scholarly journals Assessment of land use impact on hydraulic threshold conditions for gully head cut initiation

2016 ◽  
Author(s):  
Aliakbar Nazari Samani ◽  
Qiuwen Chen ◽  
Shahram Khalighi ◽  
Robert James Wasson
Keyword(s):  
Land Use ◽  
Shear Stress ◽  
Vegetation Cover ◽  
Agricultural Land ◽  
Gully Erosion ◽  
Soil Conditions ◽  
Shear Stresses ◽  
Soil Response ◽  
Threshold Phenomenon ◽  
Dry Farming

Abstract. Gully erosion is a geomorphic threshold phenomenon controlled by different environmental factors as well as human activities. In this research, we examined the effect of land use on hydraulic flow and the consequent head cut initiation for similar soil conditions using an experimental plot of 15m*0.4m. Results indicated that boundary shear stresses τcr for gully initiation in rangeland, dry farming and abandoned land are 192, 43 and 174, respectively, due to the differences in surface vegetation cover. Moreover, the dyne/cm2 turbulence of flow and soil response to an increase in water depth showed complicated behavior, which could be attributed to the effect of surface micro relief features and land use impacts. Compared to dry farming, the short vegetation cover in the rangeland decreased the effect of ground cover on flow regime. Even after seven years of abandonment, the response of agricultural land to increasing shear stress was similar to that of dry farming, which indicated the low resilience and high erosional susceptibility of soil in dry land was the environments. The main explanation for dramatic (3-4 fold) variations of τcr in dry vegetation cover and soil surface conditions. In fact, the remarkable decrease of τcr farming was related to the effect of tillage practice on soil susceptibility and aggregate used in some strength. The findings indicated that a critical shear stress of 35 dyne/cm2 physically based models for erosion prediction is not appropriate for estimating gully erosion. In addition, the duration of land abandonment has a crucial influence on soil erodibility that has been less considered in erosion models.

scholarly journals Assessment of land use impact on hydraulic threshold conditions for gully head cut initiation

2016 ◽  
Vol 20 (7) ◽  
pp. 3005-3012 ◽  
Author(s):  
Aliakbar Nazari Samani ◽  
Qiuwen Chen ◽  
Shahram Khalighi ◽  
Robert James Wasson ◽  
Mohammad Reza Rahdari
Keyword(s):  
Land Use ◽  
Shear Stress ◽  
Soil Erosion ◽  
Critical Shear Stress ◽  
Gully Erosion ◽  
Threshold Condition ◽  
Stream Power ◽  
Threshold Phenomenon ◽  
Erosion Models ◽  
Dry Farming

Abstract. A gully as an accelerated erosion process is responsible for land degradation under various environmental conditions and has been known as a threshold phenomenon. Although the effects of gullying processes have been well documented, few soil erosion models have taken into account the threshold condition necessary for gully development. This research was devoted to determining the effects of land use change on hydraulic threshold condition and stream power of water flow through an in situ experimental flume (15 m  ×  0.4 m). Results indicated that head cut initiation and detachment rates showed a better correlation to stream power indices than shear stress (τcr). The threshold unit stream power value (ωu) for head cut initiation in rangeland, abandoned land, and dry farming land was 0.0276, 0.0149, and 4.5  ×  10−5 m s−1, respectively. Moreover, the micro-relief condition of soil surface and surface vegetation affected the flow regime of discharge and velocity. It is seen that the composite hydraulic criteria of Froude number (Fr) and discharge (Q) can clearly discriminate the land uses' threshold. In fact, the remarkable decrease of τcr in dry farming was related to the effect of tillage practice on soil susceptibility and aggregate strength. The findings indicated that using the unit steam power index instead of critical shear stress could increase the models' precision for prediction of head cut development. Compared to the Ephemeral Gully Erosion Model (EGEM) equation for critical shear stress, it is important to point out that for modelling of gully erosion, using single soil attributes can lead to an inaccurate estimation for τcr. In addition, based on the findings of this research, the use of threshold values of τcr  =  35 dyne cm−2 and ωu  =  0.4 cm s−1 in physically based soil erosion models is susceptible to high uncertainty when assessing gully erosion.

