Watershed models for assessment of hydrological behavior of the catchments: a comparative study

2020 ◽  
Vol 15 (2) ◽  
pp. 261-281
Author(s):  
Sarvat Gull ◽  
Shagoofta Rasool Shah
Keyword(s):  
Soil Loss ◽  
Screening Tool ◽  
Overland Flow ◽  
Decision Makers ◽  
Nutrient Losses ◽  
Watershed Model ◽  
Watershed Models ◽  
Hydrological Parameters ◽  
Input And Output ◽  
Processing Ability

Abstract Hydrological parameters like overland flow, soil loss and nutrient losses can be studied by using different watershed models. However, all these models vary significantly in their analysis of parameters, input and output flexibility, scale accountability, processing ability, computational efficiency and capability of modeling the changes in catchments. This paper reviews different watershed models used for analyzing overland flow, soil loss and sediment yield with their shortcomings and strengths. These watershed models are described briefly along with their capabilities and shortcomings with their examples of applications, results and comparisons. An outcome of these discussions is presented in tabular format as a screening tool to allow the researchers and decision makers to choose the appropriate watershed model for the specific purpose.

Structural, Hydrologic, and Sediment Connectivity in a Shrub-Encroached and Restored Semiarid Grassland

2021 ◽  
Author(s):  
Justin Johnson ◽  
Jason Williams ◽  
Phillip Guertin ◽  
Steven Archer ◽  
Philip Heilman ◽  
...  
Keyword(s):  
Sediment Yield ◽  
Soil Loss ◽  
Rainfall Intensity ◽  
Overland Flow ◽  
Spatial Scales ◽  
Structural Connectivity ◽  
Post Treatment ◽  
Semiarid Grassland ◽  
Concentrated Flow ◽  
Shrub Canopy

<p>Shrub encroachment of semiarid grasslands is influenced by connected runoff and erosion patterns that preferentially accumulate resources under vegetated patches (canopy microsites) and deplete interspaces. Soil loss from dryland hillslopes results when areas of bare ground become structurally and functionally connected through overland flow. Although these patterns have been well-described, uncertainty remains regarding how these feedbacks respond to restoration practices. This study compared the structure and hydrologic function of a shrub-encroached semiarid grassland treated five years prior with the herbicide, tebuthiuron, to that of an adjacent untreated grassland. Through a series of hydrologic experiments conducted at increasing spatial scales, vegetation and soil structural patterns were related to runoff and erosion responses. At a fine scale (0.5 m<sup>2</sup>), rainfall simulations (120 mm·h<sup>-1</sup> rainfall intensity; 45 min) showed herbicided shrub canopy microsites had greater infiltration capacities (105 and 71 mm·h<sup>-1</sup> terminal infiltration rates) and were less susceptible to splash-sheet erosion (3 and 26 g sediment yield) than untreated shrub canopy microsites, while interspaces were statistically comparable between study sites. Concentrated flow simulations at a coarse scale (~9 m<sup>2</sup>) revealed that gaps between the bases of vegetation (i.e. basal gaps) > 2 m<sup></sup>were positively related to both concentrated flow runoff (r = 0.72, p = 0.008) and sediment yield (r = 0.70, p = 0.012). Modeled hillslope-scale (50 m<sup>2</sup>) runoff and erosion (120 mm·h<sup>-1</sup> rainfall intensity; 45 min) indicated less soil loss in the tebuthiuron-treated site (1.78 Mg·ha<sup>-1</sup> tebuthiuron; 3.19 Mg·ha<sup>-1</sup> untreated), even though runoff was similar between sites. Our results suggest interspaces in shrub-encroached grasslands continue to be runoff sources following herbicide-induced shrub mortality and may be indicators of runoff responses at larger spatial scales. In contrast, sediment sources are limited post-treatment due to lesser sediment detachment from sheet-splash and concentrated flow processes. Reduced sediment supplies provide evidence that connectivity feedbacks that sustain a shrub-dominant ecological state may have been dampened post-treatment. Our study also highlights the utility of simple measures of structural connectivity, such as basal gaps, as an indicator of hillslope susceptibility to increased runoff and erosion.</p>

