Amount Of Soil Erosion Research Articles

Use of the K factor from the Universal Soil Loss Equation can show arable land in Palau.

From the viewpoint of sustainability, the annual soil erosion must be controlled below an erosion level. Palau is an island in the Micronesia region of the western Pacific Ocean. The island receives heavy rainfall and has steep slopes, so 80% of the land is categorized within the most fragile rank, with at most 1 ton per acre per year (T factor = 1). We tested several methods of preventing soil erosion on the land, with a slope of 15.4° (13.4°-17.3°), cultivated the land, planted sweet potatoes, and compared the amount of soil erosion. Surprisingly, there was no erosion at all in all plots (including control plots), although there were 24 rainfall events and the USLE equation predicted 32 ton per ha of the soil erosion in the cropping period. For the parameters of the USLE equation used in the present study, only the K factor was not actually measured. This means the K factor was larger than the actual value. Land at low risk of soil erosion and suitable for agriculture can be found by measuring K factor locally, even if the area is categorized as unsuitable.

Landslide Susceptibility Prediction Considering Regional Soil Erosion Based on Machine-Learning Models

Soil erosion (SE) provides slide mass sources for landslide formation, and reflects long-term rainfall erosion destruction of landslides. Therefore, it is possible to obtain more reliable landslide susceptibility prediction results by introducing SE as a geology and hydrology-related predisposing factor. The Ningdu County of China is taken as a research area. Firstly, 446 landslides are obtained through government disaster survey reports. Secondly, the SE amount in Ningdu County is calculated and nine other conventional predisposing factors are obtained under both 30 m and 60 m grid resolutions to determine the effects of SE on landslide susceptibility prediction. Thirdly, four types of machine-learning predictors with 30 m and 60 m grid resolutions—C5.0 decision tree (C5.0 DT), logistic regression (LR), multilayer perceptron (MLP) and support vector machine (SVM)—are applied to construct the landslide susceptibility prediction models considering the SE factor as SE-C5.0 DT, SE-LR, SE-MLP and SE-SVM models; C5.0 DT, LR, MLP and SVM models with no SE are also used for comparisons. Finally, the area under receiver operating feature curve is used to verify the prediction accuracy of these models, and the relative importance of all the 10 predisposing factors is ranked. The results indicate that: (1) SE factor plays the most important role in landslide susceptibility prediction among all 10 predisposing factors under both 30 m and 60 m resolutions; (2) the SE-based models have more accurate landslide susceptibility prediction than the single models with no SE factor; (3) all the models with 30 m resolutions have higher landslide susceptibility prediction accuracy than those with 60 m resolutions; and (4) the C5.0 DT and SVM models show higher landslide susceptibility prediction performance than the MLP and LR models.

Evaluation of WEPP and EPM for improved predictions of soil erosion in mountainous watersheds: A case study of Kangir River basin, Iran

In the current study, WEPP and EPM models were used to estimate the amount of soil erosion and sediment in the basin of Kangir. The required data for implementation of the WEPP model were prepared in six categories including soil, climate, management, slope, drainage and reservoir based on which we took the information needed to build soil and management files. Some information such as texture, cation exchange capacity, organic matter, sand content, effective hydraulic flow and critical shear stress was used. After production of all the layers, the WEPP model was implemented using the GEOWEPP software. In this software, erosion and sediment amounts were estimated by three methods: domain, watershed and flow path methods. In the Kangir River watershed, the sediment content was 7.64 t/ha/year, 6.13 t/ha/year and 11.87 t/ha/year. Thus, the two methods of domain 7.64 t/ha/year and flow path 11.83 t/ha/year were closer to the observed sediment 10.5. Based on the EPM model, the sedimentation coefficient of the Kangir basin was 0.81. The results of the research indicate the high erodibility rate of the watershed basin. The erosion-sensitive units were located in the western and southwestern regions of the basin. In the EPM model, the erosion rate (Z) was 0.6 indicating moderate to high erodibility rate in the watershed. Furthermore, the highest erosion rate was in the western and southwestern parts of the watershed. Finally, the results of estimating soil erosion and sediment production in the watershed of Kangir illustrated that the WEPP model has a more accurate estimation of soil erosion and sediment production, and in this model, the flow path method used to estimate the amount of soil erosion and sediment production was close to the observed sediment at the hydrometric station.

