Sediment Yield Research Articles

How does landslide debris grain size control sediment transport and dynamics?

The grain size of sediment delivered to a river by hillslope processes is an important factor which could impact fluvial erosion, sediment transport, and associated geomorphic changes. Grain size distribution (GSD) is increasingly recognised as an important factor for the impact of landslides on sediment pulses and long-term erosion rates. Therefore a better comprehension of grain size control on landslide-generated sediment transport and dynamics will help with understanding post-seismic fluvial processes and landscape evolution. In this study, we modelled the recovery of the Hongxi River basin affected by the Wenchuan earthquake under different landslide GSD scenarios. The CAESAR-Lisflood (CL) model was first modified to enable the spatial input of sediment GSD, which allows the model to distinguish the grain size composition of landslide sediment and the background sediment sourced from other areas. Using the modified CL model, we simulated three different landslide GSD scenarios (Original, Coarser, Finer) by altering the original landslide sediment GSD observed from a post-earthquake basin. In particular, we analysed the fate of landslide-generated sediment using a new sediment tracing function embedded in CL. This enabled us to evaluate the role of landslide GSD variation on the spatio-temporal heterogeneity of sediment transport. Our results show that the GSD of landslide material exerts a clear control on both sediment yield and channel deposition, the sediment transport of landslides disconnected to the fluvial system is more sensitive to grain size variation, while the GSD of landslides connected to the fluvial system has less impact on sediment dynamics. The duration of landslide disturbances on basin sediment dynamics can largely be dependent on the period of time (e.g., 20 years in this study basin) taken for grain coarsening (the grain size is increasing upward), which is dominated by the evacuation of fine sediments. The modelling results and findings highlight the importance of grain size distribution of landslide material and provide information to support basin sediment management and environmental risk mitigation.

Sediment yield assessment and suggesting mitigation measures—A case study of Deme watershed, Omo‐Gibe Basin, Ethiopia

AbstractSoil erosion is a big challenge of natural resource development in Ethiopia due to the high expansion of agricultural activity and poor land‐use management. Deme watershed is one of the watersheds found in the Omo‐Gibe Basin, Ethiopia with soil erosion problems. It covers 1284.4 km2. The Soil and Water Assessment Tool (SWAT) integrated with ArcGIS was used to assess the sediment yield of the Deme watershed and develop mitigation measures for soil erosion. The purpose of this study was to assess the sediment yield and provide mitigation measures for the Deme watershed. Ground Control Point (GCP) data collection and field observation were conducted for land‐use land cover classification. The performance of the model was evaluated by coefficient of determination (R2), Nash Sutcliffe simulation efficiency (NSE), and percent bias (PBIAS). SWAT adequately reproduced the observed daily flows and sediment loads temporal evolution with R2 and NSE ≥ .7 and PBIAS < 15% both for the calibration and validation periods. The sediment‐rating curve measured an annual average suspended sediment yield of 12.79 tons per hectare per year, whereas the SWAT model predicted an annual average sediment yield of 14.35 tons per hectare per year. The spatial distribution map of sediment showed that 9 out of 17 sub‐watersheds generate a higher amount of sediment yield (15.1–45 tons/h/year) and are found to be erosion‐prone areas. For proper management of watershed terracing, filter strips, contouring, and reforestation scenarios were developed. Each scenario reduces the sediment yield by 74.29%, 58.34%, 47.78%, and 69.76%, respectively. The proper combination of these scenarios resulted in a 90% reduction in sediment yield. Policymakers and land‐use planners of different organization will benefit from this research by implementing soil and water conservation mechanisms and practices that strengthen and mitigate the natural systems of Deme watershed.

