Changes In Soil Erosion Research Articles

Soil erodibility after the removal of wood chip mulch: A wind tunnel experiment

Numerous field studies have investigated the effects of mulching on soil wind erosion. However, little is known about the changes in soil erodibility after removing the mulch layer. In this paper, we measured the physicochemical properties and aggregate characteristics of soil from an urban park after removing the mulch layer and estimated wind-erodible materials emission by wind tunnel experiments. Wood chips at 4,500 g m⁻² (mulch thickness of 5 cm, R5), 6,300 g m⁻² (mulch thickness of 7 cm, R7), and 8,100 g m⁻² (mulch thickness of 9 cm, R9) were used for mulching an area in Yuanmingyuan Park from October of 2019 to the end of February of 2021. The following four treatments were listed: unmulched soil (CK), R5, R7, and R9. Compared with CK, the soil moisture content (SM), the macro-aggregates (&gt;0.25 mm) ratio (M &gt; 0.25), the wind erodible fraction (WEF), and the dry aggregate stability (DAS) of R5, R7, and R9 were significantly increased after mulching (<i>P</i> &lt; 0.05), whereas the soil organic matter content (SOM) was only slightly increased. The calcium carbonate contents (CaCO₃) varied greatly among the different treatments. Based on the wind tunnel experiments, the distribution of wind erosion materials near the soil surface (0 to 30 cm) was fitted to logarithmic, power, and exponential functions (<i>R</i>² ranged between 0.7179 and 0.9859). The particle size distribution of all wind-erodible materials was unimodal, and the proportion of coarse particles (250 to 100 μm) was highest. Compared with the CK, the average wind erosion rate (AWER) of R5, R7, and R9 was decreased by 48.44%, 65.04%, and 70.03%, respectively, after mulching. The AWER was significantly (<i>P</i> &lt; 0.01) negatively correlated with SM, M &gt; 0.25, WEF, and DAS, and negatively correlated with CaCO₃ and SOM. The CaCO₃ was significantly (<i>P</i> &lt; 0.05) positively correlated with M &gt; 0.25, WEF, and DAS. Overall, despite the relatively short mulching period (16 months), wood chip mulch improved the physicochemical properties and aggregate characteristics of soil and decreased erodibility.

基于遥感RMMF模型的喀斯特地区水土保持功能评价

PDF HTML阅读 XML下载 导出引用 引用提醒 基于遥感RMMF模型的喀斯特地区水土保持功能评价 DOI: 10.5846/stxb202104221057 作者: 作者单位: 作者简介: 通讯作者: 中图分类号: 基金项目: 科技兴蒙重大专项课题（KJXM-EEDS-2020006） Evaluation of soil and water conservation function in karst region based on Remote Sensing RMMF Model 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:为支撑我国重点生态功能区生态效益补偿工作，以半物理水土模型RMMF （The Revised Morgan，Morgan and Finney Model）为基础，通过对模型部分输入物理量进行遥感化改进建立了遥感RMMF模型（RS-RMMF）。为在评价中进一步排除气象要素波动带来的水土流失量变化，通过RS-RMMF模型构建了单位降水截留率、单位径流冲蚀量以及单位径流运输量3项评价指标来综合评价区域生态系统本身的水土保持能力。研究选取了《全国主体功能区规划》中的桂黔滇喀斯特功能区为典型区，分别基于上述评价指标和经典RUSLE （Revised Universal Soil Loss Equation）模型开展了2011年至2019年水土保持功能计算与对比。结果表明：相比2011年，2019年喀斯特功能区的降水截留率PI0升高1.94%，径流冲蚀量H0下降5.96×10-4 Mg/hm2，径流运输量TC0下降6.0×10-7Mg/hm2，水土保持功能综合得分增加0.83，水土保持功能整体上得到小幅改善。计算结果与RUSLE模型对比结论基本一致，但在空间相对强弱的分布上存在显著差异，RS-RMMF模型的评价得分空间分布明显由植被属性主导，且受降水等因素影响较小。该模型可客观核算生态系统水土保持能力，为生态补偿机制的实施应用提供科学支撑。 Abstract:To support the ecological benefit compensation system of key ecological function areas in China, Remote Sensing RMMF (RS-RMMF) soil erosion model is established by selecting the optimized remote sensing factors and RMMF (The revised Morgan, Morgan and Finney model) model. RS-RMMF model eliminates the soil erosion changes caused by the fluctuation of meteorological elements. The function of soil and water conservation is evaluated by constructing three evaluation indexes of unit rainfall interception rate, unit runoff erosion amount and unit runoff transportation volume. Karst functional areas in Guangxi, Guizhou and Yunnan are taken as the study area based on RS-RMMF model. The results show that compared with 2011, the rainfall interception rate PI0 in 2019 increased by 1.94%, the runoff erosion amount H0 decreased by 5.96×10-4 Mg/hm2, the runoff transportation volume TC0 decreased by 6.0×10-7 Mg/hm2, and the comprehensive score increased by 0.83. The overall water and soil conservation function has been slightly improved. Compared with RUSLE, the results of RS-RMMF model are basically consistent in the overall trend from 2011 to 2019. There are significant differences in the spatial distribution of the model results. The spatial distribution of the evaluation score of RS-RMMF is dominated by vegetation, but is less affected by precipitation factors. RS-RMMF model can objectively calculate the soil and water conservation capacity of the ecosystem, and provide scientific support for the application of ecological benefit compensation system. 参考文献 相似文献 引证文献

