scholarly journals Hydrogeomorphic processes affecting dryland gully erosion: Implications for modelling

2018 ◽  
Vol 43 (1) ◽  
pp. 46-64 ◽  
Author(s):  
Roy C. Sidle ◽  
Ben Jarihani ◽  
SanLinn Ismail Kaka ◽  
Jack Koci ◽  
Abdulaziz Al-Shaibani
Keyword(s):  
Land Management ◽  
Management Practices ◽  
Overland Flow ◽  
Ground Cover ◽  
Gully Erosion ◽  
Annual Rainfall ◽  
Surface Erosion ◽  
Distributed Data ◽  
Erosion Processes ◽  
Sediment Loads

Gullies contribute high sediment loads to receiving waters and significantly degrade landscapes. In drylands, low annual rainfall and resultant poor ground cover, coupled with high-intensity storms and dispersive soils, predispose these landscapes to gully erosion. Land management, such as grazing, exacerbates gully-forming processes by degrading ground cover and compacting soils, thereby increasing and concentrating overland flow. Current surface erosion models do not adequately represent sediment export from gullied terrain due to lack of distributed data and complex hydrogeomorphic processes, such as overland flow concentration, waterfall erosion, soil pipe collapse, and mass wasting. Here, we outline the strengths and weaknesses of past modelling approaches in erodible terrain and focus on how gully erosion processes can be better simulated at appropriate scales using newly available remote-sensing techniques and databases, coupled with improved understanding of relevant hydrogeomorphic processes. We also discuss and present examples of challenges related to assessing land management practices in drylands that affect gully erosion.

scholarly journals Land Management Impacts on Soil Water Erosion and Loss of Nutrients

Proceedings ◽  
2019 ◽  
Vol 30 (1) ◽  
pp. 35 ◽  
Author(s):  
Telak ◽  
Bogunovic ◽  
Rodrigo-Comino
Keyword(s):  
Organic Matter ◽  
Soil Properties ◽  
Land Management ◽  
Sediment Yield ◽  
Management Practices ◽  
Overland Flow ◽  
Organic Matter Content ◽  
Nutrient Loss ◽  
Plant Residues ◽  
Significant Difference

Humans are the driving factor of soil erosion and degradation. Therefore, sustainable land management practices should be developed and applied. The aim of this study was to determine land management impacts on soil properties, soil loss and nutrient loss in 3 different treatments; grass-covered vineyard (GCV), tilled vineyard (TV), and tilled hazelnut orchard (HO). The study area is located in Orahovica, Croatia (45°31′ N, 17°51′ E; elevation 230 m) on ~7° slope. The soil under the study area was classified as a Stagnosol. 8 rainfall simulations (58 mm h−1, during 30 min, over 0.785 m2 plots) were performed at each treatment where the next data were noted: ponding time, runoff time, and collection of overland flow. Soil samples were taken for determination of mean weight diameter (MWD), water stable aggregates (WSA), P2O5 content, and organic matter content. Analyses of sediment revealed concentrations of P2O5 and N. All three treatments had significantly different values of MWD (GCV 3.30 mm; TV 2.94 mm; HO 2.16 mm), while WSA and organic matter significantly differs between GCV and HO. The infiltration rate showed no significant difference between treatments. Sediment yield was significantly the highest at the TV (21.01 g kg−1 runoff), while no significant difference was noted between GCV (2.91) and HO (6.59). Sediments of GCV treatment showed higher concentrations of P2O5 and N, compared to TV and HO. Nutrients loss was highest in the TV (450.3 g P2O5 ha−1; 1891.7 g N ha−1) as a result of highest sediment yield, despite the fact GCV had the highest nutrients concentrations. Results indicate that land management (and/or tillage) affects soil properties and their stability. Even tough HO was tilled and had the lowest values of organic matter, WSA, and MWD, measurements were performed immediately after tillage where the plant residues reduced potential erodibility of the soil. Such results reveal that tillage should be avoided in vineyard and hazelnut production in order to prevent soil and nutrient losses.

