Runoff and soil loss in a semi-arid shrub invaded Poplar Box (Eucalyptus populnea) woodland.

1983 ◽  
Vol 5 (1) ◽  
pp. 3 ◽  
Author(s):  
GG Johns

The ridges of the Cobar pediplain generally have only a sparce herbage cover. Much of the incident rainfall is reputed to run off, perpetuating the low pasture productivity and causing erosion. Woody shrubs have often invaded the woodlands of the pediplain. On some gentler sloping (1%) ridges dense patches of shrubs surround large eucalypts and together are known as 'thickets'. Between these thickets relatively sparsely shrubbed areas ('interthickets') occur. Runoff from small plots situated in thicket and interthicket areas of shrub invaded poplar box woodland was recorded during 1975-1981. Half the plots had been partially cleared by pushing over all shrubs with a bulldozer ('shrub-pushed', in contrast to 'unpushed'). Soil losses from the plots were measured over a four year period. Rainfall during the study was 26% greater than the long term average for the area, and provided many runoff events, particularly from intense summer storms. Runoff averaged 26% of rainfall for unpushed interthicket areas while thicket runoff was negligible. Runoff from the shrub-pushed plots was c. 25% less than from their unpushed counterparts, but this difference was not significant at P < 0.05. During the December-March period monthly runoff from unpushed interthicket plots averaged 41% of monthly rainfall in excess of 12 mm, while for the other eight months runoff averaged 24% of monthly rainfall in excess of 9 mm. Soil losses were greater during the stormier part of the year, with long term soil loss rates equivalent to 25 mm per 1000 years from enclosed interthicket plots and 55 mm per 1000 years from the gra7ed interthicket plots. Shrub-pushing appeared to increase soil losses in the short term but after two years soil loss rates decreased to be less than those from unpushed plots. Estimates of likely interthicket runoff based on long term rainfall records had a median value of 77 mm per year, or only 64% of that observed during the study period. Over the 88 years the 5 year moving average of estimated runoff fell to as low as 40 mm per year. The results are discussed in the context of waterspreading.

2018 ◽  
Vol 10 (10) ◽  
pp. 132
Author(s):  
Luana Salete Celante ◽  
Deonir Secco ◽  
Aracéli Ciotti de Marins ◽  
Daniela Trentin Nava ◽  
Flávio Gurgacz ◽  
...  

The objective of work was to quantify soil and water loss rates as a function of slope variation, correlating these rates with soybean yield. In addition to developing multiple linear regression models that associate water and soil loss rates in function of their physical attributes. The experiment was conducted in an Oxisols under a no-tillage system. The experiment was carried out in Cascavel, PR, Brazil. Four slopes (3.5%; 8.2%; 11.4% and 13.5%) were considered as treatments. The water and soil loss rates were monitored in the rainfall occurring during the crop development cycle. The water drained in each plot was collected in gutters made of polyvinyl chloride and stored in containers for the quantification of soil and water losses. The stepwise backward method was used to identify the variables that had a significant influence on water and soil losses. The unevenness of the terrain did not influence the soil and water loss rates. The maximum soil and water losses during the soybean cycle were, respectively, 0.01962 Mg ha-1 and 4.07 m3 ha-1. The maximum soil and water losses occurred when the precipitation volume was up to 82 mm. Soil and water losses showed a higher correlation with macroporosity and bulk density. Soybean grain yield showed a higher linear correlation with water, and soil loss and was higher at the slopes of 8.2% and 13.4%. The low water and soil losses demonstrate the soil capacity, managed under a no-tillage system, to minimize environmental impacts.


1991 ◽  
Vol 71 (4) ◽  
pp. 533-543 ◽  
Author(s):  
L. J. P. Van Vliet ◽  
J. W. Hall

Four erosion plots were monitored from 1983 to 1989 (6 yr) to evaluate the effects of two crop rotations and their constituent crops on runoff and soil loss under natural precipitation near Fort St. John in the Peace River region of British Columbia. Rotation 1 consisted of two cycles of summerfallow — canola (Brassica rapa)-barley (Hordeum vulgare L.), and Rotation 2 included summerfallow — canola-barley-barley underseed to red fescue (Festuca rubra L.)-fescue-fescue. Rainfall and snowmelt runoff were collected and sampled throughout the year to determine seasonal runoff and soil losses. Over the 6 yr, the cumulative runoff and soil losses were consistently greater under Rotation 1 than under Rotation 2. There was a greater than fourfold difference in total soil loss, and 33–35% more total runoff. Rainfall-induced runoff and soil losses were significantly higher for Rotation 1 than for Rotation 2. Snowmelt runoff accounted for 90 and 96% of the total annual runoff and for 39 and 80% of the total annual soil loss from Rotations 1 and 2, respectively. Two large rainfall events during 1983 and 1987, each causing a soil loss in excess of 2000 kg ha−1, accounted for between 85 and 91% of the 6-yr total rainfall-induced erosion from Rotation 1. No differences in runoff or soil loss were detected among crops but the comparisons were insensitive because of high residual variation. Key words: Runoff, soil loss, erosion plots, crop rotations


