scholarly journals Efficacy of Time-Area Method in simulating temporal variation of sediment yield in Chehelgazi watershed, Iran

2010 ◽  
Vol 42 (1) ◽  
pp. 51-60 ◽  
Author(s):  
A. Darvishan ◽  
S. Sadeghi ◽  
L. Gholami
Keyword(s):  
Temporal Variation ◽  
Sediment Yield ◽  
Water Conservation ◽  
Delivery Ratio ◽  
Storm Events ◽  
Temporal And Spatial Variation ◽  
Sediment Delivery ◽  
Sediment Control ◽  
Area Method ◽  
Temporal And Spatial

Efficacy of Time-Area Method in simulating temporal variation of sediment yield in Chehelgazi watershed, Iran The proper prediction of temporal and spatial variation of sediment yield from the watershed is a need for sediment control, river engineering and soil and water conservation studies. The present study was therefore planned to simulate the sediment graphs for Chehelgazi watershed in Gheshlagh dam upstream in Kurdistan Province, Iran, by using Time-Area Method. Towards this attempt, the study watershed was divided into 7 time-area segments based on the time of concentration. The soil erosion in each segment was estimated using the USLE and then routed to the main outlet using sediment delivery ratio as a function of land slope in two adjacent time-areas. The temporal variation of sediment was ultimately predicted with the help of lag time of sediment arrival to the outlet and the concept of superposition for 11 storm events, which occurred during winter 2006 and spring 2007. The comparison between estimated sediment graphs with corresponding observed ones verified the weak capability of the model in simulation of sediment graphs under consideration. The results also verified the calibration necessity of the model to achieve appropriate estimation for important components of the sediment graphs. The results of the calibration finally proved the considerable capability of the model in predicting of total volume of sediment yield with respective estimation and verification errors of 30.93 and 33.40%.

scholarly journals Evaluation of the SEdiment Delivery Distributed (SEDD) Model in the Shihmen Reservoir Watershed

2020 ◽  
Vol 12 (15) ◽  
pp. 6221
Author(s):  
Kent Thomas ◽  
Walter Chen ◽  
Bor-Shiun Lin ◽  
Uma Seeboonruang
Keyword(s):  
Sediment Yield ◽  
Economic Cost ◽  
Future Research ◽  
Delivery Ratio ◽  
Sediment Delivery ◽  
Sediment Control ◽  
Watershed Prioritization ◽  
Aerial Photogrammetry ◽  
Shihmen Reservoir ◽  
Reservoir Watershed

The sediment delivery ratio (SDR) connects the weight of sediments eroded and transported from slopes of a watershed to the weight that eventually enters streams and rivers ending at the watershed outlet. For watershed management agencies, the estimation of annual sediment yield (SY) and the sediment delivery has been a top priority due to the influence that sedimentation has on the holding capacity of reservoirs and the annual economic cost of sediment-related disasters. This study establishes the SEdiment Delivery Distributed (SEDD) model for the Shihmen Reservoir watershed using watershed-wide SDRw and determines the geospatial distribution of individual SDRi and SY in its sub-watersheds. Furthermore, this research considers the statistical and geospatial distribution of SDRi across the two discretizations of sub-watersheds in the study area. It shows the probability density function (PDF) of the SDRi. The watershed-specific coefficient (β) of SDRi is 0.00515 for the Shihmen Reservoir watershed using the recursive method. The SY mean of the entire watershed was determined to be 42.08 t/ha/year. Moreover, maps of the mean SY by 25 and 93 sub-watersheds were proposed for watershed prioritization for future research and remedial works. The outcomes of this study can ameliorate future watershed remediation planning and sediment control by the implementation of geospatial SDRw/SDRi and the inclusion of the sub-watershed prioritization in decision-making. Finally, it is essential to note that the sediment yield modeling can be improved by increased on-site validation and the use of aerial photogrammetry to deliver more updated data to better understand the field situations.

