scholarly journals Revised models for the proportion of suspended sediments in hillslope soil loss � an empirical understanding

2021 ◽  
Vol 6 (3) ◽  
pp. 241
Author(s):  
La Ode Hadini ◽  
Junun Sartohadi ◽  
M. Anggri Setiawan ◽  
Djati Mardiatno ◽  
Nugroho Christanto

Increasing population densities and food demands are major factors contributing to the widespread use of agricultural drylands in upper volcanic slope areas. This phenomenon poses a high risk of severe erosional events that are environmentally hazardous. Therefore, this study aims to analyze the sediment flow characteristics, based on the relationship between sediment flow and water level as well as the sediment discharge rate and soil loss. Field surveys were conducted to determine the soil measurement, slope morphology and dryland cover characteristics. The sediment flow was evaluated at the gully outlet, where 169 suspension data pairs for the modeling and 130 suspension data pairs for the validation, as well as the bed load, water level, rainfall and water flow characteristics were obtained. Tables and figures were subsequently used to represent the measurement data and analysis results for the correlation between the flow rate effects, sediment and soil loss on the water surface. The results showed that the sediment flow in volcanic landscape slopes with dryland agriculture were possibly characterized by the polynomial relationship, using the suspension discharge model, Qs=0.0322Q2+6.0625Q–1.2658. Under this condition, the average rate of soil loss in the form of sediment load and erosion rate of the catchment area occurred at 953.53 and ​​1,657.94 ton/ha/yr, respectively. Furthermore, the sediment sources in the soil loss were believed to originate from 83% of the suspended sediments and 17% bed loads. Keywords: Discharge; Dryland; Landscape; Sediment; Volcano Copyright (c) 2021 Geosfera Indonesia and Department of Geography Education, University of Jember   This work is licensed under a Creative Commons Attribution-Share A like 4.0 International License


Author(s):  
Marie Palíková ◽  
Aleš Kučera

Soil erosion is still an issue in forestry and in human water-resources activities connected with landscape management and the protection of surface waters. The methods recently assessing the water erosion include: monitoring of suspended sediments in water, monitoring of dynamics of soil pro­per­ties, assessing the inclination of soil towards soil erosion, monitoring of effectiveness of erosion control measures, erosion processes modeling etc. (Buzek, 1981; Buzek, 1983; Holý, 1994; Jařabáč, Belský, 2008).The river basin of the water tank Šance is very important as a source of potable water and this importance is advanced, when water tank is clogged up by suspended sediments.Erosion was assessed by two methods in ArcMap 9.3 working with original data: the first method is Universal equation calculating an average annual soil loss from surface (USLE) (Wischmeier, Smith, cit. in Janeček, 2002); the second method assesses the potential erosion (MPE), using specific soil properties as factors, evaluating the rate of the intensity of erosion (Kučera, Palíková; 2009).Each method uses different ways for the description of the erodibility: USLE describes a long-term average annual soil loss as a consequence of surface erosion. It gives exact values of sediments in t . ha−1 . year−1, but from the other point of view, this method is primarily created for an agricultural land. Compared with USLE, MPE solves potential erosion and gives relative values of the erosion tendency of an environment. PME could give a new point of view on the assessing of the erosion.The river basin Ostravice above water tank Šance was used to compare these two methods. As a control measure, dates of the assessment of the water sediments regime (Buzek, 2001) were used. This observation was pursued in waters of the gagin station ČHMÚ Ostrava in Staré Hamry in according Stehlík (1969). This 25-year process of measuring shows the value of 2.47 t . ha−1 . year−1 in water tank upper Ostravice (with surface 72.96 km2). USLE shows much lower values of suspended sediments (0.41 t . ha−1 . year−1 using a continuous longitude of slopes or 0.11 t . ha−1 . year−1, with regards to the interruption of slopes by the forest roads). This difference is caused by the construction of USLE, which doesn’t respect increased values of sediments after the crossing of fords by the forestry mechanization, rill erosion or inputs of sediments from watercourse and near ravines. Therefore, the high values of suspended sediments are mainly caused by forest management (Buzek, 2001).


2019 ◽  
Vol 7 (2) ◽  
pp. 100-111
Author(s):  
Miskar Maini ◽  
Junita Eka Susanti

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.


Author(s):  
Nguyễn Quang Việt ◽  
Trương Đình Trọng ◽  
Hồ Thị Nga

Vinh Linh, the northern district of Quang Tri province is characterized by a diversified topography with a large variety of elevations, high rainfall, and decreasing land cover due to forest exploiting for cultivation land. Thus, there is a high risk of erosion, soil fertility washout. With the support of GIS technology, the authors used the rMMF model to measure soil erosion. The input data of model including 15 coefficients related to topography, soil properties, climate and land cover. The simulations of rMMF include estimates of rainfall energy, runoff, soil particle detachment by raindrop, soil particle detachment by runoff, sediment transport capacity of runoff and soil loss. The result showed that amount of soil loss in year is estimated to vary between 0 kg/m2 minimum and 149 kg/m2 maximum and is divided into 4-classes of erosion. Light class almost covers the region researched (75.9% of total area), while moderate class occupies 8.1% of total area, strong classes only hold small area (16% of total area). Therefore, protection of the forest floor in sloping areas is one of the most effective methods to reduce soil erosion.


2019 ◽  
Vol 2 (1) ◽  
pp. 071-084
Author(s):  
Silwanus M. Talakua ◽  
Rafael M. Osok

The study was conducted in Wai Sari sub-watershed, Western Seram Regency Maluku to develop an accurate land degradation assessment model for tropical small islands. The Stocking’s field land degradation measurement and RUSLE methods were applied to estimate soil loss by erosion and the results of both methods were statistically tested in order to obtain a correction factor. Field indicators and prediction data were measured on 95 slope units derived from the topographic map. The rates of soil loss were calculated according to both methods, and the results were used to classify the degree of land degradation. The results show that the degree of land degradation based on the field assessment ranges from none-slight (4.04 - 17.565 t/ha/yr) to very high (235.44 - 404.00 t/ha/yr), while the RUSLE method ranges from none-slight (0.04-4.59 t/ha/yr) to very high 203.90 - 518.13 t/ha/yr.  However, the RUSLE method shows much higher in average soil loss (133.4 t/ha/yr) than the field assessment (33.9 t/ha/yr). The best regression equation of  logD/RP = - 0.594 + 1.0 logK + 1.0 logLS + 1.0 logC or D = 0.2547xRxKxLSx CxP was found to be a more suitable land degradation assessment  model for a small-scale catchment area in the tropical small islands.


2012 ◽  
Author(s):  
H. Mark Hanna ◽  
Matt Helmers
Keyword(s):  

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