Rainfall runoff in soil erosion with simulated rainfall, overland flow and cover

Soil Research ◽  
1983 ◽  
Vol 21 (2) ◽  
pp. 109 ◽  
Author(s):  
MJ Singer ◽  
PH Walker
Keyword(s):  
Soil Erosion ◽  
Soil Loss ◽  
Rainfall Intensity ◽  
Overland Flow ◽  
Podzolic Soil ◽  
Simulated Rainfall ◽  
Rainfall Runoff ◽  
Runoff Water ◽  
Soil Transport ◽  
Raindrop Impact

The 20-100 mm portion of a yellow podzolic soil (Albaqualf) from the Ginninderra Experiment Station (A.C.T.) was used in a rainfall simulator and flume facility to elucidate the interactions between raindrop impact, overland water flow and straw cover as they affect soil erosion. A replicated factorial design compared soil loss in splash and runoff from 50 and 100 mm h-1 rainfall, the equivalent of 100 mm h-1 overland flow, and 50 and 100 mm h-1 rainfall plus the equivalent of 100 mm h-' overland flow, all at 0, 40 and 80% straw cover on a 9% slope. As rainfall intensity increased, soil loss in splash and runoff increased. Within cover levels, the effect of added overland flow was to decrease splash but to increase total soil loss. This is due to an interaction between raindrops and runoff which produces a powerful detaching and transporting mechanism within the flow known as rain-flow transportation. Airsplash is reduced, in part, because of the changes in splash characteristics which accompany changes in depths of runoff water. Rain-flow transportation accounted for at least 64% of soil transport in the experiment and airsplash accounted for no more than 25% of soil transport The effects of rainfall, overland flow and cover treatments, rather than being additive, were found to correlate with a natural log transform of the soil loss data.

scholarly journals Risk of Snake Entanglement Is Affected by Installation Method of Erosion Control Blankets

2020 ◽  
Vol 11 (1) ◽  
pp. 273-278 ◽  
Author(s):  
Krista J. Ward ◽  
Kasey L. Jobe ◽  
Nicholas C. Schiwitz ◽  
Daniel Saenz ◽  
Christopher M. Schalk
Keyword(s):  
Soil Loss ◽  
Construction Projects ◽  
Road Construction ◽  
Erosion Control ◽  
Decision Makers ◽  
Experimental Setting ◽  
Control Product ◽  
Promote Plant Growth ◽  
Edge Treatment ◽  
Pass Through

Abstract At the conclusion of road construction projects, an erosion control product (e.g., blankets, spray mulch) is installed to reduce soil loss and promote plant growth. Wildlife, such as snakes (suborder Serpentes), are prone to entanglement in erosion control blankets (ECBs) that contain polypropylene mesh with fused apertures. Previous reports have noted that the occurrences of entanglements are not uniform in their distribution across an ECB, but primarily occur where the edge of the mesh is exposed. We conducted an experiment to determine if modification to the installation methods of ECBs affects the likelihood of snake entanglement. We conducted entanglement trials to compare the likelihood of snake entanglement between two treatments: 1) exposed ECB edge (i.e., perimeter) and 2) buried ECB edge. Snakes were less likely to attempt to pass through the mesh on the buried edge treatment and all entanglements occurred on the exposed edge treatment. These results provide support that modification to the installation methods reduces snake entanglement in ECBs in some settings. However, we conducted our study in an experimental setting, and it should be evaluated under natural field conditions. This research can be used to inform several parties including contractors, habitat managers, and agency decision makers on additional steps that can be taken for products that fit their application needs to minimize risks to wildlife.

scholarly journals Effects of gravel-sand mulch on the runoff, erosion, and nutrient losses in the Loess Plateau of north-western China under simulated rainfall

2020 ◽  
Vol 16 (No. 1) ◽  
pp. 22-28
Author(s):  
Yang Qiu ◽  
Xinping Wang ◽  
Zhongkui Xie ◽  
Yajun Wang
Keyword(s):  
Grain Size ◽  
Surface Runoff ◽  
Soil Loss ◽  
Bare Soil ◽  
Western China ◽  
Nutrient Losses ◽  
Gravel Mulch ◽  
Runoff And Soil Loss ◽  
North Western ◽  
Fine Gravel