scholarly journals Spatial and temporal variability of nitrous oxide emissions in a mixed farming landscape of Denmark

2012 ◽  
Vol 9 (8) ◽  
pp. 2989-3002 ◽  
Author(s):  
K. Schelde ◽  
P. Cellier ◽  
T. Bertolini ◽  
T. Dalgaard ◽  
T. Weidinger ◽  
...  
Keyword(s):  
Land Use ◽  
Nitrous Oxide ◽  
Agricultural Land ◽  
Nitrous Oxide Emissions ◽  
Soil Conditions ◽  
Spatial And Temporal Variability ◽  
N2o Emissions ◽  
N2o Production ◽  
Mixed Farming ◽  
N2o Fluxes

Abstract. Nitrous oxide (N2O) emissions from agricultural land are variable at the landscape scale due to variability in land use, management, soil type, and topography. A field experiment was carried out in a typical mixed farming landscape in Denmark, to investigate the main drivers of variations in N2O emissions, measured using static chambers. Measurements were made over a period of 20 months, and sampling was intensified during two weeks in spring 2009 when chambers were installed at ten locations or fields to cover different crops and topography and slurry was applied to three of the fields. N2O emissions during spring 2009 were relatively low, with maximum values below 20 ng N m−2 s−1. This applied to all land use types including winter grain crops, grasslands, meadows, and wetlands. Slurry application to wheat fields resulted in short-lived two-fold increases in emissions. The moderate N2O fluxes and their moderate response to slurry application were attributed to dry soil conditions due to the absence of rain during the four previous weeks. Cumulative annual emissions from two arable fields that were both fertilized with mineral fertilizer and manure were large (17 kg N2O-N ha−1 yr−1 and 5.5 kg N2O-N ha−1 yr−1) during the previous year when soil water conditions were favourable for N2O production during the first month following fertilizer application. Our findings confirm the importance of weather conditions as well as nitrogen management on N2O fluxes.

scholarly journals Optimization of the Weighted Linear Combination Method for Agricultural Land Suitability Evaluation Considering Current Land Use and Regional Differences

2020 ◽  
Vol 12 (23) ◽  
pp. 10134
Author(s):  
Shouqiang Yin ◽  
Jing Li ◽  
Jiaxin Liang ◽  
Kejing Jia ◽  
Zhen Yang ◽  
...  
Keyword(s):  
Land Use ◽  
Regional Differences ◽  
Agricultural Land ◽  
Land Suitability ◽  
Spatial Accessibility ◽  
Combination Method ◽  
Soil Conditions ◽  
Weighted Linear Combination ◽  
Suitability Evaluation ◽  
Land Suitability Evaluation

This study was aimed at optimizing the weighted linear combination method (WLC) for agricultural land suitability evaluation (ALSE) through indicator selection, weight determination, and classification of overall suitability scores in Handan, China. Handan is a representative research area with distinct agricultural advantages and regional differences in land use, where the expansion of construction land has led to a rapid decrease of agricultural land in recent years. Natural factors (topography, climate, soil conditions, and vegetation cover) and socioeconomic factors (land use and spatial accessibility) were selected to establish a more comprehensive evaluation system. The index weight was calculated by the mutual information between index suitability and current land use. The consistency index was used to identify the boundary value dividing the overall suitability score into a suitable category and unsuitable category in each sub-region. The results demonstrated that the optimized WLC-ALSE model outperformed the comparison models using conventional methods in terms of the consistency between the evaluation results and current land use. Owing to the increasing limitations of topography, soil conditions, spatial accessibility, and land use, the proportions of suitable land in Zone 1, Zone 2, and Zone 3 were 77.4%, 67.5%, and 30.9%, respectively. The agricultural land unsuitable for agriculture (14.5%) was less than non-agricultural land suitable for agriculture (7.4%), indicating that agricultural land had low growth potential in Handan. Finally, specific recommendations were made to improve agricultural land suitability, alleviate land use conflicts, and further optimize the model. The results can provide effective guidance for WLC-ALSE and land use decision-making for sustainable agriculture.