Soil erosion and runoff in improved pastures of the Clwydian Range, North Wales

1998 ◽  
Vol 130 (4) ◽  
pp. 473-488 ◽  
Author(s):  
P. A. JAMES ◽  
R. W. ALEXANDER
Keyword(s):  
Particle Size ◽  
Soil Erosion ◽  
Overland Flow ◽  
Ground Cover ◽  
Erosion Processes ◽  
North Wales

Studies of soil erosion in upland and marginal upland Britain are reviewed. Processes affecting soil erosion and runoff are described in marginal upland improved pastures of differing age in the Clwydian Hills, including one which was cultivated twice during the study period. A Gerlach-type trough was designed for trapping sediment and filtered runoff from bounded plots and for operating under grazing. Erosion and runoff amounts are interpreted in the light of ground cover, rainfall amounts and intensity, the action of grazing stock and other animals, and other influences. The chief erosion processes are the action of animals and surface wash by unconcentrated overland flow; no rilling occurred. The significance of particle size of eroded sediment is discussed.

scholarly journals Aplicação da Micromorfologia de Solos ao Estudo de Sedimentos Alúvio-Coluviais em Cabeceiras de Vale

2006 ◽  
Vol 33 (2) ◽  
pp. 3 ◽  
Author(s):  
GLAUCIA MARIA DOS SANTOS SILVA FERREIRA ◽  
MARCELO ACCIOLY TEIXEIRA DE OLIVEIRA
Keyword(s):  
Overland Flow ◽  
Gully Erosion ◽  
Aerial Photographs ◽  
Sedimentary Structures ◽  
Erosion Processes ◽  
Hillslope Evolution ◽  
Common Process ◽  
Geomorphological Units ◽  
The Relationship ◽  
Micromorphological Analysis

 Previous work on the role played by valley head areas in humid regions brought to light geomorphological units of the drainage net in which erosion and sedimentation would tend to be recurrent in time and space. Valley heads studied in Brazil had already proved to be very sensible to gully erosion processes, which, besides its importance to land degradation, also is a common process of hillslope evolution on humid regions. Gully erosion carries out from slopes important amounts of sediments, which may either, accumulate as proximal colluvium and alluvium or be conveyed through the drainage net. When colluvium and alluvium accumulate in proximal areas sedimentary structures may be preserved allowing the study of evolutionary processes. This paper is an attempt to apply micromorphological analysis to the study of the sedimentary structures preserved in gullied hillslopes of some southern Brazilian areas. The deposits are dated either in accordance to the supposed age of the gully incision, as estimated by aerial photographs, or by the record, in the field, of the depositional event. As a result, the age of the study deposits ranges from about 200 to 30 years, including fresh sediments just deposited one day before sampling. The paper stresses the relationship between macroscopic structures and micromorphological parametrical description, emphasizing interpretation of sedimentary structures as the result of variable overland flow rates on the gullied hillslopes.

On the Effectiveness of Land Management Decisions in Restoration of Hydrologic Ecosystem Services in Humid and Seasonal-Tropical Catchments

2020 ◽  
Author(s):  
Fred L. Ogden
Keyword(s):  
Ecosystem Services ◽  
Land Management ◽  
Green Infrastructure ◽  
Management Practices ◽  
Management Strategies ◽  
Annual Rainfall ◽  
Water Shortages ◽  
Water Supplies ◽  
Small Watersheds ◽  
Dependent Flow

<p>Cities in the humid- and seasonal-humid tropics depend on small watersheds for their water supplies.  Under normal conditions with ample rainfall, water supplies are reliable.   However, water shortages can occur during extended dry periods.  The literature contains contradictory findings regarding the effectiveness of different land management strategies aimed at enhanced delivery of hydrologic ecosystem services during periods of significant rainfall deficit, so-called “green infrastructure”.  Recent research results from field and modeling studies in the Panama Canal Watershed indicated that land-cover dependent flow paths play an important role in partitioning throughfall into subsurface stormflow and groundwater recharge.  Land management practices considered included continuous and rotational grazing, silvipastoral treatments, and different ages of secondary succession including old regrowth forest.  The effectiveness of land management was found to depend on both land use practice and annual rainfall as determined by orography in steep regions.   These dependencies at least partially explain some of the discrepancies in the literature.</p>