Linkages between Soil Erosion and Long-Term Changes of Landscape Pattern in a Small Watershed on the Chinese Loess Plateau

Linkages between Soil Erosion and Long-Term Changes of Landscape Pattern in a Small Watershed on the Chinese Loess Plateau

Assessment of soil erosion in the Dongting Lake Basin, China: Patterns, drivers, and implications.

Soil loss caused by erosion is a global problem. Therefore, the assessment of soil erosion and the its driving mechanism are of great significance to soil conservation. However, soil erosion is affected by both climate change and human activities, which have not been quantified, and few researchers studied the differences in the driving mechanisms of soil erosion depending on the land use type. Therefore, the spatiotemporal characteristics and changing trends of soil erosion in the Dongting Lake Basin were analyzed in this study. Geographic detectors were used to identify the dominant factors affecting soil erosion in different land use types. In this study, a sensitivity experiment was conducted to clarify the relative contributions of climate change and human activities to soil erosion changes. In addition, we studied the effects of different land use types and vegetation cover restoration on soil erosion. The results show that soil erosion in the Dongting Lake Basin decreased from 2000 to 2018. Human activities represented by land use types and vegetation coverage significantly contributed to the alleviation of soil erosion in the Dongting Lake Basin, whereas climate change represented by rainfall slightly aggravated soil erosion in the study area. The restoration of grassland vegetation and transfer of cultivated land to woodlands in the study area improved the soil erosion. The slope steepness is the key factor affecting the intensity of soil erosion in dry land, paddy fields, and unused land, whereas the vegetation coverage is the key factor affecting the intensity of soil erosion in woodland, garden land, and grassland. Detailed spatiotemporally mapping of soil erosion was used to determine the connections between soil erosion and potential drivers, which have important implications for vegetation restoration and the optimization of land use planning.

Impact assessment of land cover and land use changes on soil erosion changes (2005–2015) in Pakistan

AbstractAbrupt changes in climatic conditions, exploitation of natural resources, and land degradation exacerbate soil erosion. This study provides a comprehensive assessment of soil erosion dynamics in Pakistan for 2005 and 2015 at 1 km2 spatial resolution using six influencing factors: rainfall erosivity (R), soil erodibility (K), slope‐length (L), slope‐steepness (S), cover management (C), and conservation practice (P). The well‐accepted revised universal soil loss equation (RUSLE) was implemented to estimate soil erosion. The soil erosion maps were categorized into four classes: low (&lt;1), medium (1–5), high (5–20), and very high (&gt;20) — and transitions among these classes were determined by applying the change matrix method to assess soil erosion (ton ha‐1 yr‐1) changes from 2005 to 2015. Furthermore, spatial patterns and soil erosion dynamics were evaluated for seven administrative units of Pakistan to examine conservation efforts and ecosystem services. Major findings of this study indicate, that at the national scale, an estimated soil erosion of 1.79 ± 11.52 ton ha‐1 yr‐1 in 2005, which increased to 2.47 ± 18.14 ton ha‐1 yr‐1 in 2015. This intensification of soil erosion is coupled with land cover and land use changes (LCLUC) due to population expansion, infrastructural development, and exploitation of natural resources. This study's analytical framework and outcomes could be used for developing effective conservation policies to control soil erosion at various spatial scales in Pakistan.