Effects of post-abandonment management on surface runoff in a Mediterranean mid-mountain basin

Mid-mountain catchments across the Mediterranean basin undergone a decrease in runoff and sediment yield during the second half of the 20th century mainly due to forest cover increase following rural abandonment together with a transition to drier climatic conditions. During last decades, land use and land cover (LULC) management of these areas has become a target of environmental policy makers and stakeholders to ensure the sustainability of ecosystem services. In some areas, an active management through the reduction of vegetation density or by human afforestation has been applied, while others undergone a natural process of revegetation. In this context, assessing the contribution of different LULC management on runoff is fundamental for addressing water management and soil loss at the catchment and regional scales. Within this background, the aim of this work is to analyse the relative effects of LULC management techniques on hydrological connectivity and water yield in a Mediterranean mid-mountain basin. To pursue this objective, we applied hydrological connectivity (IC index) and ecohydrological (RHESSys) models to different sub-basins of the Leza River catchment (Iberian System, Spain), representative of three different scenarios: (i) natural revegetation; (ii) human afforestation; and (iii) shrub clearing. Results shows how hydrological connectivity tends to decrease when vegetation cover increases (i.e., natural revegetation and human afforestation) while tend to increase when shrub clearing take place. Runoff coefficient followed a similar pattern, decreasing in basins where vegetation increases and decreasing where there was vegetation clearing. Important differences were observed in terms of the distribution of connectivity changes, their location in relation to the outlet and the effects on surface runoff. Studies of this type are necessary to know the response of the Mediterranean basins to different types of management with the aim of adopting sustainable management measures to guarantee surface water resources in a context of Global Change.

Major fluvial erosion and a 500‐Mt sediment pulse triggered by lava‐dam failure, Río Coca, Ecuador

AbstractThe failure of a 144‐m‐high lava‐dam waterfall on the Río Coca, Ecuador, in February 2020 initiated a catastrophic watershed reset—regressive erosion upstream and a massive sediment pulse downstream—as the river evolves towards a new equilibrium grade. The evolution of this river corridor after a sudden base‐level fall embodies the “complex response” concepts long understood through laboratory experiments, numerical modelling and smaller‐scale field studies, but that have not been observed in the field before on this scale. This paper presents geomorphic and geotechnical data to characterize the evolution of the Río Coca since 2020. In the three years after the lava‐dam failure, the erosion front migrated almost 13 km upstream along the mainstem river and triggered secondary headcuts that began migrating up tributaries. Erosion of the mainstem and tributary valleys generated a sediment pulse estimated to be 277 million m3 and ~500 million tonnes (Mt) over three years, depositing sediment tens of meters thick over tens of kilometres downstream from the former waterfall. This sediment pulse is one of the largest in modern times, comparable to the annual sediment load of a major continent‐draining river but with orders‐of‐magnitude greater sediment yield. Geomorphic adjustment of the Río Coca represents a highly unusual natural disaster threatening life, property, water quality, the regional economy, major infrastructure and energy security. However, this event also provides a rare opportunity to learn how a large autogenic watershed disturbance and recovery evolve, with important lessons for interpreting the sedimentary record of volcanic landscapes.

Estimation of Long-Term Suspended Sediment Yield from a Small Agricultural Catchment

Estimation of Long-Term Suspended Sediment Yield from a Small Agricultural Catchment

The Implementation of Land Use Scenario to Mitigate Erosion Rate in Pidekso Dam Catchment Area

Land use in Pidekso Dam Catchment Area is the largest in moorland and rice fields, so the potential for erosion rates that produce sedimentation is relatively high and dramatically affects the operating life of the dam. This study aims to compare several land use implementation scenarios to obtain a longer operating life at Pidekso Dam. The amount of erosion rate is calculated based on the Universal Soil Loss Equation (USLE) model with the integration of Geographic Information Systems for land use implementation scenarios. The calculation results before the land use implementation scenario showed the magnitude of the erosion rate at Pidekso Dam Catchment Area of 971846.151 tons/year with a sediment yield of 116026.553 tons/year, including a very severe erosion hazard level. The operating life of Pidekso Dam is estimated to last only 33.54 years from the planned life of 50 years. Based on the analysis of several land use scenarios using vegetative and mechanical methods for the longer operating life of Pidekso Dam with the construction of sediment barriers, which reached 53.99 years.