KAJIAN EROSI LAHAN DI KAWASAN AIR STRIP RUNWAY 2600 BANDARA DEPATI AMIR (PGK) BERDASARKAN TATA GUNA LAHAN MASTERPLAN ULTIMATE

2019 ◽  
Vol 7 (2) ◽  
pp. 100-111
Author(s):  
Miskar Maini ◽  
Junita Eka Susanti
Keyword(s):  
Sediment Yield ◽  
Soil Loss ◽  
Universal Soil Loss Equation ◽  
Delivery Ratio ◽  
Sediment Delivery Ratio ◽  
Sediment Delivery ◽  
Soil Loss Equation

Standar permintaan engineering pesawat agar desain bangunan infrastruktur di area Air Strip Runway 2600 yang ada dapat mempunyai fungsi lain. Sedangkan kondisi lain sangat menentukan keselamatan karena lahan di sekitar Air Strip Runway 2600 Bandara Depati Amir (PGK) jika tidak ditutupi vegetasi seperti rumput, kondisi lain lahan yang belum ditutupi vegetasi di sekitar Air Strip Runway 2600 berpotensi akan mengalami erosi lahan, kemudian hasil erosi lahan ini akan terbawa oleh aliran air sehingga akan masuk ke saluran drainase yang akan menyebabkan sedimentasi pada saluran drainase tersebut, akhirnya akan berkurang efektifitas kinerja saluran drainase tersebut. Metode yang digunakan untuk memprediksi laju rata-rata erosi di area Air Strip Runway 2600 dengan memperhitungkan faktor erosivitas hujan, erodibilitas tanah, kemiringan lereng atau panjang lereng, pengelolaan tanaman dan konservasi tanah, yang masing masing tata guna lahan tersebut mengacu pada Masterplan Ultimate Bandara Depati Amir (PGK). Perhitungan dilakukan menggunakan persamaan USLE (Universal Soil Loss Equation) yang dikembangkan oleh Wischmeier dan Smith (1965, 1978), kemudian Sediment Delivery Ratio (SDR) dan Sediment Yield.Hasil penelitian ini, prediksi laju erosi permukaan pada area Air Strip Runway 2600 Bandara Depati Amir (PGK) tahun pertama yang mencapai 5,60 mm/tahun atau 100,76 Ton/Ha/tahun, laju erosi tahun kedua mencapai 3,38 mm/tahun atau 60,84 Ton/Ha/tahun dapat diklasifikasikan ke dalam kelas bahaya erosi sedang (kelas III) dan nilai SDR adalah sebesar 56,3%, nilai sediment yield (SR) pada tahun pertama sebesar 5.887,59 Ton/Tahun, pada tahun kedua ketika rumput pada area Air Strip telah tumbuh dengan sempurna terjadi penurunan hasil sediment yield yaitu nilai SR sebesar 3.554,85 Ton/Tahun.

scholarly journals Entropy-Based Method for Temporal Downscaling of Precipitation to Improve Sediment Delivery Ratio Assessment

2020 ◽  
Author(s):  
Pedro Alencar ◽  
Eva Paton ◽  
José de Araújo
Keyword(s):  
Maximum Entropy ◽  
Sediment Yield ◽  
Absolute Error ◽  
Reanalysis Data ◽  
Delivery Ratio ◽  
Sediment Delivery ◽  
Precipitation Characteristics ◽  
Erosion Modelling ◽  
Novel Method ◽  
Made In

Scarcity of precipitation data is still a problem in erosion modelling, especially when working in remote and data-scare areas. While much effort was made in the past to use remote sensing or reanalysis data, they are still considered to be not completely reliable, notably for sub-daily measures such as duration and intensity. A way forward are statistical analyses, which can help modellers to obtain sub-daily precipitation characteristics by using daily totals. In this paper, we propose a novel method (Maximum Entropy Distribution of Rainfall Intensity and Duration - MEDRID) to assess the duration and intensity of sub-daily rainfalls relevant for the modelling of sediment delivery ratios. We use the generated data to improve the sediment yield assessment in seven catchments with areas varying from 10 to 10 km and a broad timespan of measured data (1 to 81 years). The best probability density function derived from MEDRID to reproduce sub-daily duration is the generalised gamma distribution (NSE = 0.98), whereas for rain intensity it is the uniform (NSE = 0.87). The MEDRID method coupled with the SYPoME model (Sediment Yield using the Principle of Maximum Entropy) represents a significant improvement over empirically-based SDR models, given its average absolute error of 21% and a Nash Sutcliffe Efficiency of 0.96, (rather than 105% and -4.49, respectively).