Assessment of current and future land use/cover changes in soil erosion in the Rio da Prata basin (Brazil)

In recent years, the Cerrado biome in Brazil (Brazilian savannah) has faced severe environmental problems due to abrupt changes in land use/cover (LUC), causing increased soil loss, sediment yield and water turbidity. Thus, this study aimed to evaluate the impacts of soil loss and sediment delivery ratio (SDR) over the last 30 years to simulate future scenarios of soil losses from 2050 to 2100 and to investigate an episode of sediment delivery that occurred in the Rio da Prata Basin (RPB) in 2018. In this study, the following were used: an estimation of soil losses for 1986, 1999, 2007 and 2016 using the Revised Universal Soil Loss Equation (RUSLE), an estimation of SDR, sediment export and sediment deposition using the Integrated Valuation of Ecosystem Services and Tradeoffs (InVEST) model, an association of RUSLE factor C to LUC data for 2050 and 2100 based on the CA-Markov hybrid model, and an estimation of future soil erosion scenarios for 2050 and 2100. The results show that over the last 30 years (1986–2016), there has been a reduction in the areas of highly intense and severe degrees. Future soil erosion scenarios (2050–2100) showed a 13.84% increase in areas of soil loss >10 Mg ha−1 year−1. The results highlighted the importance of assessing the impacts of LUC changes on soil erosion and the export of sediments to agricultural watersheds in the RPB, one of the best ecotourism destinations in Brazil. In addition, the increase in soil loss in the region intensified sediment yield events and increased water turbidity. Furthermore, riparian vegetation, although preserved, was not able to protect the watercourse, showing that it is essential to adopt the best management practices in the agricultural production areas of the basin, especially where ramps are extensive or the slope is greater than 2%, to reduce the runoff velocity and control the movement of sediments on the surface towards the drainage canals. The results of this study are useful for drawing up a soil and water conservation plan for the sustainable production of agriculture and maintenance of ecosystem services in the region.

Changes in Cultivated Land Area and Associated Soil and SOC Losses in Northeastern China: The Role of Land Use Policies.

Land use policy is the driving factor influencing land use; however, little research has been conducted to identify the role of agricultural policy in influencing land cultivation and associated soil and soil organic carbon (SOC) losses. The aims of this study were to explore temporal changes in cultivated land, soil erosion, and SOC loss and to identify the role of land use policy. The present study was conducted using the revised universal soil loss equation by integrating remote sensing images from 1980, 1990, 2000, and 2017. The study found that cultivated land areas increased from 275.11 thousand km2 in 1980, to 300.03 thousand km2 in 2000, and to 344.16 thousand km2 in 2010, and then decreased by 326.94 thousand km2. The mean soil loss rates changed from 590.66 t·km−2·yr−1 in 1980 to 634.25 t·km−2·yr−1 in 2010, and then decreased to 495.66 t·km−2·yr−1 in 2017. Soil loss rate increased with increasing slope gradient. The changes in SOC loss rates demonstrated the same pattern as that of soil loss, with the largest loss rate of 728.27 kg·km−2·yr−1. These changes can be explained by changed land use policy and population growth. In future land use management, reasonable implementation of soil conservation measures should be undertaken to reduce soil and SOC losses in the black soil region of northeastern China.

Changes in rainfall erosivity over mainland China under stabilized 1.5 ℃ and 2 ℃ warming futures

Soil erosion is one of the major threats to the environment and agriculture in the world and rainfall erosivity is the most active factor to lead changes in soil erosion. Here, we use statistically downscaled, bias-corrected Community Earth System Model (CESM) low-warming simulations to investigate the future changes in rainfall erosivity in mainland China under the Paris Agreement global warming targets. The downscaled simulations evidently outperform the original CESM simulations in capturing the spatial distribution, magnitudes and annual cycle of rainfall erosivity in China in the present day (1986–2005). The rainfall erosivity will be significantly increased in most regions of China under the 1.5 °C and 2 °C warming targets and the regional mean increases are approximately 33% and 40%, respectively. In addition, the corresponding increases are even larger than 60% and 75%, respectively, in a quarter of mainland China. The increase in rainfall erosivity is resulted from the joint contributions of increases in frequency and intensity of erosive rainfall. However, it is dominated by the increase in the frequency. Compared with annual rainfall amount, the future warming will bring a four times greater impact on the soil erosion potentially caused by rainfall. Limiting global warming to 1.5 °C instead of 2 °C would reduce 17% of the increase in rainfall erosivity in China. For grain producing areas like Sichuan Basin, the middle and lower reaches of Yangtze River and South China, the values are approximately 20%. The future warming will significantly increase the potential risk of soil loss in China, and it is beneficial to relief this risk if the global warming is limited to 1.5 °C rather than 2 °C.