The Assessment on the Flood Mitigation Strategies of the Local Government Unit of Santo Tomas, Davao del Norte: A Basis for Policy Formulation

This study evaluates flood mitigation strategies implemented by the LGU of Santo Tomas, Davao del Norte, focusing on indicators such as Rehabilitation of River Banks, Bridges, Dredging, and Reforestation. Through random sampling in selected barangays, 377 respondents provided feedback, indicating Very High Descriptive Equivalents for all strategies. However, the detailed analysis identifies the Rehabilitation of River Banks as an area for improvement (mean score: 4.19), emphasizing the need for enhanced catchment drainage, floodwater capacity, and sediment yield reduction. Recommendations include regular maintenance of drainage channels, river widening, and the establishment of riparian buffer zones. Future research should explore flood-prone residents’ perceptions of LGU strategies. A proposed policy on River Bank Rehabilitation emphasizes an ecosystem-based, participatory approach to enhance resilience, increase public awareness, and promote sustainable development. Strategies encompass riparian vegetation restoration, bank stabilization, invasive species control, water quality improvement, floodplain management, and public education. Implementation rests with the LGU of Sto. Tomas and stakeholders, with ongoing monitoring and evaluation to ensure effectiveness and facilitate adjustments. This study provides valuable insights and a practical policy framework to enhance flood mitigation, specifically focusing on river bank rehabilitation in LGU-Santo Tomas, Davao del Norte.

Soil erosion and sediment yield estimation in a tropical monsoon dominated river basin using GIS-based models

The increasing soil erosion (SE) and the associated problems for society, economy, and environment sparked a lot of interest in estimating and mapping SE at different basin scales. The estimation of SE exhibits that SE ranges from 10 to 50 t ha−1 yr−1, with a mean SE of 20 t ha−1 yr−1. The very steep slopes account for 54.21% of total soil loss. The SRB areas where soil loss rates are >10 t ha−1 yr−1 are considered the target areas which account for 27% of the study area and 96% of the soil loss). The high SY is concentrated only in the first-order basins located in a higher slope zone in the northern part of the river. Besides, basin morphometry (basin shape, relative relief) and anthropogenic activities (agricultural land) are retained in the PSLR model as significant factors contributing to SY in the entire river basin.

The Signature of Climate in Fluvial Suspended Sediment Records

AbstractArid regions are often characterized by exceptionally high rates of fluvial sediment transport, but the processes responsible for this apparent connection between climate and sediment transport remain unclear. We examined decades of continuous flow records and suspended sediment concentrations from 71 rivers across the United States by comparing the suspended sediment rating curve behavior, quantified using power law coefficients and exponents, to an aridity index. Results indicate that higher aridity correlates with both greater overall suspended sediment concentration and lower sensitivity of concentration to changes in discharge, demonstrating that rivers in arid locations on average have greater suspended sediment transport efficiency across most discharges, and achieve high transport rates at a relatively lower discharge than rivers in temperate climates. Furthermore, based on additional analyses of the Normalized Difference Vegetation Index, specific suspended sediment yield, and a hydrograph flashiness index, we attribute the relationships between sediment transport and climate primarily to differences in vegetation density, precipitation, and runoff, variables that all influence both sediment supply and riverbed grain sorting. Finally, we note that the observed contrasts in sediment transport behavior likely represent climate‐driven differences in the magnitude and frequency of sediment supply rather than annual suspended sediment load, which does not depend significantly on climate. This study highlights a critical connection between multiple interrelated climatic factors and sediment transport, an important finding for future hazard mitigation in a changing climate with rapidly shifting vegetation patterns and hydrology.

Effect of Blue Agave (Agave tequilana Weber) Management on Soil Erosion

The expansion of blue agave ( Agave tequilana Weber) plantations beyond the plant’s original distribution range in the state of Jalisco, Mexico, has caused a drastic change in land use and crop patterns, exerting pressure on natural resources. This study originated based on a request from landowners who leased their land to a tequila company to grow agave in the municipality of Autlán. Therefore, this study records the effect of crop management on the degradation of non-renewable soil and water resources in plots conventionally managed by the company compared to the one managed by a private owner The sampling unit was 2 m × 5 m runoff lots, with a repetition and a control lot (without vegetation cover) with a 6% slope. Sampling was carried out in the rainy season from July to October, 2020. The results showed different behavior between repetitions. Total sediment yield in the farmer’s plot was 9.260 t ha−1 and in its control 6.844 t ha−1 versus the company’s plot of 13.796 t ha−1 and its control 5.233 t ha−1. These values reflect an increase in soil loss by 26% and 62%, respectively, due to management effects. The difference between sites is due in part to the different rainfall intensities and distribution of recorded rainfall separates the two sites. Given these results, there is a lack of knowledge of the impact of crop management on soil degradation by companies and farmers who lease or plant blue agave, in addition to the absence of a sustainable project that considers the conservation of soil and water, based on agronomic and cultural measures before, during, and after the harvest season by the municipality and state authorities and the agave-tequila companies.

