scholarly journals Analysis of Runoff and Sediment Losses from a Sloped Roadbed under Variable Rainfall Intensities and Vegetation Conditions

2020 ◽  
Vol 12 (5) ◽  
pp. 2077 ◽  
Author(s):  
Chunfeng Jia ◽  
Baoping Sun ◽  
Xinxiao Yu ◽  
Xiaohui Yang

Vegetation plays an important role in reducing soil erosion. By exploring the allocation and coverage of different types of vegetation, we can improve management practices that can significantly reduce soil erosion. In this experiment, we study runoff and sediment losses on a shrub-grass planted, grass planted, and bare slope under different rainfall intensities. Results showed that the runoff generation time for the three subgrade types decreased as rainfall intensity increased (p < 0.05). The slopes planted with either grass or shrub-grass were able to effectively delay runoff generation. As rainfall intensity increased, the runoff amount increased for all treatments, with runoff in the bare slope increasing the most. The runoff reduction rate from the shrub-grass slope ranged from 54.20% to 63.68%, while the reduction rate from the slope only planted with grass ranged from 38.59% to 55.37%. The sediment yield from the bare slope increased from 662.66 g/m2 (15 mm/h) to 2002.95 g/m2 (82 mm/h) with increasing rainfall intensity in the plot. When compared with the bare slope, both the shrub-grass and planted grass slopes were able to retain an additional 0.9 g/m2 to 4.9 g/m2 of sediment, respectively. An accurate relationship between rainfall intensity, sloped vegetation types, and runoff reduction rate was obtained by regression analysis and validated. These results can provide a reference for improving soil and water conservation via improved vegetation allocation on a sloped roadbed.

2021 ◽  
Author(s):  
Qiufen Zhang ◽  
Xizhi Lv ◽  
Rongxin Chen ◽  
Yongxin Ni ◽  
Li Ma

&lt;p&gt;The slope runoff caused by rainstorm is the main cause of serious soil and water loss in the loess hilly area, the grassland vegetation has a good inhibitory effect on the slope runoff, it is of great significance to reveal the role of grassland vegetation in the process of runoff generation and control mechanism for controlling soil erosion in this area. In this study, typical grassland slopes in hilly and gully regions of the loess plateau were taken as research objects. Through artificial rainfall in the field, the response rules of slope rainfall-runoff process to different grass coverage were explored. The results show that: (1) The time for the slope flow to stabilize is prolonged with the increase of vegetation coverage, and shortened with the increase of rainfall intensity; (2) At 60 mm&amp;#183;h &lt;sup&gt;&amp;#8722;1&lt;/sup&gt; rainfall intensity, the threshold of grassland vegetation coverage is 75.38%; at 90 mm&amp;#183;h&lt;sup&gt; &amp;#8722;1&lt;/sup&gt; rainfall intensity, the threshold of grassland vegetation coverage is 90.54%; at 120 mm&amp;#183;h &lt;sup&gt;&amp;#8722;1&lt;/sup&gt; rainfall intensity, the impact of grassland vegetation coverage on runoff is not significant; (3) the Reynolds number and Froude number of slope flow are 40.07&amp;#8210;695.22 and 0.33&amp;#8210;1.56 respectively, the drag coefficient is 1.42&amp;#8210;43.53. Under conditions of heavy rainfall, the ability of grassland to regulate slope runoff is limited. If only turf protection is considered, about 90% of grassland coverage can effectively cope with soil erosion caused by climatic conditions in loess hilly and gully regions. Therefore, in loess hilly areas where heavy rains frequently occur, grassland's protective effect on soil erosion is obviously insufficient, and investment in vegetation measures for trees and shrubs should be strengthened.&lt;/p&gt;


Water ◽  
2019 ◽  
Vol 11 (11) ◽  
pp. 2221
Author(s):  
Qihua Ran ◽  
Feng Wang ◽  
Jihui Gao

