animals with high calcium requirements, such as musk grass (Chara spp.) and clams do not occur. Even in mid-summer the coldness of the water is remarkable. The spoil banks are mainly sand and are grazed very lightly or not at all. Well-shaded ditches, and those which were deep and swift through most of the year, were practically barren of muskrats. Such ditches had very little food in the water or on the banks.