1987 ◽  
Vol 67 (1) ◽  
pp. 199-203 ◽  
Author(s):  
R. G. KACHANOSKI

Atmospheric deposition rates of 90Sr and analysis of soil samples from non-eroded sites indicated base levels of total soil 137Cs were approximately 2700 Bq m−2 in southern Ontario in 1985. Measured 137Cs losses (1965–1976) from long-term runoff plots were significantly correlated to measured soil losses during the same period. Monitoring temporal changes in soil 137Cs should be an accurate method of estimating soil loss in southern Ontario. Key words: Soil loss, 137Cs, Ontario, runoff plots


2019 ◽  
Author(s):  
Christoph Schürz ◽  
Bano Mehdi ◽  
Jens Kiesel ◽  
Karsten Schulz ◽  
Mathew Herrnegger

Abstract. The Universal Soil Loss Equation (USLE) is the most commonly used model to assess soil erosion by water. The model equation quantifies long-term average annual soil loss as a product of the rainfall erosivity R, soil erodibility K, slope length and steepness LS, soil cover C and support measures P. A large variety of methods exist to derive these model inputs from readily available data. However, the estimated values of a respective model input can strongly differ when employing different methods and can eventually introduce large uncertainties in the estimated soil loss. The potential to evaluate soil loss estimates at a large scale are very limited, due to scarce in-field observations and their comparability to long-term soil estimates. In this work we addressed (i) the uncertainties in the soil loss estimates that can potentially be introduced by different representations of the USLE input factors and (ii) challanges that can arise in the evaluation of uncertain soil loss estimates with observed data. In a systematic analysis we developed different representations of USLE inputs for the study domain of Kenya and Uganda. All combinations of the generated USLE inputs resulted in 756 USLE model setups. We assessed the resulting distributions in soil loss, both spatially distributed and on district level for Kenya and Uganda. In a sensitivity analysis we analyzed the contributions of the USLE model inputs to the ranges in soil loss and analyzed their spatial patterns. We compared the calculated USLE ensemble soil estimates to available in-field data and other study results and addressed possibilities and limitations of the USLE model evaluation. The USLE model ensemble resulted in wide ranges of estimated soil loss, exceeding the mean soil loss by over an order of magnitude particularly in hilly topographies. The study implies that a soil loss assessment with the USLE is highly uncertain and strongly depends on the realizations of the model input factors. The employed sensitivity analysis enabled us to identify spatial patterns in the importance of the USLE input factors. The C and K factors showed large scale patterns of importance in the densely vegetated part of Uganda and the dry north of Kenya, respectively, while LS was relevant in small scale heterogeneous patterns. Major challenges for the evaluation of the estimated soil losses with in-field data were due to spatial and temporal limitations of the observation data, but also due to measured soil losses describing processes that are different to the ones that are represented by the USLE.


2020 ◽  
Vol 29 (3) ◽  
pp. 591-605
Author(s):  
Oleksandr A. Svetlitchnyi

The paper deals with the forecast of changes in erosion soil losses during the spring snowmelt due to climate change in the regions of Ukraine in the middle of the 21st century (during 2031–2050) and at its end (during 2081–2100) compared with the values of the baseline period (1961–1990). The forecast is based on the use of the so-called “hydrometeorological factor of spring soil loss”. This factor is a part of the physical-statistical mathematical model of soil erosion lossduring spring snowmelt, developed at the Department of Physical Geography of Odesa I. I. Mechnikov State (since 2000 — National) University during the 1980s – 1990s. The long-term average value of the hydrometeorological factor is linearly related to the long-term average value of spring erosion soil loss. Therefore, the relative change in the hydrometeorological factor corresponds to the relative change in soil erosion losses. The developed methodology for assessing climate-induced changes in soil erosion losses in five regions of Ukraine (North, West, Center, East and South) takes into account the change in water equivalent of snow cover at the beginning of snow melting, the change in surface runoff and its turbidity, and changes in soil erodibility. The forecast of changes in erosion soil loss was carried out using projections of annual and monthly average air temperatures and precipitation for 2031–2050 and 2081–2100 in accordance with scenario A1B from AR4 of the IPCC. As a result of the research, it was found that both in the middle and at the end of the 21st century a decrease in the rate of soil erosion during the period of spring snowmelt is expected. During 2031–2050, the expected soil losses will be less than corresponding baseline period values within the West region by 79%, within the North and East regions by 81%, and within the Center region by 85%. In the South region, the spring soil losses will be zero due to the lack of snow cover. During 2081–2100 snow cover will be absent not only in the South region, but also in the Center and East regions. In the regions North and West snow cover will remain, but the spring soil erosion losses will decrease by dozens of times and will be so small that they can also be ignored.