The Effect of Land Use/Cover Change on Soil Erosion Change by Spatial Regression in Changwu County on the Loess Plateau in China

Changwu County is a typical soil and water loss area on the Loess Plateau. Soil erosion is an important ecological process, and the impact of land use/cover change on soil erosion has received much attention. The present study used remote sensing images of the study area in 1987, 1997, 2007, and 2017 to analyze the land use/cover change (LULCC), and the RUSLE model was applied to estimate the soil erosion in different times. We exploited the Sankey diagram to visualize the spatiotemporal changes in land use/cover and soil erosion. We planned to obtain the most suitable model by comparing the application of different spatial regression models (Geographically weighted regression model, Spatial lag model, Spatial error model) and Ordinary least squares in LULCC and soil erosion changes. The results revealed that land use/cover has significantly changed in the last 30 years. From 1987 to 1997, cropland expansion came mainly from planted land and orchards, which transformed 68.99 km2 and 64.93 km2, respectively. In 1997–2007, the planted land increase was mainly through the conversion of cropland. In 2007–2017, the increase in orchard area came mainly from cropland. The forest land increase was mainly from the planted land. Soil erosion in Changwu County was dominated by slight erosion and light erosion, although the area of slight erosion and light erosion continued to decrease. The annual average soil erosion increased, which was estimated at 977.84 ton km−2 year−1, 1305.17 ton km−2 year−1, 1310.60 ton km−2 year−1, and 1891.46 ton km−2 year−1 in 1987, 1997, 2007, and 2017, respectively. These amounts of transformation mainly occurred when slight erosion was converted to light erosion, light erosion was converted to moderate erosion, and moderate erosion was converted to light and severe erosion. The Spatial lag model and Spatial error model have higher accuracy than the Geographically weighted regression model and Ordinary least squares when fitting the effect of LULCC and soil erosion change, where the accuracy exceeded 0.62 in different periods.

Soil erosion dynamics on a cultivated slope in the Western Polish Carpathians based on over 30 years of plot studies

Soil erosion is one of the most important processes affecting land degradation, especially in mountainous areas. The main aim of this study was to assess the dynamics of surface runoff and soil erosion in the Carpathians (Poland), based on data from over 30 years of plot studies, determine the threshold of extreme soil erosion on agricultural slopes, and estimate the cover-management factor (C-factor) of the flysch mountains. The field research was carried out in the Bystrzanka catchment on experimental plots with potato, cereals and grassland crop. The average annual soil erosion on the potato plots was 25.67 Mg ha−1 year−1, which was 95.4 and 99.7% higher than the soil erosion on the cereal and grassland plots. Principal component analysis was used to identify the factors determining soil erosion in the Carpathians, taking into account precipitation parameters, soil conditions, plant growth phases and agricultural practices. There were positive statistically significant relationships (p < 0.05) between soil erosion and precipitation sum and surface runoff. Precipitation thresholds for soil erosion of various magnitudes were determined, and the extreme soil erosion threshold was calculated (8.79 Mg ha−1 for a single soil erosion event and 59.37 Mg ha−1 for the annual total soil erosion). In addition, the Revised Universal Soil Loss Equation was used to show the role of the C-factor (calculated based on long-term plot studies, and proposed for Poland in the literature) in soil erosion studies. Different C-factors reflect changes in average soil erosion of up to 69%. Long-term plot studies are key to agricultural production and sustainable development in mountainous areas.