The importance of pedological soil survey in land use planning, resource assessment and site investigation

1987 ◽  
Vol 4 (1) ◽  
pp. 453-466 ◽  
Author(s):  
E. M. Lee ◽  
J. S. Griffiths
Keyword(s):  
Land Use ◽  
Urban Development ◽  
Land Use Planning ◽  
Agricultural Land ◽  
Soil Survey ◽  
Soil Conditions ◽  
Structural Development ◽  
Infrastructure Development ◽  
Land Uses ◽  
Site Investigations

AbstractThe ever increasing pressure for infra-structural development in the UK heightens the conflict between the different land use demands placed on an area. This is reflected in the need for planning authorities to assess the relative suitability of potential land uses. Such assessments are important in guiding urban development away from good quality agricultural land. It is manifest that such planning decisions should be made on the basis of a comprehensive review of all relevant factors, and in particular, this includes the pedological soil conditions with their controlling influence on the ability of the land to support different land uses.Past pedological studies have tended to concentrate on the evaluation of land suitability for agricultural uses. However, such studies are also of value when assessing the suitability of other potential uses including, forestry, recreational uses, natural resources or general infrastructure development.In site investigations for infrastructure or resource development pedological studies have a role to play both at the feasibility and detailed investigation stages. During a feasibility study, particularly when used in conjunction with a programme of geotechnical mapping, a pedological approach to the examination of point samples can be an important aid in the determination of the areal extent of engineering soil units. In detailed investigations pedological assessments during pitting operations can determine such items as the depth of topsoil to be removed and stored during stripping, if a profile has developed through in-situ weathering of bedrock or a derived superifical cover and will assist in the identification of poor drainage areasIn this paper examples are presented of soil surveys used to assess the suitability of areas for recreational use, urban development and forestry. Also, by comparing the approaches to soil description contained within BS 5930, Code of Practice for Site Investigations (British Standards Institution 1981), and the Soil Survey Field Handbook (Hodgson 1974), some recommendations are made for adopting pedological description techniques in geotechnical site investigations.

scholarly journals Impact of coastal inundation on ecology and agricultural land use case study in central Java, Indonesia

2011 ◽  
Vol 30 (3) ◽  
pp. 19-32 ◽  
Author(s):  
Muh Marfai
Keyword(s):  
Land Use ◽  
Agricultural Land ◽  
Regional Scale ◽  
Agricultural Land Use ◽  
Use Case ◽  
Coastal Inundation ◽  
Central Java ◽  
Dry Farming ◽  
The Impact

Impact of coastal inundation on ecology and agricultural land use case study in central Java, Indonesia Focusing on the regional scale, this study provides information concerning the existing ecological problems associated with coastal inundation in the northern part of coastal area in Central Java Province, Indonesia. The objectives of this paper are to map the coastal inundation, to investigate the impact of coastal inundation on coastal environment and ecology, and to assess the impact of inundation on agricultural land use. An integration of techniques, namely neighborhood analysis, iteration operation, and superimposed analysis method has been applied to generate the digital map and to analyze the impact of inundation. Fieldwork measurement has been done using cross-profiling in order to observe the impact of inundation on the coastal ecosystem. Based on the scenario of 100 cm and 150 cm of inundation, the affected area is about 15 207.6 Ha and 16 687.31 Ha, respectively. Fishpond, dry farming and paddy field are the most affected agricultural areas due to coastal inundation.

Area-wide detection and spatial modeling of signs of bioturbation activity along a climate and elevation gradient in Chile using UAV and their dependence on vegetation and soil characteristics

2020 ◽  
Author(s):  
Paulina Grigusova ◽  
Diana Kraus ◽  
Annegret Larsen ◽  
Alexander Klug ◽  
Robin Fischer ◽  
...  
Keyword(s):  
Land Use ◽  
Surface Roughness ◽  
Vegetation Cover ◽  
Point Cloud ◽  
Elevation Gradient ◽  
Soil Characteristics ◽  
Soil Conditions ◽  
Vegetation Density ◽  
Climate Zones ◽  
Semi Arid