Sensitivity Analysis of Vegetation Coverage to Soil Loss Rate in Red Soil Region of South China

Vegetation is an important basic component of terrestrial ecosystem and one of the most sensitive factors affecting soil erosion. How to analyse the quantitative relationship between fractional vegetation cover (FVC) and soil erosion and determine the sensitive coverage of erosion is of great significance for guiding government departments to implement soil and water conservation policies. In this paper, through the variable-controlling mothed, the forest land, grassland and bare land in Changting County, a typical red soil region in southern China, were used as experimental areas to study the sensitivity of FVC change to soil erosion. The soil erosion amount was calculated by RUSLE model, and soil loss rate (rsl) were used to characterize soil erosion. The results show that when FVC changes from 0 to 0.8, the fitting curves rsl are in accordance with the logistic model distributions, with a high coefficient of determination R2, and the sensitivity of rsl is less sensitive in the range of 0∼0.05, it is most sensitive when FVC reaches a certain level, and there is basically no sensitivity when it reaches 0.7 or above; the fitting curves of rsl at different slope levels are similar to their overall distribution, which are consistent with the logistic models, and R2 is above 0.99, the curves of rsl at each slope level are different in the same FVC interval, for areas with poor vegetation coverage (0∼0.2) and high slope (>25°), the curve is less sensitive to terrain; rsl generally has higher sensitivity in the range of 0.2∼0.6 coverage; in areas above 0.6, the sensitivity decreases to zero.

Temporal and spatial relationships between soil erosion and ecological restoration in semi-arid regions: a case study in northern Shaanxi, China

ABSTRACT To assess the effects of the Grain for Green Program (GGP) on soil erosion is essential to support better land management policies in the Chinese Loess Plateau. Studies on the evaluation of the effects of the GGP on soil erosion have garnered heightened attention. However, few studies examined the efficiency of GGP on soil erosion control through spatial relationship analysis. Thus, this study focuses on analyzing the spatial variation relationship between soil erosion and GGP in northern Shaanxi, Chinese Loess Plateau, from 1988 to 2015. The Universal Soil Loss Equation was used to quantify changes in soil erosion at the regional and watershed scales, and the Geographically Weighted Regression model was used to analyze the spatial relationships between land use and land cover (LULC) and soil erosion. Our results indicated that the major characteristic of LULC change during the GGP was a rapid increase of vegetation area and a rapid decrease of cropland. Bare lands contributed to the most serious soil loss, followed by croplands and sparse grasslands. The GGP had a globally positive influence on the decrease in soil erosion over the study area, but the amount of soil erosion in western and northern regions maintained a severe level. Spatial heterogeneity in the nature of the relationships among different vegetation, croplands, and soil erosion was also observed. The change rate of wood and the change rate of soil erosion in northern sub-watershed represented a negative relationship, while the change rate of sparse grassland was negatively correlated to the change rate of soil erosion in 21 sub-watersheds, account for 72% of the study area. The GGP implemented in northern sub-watersheds were more effective for soil erosion control than southern sub-watersheds. We propose that current areas of vegetation can support soil erosion control in the whole northern Shaanxi, but local-scale ecological restoration can be considered in northern sub-watersheds.

Soil erosion and sediment interception by check dams in a watershed for an extreme rainstorm on the Loess Plateau, China

The magnitude of soil erosion and sediment load reduction efficiency of check dams under extreme rainstorms is a long-standing concern. The current paper aims to use check dams to deduce the amount of soil erosion under extreme rainstorms in a watershed and to identify the difference in sediment interception efficiency of different types of check dams. Based on the sediment deposition at 12 check dams with 100% sediment interception efficiency and sub-catchment clustering by taking 12 dam-controlled catchments as clustering criteria, the amount of soil erosion resulting from an extreme rainstorm event on July 26, 2017 (named “7·26” extreme rainstorm) was estimated in the Chabagou watershed in the hill and gully region of the Loess Plateau. The differences in the sediment interception efficiency among the check dams in the watershed were analyzed according to field observations at 17 check dams. The results show that the average erosion intensity under the “7–26” extreme rainstorm was approximately 2.03 × 104 t/km2, which was 5 times that in the second largest erosive rainfall in 2017 (4.15 × 103 t/km2) and 11–384 times that for storms in 2018 (0.53 × 102 t/km2 - 1.81 × 103 t/km2). Under the “7–26” extreme rainstorm, the amount of soil erosion in the Chabagou watershed above the Caoping hydrological station was 4.20 × 106 t. The sediment interception efficiency of the check dams with drainage canals (including the destroyed check dams) and with drainage culverts was 6.48 and 39.49%, respectively. The total actual sediment amount trapped by the check dams was 1.11 × 106 t, accounting for 26.36% of the total amount of soil erosion. In contrast, 3.09 × 106 t of sediment were input to the downstream channel, and the sediment deposition in the channel was 2.23 × 106 t, accounting for 53.15% of the total amount of soil erosion. The amount of sediment transport at the hydrological station was 8.60 × 105 t. The Sediment Delivery Ratio (SDR) under the “7·26” extreme rainstorm was 0.21. The results indicated that the amount of soil erosion was huge, and the sediment interception efficiency of the check dams was greatly reduced under extreme rainstorms. It is necessary to strengthen the management and construction technology standards of check dams to improve the sediment interception efficiency and flood safety in the watershed.