Sediment Deposition and Its Evaluation in the Earthen Dam (Arzengarzen) In Budgam District of Jammu and Kashmir

Abstract: The management of sedimentation in a reservoir offers a comprehensive assessment of the sediment transportation and erosion processes. Understanding sedimentation is helpful for managing reservoirs. Dam silting volumes can be evaluated by bathymetric surveys. The Arzengarzen earthen dam in Budgam district of Jammu and Kashmir had two surveys conducted, and the data are available. Initial data regarding the amount and variability of silting as well as the mechanism of sediment deposition are provided by the measurements. The average annual specific sediment output of the Arzengarzen earthen dam watershed is projected to be 2851 t m 3 /yr based on measurement results. The average yearly volume of confined sediment varies, ranging from 2300 m3 in 2010 Over time, the sedimentation rate rises from 0.20 to 0.43%. The findings show a relationship between the presence of soils on steep slopes and particular rates of erosion. The only source of income in the area (Agriculture )is at risk due to the strain that the area's population has placed on the land through overgrazing and plowing, which has caused increased erosion and further deterioration.

SOIL EROSION AND IMPACT ON RECREATIONAL RESOURCES IN THE SHYNGYRLAU BASIN, WESTERN KAZAKHSTAN: A MULTI-ANALYTICAL ASSESSMENT

Over the past decades, water erosion has increased significantly in the Shyngyrlau River basin. Recreational development, haphazard construction and operation of roads have led to increased water erosion and the formation of numerous linear erosion forms. Erosion reduces the natural resource status of the region. Water erosion develops in most cases along roads laid along the thalwegs of the ravine-hollow network. The light substrate along with sparse vegetation cover (the sparseness is aggravated by intensive grazing) predetermine its rapid development. Water erosion is an acute problem arising from the present climate change, agricultural intensification and diverse forms of anthropogenic land degradation. Assessment of present and potential soil erosion is useful for landscape preservation as well as development planning. Multi-analytical modeling can provide a quantitative and consistent estimation of soil erosion and sediment yield under locally specific environmental conditions. The soil loss model, Revised Universal Soil Loss Equation (RUSLE), integrated with GIS, has been used to estimate soil loss in the Shyngyrlau Basin (a left-bank tributary of the Ural River, NW Kazakhstan). The RUSLE model is based on remote sensing and field data; erosion probabilities were determined using GIS. The percentage ratio of the soil loss in the Shyngyrlau River basin shows erosion variation of 0.001–2.47 t/ha/yr. The degree of erosion increases with the length of the slope. A new factor Chip curvature (Cu factor), defining the accuracy of the soil loss results, was defined. According to this factor, soil erosion in the study area is 0.007–2.48 t/ha/yr within the low erosion class. The lowest indicator of the K factor is 0.2 in sandy clay soils used as pasturelands. The highest K factor (0.3) relates to clayey arable soils. The research results add to implementation of new strategies in soil management and conservation practices reducing soil erosion in the Shyngyrlau Basin. Both climate and anthropogenic factors are seen behind the activated ground erosion. The development of forms of water erosion leads to a violation of the integrity of modern natural complexes of the West Kazakhstan region, which significantly reduces their stability and recreational potential.