<p>The impact of soil dwelling animals on the terrain shaping is assumed to be largely coupled with vegetation and soil characteristics, particularly in arid and semi-arid regions. The vegetation determines the habitat availability by providing necessary resources such as food and shelter while the burrowing activities of soil dwelling animals impacts at the same time soil properties and nutrient fluxes needed for plant growth. This important relationship and feedbacks between bioturbators, vegetation, climate, soil conditions and landscape shaping is to date completely understudied, particularly the dependencies between soil animals and the vegetation cover. Thus, comprehensive studies to gain a detailed understanding are urgently required. Here, we modeled the presence of all signs of bioturbation (burrows, holes and mounds) within a study area of 1 km<sup>2</sup> with an elevation gradient of 100m height difference in a semi-arid (Santa Gracia, Chile) and Mediterranean (NP La Campana, Chile) zone of coastal Chile using UAV (unmanned aerial vehicle) images. We then compared their relationship between the two climate zones in regard to the vegetation, elevation and soil characteristics. <span>The images were obtained at a flight altitude of 15-60 meters above one study area per each climate zone by means of a Solo quadropter drone equipped with a RGB GoPro camera. Ancillary </span><em><span>in-situ</span></em> <span>data were measured within 10 plots per study area with a size of 10m x 10m. Within the plots, the amount and size of the burrows and mounds as well as the vegetation cover was quantified. In addition, the GPS coordinates of several holes and mounds with a diameter of 10cm and above were measured. Twenty representative soil samples in regard to the land cover, vegetation type and presence of bioturbation activity were taken along the elevation gradient and analyzed for skeleton fraction, soil texture, bulk density and water content. </span>The RGB images obtained by the drone system were firstly used for a supervised land-use classification and to calculate the vegetation density across the study area. The surface roughness was estimated by creating the point cloud of the area and calculating the standard deviation of the point cloud and original images using moving window of 5x5 pixels/points. The presence of soil animal activity was modeled using random forest where drone images, digital elevation model, surface roughness and land cover characteristics (land use, vegetation density and type) were used as predictors. The results showed modeled spatial distribution of burrows and mounds within the study areas, and a dependence of the predicted bioturbation activity on vegetation density and type as well as on elevation and soil conditions along the elevation gradient at both sites. The dependencies are finally compared between the two climate zones.</p>

scholarly journals ERODIBILITAS TANAH (K) PADA BERBAGAI TUTUPAN LAHAN DI DESA BARU KECAMATAN SILAT HILIR KABUPATEN KAPUAS HULU

2021 ◽  
Vol 8 (4) ◽  
pp. 773
Author(s):  
Lidia Injiliana ◽  
Tri Widiastuti ◽  
Joko Nugroho Riyono
Keyword(s):  
Land Use ◽  
Land Cover ◽  
Agricultural Land ◽  
Research Area ◽  
Soil Conditions ◽  
Land Type ◽  
Determining Factors ◽  
Class 1 ◽  
Land Cover Map ◽  
Land Changes

Land degradation will result in widespread land damage, especially damage to forest land. Changes in land use from permanent vegetation to intensive agricultural land make the soil more easily eroded. One of the determining factors of erosion is soil erosion and soil cover vegetation. Soil erodiability is the average amount of soil lost each year per unit of the index, while the land cover is useful to protect the soil from the threat of damage by erosion and improve soil conditions. The research area located in Silat Hilir Sub-District of Kapuas Hulu Regency is a strategic area of the district from the point of economic importance. The Upper Kapuas Statistics Agency says there is a change in land use from year to year. The changes occurred not only in the increase in land use but also on changes in land use. The purpose and benefit of this research are to know the class of soil erodiability as well as to provide information on the class of land erodiability in The New Village of Silat Hilir District of Kapuas Hulu Regency. The value of soil erodiability is calculated using the Wischmeier and Smith formulas (1978) and determined based on the overlay of two maps, namely the land type map and the land cover map. Soil erodibility on various land cover in Silat Hilir Sub-District of Kapuas Hulu sub-district consists of 4 classes of land erodiability, among others: class 1 (very low), class 2 (low), class 4 (somewhat high), and class 5 (high).Keywords: Erodibility, Land Cover, Soil

