Effects of sediment load on hydraulics of overland flow on steep slopes

Sediment and nutrient data from USGS gauged stream sites in New Mexico and from rainfall simulation experiments were compiled and analyzed. Above a suspended sediment concentration of about 500 mg/l, associated concentrations of total phosphorus are highest in overland flow and then progressively decrease from agricultural drains to ephemeral washes to undammed rivers. Within a stream type, sediment-related concentrations of total phosphorus typically differed between larger and smaller basins. Small rivers had higher phosphorus transport per unit of sediment load than larger rivers. Small and medium sized washes had different relationships between phosphorus and sediment than did large and very large washes.

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Mitigation of surface runoff and erosion impacts on catchment by stone hedgerows

Soil and Water Research ◽

10.17221/31/2011-swr ◽

2011 ◽

Vol 6 (No. 4) ◽

pp. 153-164 ◽

Cited By ~ 5

Author(s):

P. Kovář ◽

D. Vaššová ◽

M. Hrabalíková

Keyword(s):

Surface Runoff ◽

Overland Flow ◽

Extreme Rainfall ◽

Field Measurements ◽

Lower Surface ◽

Model Parameters ◽

Contour Lines ◽

Soil Hydraulic Parameters ◽

Rainfall Runoff Model ◽

Steep Slopes

This paper presents the results of a study on the influence of hedgerows on the process of the surface runoff in the experimental catchment Verneřice 1, Ústí n. L. region, the Czech Republic. The influence of hedgerows on the surface runoff was simulated using the KINFIL rainfall-runoff model. The model parameters were assessed from the field measurements of the soil hydraulic parameters, in particular the saturated hydraulic conductivity and sorptivity. The catchment area is characterised by stone hedgerows constructed by land users throughout the past centuries, using stones collected from the adjacent agricultural fields. Presently, the hydraulic properties of these hedgerows reflect the characteristics of the mixture of stones, deposited soil, and vegetation litter, and they are more permeable than soil on the areas between them. Due to this fact, the permeability of the hedgerows produces a higher infiltration and a lower surface runoff. Therefore, the overland flow vulnerability and impact of water erosion decrease if they are situated in parallel to the contour lines system. The model was applied for two scenarios in the catchment – with and without hedgerows – to assess their effects on extreme rainfalls with a short duration. The surface runoff caused by extreme rainfall was simulated in order to show how hedgerows can mitigate the resultant flood and erosion. This paper provides relevant hydrological data and summarises the influence of man-made hedgerows on the overland flow control, i.e. on long and steep slopes surface runoff.

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On the diffusion wave model for overland flow: 1. Solution for steep slopes

Water Resources Research ◽

10.1029/wr024i005p00734 ◽

1988 ◽

Vol 24 (5) ◽

pp. 734-744 ◽

Cited By ~ 77

Author(s):

R. S. Govindaraju ◽

S. E. Jones ◽

M. L. Kavvas

Keyword(s):

Overland Flow ◽

Wave Model ◽

Diffusion Wave ◽

Steep Slopes ◽

Diffusion Wave Model

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Experimental study of post-eruption overland flow and sediment load from slopes overlain by pyroclastic-flow deposits, Unzen volcano, Japan

Géomorphologie relief processus environnement ◽

10.4000/geomorphologie.3962 ◽

2007 ◽

Vol 13 (3) ◽

pp. 237-246 ◽

Cited By ~ 10

Author(s):

Yasuhiro Ogawa ◽

Hiromu Daimaru ◽

Akira Shimizu

Keyword(s):

Experimental Study ◽

Pyroclastic Flow ◽

Overland Flow ◽

Sediment Load ◽

Unzen Volcano

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Diffused and localized sediment production processes in a distributed transport model

10.5194/egusphere-egu2020-7671 ◽

2020 ◽

Author(s):

Giulia Battista ◽

Peter Molnar ◽

Fritz Schlunegger ◽

Paolo Burlando

Keyword(s):