Soil Sediment Loading and Related Environmental Impacts from Farms

2017 ◽  
Author(s):  
Vito Ferro
Keyword(s):  
Organic Matter ◽  
Spatial Distribution ◽  
Soil Erosion ◽  
Sediment Yield ◽  
Water Storage ◽  
Sediment Deposition ◽  
Delivery Ratio ◽  
Sediment Delivery Ratio ◽  
Sediment Delivery ◽  
Soil Particles

Beyond damage to rainfed agricultural and forestry ecosystems, soil erosion due to water affects surrounding environments. Large amounts of eroded soil are deposited in streams, lakes, and other ecosystems. The most costly off-site damages occur when eroded particles, transported along the hillslopes of a basin, arrive at the river network or are deposited in lakes. The negative effects of soil erosion include water pollution and siltation, organic matter loss, nutrient loss, and reduction in water storage capacity. Sediment deposition raises the bottom of waterways, making them more prone to overflowing and flooding. Sediments contaminate water ecosystems with soil particles and the fertilizer and pesticide chemicals they contain. Siltation of reservoirs and dams reduces water storage, increases the maintenance cost of dams, and shortens the lifetime of reservoirs. Sediment yield is the quantity of transported sediments, in a given time interval, from eroding sources through the hillslopes and river network to a basin outlet. Chemicals can also be transported together with the eroded sediments. Sediment deposition inside a reservoir reduces the water storage of a dam. The prediction of sediment yield can be carried out by coupling an erosion model with a mathematical operator which expresses the sediment transport efficiency of the hillslopes and the channel network. The sediment lag between sediment yield and erosion can be simply represented by the sediment delivery ratio, which can be calculated at the outlet of the considered basin, or by using a distributed approach. The former procedure couples the evaluation of basin soil loss with an estimate of the sediment delivery ratio SDRW for the whole watershed. The latter procedure requires that the watershed be discretized into morphological units, areas having a constant steepness and a clearly defined length, for which the corresponding sediment delivery ratio is calculated. When rainfall reaches the surface horizon of the soil, some pollutants are desorbed and go into solution while others remain adsorbed and move with soil particles. The spatial distribution of the loading of nitrogen, phosphorous, and total organic carbon can be deduced using the spatial distribution of sediment yield and the pollutant content measured on soil samples. The enrichment concept is applied to clay, organic matter, and all pollutants adsorbed by soil particles, such as nitrogen and phosphorous. Knowledge of both the rate and pattern of sediment deposition in a reservoir is required to establish the remedial strategies which may be practicable. Repeated reservoir capacity surveys are used to determine the total volume occupied by sediment, the sedimentation pattern, and the shift in the stage-area and stage-storage curves. By converting the sedimentation volume to sediment mass, on the basis of estimated or measured bulk density, and correcting for trap efficiency, the sediment yield from the basin can be computed.

scholarly journals Assessment of uncertainties in soil erosion and sediment yield estiamtes at ungauged basins: an application to the Garra River basin, India

2017 ◽  
Author(s):  
Somil Swarnkar ◽  
Anshu Malini ◽  
Shivam Tripathi ◽  
Rajiv Sinha
Keyword(s):  
Soil Erosion ◽  
River Basin ◽  
Sediment Yield ◽  
Uncertainty Propagation ◽  
River Basins ◽  
Large River ◽  
Delivery Ratio ◽  
Mountainous Region ◽  
Ungauged Basins ◽  
Sediment Delivery