Scenario-based modelling of soil conservation function by rangeland vegetation cover in northeastern Iran

Soil conservation is one of the most important regulative functions of natural ecosystems. Vegetation cover significantly contributes to soil conservation. This study aims at investigating changes in erosion and sedimentation and the annual economic value of soil conservation by vegetation cover in northeastern Iran, by application of Revised Universal Soil Loss Equation (RUSLE), Sediment Delivery Distributed models (SEDD) and replacement cost method. The results demonstrated that the topography factor (LS-factor) was the most important factor contributing to soil erosion in the region. Also the mean soil erosion and the Specific Sediment Yield (SSY) were 14.84 and 2.82 ton ha−1 yr−1 in rangeland areas. More than half of the basin’s area (62%) was characterised as negligible and slight soil erosion class (0–10 ton ha−1 yr−1), and 18% as severe and very severe (25–100 ton ha−1 yr−1). Soil conservation function by vegetation cover was equal to 356,893 m3 yr−1, with the economic value of US$ 55,335 yr−1. According to the SEDD results, the amount of sediment trapped by the rangeland vegetation cover was 200,763 ton yr−1, with annual economic value of US$ 5,347,500 yr−1 By increasing vegetation cover, the annual soil erosion and sedimentation will extremely decrease and a larger part of the study area would experience slight to moderate erosion. Our findings showed that RUSLE/SEDD model provides a robust spatially-explicit platform to quantify the amount and distribution pattern of soil erosion and sedimentation to management and conservation practices, if the calibration and localization of the model are accomplished.

Use of the K factor from the Universal Soil Loss Equation can show arable land in Palau

Palau is an island in the Micronesia region of the western Pacific Ocean. The island receives heavy rainfall and has steep slopes, so 92% of the land is categorized within the most erodible rank, with a T factor of 5. A recent study reported that the water infiltration rate is proportional to the root mass of the crop soil; therefore, we attempted to evaluate the performance of root mass for preventing soil erosion. We covered parts of the land, with a slope of 15.4° (13.4°-17.3°), with weed control fabric to prevent the growth of grass and roots, then removed the fabric, cultivated the land, planted sweet potatoes, and compared the amount of soil erosion with other areas. Surprisingly, there was no erosion at all in the test plots, although there were 24 rainfall events that caused erosion. For the parameters of the Universal Soil Loss Equation (USLE) equation used in the present study, only the K factor was not actually measured. This means the K factor was larger than the actual value. Land at low risk of soil erosion and suitable for agriculture can be found by measuring K factor locally, even if the area is categorized as unsuitable.

Multi-objective optimization of soil erosion parameters using response surface method (RSM) in the Emamzadeh watershed