Surface Roughness ◽

High Resolution ◽

Overland Flow ◽

Sediment Load ◽

Transport Model ◽

Sediment Sources ◽

Local Surface ◽

Sediment Production ◽

Production Processes ◽

Spatially Distributed

The identification of preferential sediment production areas within a river basin is essential to improve predictions of sediment load and its sources, and to identify sources of potential water pollution. The role of these localized sediment sources is especially relevant in the sediment budget of alpine basins, where erosion in highly non-uniform and mass movements play a major role in the mobilization of sediments. While sediment tracers are useful to assess the origin of river-borne sediments, currently very few spatially distributed sediment transport models include the sediment production from a variety of sources and track sediment from source to outlet.In this work, we present a new approach to include the production of sediment from localized sources, in addition to diffusive overland flow erosion, in a spatially distributed sediment production and transport model. This extension of the hydrological model Topkapi-ETH simulates the mobilization of sediments by (i) overland flow erosion, (ii) sediment pickup from landsliding areas by overland flow and (iii) river discharge, and (iv) sediment pickup from deeply incised valleys by channel flow. Landslides and incised valleys were identified from geological/geomorphological maps and a high resolution DEM of the study basin. To model the contribution of landslides, we introduce a parameter &#955; for gully competence, which describes the effectiveness of overland flow in mobilizing the sediments. Overall, &#955; affects the contributions of the different sediment production processes to the modelled sediment load at the basin outlet. To estimate a value of &#955; for the case study, we propose the local surface roughness to quantify the gully development onto the landslide surfaces. Additionally, we use available 10Be measurements across the basin to assign a concentration to each sediment production process and select the end member value of &#955; that best reproduces the observed 10Be concentrations at the outlet.Our simulations indicate that including the production of sediments from localized sources with processes (ii) to (iv) is essential to capture the highest observed concentrations with the model. Moreover, the same observed suspended sediment concentrations at the outlet may be obtained with different combinations of sediment production processes in function of the gully competence. Finally, the local surface roughness analysis and the use of 10Be concentration as a sediment tracer suggest that channel processes are dominant over hillslope sediment production in the study basin.In conclusion, our work shows that combinations of physically-based sediment transport modelling with geomorphological mapping of localized sediment sources, high-resolution topographic information and point measurements of cosmogenic radionuclide concentrations allow to infer the dominant sediment production processes in river basins.

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Sediment Transport Model for a Surface Irrigation System

Applied and Environmental Soil Science ◽

10.1155/2013/957956 ◽

2013 ◽

Vol 2013 ◽

pp. 1-10 ◽

Cited By ~ 1

Author(s):

Damodhara R. Mailapalli ◽

Narendra S. Raghuwanshi ◽

Rajendra Singh

Keyword(s):

Sediment Transport ◽

Overland Flow ◽

Sediment Load ◽

Transport Model ◽

Irrigation System ◽

Hydraulic Model ◽

Furrow Irrigation ◽

Management Tool ◽

Surface Irrigation ◽

Sediment Transport Model

Controlling irrigation-induced soil erosion is one of the important issues of irrigation management and surface water impairment. Irrigation models are useful in managing the irrigation and the associated ill effects on agricultural environment. In this paper, a physically based surface irrigation model was developed to predict sediment transport in irrigated furrows by integrating an irrigation hydraulic model with a quasi-steady state sediment transport model to predict sediment load in furrow irrigation. The irrigation hydraulic model simulates flow in a furrow irrigation system using the analytically solved zero-inertial overland flow equations and 1D-Green-Ampt, 2D-Fok, and Kostiakov-Lewis infiltration equations. Performance of the sediment transport model was evaluated for bare and cropped furrow fields. The results indicated that the sediment transport model can predict the initial sediment rate adequately, but the simulated sediment rate was less accurate for the later part of the irrigation event. Sensitivity analysis of the parameters of the sediment module showed that the soil erodibility coefficient was the most influential parameter for determining sediment load in furrow irrigation. The developed modeling tool can be used as a water management tool for mitigating sediment loss from the surface irrigated fields.

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Monitoring and modeling the impact of soil conservation scenarios to limit overland flow and sediment supply from unpaved roads in a small catchment of Southern Brazil

10.5194/egusphere-egu2020-10936 ◽

2020 ◽

Author(s):

Alice Dambroz ◽

Jean Minella ◽

Cristiano Silva ◽

Alexandre Schlesner ◽

Felipe Bernardi ◽

...