1993 ◽  
Vol 73 (4) ◽  
pp. 469-480 ◽  
Author(s):  
L. J. P. van Vliet ◽  
R. Kline ◽  
J. W. Hall

Three tillage treatments were evaluated over a 4-yr period for their effects on runoff and soil loss under natural precipitation on a Donnelly silt loam soil (Solonetzic Gray Luvisol) near Dawson Creek in the Peace River region of British Columbia. Conventional-tilled (CT) plots (spring or fall cultivation) received twice the amount of tillage as the reduced-tilled (RT) plots, while the zero-tilled (ZT) plots were only disturbed at seeding once a year. The plots were seeded to barley (Hordeum vulgare L.). Rainfall and snowmelt runoff were collected throughout the year to determine seasonal runoff and soil losses. The effects of the tillage treatments on runoff and soil loss depended on the season (whether caused by rainfall or snowmelt) and the crop year. Mean snowmelt runoff was ZT > CT > RT. Conventional tillage had significantly higher rainfall runoff and soil loss from snowmelt than the other two tillage treatments, with no significant differences between RT and ZT. Mean rainfall-induced soil loss was significantly different for each tillage treatment, with CT > RT > ZT. Soil losses from snowmelt were low, less than 30% of those from rainfall, since snowfall was 45% below normal. Soil losses from rainfall were consistently higher than from snowmelt for each tillage treatment in each of the four crop years and provided over 75% of the 4-yr total annual soil loss. Tillage effects were more pronounced in years with low runoff and soil loss than in years with high runoff and soil loss. Zero tillage and RT are effective in reducing average annual soil losses by 81 and 53%, respectively, of those observed under conventional tillage. Key words: Runoff, soil loss, erosion plots, seasons, tillage


Soil Systems ◽  
2020 ◽  
Vol 4 (2) ◽  
pp. 19 ◽  
Author(s):  
José M. Mirás-Avalos ◽  
Juan M. Ramírez-Cuesta ◽  
María Fandiño ◽  
Javier J. Cancela ◽  
Diego S. Intrigliolo

Water erosion is a severe threat to soil resources, especially on cultivated lands, such as vineyards, which are extremely susceptible to soil losses. In this context, management practices aiming at reducing erosion risks must be favored. This current study aimed at estimating soil losses in two vineyards under Atlantic climatic conditions (Galicia, North West Spain). The capacity of two management practices for reducing soil erosion was tested and compared with tilled soil in the inter-rows: (i) application of mulching, and (ii) maintaining native vegetation. Soil losses were assessed using erosion pins and micro-plots. In addition, the improved stock unearthing method (ISUM) was employed in one of the vineyards to estimate soil remobilization since plantation. Soil loss rates in one of the vineyards were lower when soil was managed under mulching (0.36 Mg ha−1) and native vegetation (0.42 Mg ha−1), compared to tilled soil (0.84 Mg ha−1). Sediment losses measured in the second vineyard ranged between 0.21 and 0.69 Mg ha−1, depending on the treatment, but no clear conclusions could be drawn. Long-term soil loss, as estimated by ISUM, was of the same order of magnitude than that obtained by erosion pins and micro-plots. In both vineyards, soil loss rates were lower than those registered in Mediterranean vineyards, and were below the limit for sustainable erosion in Europe. Nevertheless, soil management practices alternative to tillage in the inter-row might reduce erosion risks under Atlantic climate conditions.


Soil Systems ◽  
2019 ◽  
Vol 3 (4) ◽  
pp. 62 ◽  
Author(s):  
Kinnell

Soil erosion caused by rain is a major factor in degrading agricultural land, and agricultural practices that conserve soil should be used to maintain the long-term sustainability of agricultural land. The Universal Soil Loss Equation (USLE) was developed in the 1960s and 1970s to predict the long-term average annual soil loss from sheet and rill erosion on field-sized areas as an aid to making management decisions to conserve soil. The USLE uses six factors to take account of the effects of climate, soil, topography, crops, and crop management, and specific actions designed to conserve soil. Although initially developed as an empirical model based on data from more than 10,000 plot years of data collected in plot experiments in the USA, the selection of the independent factors used in the model was made taking account of scientific understanding of the drivers involved in rainfall erosion. In addition, assumptions and approximations were needed to make an operational model that met the needs of the decision makers at that time. Those needs have changed over time, leading to the development of the Revised USLE (RUSLE) and a second version of that, the Revised USLE, Version 2 (RUSLE2). While the original USLE model was not designed to predict short-term variations in erosion well, these developments have involved more use of conceptualization in order to deal with the time-variant impacts of the drivers involved in rainfall erosion. The USLE family of models is based on the concept that the “unit” plot, a bare fallow area 22.1 m long on a 9% slope gradient with cultivation up and down the slope, provides a physical situation where the effect of climate and soil on rainfall erosion can be determined without the need to consider the impact of the four other factors. The science and logic associated with this approach is reviewed. The manner by which the soil erodibility factor is determined from plot data ensures that the long-term average annual soil loss for the unit plot is predicted well, even when the assumption that event soil loss is directly related to the product of event rainfall energy, and the maximum 30-min intensity is not wholly appropriate. RUSLE2 has a capacity to use CLIGEN, the weather generator used in WEPP, and so can predict soil losses based on individual storms in a similar way to WEPP. Including a direct consideration of runoff in determining event erosivity enhances the ability to predict event soil losses when runoff is known or predicted well, but similar to more process-based models, this ability is offset by the difficulty in predicting runoff well.


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