Gravel mulching is a characteristic agricultural technique that has been used for hundreds of years in the north-western Loess Plateau of China. However, the effects of the gravel-sand mulch on the processes of the runoff, soil erosion, and nutrient losses are neither fully distinguished nor even known in many parts of the world. This study investigated how different gravel particle sizes in the mulch affected the runoff, erosion as well as the extent of the nutrient losses in the surface runoff. The laboratory experiments were conducted using a rainfall simulator with three gravel mulch treatments: (1) fine gravel mulch (FG); (2) medium gravel mulch (MG); (3) coarse gravel mulch (CG) and a control group, bare soil (BS). The results of these rainfall simulation experiments gave estimates on how the grain size influences the runoff and losses of the soil and its nutrients. Applying the gravel mulch significantly delayed the runoff’s starting time when compared with the bare soil. Both the total runoff and soil loss increased with the grain size of the gravel mulch. Compared with the bare soil, the lowest surface runoff and soil loss was observed from the fine gravel treatment. These results clearly show that gravel mulch plays an important role in the runoff and sediment generation processes, and that it significantly reduces the surface runoff and soil loss. The losses of the total nitrogen (TN), total phosphorus (TP), and total organic carbon (TOC) from the bare soil were much higher than those under the gravel mulching. The fluctuations in these nutrient-loss processes were the most intense in the CG treatment, while the TC content, in initial runoff, was significantly higher in the FG than the other treatments. Our findings suggest gravel mulch is a useful water and soil conservation technique in the loess area of north-western China, and these results can inform one on the theoretical principles for properly utilising gravel-mulched fields.

Measuring Soil Loss and Subsequent Nutrient and Organic Matter Loss on Farmland

2017 ◽  
Author(s):  
Vito Ferro ◽  
Vincenzo Bagarello
Keyword(s):  
Organic Matter ◽  
Soil Organic Matter ◽  
Soil Loss ◽  
Soil Structure ◽  
Overland Flow ◽  
Organic Matter Content ◽  
Matter Content ◽  
Water Infiltration ◽  
Surface Erosion ◽  
Rill Erosion

Field plots are often used to obtain experimental data (soil loss values corresponding to different climate, soil, topographic, crop, and management conditions) for predicting and evaluating soil erosion and sediment yield. Plots are used to study physical phenomena affecting soil detachment and transport, and their sizes are determined according to the experimental objectives and the type of data to be obtained. Studies on interrill erosion due to rainfall impact and overland flow need small plot width (2–3 m) and length (< 10 m), while studies on rill erosion require plot lengths greater than 6–13 m. Sites must be selected to represent the range of uniform slopes prevailing in the farming area under consideration. Plots equipped to study interrill and rill erosion, like those used for developing the Universal Soil Loss Equation (USLE), measure erosion from the top of a slope where runoff begins; they must be wide enough to minimize the edge or border effects and long enough to develop downslope rills. Experimental stations generally include bounded runoff plots of known rea, slope steepness, slope length, and soil type, from which both runoff and soil loss can be monitored. Once the boundaries defining the plot area are fixed, a collecting equipment must be used to catch the plot runoff. A conveyance system (H-flume or pipe) carries total runoff to a unit sampling the sediment and a storage system, such as a sequence of tanks, in which sediments are accumulated. Simple methods have been developed for estimating the mean sediment concentration of all runoff stored in a tank by using the vertical concentration profile measured on a side of the tank. When a large number of plots are equipped, the sampling of suspension and consequent oven-drying in the laboratory are highly time-consuming. For this purpose, a sampler that can extract a column of suspension, extending from the free surface to the bottom of the tank, can be used. For large plots, or where runoff volumes are high, a divisor that splits the flow into equal parts and passes one part in a storage tank as a sample can be used. Examples of these devices include the Geib multislot divisor and the Coshocton wheel. Specific equipment and procedures must be employed to detect the soil removed by rill and gully erosion. Because most of the soil organic matter is found close to the soil surface, erosion significantly decreases soil organic matter content. Several studies have demonstrated that the soil removed by erosion is 1.3–5 times richer in organic matter than the remaining soil. Soil organic matter facilitates the formation of soil aggregates, increases soil porosity, and improves soil structure, facilitating water infiltration. The removal of organic matter content can influence soil infiltration, soil structure, and soil erodibility.