Using rill/interrill comparisons to infer likely responses of erosion to slope length: implications for land management

Soil Research ◽  
1996 ◽  
Vol 34 (4) ◽  
pp. 489 ◽  
Author(s):  
RJ Loch
Keyword(s):  
Land Management ◽  
Overland Flow ◽  
Unit Area ◽  
Management Strategies ◽  
Residue Management ◽  
Moderate Increase ◽  
Vegetative Cover ◽  
Slope Length ◽  
Erosion Rates ◽  
Erosion Processes

With the release of the Revised Universal Soil Loss Equation (RUSLE) there is potential to consider a range of responses of erosion to increasing slope length. This paper presents data to illustrate commonly observed effects of increasing overland flow on erosion processes and erosion rates, and considers the application of the data to specifying land management strategies and forms of vegetative cover most suited to particular soils. It also discusses a methodology for assessing relevant slope length factors for the RUSLE based on rill/interrill susceptibility. Three basic responses to slope length are noted: (i) little increase in erosion per unit area with increasing length, due to either the failure of rills to develop for the range of overland flows considered, or rill formation at very low hows with no further increase in erosion rates as flow rates increase; (ii) moderate increase in erosion per unit area with slope length associated with slight rill development; and (iii) large increases in erosion per unit area with slope length as rilling develops strongly. These responses have significance for the relative importance of surface and contact cover (and therefore, for the plant species grown and/or residue management strategy adopted), and for the use of contour banks to reduce slope length.

Gully erosion prediction across a large region: Murray - Darling Basin, Australia

Soil Research ◽  
2012 ◽  
Vol 50 (4) ◽  
pp. 267 ◽  
Author(s):  
Andrew O. Hughes ◽  
Ian P. Prosser
Keyword(s):  
Gully Erosion ◽  
Annual Rainfall ◽  
Multivariate Statistical ◽  
Erosion Processes ◽  
Erosion Prediction ◽  
Environmental Controls ◽  
Murray Darling Basin ◽  
Significant Process ◽  
Multivariate Statistical Model ◽  
Gully Density

Gully erosion is a significant process for delivering sediment to streams, and can be the dominant erosion process in some regions. As with other forms of erosion, we need methods to predict the extent and patterns of gully erosion across large areas. Such methods also improve our understanding of the environmental controls on gully erosion. Here, patterns of gully density are predicted across the 1 × 106 km2 Murray–Darling Basin in Australia, using aerial photograph mapping of gullies across part of the Basin and a multivariate statistical model of a range of environmental factors. Across the Basin, at a 10-km grid resolution, gully density is predicted to vary from 0 to 1.2 km km–2, with 22% of the Basin having a gully density >0.1 km km–2 and 3% a density >0.5 km km–2. The model is reasonably successful at predicting the variations in mapped gully density compared with similar attempts to predict erosion processes at this scale. Hillslope gradient and mean annual rainfall are the most important single factors across the region. The predicted mean gully density across the Basin is 0.08 km km–2 and gullies contribute up to 27 × 106 t year–1 of sediment to the river network. This is more than the amount that has been estimated from the combined contribution of hillslope (14 × 106 t year–1) and riverbank (8.6 × 106 t year–1) erosion by other studies within the Basin.

scholarly journals Vegetation, ground cover, soil, rainfall simulation, and overland-flow experiments before and after tree removal in woodland-encroached sagebrush steppe: the hydrology component of the Sagebrush Steppe Treatment Evaluation Project (SageSTEP)

2020 ◽  
Vol 12 (2) ◽  
pp. 1347-1365 ◽  
Author(s):  
C. Jason Williams ◽  
Frederick B. Pierson ◽  
Patrick R. Kormos ◽  
Osama Z. Al-Hamdan ◽  
Justin C. Johnson
Keyword(s):  
Experimental Data ◽  
Overland Flow ◽  
Surface Soil ◽  
Ground Cover ◽  
Rainfall Simulation ◽  
Sagebrush Steppe ◽  
Erosion Rates ◽  
Erosion Processes ◽  
Tree Removal ◽  
Flow Experiments