Variations of streamflow and sediment yield in the Mosul-Makhool Basin, North Iraq under climate change: a pre-dam construction study

Abstract The Makhool Dam has brought much attention to the Mosul-Makhool Basin (MMB) in Iraq. Dam construction needs comprehensive studies on the impact of climate change on streamflow and sediment yield in watersheds that supply dams; however, there have been no such investigations conducted on the MMB. An ensemble of three General Circulation Models from Coupled Model Intercomparison Project Phase 6 (CMIP6) with two Shared Socioeconomic Pathways scenarios (SSP2–4.5 and SSP5–8.5) was used to predict the impact of climate change. A distribution mapping downscaling method was utilized to improve the biased climate data. The results indicate that precipitation decreased by 9.5 and 18.7% under SSP2–4.5 and SSP5–8.5 scenarios at the end of the 21st century. The average maximum and minimum temperatures are projected to rise by 2.4 and 1.8 °C in SSP2–4.5 and rise by 3.5 and 2.8 °C in SSP5–8.5 during the study period. The streamflow is expected to decrease by 36.6 and 45.9%, and sediment yield will reduce by 46 and 55% within the same scenarios. Understanding the consequences of climate change helps to face abrupt climate changes to manage dam construction and treat water resources successfully. The results of this research are expected to contribute to improving water management strategies in the study region.

Artificial Neural Network Based Runoff and Sediment Yield Modeling of Maybar Watershed, Awash Basin, Ethiopia

Artificial Neural Network Based Runoff and Sediment Yield Modeling of Maybar Watershed, Awash Basin, Ethiopia

Effects of multiple factors on particle size selectivity under artificial extreme rainfall events on simulated Gobi surface

Understanding multiple-factor effects on particle size selectivity by extreme rainfall events in Ala-Shan Gobi desert is of great significance for better estimation of potential Asian dust emission sources. Artificial rainfall simulation experiments were used to investigate the particle size selectivity characteristics by extreme rainfall events under different rainfall intensities (20 mm h−1 and 40 mm h−1), slope gradients (3° and 15°) and gravel coverages (0, 30%, and 60%). Moreover, the relations of clay content (Clc), silt content (Sic), fine particle (< 50 μm) content (Fic) and enrichment ratio of fine particles (ER<50) with multiple factors were regressed and validated. Results show that rainfall intensity significantly (P < 0.05) affect runoff and sediment yield processes, but slope gradient was a dominant factor that changed particle size distribution (PSD). The selectivity of fine particles was higher at low rainfall intensity (20 mm h−1), gentle slope (3°) and moderate gravel coverage (30%), with ER<50 reaching 6.14, which dominate the potential Asian dust emission sources. The interaction were discussed and classified into ‘Synergy’ and ‘Trade-off’. Clc and Fic showed negative exponential relationship with rainfall intensity and slope gradient, but positive exponential relationship with gravel coverage. While Sic and ER<50 showed negative power function relationship with rainfall intensity, slope gradient and gravel coverage. These findings could help to understand the effects of multiple factors on potential sources of Asian dust emission under extreme rainfall events in Gobi region of northwestern China and provide basic science reference for the prediction of dust emission in this region.

Sediment Yield in the Caucasus Mountains and Its Trends as a Reflection of Climate Change and Anthropogenic Impact

Sediment Yield in the Caucasus Mountains and Its Trends as a Reflection of Climate Change and Anthropogenic Impact

Estimating Sediment Yield at Sungai Pusu Watershed using Soil and Water Assessment Tool (SWAT) Model

Sediment yield is the net result of soil erosion and sediment deposition processes. In the watershed, sediment yields are dominantly determined by stream flow, drainage area, and channel size. Land-use activity conducted by human is one of the major contributions to the sediment yield in the watershed. The study area covered in this study is the Sungai Pusu which flows through International Islamic University Malaysia (IIUM). Significant amount of sediments is deposited in Sungai Pusu due to the improper land clearing activities that are taking place along the river’s main tributaries. As a result, the water quality of Sungai Pusu is rapidly deteriorating. Sediment yield estimation is crucial in order to design suitable measure to rehabilitate the river. The aim of this study is to estimate sediment yield at Sungai Pusu watershed using SWAT model. Remote sensing and Geographic Information System (GIS) were used to evaluate sedimentation over time in the Sungai Pusu watershed. The SWAT model was performed to simulate water balance, stream flow, and sediment yield. The annual sediment yield obtained by the model is 427-ton ha-1 year-1.