Digital mapping of RUSLE slope length and steepness factor across New South Wales, Australia

Soil Research ◽  
2015 ◽  
Vol 53 (2) ◽  
pp. 216 ◽  
Author(s):  
Xihua Yang
Keyword(s):  
Land Use Planning ◽  
Soil Loss ◽  
Overland Flow ◽  
New South ◽  
New South Wales ◽  
Slope Angle ◽  
Universal Soil Loss Equation ◽  
Slope Length ◽  
South Wales ◽  
Soil Loss Equation

The Universal Soil Loss Equation (USLE) and its main derivate, the Revised Universal Soil Loss Equation (RUSLE), are widely used in estimating hillslope erosion. The effects of topography on hillslope erosion are estimated through the product of slope length (L) and slope steepness (S) subfactors, or LS factor, which often contains the highest detail and plays the most influential role in RUSLE. However, current LS maps in New South Wales (NSW) are either incomplete (e.g. point-based) or too coarse (e.g. 250 m), limiting RUSLE-based applications. The aim of this study was to develop automated procedures in a geographic information system (GIS) to estimate and map the LS factor across NSW. The method was based on RUSLE specifications and it incorporated a variable cutoff slope angle, which improves the detection of the beginning and end of each slope length. An overland-flow length algorithm for L subfactor calculation was applied through iterative slope-length cumulation and maximum downhill slope angle. Automated GIS scripts have been developed for LS factor calculation so that the only required input data are digital elevation models (DEMs). Hydrologically corrected DEMs were used for LS factor calculation on a catchment basis, then merged to form a seamless LS-factor digital map for NSW with a spatial resolution ~30 m (or 1 s). The modelled LS values were compared with the reference LS values, and the coefficient of efficiency reached 0.97. The high-resolution digital LS map produced is now being used along with other RUSLE factors in hillslope erosion modelling and land-use planning at local and regional scales across NSW.

LAVSED-I — Un modèle pour prédire l'érosion des bassins et le transfert de sédiments fins dans les cours d'eau nordiques

1986 ◽  
Vol 13 (2) ◽  
pp. 150-161 ◽  
Author(s):  
M. Frenette ◽  
P. Y. Julien
Keyword(s):  
Land Use ◽  
Computer Modeling ◽  
Sediment Yield ◽  
Soil Loss ◽  
Overland Flow ◽  
Computational Procedure ◽  
Modeling Techniques ◽  
Operational Development ◽  
Soil Losses ◽  
Soil Loss Equation

Computer modeling techniques are used for predicting soil losses from overland flow and subsequent suspended sediment yield from large watersheds. The model LAVSED-I (LAVal SEDidentological model No. 1) is based on the universal soil-loss equation of Wischmeier and Smith and the equation of Kiline and Richardson. The model subdivides the watershed into square units varying in size from 0.3 to 3000 km2 and the computational procedure is subdivided in four components: precipitation, physical characteristics of watersheds, erosion/sedimentation, and land use. This paper describes the operational development and the application of the model to a prototype-scale watershed. A map for the annual soil loss is presented for the Chaudière watershed (area = 5830 km2). Results of mapping compared with the sediment yield observed are shown in the paper.

scholarly journals Modelling the Event-Based Hydrological Response of Mediterranean Forests to Prescribed Fire and Soil Mulching with Fern Using the Curve Number, Horton and USLE-Family (Universal Soil Loss Equation) Models