Abstract. Rainfall simulation and overland-flow experiments enhance understanding of surface hydrology and erosion processes, quantify runoff and erosion rates, and provide valuable data for developing and testing predictive models. We present a unique dataset (1021 experimental plots) of rainfall simulation (1300 plot runs) and overland-flow (838 plot runs) experimental plot data paired with measures of vegetation, ground cover, and surface soil physical properties spanning point to hillslope scales. The experimental data were collected at three sloping sagebrush (Artemisia spp.) sites in the Great Basin, USA, each subjected to woodland encroachment and with conditions representative of intact wooded shrublands and 1–9 years following wildfire, prescribed fire, and/or tree cutting and shredding tree-removal treatments. The methodologies applied in data collection and the cross-scale experimental design uniquely provide scale-dependent, separate measures of interrill (rain splash and sheet flow processes, 0.5 m2 plots) and concentrated overland-flow runoff and erosion rates (∼9 m2 plots), along with collective rates for these same processes combined over the patch scale (13 m2 plots). The dataset provides a valuable source for developing, assessing, and calibrating/validating runoff and erosion models applicable to diverse plant community dynamics with varying vegetation, ground cover, and surface soil conditions. The experimental data advance understanding and quantification of surface hydrologic and erosion processes for the research domain and potentially for other patchy-vegetated rangeland landscapes elsewhere. Lastly, the unique nature of repeated measures spanning numerous treatments and timescales delivers a valuable dataset for examining long-term landscape vegetation, soil, hydrology, and erosion responses to various management actions, land use, and natural disturbances. The dataset is available from the US Department of Agriculture National Agricultural Library at https://data.nal.usda.gov/search/type/dataset (last access: 7 May 2020) (doi: https://doi.org/10.15482/USDA.ADC/1504518; Pierson et al., 2019).

scholarly journals The Effect of Landscape Interventions on Groundwater Flow and Surface Runoff in a Watershed in the Upper Reaches of the Blue Nile

Water ◽  
2019 ◽  
Vol 11 (10) ◽  
pp. 2188 ◽  
Author(s):  
Adugnaw T. Akale ◽  
Dessalegn C. Dagnew ◽  
Mamaru A. Moges ◽  
Seifu A. Tilahun ◽  
Tammo S. Steenhuis
Keyword(s):  
Groundwater Flow ◽  
Land Management ◽  
Surface Runoff ◽  
Management Practices ◽  
Agricultural Land ◽  
Annual Rainfall ◽  
Flow Index ◽  
Discharge Data ◽  
Blue Nile ◽  
Stream Discharge

Anthropogenic landscape conversion from forest to agricultural land affects baseflow. Baseflow is a source of potable water and can be used for the irrigation of high value crops. Finding ways to increase base and inter flow (i.e., groundwater flow) is, therefore, essential for the improvement of the livelihood of rural inhabitants. Therefore, the objective is to investigate the effect of landscape interventions on stream discharge and, in particular, on groundwater flow. The Tikur-Wuha experimental watershed in the upper reaches of the Blue Nile was selected because discharge data were available before and after implementation of a suite of land management practices that, among others, enhanced the percolation of water to below the rootzone. The parameter efficient distributed (PED) model was used to separate overland flow from total flow. The groundwater flow index (GWFI), defined as the quotient of the annual groundwater flow to the total stream discharge at the outlet of the watershed, was calculated. Our analysis with the PED model showed that at similar annual rainfall amounts, more baseflow and less surface runoff was generated after the landscape intervention, which promoted deep infiltration of the rainwater. The decrease in surface runoff shortly after the implementation of the land management practices is similar to observations in other watersheds in the Ethiopian highlands.

scholarly journals Vegetation, ground cover, soil, rainfall simulation, and overland flow experiments before and after tree removal in woodland-encroached sagebrush steppe: the hydrology component of the Sagebrush Steppe Treatment Evaluation Project (SageSTEP)