Rainfall patterns and landform characteristics are controlling factors in runoff and soil erosion processes. At a hillslope scale, there is still a lack of understanding of how rainfall temporal patterns affect these processes, especially on slopes with a wide range of gradients and length scales. Using a physically-based distributed hydrological model (InHM), these processes under different rainfall temporal patterns were simulated to illustrate this issue. Five rainfall patterns (constant, increasing, decreasing, rising-falling and falling-rising) were applied to slopes, whose gradients range from 5° to 40° and projective slope lengths range from 25 m to 200 m. The rising-falling rainfall generally had the largest total runoff and soil erosion amount; while the constant rainfall had the lowest ones when the projective slope length was less than 100 m. The critical slope of total runoff was 15°, which was independent of rainfall pattern and slope length. However, the critical slope of soil erosion amount decreased from 35° to 25° with increasing projective slope length. The increasing rainfall had the highest peak discharge and erosion rate just at the end of the peak rainfall intensity. The peak value discharges and erosion rates of decreasing and rising-falling rainfalls were several minutes later than the peak rainfall intensity.


2018 ◽  
Vol 46 (2) ◽  
pp. 553-562 ◽  
Author(s):  
Ataollah KAVIAN ◽  
Leila GHOLAMI ◽  
Maziar MOHAMMADI ◽  
Velibor SPALEVIC ◽  
Moghadeseh FALAH SORAKI

Soil erosion is one of the key challenges in soil and water conservation. Vegetation that covers soil and organic and inorganic mulch is very useful for the control of erosion processes. This study examined treatment with wheat residual (as agriculture mulch) on infiltration, time to runoff, runoff coefficient, sediment concentration and soil erosion processes. The study has been conducted for sandy-loam soil taken from summer rangeland (Northern Iran) with simulated rainfall intensities of 50 and 100 mm h-1. The experiment was conducted in slopes of 30% in three replications with two amounts of wheat residual of 50 and 90 %. The results showed that conservation percent of soil erosion for wheat residual 50 and 90% was 61.68 and 73.25%, respectively (in rainfall intensity of 50 mm h-1). Also, the conservation percent of soil erosion for wheat residual of 50 and 90% cover was 70.68 and 90.55, respectively (in rainfall intensity of 100 mm h-1). It was concluded that the conservation treatments could reduce runoff coefficient, sediment concentration and soil erosion and increase the time to runoff and infiltration coefficient. This effect was significant on time for infiltration, sediment concentration and soil erosion variables (R2=0.99), time to runoff and runoff coefficient variables (R2=0.95). The interaction effects of rainfall intensity and soil conservation was significant for sediment concentration and soil erosion variables (R2=0.99).


2020 ◽  
Vol 15 (4) ◽  
pp. 323-331
Author(s):  
Giorgio Capello ◽  
Marcella Biddoccu ◽  
Eugenio Cavallo

Vineyards’ soils are especially threatened by the risk of soil compaction and soil erosion, with negative consequences for wine production and provisioning of ecosystem services. The adopted inter-rows soil management influences the response of vineyard to different types of rainfall events, in terms of runoff and soil erosion. Actually, the use of cover crops in vineyards is widely considered as an effective measure for conservation of water and soil. A 3-years study was carried out in Piedmont (NW Italy) to evaluate the effectiveness of grass cover as a soil water conservation measure, compared with tillage, and particularly the influence of different types of rainfall events and tractor traffic in determining hydrological and erosive response of the vineyard. During the investigation period (November 2016 - December 2019), climate variables, runoff, and soil losses were continuously monitored along with vineyard management operations. Very different yearly precipitation characterized the observed period, including the driest and wettest year in the last 20 years. Runoff and soil erosion caused by different types of rainfall events (long-lasting, intense and normal) in two vineyard’s plots managed with permanent grass cover and tillage, respectively, have been compared. In addition, the influence of the number of tractor traffic was taken into account. Runoff volume was principally affected by soil management, while sediment yield was influenced by the type of event. Both were higher in the tilled plot than in the grassed one, for all types of events, even if differences were not always significant. Grass cover reduced by 65% the runoff, with the highest efficiency during intense events. Soil losses were reduced on average by 72%, with 74% efficiency during the most erosive intense events and the lowest protection (56%) during long-lasting rainfall. Moreover, the response of grass cover plot was less influenced by traffication. The study demonstrates the efficiency of grass cover in reducing water and soil losses also during extreme events, that are predicted to be more frequent in the climate change scenario.


