12,777 research outputs found
Comparative Assessment of Splash Erosion Measuring Devices in Auchi Polytechnic, Auchi, Edo State
Soil erosion is recognized as a global threat against the sustainability of the natural ecosystem and the environment because of its severe effects in agricultural productivity, damage to infrastructure and pollution of water bodies. This study aims to compare the splash erosion on open field using Morgan and splash board method. The fabrication of the splash cups and splash board was carried based on the principles of the already existing devices in literature and in the department of Agricultural and Bio-Environmental Engineering Technology Auchi Polytechnic Auchi. The rainstorm depth ranged from 7 to 81 mm and the computed KE obtained ranged from 294 to 3233.4 J/m2. A total of 15 rainfall events were used in the season. For site A the amount of soil splashed per rainfall event ranged from 0.02 g/m2 to 4.77 g/m2 and zero (no splash) to 2.39 g/m2 for Morgan cup and Splash board device respectively. Studies of splash erosion on cultivated land should be made to determine the effect of cultivation on the soil in the area. Keywords: Morgan’s Splash cup, splash board, kinetic energy, soil erosion, splash erosion, rainstorm DOI: 10.7176/JEES/11-4-06 Publication date: April 30th 202
The effect of slope steepness and antecedent moisture content on interrill erosion, runoff and sediment size distribution in the highlands of Ethiopia
Soil erosion is a two-phase process consisting of the detachment of individual particles and their transport by the flowing water. This study discusses the results of laboratory experiments in which for three soils, the runoff depth, sediment yield, splash erosion and sediment size were measured. Rainfall intensity, slope and antecedent moisture contents were varied in the experiment. The soil types ranged from clay to sandy clay loam (Alemaya Black soil, Regosols and Cambisols). Rainfall was applied for six sequential 15-min periods with rainfall intensities varying between 55 and 120 mm h<sup>−1</sup>. The three slopes tested were 9, 25, and 45 %. Results show that as slope increased from 9 to 25 %, splash erosion and sediment yield increased. An increase in slope from 25 to 45 % generally decreases in splash erosion. Sediment yield for one soil increased and one soil decreased with slope and for the third soil the trend was different between the two initial moisture contents. Sediment yield was correlated (<i>r</i> = 0.66) with runoff amounts but not with splash erosion. Interrill erosion models that were based on the flowing water and rainfall intensity fitted the data better than when based on rainfall intensity solely. Models that assume a positive linear relationship between erosion and slope may overestimate sediment yield
A new concept for estimating the influence of vegetation on throughfall kinetic energy using aerial laser scanning
Soil loss caused by erosion has enormous economic and social impacts. Splash effects of rainfall are an important driver of erosion processes; however, effects of vegetation on splash erosion are still not fully understood. Splash erosion processes under vegetation are investigated by means of throughfall kinetic energy (TKE). Previous studies on TKE utilized a heterogeneous set of plant and canopy parameters to assess vegetation’s influence on erosion by rain splash but remained on individual plant- or plotlevels. In the present study we developed a method for the area-wide estimation of the influence of vegetation on TKE using remote sensing methods. In a literature review we identified key vegetation variables influencing splash erosion and developed a conceptual model to describe the interaction of vegetation and raindrops. Our model considers both amplifying and protecting effect of vegetation layers according to their height above the ground and aggregates them into a new indicator: the Vegetation Splash Factor (VSF). It is based on the proportional contribution of drips per layer, which can be calculated via the vegetation cover profile from airborne LiDAR datasets. In a case study, we calculated the VSF using a LiDAR dataset for La Campana National Park in central Chile. The studied catchment comprises a heterogeneous mosaic of vegetation layer combinations and types and is hence well suited to test the approach.We calculated a VSF map showing the relation between vegetation structure and its expected influence on TKE. Mean VSF was 1.42, indicating amplifying overall effect of vegetation on TKE that was present in 81% of the area. Values below 1 indicating a protective effect were calculated for 19% of the area. For future work, we recommend refining the weighting factor by calibration to local conditions using field-reference data and comparing the VSF with TKE field measurements
Stability of Agricultural Ecosystems: Documentation of a Simple Model for Soil Erosion Assessment
Documentation is presented of a model for assessing the stability of the soil erosion component of an agricultural ecosystem. The model uses a simplified version of the Meyer-Wischmeier approach to predict the annual rate of soil erosion by water on hillslopes and this is compared with the rates of weathering and top soil renewal to determine changes in the depth of the soil profile and the top soil or rooting layer. Erosion is taken to be the result of splash detachment and runoff transport. Splash detachment is related to rainfall energy and rainfall interception by the crop. Runoff volume and sediment transport capacity are estimated from equations first presented by Kirkby. The results of trials with the model in the Silsoe area of Bedfordshire, England, show that realistic values of runoff and erosion are obtained for a range of soil and crop conditions. The model can be used to assess the stability of the erosion system under existing landuse conditions and to determine what changes need to be made in the erosion system to produce stability when unstable conditions are predicted
Potential use of BEST® sediment trap in splash-saltation transport process by simultaneous wind and rain tests
The research on wind-driven rain (WDR) transport process of the splash-saltation has increased over the last twenty years as wind tunnel experimental studies provide new insights into the mechanisms of simultaneous wind and rain (WDR) transport. The present study was conducted to investigate the efficiency of the BEST® sediment traps in catching the sand particles transported through the splash-saltation process under WDR conditions. Experiments were conducted in a wind tunnel rainfall simulator facility with water sprayed through sprinkler nozzles and free-flowing wind at different velocities to simulate the WDR conditions. Not only for vertical sediment distribution, but a series of experimental tests for horizontal distribution of sediments was also performed using BEST® collectors to obtain the actual total sediment mass flow by the splash-saltation in the center of the wind tunnel test section. Total mass transport (kg m-2) were estimated by analytically integrating the exponential functional relationship using the measured sediment amounts at the set trap heights for every run. Results revealed the integrated efficiency of the BEST® traps at 6, 9, 12 and 15 m s-1 wind velocities under 55.8, 50.5, 55.0 and 50.5 mm h-1 rain intensities were, respectively, 83, 106, 105, and 102%. Results as well showed that the efficiencies of BEST® did not change much as compared with those under rainless wind condition
Bioerosion on shore platforms developed in the Waitemata Formation, Auckland
Bioerosion - the removal of lithic substrate by the erosive activities of living organisms- has not previously been discussed for New Zealand shore platforms. This paper aims at drawing attention to bioerosion as a process active in shore platform development. Detailed reference is made to bioerosion occurring on the alternating sandstones and siltstones of the Waitemata Formation found outcropping on the coastline around Auckland. In this area several facets of shore platform morphology may be attributed to the direct effects of boring and browsing marine organisms. A classification of animals causing bioerosion, based on mechanism of erosion, is presented, and the geomorphic significance of the various groups discussed
Development of laboratory instrumentation for the study of soil erodibility
In order to carry out a study of the relative efficiency of various erodibility indices, and of the relative erodibility of soils developed in the Peak District of Derbyshire (England), three instruments were developed. These instruments were: a wet-sieve aggregate analyser of the Yoder pattern, a compact laboratory rainfall simulator using spray nozzles, a radiant drying unit using infra-red lamps. The efficiency of the instruments and the validity of the operating -techniques are critically evaluated and suggestions for improvement are advanced
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