Keyword(s):

Soil Erosion ◽

Soil Conservation ◽

Overland Flow ◽

Peak Flow ◽

Sediment Supply ◽

Unpaved Roads ◽

Rainfall Events ◽

The Road ◽

Shallow Soils ◽

Steep Slopes

Erosion processes are accelerated by the presence of unpaved roads in catchments with shallow soils and steep slopes, favoring overland flow and sediment connectivity between hillslopes and the river network. Soil erosion modeling studies conducted at the catchment scale focus primarily on the hydrological behavior of cultivated hillslopes. Few studies address unpaved roads and suitable practices to limit their impact on hydro-sedimentary transfers in a catchment system. This study simulates soil conservation measures on unpaved roads and hillslopes and their effect on the hydrological and erosive dynamics in a small order catchment. The rainfall events were monitored at Lajeado Ferreira&#8217;s creek, in Arvorezinha, Southern Brazil (1.2 km&#178;). The catchment is characterized by shallow soils, steep slopes, intense agricultural activity and sediment yields (SY) of around 150 t km-2 y-1. Unpaved roads cover about 3% of the catchment surface area and supply 36% of the annual average SY. The Limburg Soil Erosion Model (LISEM) was used to simulate the roads&#8217; impact on soil erosion. Eight rainfall events, monitored from 2014 to 2017, were calibrated. Rainfall ranged from 9 to 97 mm, total runoff volume (Q) varied from 1462 to 60765 m&#179; and SY from 0.6 to 81 tons. These events represent different precipitation and land use conditions, so that the road&#8217;s effects on the hydrological dynamics of this catchment may be investigated. Then, modeling scenarios consisting of three levels of intervention to mitigate sediment supply were tested. &#160;The low intervention (LI) level was based on cost-efficient practices, applied to the road only through the installation of rockfill and energy-deflecting small reservoirs. The medium intervention (MI) included the sowing of grass for gutter protection on the road area and filter strips were installed near the drainage channels. For the high intervention scenario (HI), additional grass strips were installed on hillslopes. Their impact was evaluated by comparing the hydrosedimentological variables Q (m&#179;), peak flow (L s-1) and SY (tons), modelled at the catchment&#8217;s outlet. Rockfill and energy-deflecting small reservoirs were not enough for reducing peak flow (Qp), on average. Indeed, the main proportion of overland flow originates from other landscape components, such as hillslopes. Under the MI and HI scenarios, Qp decreased by 2 and 46%, respectively. The LI and MI scenarios led to an average Q reduction of 12%, compared to 53% under scenario HI. For one event, HI promoted a reduction of 92% of calculated Q, representing 15,693 m&#179;. HI also showed the most positive effects on limiting SY. It becomes evident that hillslope interventions are necessary, as they allow increasing infiltration, reducing both runoff volume and stream power when the flow reaches the roads. For rainfall events of higher magnitude, it was observed that HI was responsible for reducing Qp between 9 and 25%, while during smaller events, this reduction reached 61 to 93%. This indicates the importance of managing roads in order to reduce runoff energy and concentration, but also to take measures on hillslopes to limit overland flow and erosion inputs, as well as to delay peak Q.

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Slope threshold in rill flow resistance

10.5194/egusphere-egu21-10212 ◽

2021 ◽

Author(s):

Alessio Nicosia ◽

Vito Ferro

Keyword(s):