Abstract. High soil erosion and excessive sediment load are serious problems in several Himalayan River basins. To apply mitigation procedures, precise estimation of soil erosion and sediment yield with associated uncertainties are needed. Here, Revised Universal Soil Loss Equation (RUSLE) and Sediment Delivery Ratio (SDR) equations are used to estimate the spatial pattern of soil erosion (SE) and sediment yield (SY) in the Garra River basin, a small Himalayan tributary of River Ganga. A methodology is proposed for quantifying and propagating uncertainties in SE, SDR and SY estimates. Expressions for uncertainty propagation are derived by first-order uncertainty analysis, making the method viable even for large river basins. The methodology is applied to investigate the relative importance of different RUSLE factors in estimating the magnitude and uncertainties of SE over two distinct morpho-climatic regimes of the Garra River basin, namely, upper mountainous region & lower alluvial plains. The results suggest that average SE in the basin falls in very high category (20.4 ± 4.1 t/ha/y) with higher values in the upper mountainous region (84.4 ± 13.9 t/ha/y) than in the lower alluvial plains (17.7 ± 3.6 t/ha/y). Furthermore, the topographic steepness (LS) and crop practice (CP) factors exhibit higher uncertainties than other RUSLE factors. The annual average SY is estimated at two locations in the basin – Nanak Sagar dam (NSD) for the period 1962–2008 and Husepur gauging station (HGS) for 1987–2002. The SY at NSD and HGS are estimated to be 8.0 ± 1.4 × 105 t/y and 7.9 ± 1.7 ×106 t/y, respectively, and the estimated 90 % confidence interval contains the observed values 6.4 × 105 t/y and 7.2 × 106 t/y. The study demonstrated the usefulness of the proposed methodology for quantifying uncertainty in SE and SY estimates at ungauged basins.

scholarly journals MODELLING RESERVOIR SEDIMENTATION AT BIN EL OUIDANE DAM, MOROCCO

AGROFOR ◽  
2018 ◽  
Vol 2 (1) ◽  
Author(s):  
El Mouatassime SABRI ◽  
Ahmed BOUKDIR ◽  
Rachid El MASLOUHI ◽  
Mustapha MABROUKI ◽  
Abdellah EL MAHBOUL ◽  
...  
Keyword(s):  
Information System ◽  
Soil Erosion ◽  
Sediment Yield ◽  
Delivery Ratio ◽  
Reservoir Sedimentation ◽  
Mountainous Areas ◽  
Sediment Delivery Ratio ◽  
Sediment Delivery ◽  
Sparse Vegetation ◽  
Bin El Ouidane

This study was conducted in the Oued El Abid watershed upstream of the Bin ElOuidane dam, in Tadla-Azilal province (Morocco) to quantify the dam siltationrates. To assess the annual soil erosion and the sediment yield the universal soilloss equation (USLE) was used. A geographic information system (GIS) was usedto generate and integrate maps of the USLE factors. A spatial distribution of soilerosion in the Oued El Abid watershed was obtained. The soil erosion wasdetermined for each rural commune in order to identify the soil erosion hotspot andestimate the amount of soil that has been transported downstream (Bin El OuidaneDam). Soil erosion ranged from very limited values for flat and well covered areasto over 2100 t /ha/y in mountainous areas with sparse vegetation. The total annualsoil loss within the watershed is estimated at 19. 6 million tons per year. Anequation of sediment delivery ratio (SDR) based on river gradient was calculated.It was found that the value of SDR at the outlet of the watershed Oued El Abid was0. 65 with a sediment yield of 12. 74 million tons per year which affect thedurability of the dam.

scholarly journals Contemporary Sediment Delivery Ratios for Small Catchments Subject to Shallow Rainfall Triggered Earthflows in the Waipaoa Catchment, North Island, New Zealand

2021 ◽  
Author(s):  
◽  
Katie Elizabeth Jones
Keyword(s):  
River Mouth ◽  
Storm Event ◽  
Delivery Ratio ◽  
Storm Events ◽  
Spatial And Temporal Patterns ◽  
Channel Coupling ◽  
Sediment Delivery ◽  
Catchment Size ◽  
Fluvial Network ◽  
Small Catchments