Tools for Planning Local Mitigation of Water‐Driven Soil Erosion Resulting from Impacts of Future Climate Change

AbstractDue to the consequences of climate change impacts municipal planners and local administrations need to develop long‐term strategies to protect soil bodies. For this purpose, practicable and free available tools are developed, that allow to estimate the erosivity of rainfall and discharge, considering the effects of land use changes and climate change impacts. This paper presents a stepwise estimation of water erosivity at agricultural areas as well as streams using the developed practicable tools step model of infiltration with calculation of direct flow and soil erosion (ero‐SMINF), German universal soil loss equation integrated into a geographic information system (ABAGis), and stream erosion model (SEM). The tools are developed and tested at two catchments in mountainous areas in Central Germany, Vietzbach and Regenbeek. The results for the Vietzbach catchment, which is mostly affected by sheet erosion, indicated that most of the erosive events occur during summer. The most probable change in soil erosion resulting from climate change (RCP8.5) shows an increasing erosion of up to 16% comparing to the current state. In the Regenbeek catchment, where stream bed erosion is dominant, calculations with the SEM show for the same scenario, that erosion can be reduced mainly by widening the stream bed.

Conservation management decreases surface runoff and soil erosion

Conservation management practices – including agroforestry, cover cropping, no-till, reduced tillage, and residue return – have been applied for decades to control surface runoff and soil erosion, yet results have not been integrated and evaluated across cropping systems. In this study we collected data comparing agricultural production with and without conservation management strategies. We used a bootstrap resampling analysis to explore interactions between practice type, soil texture, surface runoff, and soil erosion. We then used a correlation analysis to relate changes in surface runoff and soil erosion to 13 other soil health and agronomic indicators, including soil organic carbon, soil aggregation, infiltration, porosity, subsurface leaching, and cash crop yield. Across all conservation management practices, surface runoff and erosion had respective mean decreases of 67% and 80% compared with controls. Use of cover cropping provided the largest decreases in erosion and surface runoff, thus emphasizing the importance of maintaining continuous vegetative cover on soils. Coarse- and medium-textured soils had greater decreases in both erosion and runoff than fine-textured soils. Changes in surface runoff and soil erosion under conservation management were highly correlated with soil organic carbon, aggregation, porosity, infiltration, leaching, and yield, showing that conservation practices help drive important interactions between these different facets of soil health. This study offers the first large-scale comparison of how different conservation agriculture practices reduce surface runoff and soil erosion, and at the same time provides new insight into how these interactions influence the improvement or loss of soil health.

Kajian Faktor Penyebab Banjir dalam Perspektif Wilayah Sungai: Pembelajaran Dari Sub Sistem Drainase Sungai Beringin

Urbanization causes a shift in human activities and increases the occupancy of open spaces in the hilly areas of Semarang City. As a strategic area in the city of Semarang, Mijen and Ngaliyan Districts, which are the upstream and transition areas of the Beringin Drainage Sub-System, are experiencing economic and social growth. This then has an impact on the intensity of the floods that occur in Tugu District as its downstream area. This study aims to analyze the factors that cause flooding in the area of the Beringin Drainage Sub-System from a theoretical review to validate the results through interviews and field surveys. This study uses a qualitative descriptive analysis method by examining documents, research journals, books and maps and other related documents. From the results of the study, it can be concluded that the factors causing floods in the Beringin Drainage Sub-System area include changes in land use, rainfall and soil types, slope levels, erosion and sedimentation and inadequate capacity of the drainage system are phenomena and processes that are interrelated with one another. Strategic efforts are needed to anticipate flood events that occur almost annually in the Beringin Drainage Sub-System area.

A detailed reconstruction of changes in the factors and parameters of soil erosion over the past 250 years in the forest zone of European Russia (Moscow region)

Accelerated soil erosion is a major threat to soil, and there are great variations in the rate of soil erosion over time due to natural and human-induced factors. The temperate forest zone of Russia is characterized by complex stages of land-use history (i.e. active urbanization, agricultural development, land abandonment, etc.). We have for the first time estimated the rates of soil erosion by the WaTEM/SEDEM model (rainfall erosion) and by a regional model (snowmelt erosion) over the past 250 years (from 1780 to 2019) for a 100-km2 study site in the Moscow region of Russia. The calculations were made on the basis of a detailed historical reconstruction of the following factors: the location of the arable land, crop rotation, the rain erosivity factor, and the maximum snow water equivalent. The area of arable land has decreased more than 3.5-fold over the past 250 years. At the end of the 20th century, the rates of gross erosion had declined more than 5.5-fold (from 28 × 103 to 5 × 103 tˑha−1ˑyr−1) in comparison with the end of the 18th century. Changes in the boundaries of arable land and also the relief features had led to a significant intra-slope accumulation of sediments. As a result of sediment redeposition within the arable land, the variation in net soil erosion was significantly lower than the variation in gross soil erosion. The changes in arable land area and in crop composition are the factors that have to the greatest extent determined the changes in soil erosion in this territory.