Soil erosion is one of the most leading environmental and public health problems in the world which dislodges considerable volumes of soil annually. In order to control soil erosion, several soil factors should be taken into account. Regarding the importance of soil properties on erosion occurrence, it is necessary to focus on soil properties. The aim of this study is to evaluate the effect of physical parameters that consist of sand %, silt %, clay %, SP % and stone % along with hydraulic properties including theta s, theta r, alpha n and Ks (cm/day) on the amount of soil erosion in Emamzadeh watershed. The above-mentioned factors were optimized using response surface methodology. The soil texture in the study area is mostly silty clay loam, and the main soil orders are Entisols and Inceptisols. Moreover, the main land use in the study area is forest–rangeland. The results proved that both physical and hydraulic valuables illustrated a significant effect on all of the independent parameters. The optimized values of different physical parameters were 60.241 for sand, 14 for silt, 41.025 for clay, 58.729% for SP and 3.83% for stone. A theta r of 0.09, theta s of 0.457 alpha of 0.014, n of 1.3 and Ks of 46.01 were found to be optimal values. The results of this study indicated that at optimal studied parameters, the values of the soil erosion before and after application of management scenarios were found to be 11.537 and − 2.253, respectively. Results show that both physical and hydraulic parameters have significant effects at the 1% level on the soil erosion before and after application of management scenarios. The obtained results could assist policy-makers with decisions aimed at minimizing soil erosion in this watershed. In summary, using the simulation–optimization techniques helps to evaluate the effect of management scenarios, then select and apply the best one to minimize the soil erosion outcomes.

Model of rainfall erosion index for predicting the potential erosion rate by using a rainfall simulator

The intent of this research is to investigate the rainfall erosion index that has the highest correlation to the surface runoff volume and the amount of soil erosion. In addition, the aim of this research is to determine the effective rainfall erosion index to predict soil erosion based on observations. This research was conducted in a hydrology laboratory by using a rainfall simulator. The three methods that were used for analysing rainfall erosion were the formulas of EI30 by Bols, Utomo, and Lenvain. The result is expected to become a consideration in selecting the model of rainfall erosion index due to the rainfall factor as the input of soil erosion prediction. This research provides a temporary hypothesis for obtaining the value of the rain erosivity index with a different value from previous studies with EI30, which leads to the latest model for estimating and predicting from the Bols equation. Based on this research, the rain erosivity index was obtained with a predicting value and final equation of EI30 = 5.128 x (Rain)1.26 x (Days)0.47 x (Maxp)0.53 x (High)0.61 with the explained value from research analysis being EI30 = 5.128 x (50.002)1.35 x (23)0.47 x (622)0.53 x (12)0.61. Analysis was then performed with trial and error, and the conclusion of this research is a high rain erosivity index.

Erosion of dune sands stabilised by grouting with lime–silica fume mix

Dune sands are often an environmental hazard during strong winds and sand storms, particularly in the summer months. Wherever a granular soil surface is left unprotected, it can be subjected to wind erosion and dune formation. In this study, an attempt was made to stabilise sand dunes by grouting with a slurry of lime–silica fume (L–SF) material. Dune sand samples were collected from northern Iraq. In situ field density of the soil was determined by sand-cone tests for moisture content, classification, compaction, relative density, direct shear and chemical tests. Erosion tests were conducted using centrifugal fans, with wind applied to the soil at a speed of 90 km/h for 11 min. Silica fume (SF) and a L–SF mix were used for stabilisation and their effects on the dune sands were investigated. For grouting, a 1000 ml grout pump was used to stabilise a liquid tank of the L–SF mix; the maximum pumping pressure was about 25 kPa. It was found that when the dune sand was with a slurry of L–SF, there was a reduction in erosion by about 70% for a stabiliser grout of 33% (Lime to SF ratio, 3L : 4SF) with 67% water of the total mixture weight. The stabilisation effect increased with increases in the number and depth of grouting holes around the stabilised area. When wind was applied at a rate of about 90 km/h for 11 min, the eroded natural sand dune surface was about 66 mm, while for soil stabilised by grouting with L–SF, the erosion was 17–36 mm. An increase in the number of injection points and a reduction in the distances between them reduced the amount of soil erosion.

Evaluation of Survival, Growth Performance, Feed Value and Biomass Production of Multipurpose Tree and Shrub Species in North Shewa Administrative Zone, Ethiopia