Forests ◽  
2020 ◽  
Vol 11 (3) ◽  
pp. 329 ◽  
Author(s):  
Jia Luo ◽  
Xiaoling Zhou ◽  
Matteo Rubinato ◽  
Guijing Li ◽  
Yuxin Tian ◽  
...  

Vegetation plays a significant role in controlling soil erosion. However, the effects of each vegetation type on soil erosion have not been fully investigated. In order to explore the influence of multiple vegetation covers on soil erosion and surface runoff generation, 10 different vegetation types, typical of the Nverzhai small basin, have been selected for this study. Regional precipitation, surface runoff, and sediment yield were measured from 2007 to 2018. The wettest year recorded was 2012. Recorded data confirmed that July was the wettest month in this region while January and December were the driest months. Furthermore, surface runoff and sediment yield associated with different vegetation types gradually decreased after 2013, which is the quantification of the consequences due to afforestation processes started in this area. Surface runoff and sediment content recorded for the configuration of sloping farmland were the largest between the different investigated vegetation types. The smallest were the broad-leaved mixed forest, the coniferous mixed forest, and shrubs. Finally, a significant linear positive correlation was found between rainfall and surface runoff, as well as sediment yield (R2 = 0.75). This suggests that climate change implications could be limited by using the more efficient vegetation covering. This research indicates that the ground cover is a key element in controlling soil and water loss, as well as vegetation measures, with high ground cover (i.e., broad-leaved trees). These measures should be strongly recommended for soil erosion control and surface runoff reduction. Moreover, these outcomes can be very helpful for vegetation restoration and water conservation strategies if implemented by local authorities.


2021 ◽  
Vol 5 (1) ◽  
pp. 9-27
Author(s):  
Meseret Bekele

Water induced soil erosion has been continued to threaten the land resources in sub humid northwestern highlands of Ethiopia. Human-induced land cover (LC) changes due to improper land management practices are contributing factors in deteriorating soil quality. Soil and water conservation measures have been implemented without site-specific scientifically quantified soil erosion data and priority bases in this regard; this study was conducted with a view to quantifying soil erosion in Anka-Shashara watershed. To do this, we have opted to use the RUSLE model based on geographic information systems. By collecting data on rainfall, soils, vegetation, slopes and conservation practices separately as a layer and determining the pixel values for each of these factors, a quantified assessment of erosion in the basin is obtained. The result reveals that the mean annual soil loss (15.22t/ha/yr) of the most parts of study area falls in tolerable levels and almost 66% (1594 ha), moderate level about 23% and 10% at high level of watershed. The soil loss of watershed is classified in to four main classes. None to Slight rates of soil erosion (0-10t/ha) is cover the almost 66% of watershed moderate about 23% and high about 10% of erosion rate as seen from the erosion rate distribution map. The upstream of catchment needs management and protection of those existing resources and the fundamental attention for SWC as recommended bases. Therefore, to reduce sedimentation problem and ensue sustainability of the watershed need to special attention for implementing recommended SWC intervention at the earlier.


2021 ◽  
Author(s):  
Li Zhang ◽  
Caihong Hu ◽  
Shengqi Jian ◽  
Qiang Wu ◽  
Guang Ran ◽  
...  