Lake Watershed Dynamics and Bathymetry Modeling of Rara and Begnas Lakes in Nepal

Lake evolution and its changes over time are an evident and easily measurable signal of human activities and climate change impacts in mountain regions. This study presents bathymetric modeling of permanent lakes (Begnas and Rara Lakes) located in two different geographic settings of Nepal. Moreover, temporal changes in land cover and soil erosion of the lake watersheds, as well as climatic trends around these lakes, are assessed. This study supports establishing reference sites for exploring scientific evidence on the impacts of anthropogenic and climate change on lake hydrological systems. Second-order polynomial models best represent the relationship between lake depth and volume. Rara Lake had a maximum depth of 169 m with an area of 10.52 km2 and a volume of 1013.305 million cubic meters (Mm3), whereas Begnas Lake had a maximum depth of 12.5 m with an area of 2.98 ± 0.10 km2 and a water volume of 13.539 Mm3 in the year 2019. Both lake regions are experiencing changes in temperature and rainfall. The area and volume of Rara Lake and its watershed have been relatively stable even with minimal land-cover change during the recent decades. Begnas Lake and its watershed have experienced significant changes in the last few decades. This study concludes that human activities in the Begnas Lake watersheds are the primary source of lake area variation rather than climate change.

Economic growth and deforestation in African countries: Is the environmental Kuznets curve hypothesis applicable?

Deforestation is a significant environmental problem, contributing to biodiversity loss, land degradation, soil erosion, and climate change. During the past half-century, the continent of Africa has suffered massive losses of forested areas due to the changing structure of economies, increasing population, and expanding globalization. This research examines statistical evidence for the Environmental Kuznets Curve (EKC) hypothesis as applied to deforestation occurring within Africa from 1990 to 2016. Changes in forest cover data are explained with Generalized Method of Moments (GMM) estimators to overcome the endogeneity problems arising from reverse causality. The empirical results of Panel GMM confirm the EKC hypothesis is valid for deforestation in Africa with a turning point estimated to be US $3000. Heterogenous panel non-causality findings suggest that Africa could deter and reverse deforestation through appropriate land-use and forest products trade policies, and the consequences of these policies would not impact their economic growth.

Key factors affecting discharge, soil erosion, nitrogen and phosphorus exports from agricultural polder

Quantifying the relative effect of driving factors on polder hydrological processes and identifying the key factors are prerequisites to adopting effective measures for alleviating flooding, soil loss, and eutrophication. Based on the output results of calibrated Polder Hydrology and Nitrogen modeling System (PHNS) and Polder Hydrology and Phosphorus modeling System (PHPS), the boosted regression tree (BRT) model screened key influential factors and identified the corresponding threshold point values in a typical Chinese agricultural polder. Temporal changes in discharge and soil erosion were most sensitive to weather factors, while those of nitrogen and phosphorus exports were mainly influenced by human management actions. Precipitation was the largest contributor to the temporal variation of discharge (51.5%), soil erosion (69.4%). Vegetation cover and management factor of dryland C2 (34.5%) defined as the ratio of sediment loss from cropland to the corresponding loss from clean-tilled and continuous fallow, and phosphorus fertilization application to paddy field (30.7%) were the two determinants of phosphorus export, whilst surface water level to stop pump drainage (48.2%) had the largest contributions to nitrogen export. Precipitation from 0 to 50 mm/d contributed to a significant increase in discharge, soil erosion and nitrogen and phosphorus exports. Vegetation cover and management factor of paddy field C1 under 0.28 contributed to an elevated risk of nitrogen export, and C2 below 0.34 facilitated soil loss and phosphorus export.