<p>The Waipaoa catchment is generally considered to have high hill slope channel coupling due to the large volumes of sediment output at the river mouth. Yet the percentage of sediment that is transported within the fluvial system is low when considered in terms of the total volume of sediment mobilised during episodic failure events. Clearly, there is a discrepancy between generation of sediment and its delivery to the fluvial network. Previous research has suggested there is a strong decrease in catchment connectivity as catchment size increases. However, little research has been undertaken to understand the changes in hillslope-channel coupling over time. This study focuses on the connectivity of shallow rainfall triggered earthflows located in small catchments located within three different land systems in the Waipaoa Catchment. A multiple regression model was developed to predict the sediment delivery ratio for individual earthflows based on an empirical dataset of earthflows which occurred during a storm event in 2002. The results from this modelling were applied to five larger sub-catchments where sequential aerial photograph analysis (1940s to 2004) was used to determine connectivity. From this, spatial and temporal patterns in the catchment sediment delivery ratios were identified. The expected decrease in sediment delivery ratios was observed as catchment size increased. However, the temporal pattern to sediment delivery is not so clear. It appears that catchment evolution, referring specially to the Terrain Event Resistance Model developed by Crozier and Preston (1999), does not have a significant influence on sediment delivery ratios within the six decades examined in this thesis. Furthermore, while earthflows are considered the ultimate source of sediment during storm events, they are not always the mechanism by which this sediment enters the fluvial network. It is also vital to consider rates of gullying, sheet erosion and riparian erosion.</p>

scholarly journals Assessment of uncertainties in soil erosion and sediment yield estimates at ungauged basins: an application to the Garra River basin, India

2018 ◽  
Vol 22 (4) ◽  
pp. 2471-2485 ◽  
Author(s):  
Somil Swarnkar ◽  
Anshu Malini ◽  
Shivam Tripathi ◽  
Rajiv Sinha
Keyword(s):  
Soil Erosion ◽  
River Basin ◽  
Sediment Yield ◽  
Uncertainty Propagation ◽  
River Basins ◽  
Large River ◽  
Delivery Ratio ◽  
Mountainous Region ◽  
Ungauged Basins ◽  
Sediment Delivery

Abstract. High soil erosion and excessive sediment load are serious problems in several Himalayan river basins. To apply mitigation procedures, precise estimation of soil erosion and sediment yield with associated uncertainties are needed. Here, the revised universal soil loss equation (RUSLE) and the sediment delivery ratio (SDR) equations are used to estimate the spatial pattern of soil erosion (SE) and sediment yield (SY) in the Garra River basin, a small Himalayan tributary of the River Ganga. A methodology is proposed for quantifying and propagating uncertainties in SE, SDR and SY estimates. Expressions for uncertainty propagation are derived by first-order uncertainty analysis, making the method viable even for large river basins. The methodology is applied to investigate the relative importance of different RUSLE factors in estimating the magnitude and uncertainties in SE over two distinct morphoclimatic regimes of the Garra River basin, namely the upper mountainous region and the lower alluvial plains. Our results suggest that average SE in the basin is very high (23 ± 4.7 t ha−1 yr−1) with higher values in the upper mountainous region (92 ± 15.2 t ha−1 yr−1) compared to the lower alluvial plains (19.3 ± 4 t ha−1 yr−1). Furthermore, the topographic steepness (LS) and crop practice (CP) factors exhibit higher uncertainties than other RUSLE factors. The annual average SY is estimated at two locations in the basin – Nanak Sagar Dam (NSD) for the period 1962–2008 and Husepur gauging station (HGS) for 1987–2002. The SY at NSD and HGS are estimated to be 6.9 ± 1.2 × 105 t yr−1 and 6.7 ± 1.4 × 106 t yr−1, respectively, and the estimated 90 % interval contains the observed values of 6.4 × 105 t yr−1 and 7.2 × 106 t yr−1, respectively. The study demonstrated the usefulness of the proposed methodology for quantifying uncertainty in SE and SY estimates at ungauged basins.

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