In the Ethiopian highlands, lack of the availability of multipurpose tree species is a major problem challenging the livelihoods of the local farmers. For example, the shortage of multipurpose trees in such areas has caused huge amount of soil erosion, land degradation and ultimately led to poor agricultural production. In addition, local farmers have little experience in planting multipurpose tree species and there was little species choice for fodder, fuelwood and soil rehabilitation purposes. Even though there are some efforts made in the past to introduce multipurpose tree species in the highland areas, there are only a few species adopted by the local farmers. The aim of this study was to select the best multipurpose tree species that help improve agriculture productions in the mid land areas found in North Shewa Administrative Zone, Ethiopia. Accordingly, eight multipurpose tree and shrub species namely:Albizia chinensis, Desmanthus virgatus, Caliandra houstunian, Genistamon spossulana, Femingia macrophyla, Robinia pseudoacacia, Leuceana diversifolia, and Medica goarboria were included in this study. Randomly Completely Block Design (RCBD) was employed with three replication and sixteen plants were planted in each plot. The experiment was done for six years. The results suggested that Leuceana diversifolia, Albizia chinensis, Genistamon spossulana, Femingia macrophyla and Desmanthus virgatus showed better growth and height performance. On the other hand, Medica goarboria, Caliandra houstunian and Robinia pseudoacacia had poor height and growth performance. The crude protein content of Albizia chinensis, Desmanthus virgatus, Caliandra houstunian and Leuceana diversifolia ranged between 18.02 and 19.69 percent which is important to fulfill the dietary requirements for dairy cows. The highest leaf biomass production was obtained from L. diversifolia (3644 kg/ha).Whereas, C. houstunia gave the least leaf biomass. L. diversifolia trees increased soil pH and organic carbon significantly under soil depth of (0-15cm). Desmanthus virgatus has highest Phosphorus uptake at 15-30 depth of soil. The conclusion from this study is that multipurpose tree and shrub species can be used for supplements for livestock feed in north Shewa condition. In addition, these multipurpose species can help to improve soil conditions especially in degraded areas where soil condition is poor.

基于规划目标的京津风沙源治理区生态保护与修复效应

PDF HTML阅读 XML下载 导出引用 引用提醒 基于规划目标的京津风沙源治理区生态保护与修复效应 DOI: 10.5846/stxb201806161346 作者: 作者单位: 作者简介: 通讯作者: 中图分类号: 基金项目: 中央级公益性科研院所基本科研业务专项（GYZX190204）；国家重点研发计划项目（2017YFC0506500）；中国科学院前沿科学重点研究项目（QYZDB-SSW-DQC005） The ecological effects of ecosystem conservation and restoration in Beijing-Tianjin sand source regions based on the planning objects Author: Affiliation: Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:为改善和优化京津及周边地区生态环境状况，减轻风沙危害，2003年启动实施了京津风沙源治理工程。基于工程规划目标评估了京津风沙源治理区生态保护与修复效应，结果表明：（1）草地和林地作为京津风沙源治理区绿色生态屏障的主要组成，分别占治理区面积的57.3%和9.7%，而风沙策源地的耕地和沙地分别占17.2%和6.4%。（2）2003-2017年，京津风沙源治理区草地、耕地、沙地面积减少，而林地和其他类型面积增加。治理区植被覆盖度平均提高了2.3%，其中林地提高了4.3%，草地提高了2.4%。（3）沙尘天气发生的春季，治理区土壤风蚀量减少了54%。在防风固沙服务总量的贡献中，草地和沙地贡献了71%。因此，草地和沙地生态系统的植被恢复，对治理区生态系统防风固沙服务的提高发挥了最为重要的作用。（4）除治理区植被有所恢复外，由于气候整体变暖，近15年风场强度有所减弱，特别是沙尘天气易发生的春季风场强度减弱近45%，也是影响京津风沙源治理区风蚀量下降的一个重要原因。 Abstract:In order to improve and optimize the ecological environment in Beijing, Tianjin and surrounding areas, and mitigate the hazards of wind and sand, the Beijing-Tianjin Sand Sources Control Project (BTSSCP) was launched in 2003. The ecological effects of the BTSSCP were assessed according to the planning objects. The results showed that (1) the main parts of green ecological barrier in Beijing-Tianjin sand source regions were grassland and forest that accounted for 57.3% and 9.7% of the total area respectively, followed by cropland and sandy land that accounted for 17.2% and 6.4% of the total area respectively. (2) In 2003-2017, the area of grassland and cropland in the project region of first-stage BTSSCP decreased, while the area of forest and sand land increased. The area of the grassland, sand land and cropland in the project region of second-stage BTSSCP increased and the forest area decreased. In the past 15 years, the average vegetation coverage in the project region of BTSSCP increased by 2.3%, and the natural vegetation with increased coverage accounted for about 63% of the total area, of which the vegetation coverage of forest increased by 4.2% and the grassland increased by 2.4%. However, the average vegetation coverage in desert steppe did not increase. (3) From 2003 to 2017, the amount of soil wind erosion in the project region of BTSSCP reduced by 54%. In the total amount of soil erosion, the dust materials that can be transported remotely and directly had a direct impact on Beijing, Tianjin and Hebei were also reduced. (4) Among the factors that control soil wind erosion, the dominant grassland and sandy land contributed to 71%, which played an important role in improving the sand fixation service of the vegetation in sand source regions. In addition, the intensity of wind in spring reduced by 45% was also an important factor affecting the decrease of wind erosion in the project region of BTSSCP. 参考文献 相似文献 引证文献

