1,731,123 research outputs found
Gully impact on soil moisture in the gully bank
No full textIn order to preliminarily look at rules for soil moisture changes in the bank of the gully and to provide some recommendations for vegetative restoration in gully bank regions in the Loess Plateau, changes of soil moisture with depth and distance to the gully edge and their dynamic changes with time were observed to study the soil water characteristics in the bank of the gully. The results showed that soil water content increased with increasing distance from the gully edge, whereas for the same time period, the closer the distance to the gully wall, the greater the water loss; and that the influential distance of side evaporation decreased as depth increased
Evaluation of vegetation and stream health within sites supported by the Hamilton City Council Plants for Gullies Programme
No full textBetween August 2012 and March 2013, the Environmental Research Institute, University of Waikato, conducted a survey of randomly selected Hamilton gully sites which had received plants from the Hamilton City Council’s Plants for Gullies Programme. This survey assessed recent plantings, existing gully vegetation and stream health, along with property owner awareness and engagement with the key restoration principles.
The Plants for Gullies Programme has been extremely well received by the Hamilton community and gully owners. Survey participants were actively restoring their gully sites with the most common goal (c. 40%) being the establishment of native plant dominance within 10 years. Gully owners have a good understanding of restoration theory and practise; on average, plant placement in the gullies scored 15.7 out of 20 with consideration of plant environmental requirements and the concept of ecosourcing was understood by c. 76% of landowners surveyed. Also, most of the interviewed participants (c. 80%) were active in seeking guidance from other gullies, often through organised tours.
Current stream health was qualitatively assessed and characterised at each of the gully sites. Results provide baseline data for future monitoring. The majority of surveyed sites (c. 50%) had sand or silt substrate and the Bankwood gully had the best features for fauna habitat (e.g. debris and areas of low flow). At the time of visit, c. 60% of surveyed streams had clear water clarity. The poorest water clarity scores were in the Waitawhiriwhiri gully. When assessed on width, length and density, the average riparian buffer score was 12.8 out of 20 while the average stream shading score was 12.7 out of 20. The average bank stability score was 13.1 out of 20, reflecting an erosion problem that many gully owners talked about.
Surveyed gullies were diverse in terms of native and exotic vegetation structure and composition; native species contributed between c. 30% to 100% of surveyed trees and shrubs, whereas groundcovers were predominantly exotic. This assessment of gully sites has shown that the Plants for Gullies Programme improves native species diversity through the re-introduction of species that are not naturally regenerating. The Plants for Gullies programme is a powerful tool for engaging private landowners and making cost-effective change to Hamilton City’s native biodiversity. There is now a community of willing gully owners who will continue to restore their gullies with the support of a programme or network. It is our recommendation that the Plants for Gullies Programme is reinstated before this community loses momentum
Clay Gully Road
No full textA car drives down the dirt road to Fleta Carlton's home on Clay Gully Roa
Achieving change through gully erosion research
No full textThis is an introduction to a special issue arising from the 8th International Conference on Gully Erosion, held in Townsville, Australia in 2019. Research has improved understanding of gully erosion processes and increasingly emphasizes sophisticated near-and-remotely sensed methods to characterize and measure gullies. These data can then be analysed using equally sophisticated models and scenarios can be simulated. These advances improve the capacity to predict gully initiation and development over time and space. It is often assumed that better prediction translates into greater impact and uptake of research to solve real world gully erosion problems. Examples of impressive associations between research programmes and major gully management programmes are evident. However, there has been little assessment of the impact of gully research. We argue for a greater focus on achieving impact including interventions that better manage and prevent gully erosion. Opportunities to deliver research impact are assessed using three indicators of progression towards impact; the practical usability of research, whether it is in use by non-researchers, and whether it is useful in guiding improvements in management. Like other natural hazards, gully erosion is a phenomenon of the social, economic and environmental context in which it occurs. Defining the contexts and consequences of gully erosion and using these to frame further research is therefore a means to increase research impact. Enhancing collaboration between research disciplines and with practitioners who act on the research, and a greater focus on the translation of results into practice, is another avenue. Expanding the monitoring and evaluation of gully management can better demonstrate the impact of past research and enable further useful investigations. We urge gully erosion researchers to consider the potential impact of their research, including how it can more effectively inform better and more cost-effective management and political decisions.Full Tex
Ecological restoration in Hamilton City, North Island, New Zealand
No full textHamilton City (New Zealand) has less than 20 hectares of high-quality, indigenous species dominated ecosystems, and only 1.6% of the original indigenous vegetation remains within the ecological district. A gradual recognition of the magnitude of landscape transformation has gathered momentum to the stage that there is now a concerted public and private effort to retrofit the City by restoring and reconstructing indigenous ecosystems. The initial focus was on rehabilitating existing key sites, but has shifted to restoring parts of the distinctive gully landform that occupies some 750 ha or 8% of the City. A new initiative at Waiwhakareke (Horseshoe Lake) will involve reconstruction from scratch of a range of ecosystems characteristic of the ecological district over an area of 60 ha. This address will examine a vision for ecological restoration in Hamilton City within the context of policy, education, and community dimensions that have triggered a shift from traditional parks and gardens management to ecosystem management
MERGE: modelling erosion resistance for gully erosion - a process-based model of erosion from an idealised linear gully