2019 ◽  
Author(s):  
C. Jason Williams ◽  
Frederick B. Pierson ◽  
Patrick R. Kormos ◽  
Osama Z. Al-Hamdan ◽  
Justin C. Johnson
Keyword(s):  
Experimental Data ◽  
Overland Flow ◽  
Surface Soil ◽  
Ground Cover ◽  
Rainfall Simulation ◽  
Sagebrush Steppe ◽  
Erosion Rates ◽  
Erosion Processes ◽  
Tree Removal ◽  
Flow Experiments

Abstract. Rainfall simulation and overland-flow experiments enhance understanding of surface hydrology and erosion processes, quantify runoff and erosion rates, and provide valuable data for developing and testing predictive models. We present a unique dataset (1021 experimental plots) of rainfall simulation (1300 plot runs) and overland flow (838 plot runs) experimental plot data paired with measures of vegetation, ground cover, and surface soil physical properties spanning point to hillslope scales. The experimental data were collected at three sloping sagebrush (Artemisia spp.) sites in the Great Basin, USA, each subjected to woodland-encroachment and with conditions representative of intact wooded-shrublands and 1–9 yr following wildfire, prescribed fire, and/or tree cutting and shredding tree-removal treatments. The methodologies applied in data collection and the cross-scale experimental design uniquely provide scale-dependent, separate measures of interrill (rainsplash and sheetflow processes) and concentrated overland-flow runoff and erosion rates along with collective rates for these same processes combined over the patch scale (tens of meters). The dataset provides a valuable source for developing, assessing, and calibrating/validating runoff and erosion models applicable to diverse plant community dynamics with varying vegetation, ground cover, and surface soil conditions. The experimental data advance understanding and quantification of surface hydrologic and erosion processes for the research domain and potentially for other patchy-vegetated rangeland landscapes elsewhere. Lastly, the unique nature of repeated measures spanning numerous treatments and time scales delivers a valuable dataset for examining long-term landscape vegetation, soil, hydrology, and erosion responses to various management actions, land use, and natural disturbances. The dataset is available from the National Agricultural Library at https://data.nal.usda.gov/search/type/dataset (DOI: https://doi.org/10.15482/USDA.ADC/1504518; Pierson et al., 2019).

Low watershed hydrological and erosion response after fire can be explained by connectivity

2020 ◽  
Author(s):  
Jinfeng Wu ◽  
Jantiene E.M. Baartman ◽  
João P. Nunes
Keyword(s):  
Overland Flow ◽  
Burn Severity ◽  
Watershed Scale ◽  
Hydrological Responses ◽  
Erosion Processes ◽  
Altered Hydrology ◽  
Sediment Loads ◽  
Before And After ◽  
Mediterranean Regions ◽  
Major Factors

<p>Mediterranean regions have always been affected by wildfires. However, no studies investigating post-fire hydrological responses and erosion at the watershed scale (~>10 km2) were conducted in Mediterranean. In this study, the discharge and sediment measurements at the outlet of a Mediterranean watershed were observed to test changes in hydrological responses and sediment loads before and after the fire. Besides, aid by the PCA analysis and analysis of connectivity patterns and changes using the index of connectivity (IC), we analyze the hydrological responses and erosion to a wildfire at the watershed scale. Although most of vegetation was removed after the wildfire, it did not, overall, lead to a significant increase in hydrological responses and sediment loads at the watershed scale. Our results can be explained by three major factors. Firstly, much lower rainfall the first two hydrological years after the fire occurred in our watershed. Secondly, as a result of the scale dependency of hydrological and erosion processes, fire-enhanced overland flow and sediment transport occurred locally on hillslope with high burn severity but did not (yet) reach the outlet. Finally, and arguably, most importantly, connectivity in our study area is relatively low and, although it increases after the fire, it remains generally low. Even though post-wildfire connectivity in our watershed increased by 20%, this increase in connectivity was mainly located in the upstream-most part of this catchment, with much less increased connectivity in the downstream areas, which are closer to the catchment outlet. We concluded that the fire consumed vegetation and altered hydrology and erosion processes but didn’t significantly influence downstream water quantity and quality. Connectivity linked to burn severity was suitable for evaluating the effect of wildfire on hydrological responses and erosion. Moreover, this method also appears to be reasonable in assessing and mitigating post-fire water contamination risk.</p>

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