Abstract The effects of long-term natural climate change and human activities on runoff generation mechanism in the middle Yellow River Basin are long-standing concerns. This study analyzed the characteristics of hydro-climatic variables in the meso-scale Tuweihe catchment based on the observed data for the period 1956–2016 and a climate elastic method. The spatial distribution of dominant runoff processes (DRP) following land use changes in case of rainfall was identified. The results show significant decreasing trends in annual runoff, whereas slightly downward trends are identified for annual precipitation and potential evapotranspiration, 1984 is detected as the mutation year of the study period. The average contributions of climate change and human activities to the runoff reduction in the Tuweihe catchment were 33.2% and 66.8%, respectively. In general, the influences of human activities on runoff are applied mostly through the alteration of the catchment characteristics. The dominant runoff processes changes between 1980 and 2015 show significant effects of large-scale soil and water conservation measures in the Tuweihe catchment. We found that Hortonian overland flow (HOF) and fast subsurface flow (SSF1) were the two main processes in 1980 (30.3% and 34.4% respectively), but the proportion of HOF decreased by 9.6% in 2015. The proportions of saturation overland flow (SOF) and SSF have increased to varying degrees, which means that the catchment is more prone to generate subsurface flow processes. Consequently, under similar rainfall conditions, the runoff yield of flood events decreases in the second period.


Water ◽  
2019 ◽  
Vol 11 (12) ◽  
pp. 2596 ◽  
Author(s):  
Seeger ◽  
Rodrigo-Comino ◽  
Iserloh ◽  
Brings ◽  
Ries

The Mosel Wine region has suffered during the last decades a decrease in productive area, mostly on steep sloping vineyards. To avoid the spread of diseases, the extraction of grapevines on abandoned vineyards is mandatory in Rhineland-Palatinate. At the same time, the organic production of wine is growing slowly, but well established in the area. We assess in this paper the degree of the land-use changes, as well as their effect on runoff generation and sediment production, depending on the age of the abandonment, as well as the type and age of the land management, whether organic or conventional. Land use data were obtained to identify land-use change dynamics. For assessment of runoff generation and soil erosion, we applied rainfall simulation experiments on the different types of vineyard management. These were organically managed, conventionally managed and abandoned ones, all of varying ages. During the last decades of the last century, a decrease of around 30% of vineyard surface could be observed in Germany’s Mosel Wine Region, affecting mostly the steep sloping vineyards. Despite a high variability within the types of vineyard management, the results show higher runoff generation, and soil erosion associated with recently installed or abandoned vineyards when compared to organic management of the vineyards, where erosion reached only 12%. In organic management, runoff and erosion are also reduced considerably, less than 16%, after a decade or more. Thus, organic vineyard management practices show to be very efficient for reduction of runoff and erosion. Consequently, we recommend to adopt as far as possible these soil management practices for sustainable land management of steep sloping vineyards. In addition, soil protection measures are highly recommended for vineyard abandonment according to the law.


Land ◽  
2021 ◽  
Vol 10 (9) ◽  
pp. 964
Author(s):  
Ioannis K. Tsanis ◽  
Konstantinos D. Seiradakis ◽  
Sofia Sarchani ◽  
Ioanna S. Panagea ◽  
Dimitrios D. Alexakis ◽  
...  

The risk of erosion is particularly high in Mediterranean areas, especially in areas that are subject to a not so effective agricultural management–or with some omissions–, land abandonment or wildfires. Soils on Crete are under imminent threat of desertification, characterized by loss of vegetation, water erosion, and subsequently, loss of soil. Several large-scale studies have estimated average soil erosion on the island between 6 and 8 Mg/ha/year, but more localized investigations assess soil losses one order of magnitude higher. An experiment initiated in 2017, under the framework of the SoilCare H2020 EU project, aimed to evaluate the effect of different management practices on the soil erosion. The experiment was set up in control versus treatment experimental design including different sets of treatments, targeting the most important cultivations on Crete (olive orchards, vineyards, fruit orchards). The minimum-to-no tillage practice was adopted as an erosion mitigation practice for the olive orchard study site, while for the vineyard site, the cover crop practice was used. For the fruit orchard field, the crop-type change procedure (orange to avocado) was used. The experiment demonstrated that soil-improving cropping techniques have an important impact on soil erosion, and as a result, on soil water conservation that is of primary importance, especially for the Mediterranean dry regions. The demonstration of the findings is of practical use to most stakeholders, especially those that live and work with the local land.


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