The gullies of southeast Nigeria: an ecogeomorphic investigation

2020 ◽  
Author(s):  
Ikenna Osumgborogwu ◽  
John Wainwright ◽  
Laura Turnbull-Lloyd
Keyword(s):  
Land Use ◽  
Civil War ◽  
Focus Group ◽  
Human Activities ◽  
Vegetation Cover ◽  
Land Use Changes ◽  
Slope Angle ◽  
Gully Erosion ◽  
Remotely Sensed Data ◽  
Group Meetings

<p>Gully erosion was unknown in the Orlu area of Southeast Nigeria before the Nigerian civil war (from 1967 to 1970) but has now become endemic and continues to present day.  Human activities are central to this acceleration of erosion due to their intervention with ecogeomorphic processes. This paper aims to improve understanding of ecogeomorphic drivers of gully erosion using case studies from the Orlu area of southeast Nigeria, and to achieve this aim, focus-group meetings and analyses of remotely sensed data were adopted. High-resolution (0.61 – 5 m) satellite imagery for 2009 and 2018 were acquired from different platforms and used for gully mapping and monitoring while ASTAR DEM was used to estimate topological parameters. Upslope contributing areas were produced for two gullies; A and U, while gully evolutions between 2009 and 2018 were related to changes in contributing areas during same time span. Ecogeomorphic and climatic drivers such as vegetation-cover change, slope angle, elevation, rainfall, and nearness to roads and rivers were studied and their associations with gullying established. Vegetation cover was classified into three: non-vegetated, open vegetation and trees while daily surface runoff between 2009 and 2018 was estimated for these vegetation classes using the Curve Number approach. Results from focus-group meetings show that both gullies started in 1969 during the civil war as a result of increase in population density arising from the influx of refugees as well as other military activities. Gully growth was sustained after the civil war was a result of land use changes. Average gully headcut retreat rate between 2009 and 2018 was 64 m yr<sup>-1</sup> and 12.2 m yr<sup>-1</sup> for gully A and U respectively, while a positive correlation was recorded between change in vegetation cover in contributing areas and increase in gullied area with Pearson’s correlation of 0.6 and r<sup>2</sup> of 0.4. The runoff model predicted runoff for only the non-vegetated areas with runoff coefficients ranging from 11.5 % to 22 %. Slope angle, profile and plan curvature had positive associations with gullies while elevation, nearness to rivers and nearness to roads recorded negative correlations with gullies. In conclusion, while geomorphic drivers such as slope angle are preparatory factors, human activities including civil wars and land-use changes are forcing factors of gully erosion. This study has implications for gully remediation especially as regards land use management of upslope contributing areas.</p><p><strong>Keywords: Gully erosion, Ecogeomorphology, upslope contributing area, south east Nigeria</strong></p>

Water balance comparison of two small experimental basins with different vegetation cover

Biologia ◽  
2009 ◽  
Vol 64 (3) ◽  
Author(s):  
Pavla Pekárová ◽  
Pavol Miklánek ◽  
Milan Onderka ◽  
Silvia Kohnová
Keyword(s):  
Land Use ◽  
Vegetation Cover ◽  
Crop Production ◽  
Forest Cover ◽  
Agricultural Land ◽  
Water Cycle ◽  
Chemical Properties ◽  
Water Runoff ◽  
State Farm ◽  
Land Use Practices

AbstractIn a river, the flow directly affects the physical and chemical properties of its water, with further consequences for aquatic biota. Land use practices and vegetation cover play a significant role in the water cycle. The wide-spread perception of forest cover, in terms of hydrology is that forests may reduce water runoff: although in rare instances the contrary has been reported. Water runoff varies seasonally and depends on the forest tree species. By no means can it be considered constant over large expanses of area or for various rainfall patterns. In this paper, the results of a long-term hydrological survey conducted in two experimental microbasins (operated by the Institute of Hydrology SAS, IH SAS) with different land use practices are presented. The Rybárik microbasin (0.119 km2) is dominated by row crop production. The basin was 70% cultivated by the state farm and 30% by a private farm. The Lesný microbasin (0.086 km2) is covered by a deciduous hornbeam regrowth forest (Carpinus betulus). The analysis revealed that the difference in the runoff from the forest and the agricultural land increases with increasing precipitation; however, at some point (extreme precipitations with low probability) the runoff from these basins is nearly equal.

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