Friction Factor ◽

Flow Resistance ◽

Sediment Load ◽

Steep Slope ◽

Limiting Factor ◽

Rill Erosion ◽

Hydraulic Characteristics ◽

Transport Capacity ◽

Steep Slopes ◽

Rill Flow

Rills are small, steep sloping and ephemeral channels, shaped in soils, in which shallow flows move. Rill erosion strictly depends on hydraulic characteristics of the rill flow and for this reason flow discharge Q, rill width w, water depth h, mean flow velocity V, and friction factor are required to model the rill erosion process.Erosive phenomena strictly depend on the attitude of the soil particles to be detached (detachability) and to be transported (transportability). These properties are affected by soil texture and influence the sediment load G to be transported by flow. The actual sediment load depends on the transport capacity Tc of the flow, which is the maximum amount of sediment, with given sizes and specific weight, that can be transported by a flow of known hydraulic characteristics.According to Jiang et al. (2018) the hydraulic mechanisms of soil erosion for steep slopes are different from those for gentle slopes. Recent research on Tc equations exploring slopes steeper than 18% (Ali et al., 2013; Zhang et al., 2009; Wu et al., 2016) established that Tc relationships designed for gentle slopes (<18%) are unsuitable to be applied to steep slopes (17&#8211;47%). Also Peng et al. (2015) noticed that <<there has been little research concerning rill flow on steep slopes (e.g. slope gradients higher than 10&#176;)>>. In other words, the slope of 18% could be used to distinguish between the &#8220;gentle slope&#8221; and the &#8220;steep slope&#8221; case for the recognized difference in hydraulic and sediment transport variables.The applicability of a theoretical rill flow resistance equation, based on the integration of a power velocity distribution (Barenblatt, 1979; 1987), was tested using measurements carried out in mobile rills shaped on plots having different slopes (9, 14, 15, 18, 22, 24, 25 and 26%) and soil textures (clay fractions ranging from 32.7% to 73% and silt of 19.9% &#8211; 30.9%), and measurements available in literature (Jiang et al. (2018), Huang et al. (2020) and Yang et al. (2020)).The Darcy-Weisbach friction factor resulted dependent on slope, Froude number, Reynolds number and CLAY and SILT percentages, which represent soil transportability and detachability, respectively. This theoretical approach was applied to two different databases distinguished by the slope threshold of 18%. The results showed that, for gentle slopes (< 18%), the Darcy-Weisbach friction factor increases with slope, CLAY and SILT content. Taking into account that for gentle slopes the hydraulic characteristics limit the transport capacity, for this condition Tc and the sediment load G are both limiting factors.For steep slopes (> 18%), the flow resistance increases with slope and the ratio between SILT and CLAY percentage. Steep slopes determine high values of the transport capacity, which is consequently not a limiting factor. Thus, in this condition the actual sediment load is determined exclusively by the ratio between SILT and CLAY percentage. In other words, the only limiting factor for a steep slope condition is the sediment which can be transported (i.e. the sediment load G), affected by its soil detachability and transportability.

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Modeling the effects of sediment concentration on the propagation of flash floods in an Andean watershed

10.5194/nhess-2019-168 ◽

2019 ◽

Author(s):

María Teresa Contreras ◽

Cristián Escauriaza

Keyword(s):

Urban Areas ◽

Overland Flow ◽

Mass Conservation ◽

Sediment Concentration ◽

Early Warning Systems ◽

Flash Floods ◽

Mountain Ranges ◽

The Andes ◽

High Concentrations ◽

Steep Slopes

Abstract. Rain-induced flash floods are common events in regions near mountain ranges. In peri-urban areas near the Andes the combined effects of the changing climate and ENSO have resulted in an alarming proximity of populated areas to flood-prone streams, increasing the risk for cities and infrastructure. Simulations of rapid floods in these watersheds are particularly challenging, due to the complex morphology, the insufficient hydrometeorological data, and the uncertainty posed by the variability of sediment concentration. High concentrations produced by hillslope erosion and rilling by the overland flow in areas with steep slopes and low vegetational covering can change significantly the dynamics of the flow as the flood propagates in the channel. In this investigation, we develop a two-dimensional finite-volume numerical model of the non-linear shallow water equations coupled with the mass conservation of sediment to study the effects of different densities, which include a modified version of the quadratic stress model to quantify the changes on the flow rheology. We carry out simulations to evaluate the effects of the sediment concentration on the floods in the Quebrada de Ramon watershed, a peri-urban Andean basin in central Chile. We simulate a confluence and a total length of the channel of 10.4 km, with the same water hydrographs and different combinations of sediment concentrations in the tributaries. Our results show that the most important effects on the flood propagation are observed in the range of concentrations from 0 % to 20 %. Simulations also show that variables such as the arrival time of the peak flow, and the shape of the hydrograph at different locations along the channel are not significantly affected by the sediment concentration and depend mostly on the steep channel morphology. Through this work we provide a framework for future studies aimed at improving hazard assessment, urban planning, and early warning systems in urban areas near mountain streams with limited data and affected by rapid flood events.

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