Evaluations of water yield and soil erosion in the Shaanxi-Gansu Loess Plateau under different land use and climate change scenarios

More water yield and less soil erosion are crucial to the sustainable development of the Loess Plateau and Yellow River basin. Different land use policies and climate change scenarios may have great implications on water yield and soil erosion. In this paper, four land development scenarios and two climate change scenarios are designed and applied to the Shaanxi-Gansu Loess Plateau. The InVEST model is applied to quantitatively evaluate the water yield and soil erosion modulus in 2030. It showed: (1) Arable land and grassland is always the dominant land types in the Shaanxi-Gansu Loess Plateau and cover more than 76% of the area. The business-as-usual and ecological protection priority scenarios may lead to increases in the local food security risks, with 1.9% and 1.4% gaps in the total food requirements. (2) Under the RCP2.6 scenario, the annual water yield and annual soil erosion amount increased by more than 63% (2.84*109 m3) and 22% (96.0*106 t), respectively. Under the RCP4.5 scenario, the annual water yield and annual soil erosion decreased by more than 48% (2.17*109 m3) and 26% (114.3*106 t), respectively. (3) The influence of climate change on water yield and soil erosion is far greater than that of land use change. The contribution of climate change to the water yield changes is 92.8–99.6%, while the contribution of land use change is 0.4–7.2%. The contribution rate of climate change to soil erosion changes is 84.8–91.1%, while the contribution rate of land use change is 8.9–15.2%. The key ecological services, such as food production, water yield, soil and water conservation, should be carefully weighed and coordinated in the Loess Plateau and areas with limited land surfaces, such as small island development states.

Change of Soil Erosion Characteristic under Different Vegetation

The runoff amount, soil erosion amount and infiltration rate were analyzed on different rainfall and different underlying horizon in base of yellow river institute of hydraulic research at 2018. The date shows: the runoff amount of bare slope is 7 times that of grass slope, the runoff amount of heavy rainfall is 2 times that of middle rainfall and is 20 times that of small rainfall; the soil erosion amount of bare slope and arable slope is 100 times that of grass slope; the steady soil erosion amount of small rainfall is 1/4 times that of middle rainfall and is 1/30 times that of heavy rainfall on grass slope; the infiltration rate of bare slope and arable slope is 1/3 times of grass slope; the grass slope infiltration rate is about 0.6mm/min in small rainfall, the middle and heavy rainfall get the steady infiltration rate at experiment continue 30min and 12min.

Study on soil erosion Simulation in Tianshui Maiji district based on InVEST-SDR model with GIS and RS

The Maiji district of Tianshui city locates in the transition regions of semi-arid and semi-humid with fragile ecosystems, so it is of great scientific and practical significance to analyse and study its characteristics and influencing factors of soil erosion. Based on GIS, RS and InVEST-SDR model, this paper simulates the soil erosion in 2015 and analyses the effect of different influencing factors on soil erosion. The results showed that: 1) In 2015, the soil erosion in the study area was mainly slight and light erosion, in spatially, the north-western part of the study area was more eroded than other regions; 2) The effect of vegetation cover on soil erosion presented bimodal pattern mode; 3) The effects of elevation and slope on soil erosion had a critical value of 1300 m and 30 degree; 4) Forestland was the main type of land use that produced the largest amount of soil erosion in the region, followed by cropland and grassland.