Frequency analysis of storm-scale soil erosion and characterization of extreme erosive events by linking the DWEPP model and a stochastic rainfall generator

Soil erosion affects agricultural landscapes worldwide, threatening food security and ecosystem viability. In arable environments, soil loss is primarily caused by short, intense rainstorms, typically characterized by high spatiotemporal variability. The complexity of erosive events challenges modeling efforts and explicit inclusion of extreme events in long-term risk assessment is missing. This study is intended to bridge this gap by quantifying the discrete and cumulative impacts of rainstorms on plot-scale soil erosion and providing storm-scale erosion risk analyses for a cropland region in northern Israel. Central to our analyses is the coupling of (1) a stochastic rainfall generator able to reproduce extremes down to 5-minute temporal resolutions; (2) a processes-based event-scale cropland erosion model (Dynamic WEPP, DWEPP); and, (3) a state-of-the-art frequency analysis method that explicitly accounts for rainstorms occurrence and properties. To our knowledge, this is the first study in which DWEPP runoff and soil loss are calibrated at the plot-scale on cropland (NSE is 0.82 and 0.79 for event runoff and sediment, respectively). We generated 300-year stochastic simulations of event runoff and sediment yield based on synthetic precipitation time series. Based on this data, the mean annual soil erosion in the study site is 0.1 kg m−2 [1.1 t ha−1]. Results of the risk analysis indicate that individual extreme rainstorms (>50 return period), characterized by high rainfall intensities (30-minute maximal intensity > ~60 mm h−1) and high rainfall depth (>~200 mm), can trigger soil losses even one order of magnitude higher than the annual mean. The erosion efficiency of these rainstorms is mainly controlled by the short-duration (≤30 min) maximal intensities. The results demonstrate the importance of incorporating the impact of extreme events into soil conservation and management tools. We expect our methodology to be valuable for investigating future changes in soil erosion with changing climate.

Projected climate change impacts on soil erosion over Iran

In the past few decades, there has been increasing interest in studying various environmental phenomena derived from climate change and its social, environmental, and economic serious impacts. It is particularly critical to developing countries where resources are limited, and conditions may worsen in the midst of environmental disasters caused by soil erosion, leading to indispensable costs in resources and human lives. Since no studies have investigated these implications on a regional scale for the case of Iran, here we assessed the impact of climate change on soil erosion across the country. The RUSLE model was employed to estimate potential soil erosion based on historical climate records and projected future data to assess climate change implications. Daily rainfall data (1987–2006) from 103 meteorological stations were used to bias correct the Climate Forecast System Reanalysis (CFSR) rainfall data. Furthermore, CFSR data, as the historical record period data (1987–2006), was used for bias correcting five General Circulation Models (GCMs) to develop rainfall erosivity values for the future climate period (2046–2065) under SSP2-4.5 and SSP5-8.5 scenarios. Based on these data sets, rainfall erosivity maps were developed to compare the variations with projected climate results across Iran. Results show an overall decrease in rainfall erosivity and soil erosion in most provinces. Considering the average outputs of five GCMs and under both SSPs, the most affected provinces with projected soil erosion decrease are P.11 and P.14, whereas the highest increase in soil erosion is likely to occur in P.13 by SSP5-8.5. In the northern provinces, particularly in P.7, the highest increase in soil erosion is expected. It was also noted that the highest range of soil erosion change among the five selected GCMs occurs at P.27, with the maximum increase of above 135% and the minimum decrease of 71% from the historical period. The present study represents the first assessment of soil erosion at a large scale in Iran, providing an overview of soil erosion that may be useful for soil and water conservation planning, hazard mapping, agriculture, and other activities that are subject to soil erosion.

The Influence Mechanism of Freeze-Thaw on Soil Erosion: A Review

As an important type of soil erosion, freeze-thaw erosion occurs primarily at high latitude and altitude. The overview on the effect of freeze-thaw on soil erosion was provided. Soil erosion was affected by freeze-thaw processes, as thawing and water erosion reinforce each other. Remote sensing provided an unprecedented approach for characterizing the timing, magnitude, and patterns of large-scale freeze-thaw and soil erosion changes. Furthermore, the essence of soil freeze-thaw was the freeze and thaw of soil moisture in the pores of soil. Freeze-thaw action mainly increased soil erodibility and made it more vulnerable to erosion by destroying soil structure, changing soil water content, bulk density, shear strength and aggregate stability, etc. However, the type and magnitude of changes of soil properties have been related to soil texture, water content, experimental conditions and the degree of exposure to freeze-thaw. The use of indoor and field experiments to further reveal the effect of freeze-thaw on soil erosion would facilitate improved forecasting, as well as prevention of soil erosion during thawing in regions with freeze-thaw cycles.