No full textGullies are responsible for as much as 40% of the accelerated erosion impacting the Great Barrier Reef lagoon. Consequently, to protect the reef from the impacts of poor water quality associated with eroded sediment, the remediation of gullied landscapes is important. The geographic location and geomorphic characteristics of gullies affects their erosion characteristics and the extent to which eroded sediments may be transported to the reef. Existing models of gully erosion are predominantly empirical in nature, and are poorly suited to represent the potential benefits of different interventions in the data scarce environment that exists. The Queensland Government, through the Queensland Water Modelling Network, identified the development of process-based models of gully erosion as necessary to support efforts to protect the reef. MERGE (modelling erosion resistance for gully erosion) was developed to address this need. MERGE exhibits the expected characteristics for gully erosion including achieving a steady concentration under constant conditions, the development of a depositional layer, as well as first flush effects and hysteresis in the dynamic case. Analytical steady-state solutions are found to be excellent approximations to the full dynamic solutions. The suitability of the model to represent interventions is demonstrated for the example cases of porous check dams and improved ground cover.Full Tex
Solids dynamics in gully pots
No full textRunoff entering urban drainage systems contains suspended solids, which carry pollutants and may cause blockages in downstream parts of the system (for example infiltration facilities). Suspended solids inflow should, therefore, preferably be controlled by solids removal at gully pots. This paper presents the results of lab experiments on the solids accumulation in gully pots in a scale 1:1 setup. The accumulation process is initially dominated by settling in the gully pot. When a substantial sediment bed is created, the bed starts to interact with the flow, the removal efficiency of solids decreases, and the bed eventually reaches an equilibrium level. The effects of the discharge, sediment size, and geometry on these processes are assessed. The accumulation rate and equilibrium bed level are strongly affected by the flow pattern which is influenced by the combination of the position the jets impinge on the water and the gully pot’s outlet position.Sanitary Engineerin
Monitoring soil erosion in the Souss basin, Morocco, with a multiscale object-based remote sensing approach using UAV and satellite data
No full textThis article presents a multiscale approach for detecting and monitoring soil erosion phenomena (i.e. gully erosion) in the agro-industrial area around the city of Taroudannt, Souss basin, Morocco. The study area is characterized as semi-arid with an annual average precipitation of 200 mm. Water scarcity, high population dynamics and changing land use towards huge areas of irrigation farming present numerous threats to sustainability. The agro-industry produces citrus fruits and vegetables in monocropping, mainly for the European market. Badland areas strongly affected by gully erosion border the agricultural areas as well as residential areas. To counteract the significant loss of land, land-leveling measures are attempted to create space for plantations and greenhouses. In order to develop sustainable approaches to limit gully growth the detection and monitoring of gully systems is fundamental. Specific gully sites are monitored with unmanned aerial vehicle (UAV) taking small-format aerial photographs (SFAP). This enables extremely high-resolution analysis (SFAP resolution: 2-10 cm) of the actual size of the gully channels as well as a detailed continued surveillance of their growth. Transferring the methodology on a larger scale using Quickbird satellite data (resolution: 60 cm) leads to the possibility of a large-scale analysis of the whole area around the city of Taroudannt (Area extent: ca. 350 km²). The results will then reveal possible relationships of gully growth and agro-industrial management and may even illustrate further interdependencies. The main objective is the identification of areas with high gully-erosion risk due to non-sustainable land use and the development of mitigation strategies for the study area
Multi-parametric GIS analysis to assess gully erosion susceptibility: a test in southern Sicily, Italy
No full text: A GIS-analysis was carried out in a test basin of southern Sicily, the Magazzolo River basin, in order to
assess susceptibility conditions to gully erosion phenomena. The linear density of ephemeral and permanent
gullies computed within each class of nine environmental variables was used to generate a gully erosion susceptibility map for the area. A validation procedure carried out in order to test the reliability of the adopted method
highlighted a clear correlation between the occurrence of gullies and the computed susceptibility level
Overland-Gully-Sewer (2D-1D-1D) Urban Inundation Modeling based on Cellular Automata Framework
No full textA new overland-gully-sewer (2D-1D-1D) urban inundation modeling is herein proposed. 10 The authors have developed an integrated approach for overland-gully-sewer urban inundation simulations, which comprises 2D overland flow modeling (2D-OFM) by solving the two-dimensional non-inertia shallow water equations (2D-NISWEs), one-dimensional gully flow modeling (1D-GFM), and one-dimensional sewer flow modeling (1D-SFM). This approach can achieve good accuracy on urban inundation simulations. Nevertheless, such physically-based 2D overland flow modeling with the non-inertia SWEs (2D-OFM-NISWEs) requires substantial computational procedures, so that it is not suitable for real-time evaluation of inundation in urban areas. To resolve this limitation, the present study proposes a new integrated approach for overland-gully-sewer urban inundation modeling, in which the cellular automata (CA) framework is adopted for 2D-OFM to improve its suitability, and 1D-GFM and 1D-SFM are modeled by SWMM. A novel linkage among 2D-OFM-CA, 1D-GFM, and 1D-SFM is developed. A theoretical comparison of the governing equations and computational procedures between the two approaches is first conducted. Two historical flood events in Taipei city are next selected to perform the numerical accuracy verification and numerical efficiency evaluation. Analysis of inundation depths/velocities between the two approaches is conducted, and investigation of the drained and surcharged/inversed discharges of the two approaches is also made. The numerical comparisons between the two approaches indicate that the proposed approach can maintain good accuracy with significant reduction on its computing time. This newly proposed approach can finish a 3 hours short-duration urban inundation simulation on a case study with 335,621 cells within 12-17 mins. As a result, this CA-based approach is proved to be a useful tool for real-time urban inundation modeling
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