Assessment of plot-scale sediment transport on young moraines in the Swiss Alps using a fluorescent sand tracer

Abstract. Glacial retreat uncovers large bodies of unconsolidated sediment that are prone to erosion. However, our knowledge of overland flow (OF) generation and sediment transport on moraines that have recently become ice-free is still limited. To investigate how the surface characteristics of young moraines affect OF and sediment transport, we installed five bounded runoff plots on two moraines of different ages in a proglacial area of the Swiss Alps. On each plot we conducted three sprinkling experiments to determine OF characteristics (i.e., total OF and peak OF flow rate) and measured sediment transport (turbidity, sediment concentrations, and total sediment yield). To determine and visualize where sediment transport takes place, we used a fluorescent sand tracer with an afterglow as well as ultraviolet (UV) and light-emitting diode (LED) lamps and a high-resolution camera. The results highlight the ability of this field setup to detect sand movement, even for individual fluorescent sand particles (300–500 µm grain size), and to distinguish between the two main mechanisms of sediment transport: OF-driven erosion and splash erosion. The higher rock cover on the younger moraine resulted in longer sediment transport distances and a higher sediment yield. In contrast, the higher vegetation cover on the older moraine promoted infiltration and reduced the length of the sediment transport pathways. Thus, this study demonstrates the potential of the use of fluorescent sand with an afterglow to determine sediment transport pathways as well as the fact that these observations can help to improve our understanding of OF and sediment transport processes on complex natural hillslopes.

Evaluating the effects of DEM and soil data resolution on streamflow and sediment yield simulations in the Upper Blue Nile basin.

While the availability of "big data" on biophysical parameters through citizen science and/or from public/private sources is expected to help in addressing data scarcity issues, there is little understanding of whether and/or how such data will improve watershed simulations. This research aimed to evaluate whether improvements in resolutions of Digital Elevation Model (DEM) and soil data will enhance streamflow and sediment yield simulations and thereby improve soil and water management decisions. The study was conducted in two different-sized watersheds (Anjeni and Gilgel Abay with ~ 1 km2 and ~ 1655 km2 area, respectively) in the Upper Blue Nile basin in Ethiopia. Effects of DEM and soil data resolutions on streamflow and sediment yield were evaluated using the Soil and Water Assessment Tool (SWAT). The results showed that the effect of DEM and soil data resolution on streamflow and sediment yield simulation was scale dependent finer resolution DEM and soil datasets improved streamflow and sediment yield simulations in the smaller Anjeni watershed, whereasDEM resolution had no effect in the bigger Gilgel Abay watershed. Small watersheds are often used to understand watershed processes, and thus theuse of finer-resolution spatial data for watershed simulations could result in better results. Findings from the smaller Anjeni watershed suggested that the combined use of finer resolution DEM and soil data could potentially improve sediment yield simulations although the lack of observed sediment yield data did not allow verification of this at the larger Gilgel Abay watershed.

Influence of check dams on water and sediment processes and deposition patterns under simulated rainfall conditions

The Loess Plateau in China has the highest soil erosion and water loss rates in the world. Therefore, check dams, which are more useful engineering measures, have been established to improve soil and water conservation in small watershed. To determine check dam configuration pattern influence on runoff, sediment yield, erosion and deposition pattern in watershed, we conducted a rainfall simulation experiment using the qiao gully small watershed as our normal-scale model. We analysed the runoff and sediment yield characteristics and deposition patterns under four types of check dam configurations: no dams constructed, dam in first order stream channel, dam in second order stream channel, and dams in both channels. Our findings revealed that the runoff and sediment concentrations increased with time, regardless of check dam configuration. The significant effects of check dams on the evolution of storm runoff processes in a small watershed. Compared to no dams, double dams best inhibited runoff reduction and lowered sediment deposition, while construction of one dam in the primary channel was more effective than one dam in the secondary channel. In summary, check dam construction reduced channel erosion, rill erosion, and bank slope collapse at the channel head, while raising the dam-controlled watershed base level. Our findings provide a reference for designing check dams in optimal configurations on plateaus such as the Loess Plateau. The results of this study are of great practical significance in revealing the process of storm runoff and identifying key parts of soil erosion–deposition in the watershed.