Land ◽  
2021 ◽  
Vol 10 (11) ◽  
pp. 1166
Author(s):  
Bruno Gianmarco Carra ◽  
Giuseppe Bombino ◽  
Manuel Esteban Lucas-Borja ◽  
Pietro Denisi ◽  
Pedro Antonio Plaza-Álvarez ◽  
...  
Keyword(s):  
Prescribed Fire ◽  
Soil Loss ◽  
Overland Flow ◽  
Curve Number ◽  
Soil Conditions ◽  
Mediterranean Forests ◽  
Hydrological Response ◽  
Infiltration Excess ◽  
Runoff And Soil Loss ◽  
Scs Cn

The SCS-CN, Horton, and USLE-family models are widely used to predict and control runoff and erosion in forest ecosystems. However, in the literature there is no evidence of their use in Mediterranean forests subjected to prescribed fire and soil mulching. To fill this gap, this study evaluates the prediction capability for runoff and soil loss of the SCS-CN, Horton, MUSLE, and USLE-M models in three forests (pine, chestnut, and oak) in Southern Italy. The investigation was carried out at plot and event scales throughout one year, after a prescribed fire and post-fire soil mulching with fern. The SCS-CN and USLE-M models were accurate in predicting runoff volume and soil loss, respectively. In contrast, poor predictions of the modelled hydrological variables were provided by the models in unburned plots, and by the Horton and MUSLE models for all soil conditions. This inaccuracy may have been due to the fact that the runoff and erosion generation mechanisms were saturation-excess and rainsplash, while the Horton and MUSLE models better simulate infiltration-excess and overland flow processes, respectively. For the SCS-CN and USLE-M models, calibration was needed to obtain accurate predictions of surface runoff and soil loss; furthermore, different CNs and C factors must be input throughout the year to simulate the variability of the hydrological response of soil after fire. After calibration, two sets of CNs and C-factor values were suggested for applications of the SCS-CN and USLE-M models, after prescribed fire and fern mulching in Mediterranean forests. Once validated in a wider range of environmental contexts, these models may support land managers in controlling the hydrology of Mediterranean forests that are prone to wildfire risks.

Corrigendum to: A comparison using the caesium-137 technique of the relative importance of cultivation and overland flow on soil erosion in a steep semi-tropical sub-catchment

Soil Research ◽  
2001 ◽  
Vol 39 (5) ◽  
pp. 1183
Author(s):  
A. S. Wiranatha ◽  
C. W. Rose ◽  
M. S. Salama
Keyword(s):  
Soil Erosion ◽  
Spatial Pattern ◽  
Soil Loss ◽  
Overland Flow ◽  
Relative Importance ◽  
Valley Bottom ◽  
Spatial Trends ◽  
Erosion Mechanisms ◽  
Soil Accumulation ◽  
Periodic Flooding

The spatial pattern of net soil loss on 6 downslope transects in a small semi-tropical sub-catchment was measured in 1990—91 using the resident caesium-137 deficit technique. The sub-catchment consisted of 2 opposing hillslopes which shed water to an intermittent stream in the valley bottom of the sub-catchment. There were 3 transects on each of the opposing hillslopes, and measurement indicated net soil loss from all 6 transects. Furthermore, the spatial pattern of caesium-137 deficit did not indicate the accumulation of soil expected due to the slope decrease toward the bottom of the valley. Possible explanations of this finding could be the effect of periodic flooding of the intermittent valley stream, or seepage-accelerated erosion. Pineapple cultivation in the sub-catchment since 1950 included intensive cultivation at 4-year intervals by downslope-moving rotary hoe. The paper develops a theoretical prediction of the spatial pattern of net soil loss expected due to such cultivation, as well as the expected pattern of soil loss due to overland flow on the hillslopes. The spatial patterns of soil loss due to these 2 different soil erosion mechanisms were then compared with the pattern of net soil loss indicated by caesium-137 depletion to provide an assessment of their likely relative importance in contributing to soil loss. In the upper part of each hillslope, this comparison of spatial trends did not allow the dominant cause of soil erosion to be distinguished. Both the model of erosion due to cultivation and that due to hillside overland flow predicted soil accumulation in the lower valley sides where slope decreased. Neither model represented the net loss of such accumulated soil indicated by caesium-137 deficit, and this loss possibly occurred during periodically observed flooding of the valley floor, or due to surface burial with caesium-137 depleted subsoil.

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