Erosion and Sediment Control Best Management Practices in Agricultural Farms for Effective Reservoir Sedimentation Management at Cameron Highlands

For many years, lands in Cameron Highland have been opened and leveled for agricultural farming and intensive crop production. Land-disturbing activities such as agricultural operations that are conducted on regions with steep slopes leads to a high potential of soil erosion, sedimentation and landslide occurrences. As a results, this phenomenon producing large amounts of sediment transported and deposited to the receiving waters or reservoirs. The development of best management practices (BMPs) for agricultural activities is an important step towards minimizing the amount of soil erosion and landslide incidents in Cameron Highlands. Therefore, this Erosion and Sediment Control Guideline for Agricultural Activities in Hilly Area aims to minimize erosion and sedimentation from the agricultural area in Cameron Highlands especially in the scope of reservoir sedimentation management. There numbers of steps taken in order to establish this guidelines. The first step is to define the scope with the purpose of the guideline and conduct a literature review. In order to assess the quality and feasibility of the study to formulate the frameworks, engagement with stakeholders was conducted. Lastly is to undergo review and update based on the recommendations by related stakeholders. Finally, before the establishment of guidelines, all recommendations by related stakeholders are take in account that consists of Best Management Practices components which will be applied in the agricultural area to mitigate issues and problems especially in erosion control and reservoir sedimentation management. The Erosion Control Measures are including agronomic measures, soil management, mechanical methods and Rainwater Harvesting Techniques. Subsequently, these measures are used to apply in open or sheltered farming to control the erosion and sedimentation issues based on the erosion risk level. As a conclusion, this guideline will be useful for the stakeholders especially to local community, dam owners and local authority to mitigate and solve the issues related to erosion and sedimentation in hilly agricultural area.

Stemflow contributions to soil erosion around the stem base under simulated maize-planted and rainfall conditions

Stemflow is a primary pathway through which rainwater reaches the ground surface under crop cover. Substantial research suggests that stemflow amounts approach or exceed half the total precipitation on maize cropland; however, few studies have quantified the effect of stemflow on soil erosion during rainfall events. This study aimed to measure the effect of stemflow on soil erosion under controlled situations and determine the effects of stemflow on soil erosion. Maize stems were simulated using a 2-cm diameter PVC tube in 1.3 by 0.25 m steel boxes to introduce stemflows to the soil surface at a 10° slope. The rainfall intensities were 60, 90 and 120 mm/h; the stemflow amounts were 5, 10 and 15 g/s. The results showed that stemflow significantly increased soil erosion. As stemflow increased, the surface runoff and sediment rates sharply increased. Compared with a control slope (no stemflow), stemflow increased the surface runoff and sediment rates by more than three and twelve times, respectively. This result occurred because stemflow contributes to the formation of concentrated flows, which easily trigger rill erosion around the stem base. The sediment rate further increased with rill development. Soil erosion was small if stemflow did not occur during a rainfall event; otherwise, soil erosion was extensive due to stemflow-induced rill erosion. Our results provide new insights for the analysis of crop cover effects and soil erosion on cultivated lands. For maize-planted slopes, stemflow may also be indispensable when determining the soil erosion amount.

Spatially explicit quantification of total soil erosion by RTK GPS in wind and water eroded croplands

Quantification of total soil erosion in wind and water eroded croplands is essential for assessing their contributions and the interaction between them. However, it is difficult to quantify total soil erosion amounts by the traditional monitoring and modelling approaches of wind erosion and water erosion. To address this problem, a Real Time Kinematic Global Positioning System (RTK GPS) was applied for a series of wind and water eroded croplands in the Bashang area in North China to quantify the total soil erosion amount over a period of 44 years. By comparing the elevation of the croplands with a reference surface without erosion, the total soil erosion modulus and its spatial variation were determined. Results showed that the erosion moduli of the six croplands ranged from 1.09 to 45.34 Mg ha−1 y−1 with an average modulus of 17.02 Mg ha−1 y−1. The croplands in the west suffered from more intense wind erosion compared to the middle and eastern areas; this was due to the presence of forest-grasslands, which served as wind breaks for the croplands in the middle and eastern regions. However, the croplands in the east showed the highest total erosion modulus, which was due to the influences of a gully. Within the croplands, the slope areas suffered from intense soil erosion which was mainly owing to water erosion. The reliability and uncertainty of this approach were discussed in terms of the equipment precision, results accuracy, and possible deposition on the reference surface. This study shows that when a suitable reference surface is identified and the erosion amount is considerable, RTK GPS survey can be used as a reliable and effective method to assess the spatially explicit total soil erosion in croplands influenced by both wind and water erosion.

Modelling Effects of Rainfall Patterns on Runoff Generation and Soil Erosion Processes on Slopes

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.