scholarly journals THE ROLE OF UNPAVED ROADS IN THE SEDIMENT BUDGET OF A SEMI-ARID MESOSCALE CATCHMENT

Author(s):  
Teresa Raquel Lima Farias ◽  
Pedro Medeiros ◽  
José Carlos de Araujo ◽  
Joaquin Navarro Hevia

High rates of erosion and runoff production on road infrastructure have been documented, indicating that unpaved roads might be significant sources of sediment in catchments. In this paper, the production of surface sediments from unpaved rural roads at different scales is assessed. The study took place in northeastern Brazil, in a semiarid area of the Caatinga biome, vulnerable to desertification. Sediment production data from road surface segments were monitored for two years (2013-2014) under conditions of natural precipitation. By using hydrosedimentological modeling and Geographic Information System (GIS), the sediment budget was calculated at the meso-scale basin (aprox. 930 km²), in order to identify the relative contribution of roads to the sediment balance. Universal Soil Loss Equation (USLE) associated with Maner’s sediment delivery ratio (SDR) equation, proved to be an adequate approach for predicting sediment yield on the road segment scale; the best results were obtained for the road without traffic, due to the non-interference in this segment of external factors, such as traffic and maintenance activities, not explicitly considered in the model formulation. The modeling procedure showed that the roads, which occupy only 0.7% of the catchment surface, were responsible for approximately 7% of soil loss in the area. Furthermore, sediment connectivity might be enhanced by roads, which cross the river network and, therefore, deliver more directly the sediment generated at hillslopes. This is particularly important in the studied environment, where sediment connectivity is low due to limited runoff and the existence of a dense network of surface water reservoir

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.


2019 ◽  
Author(s):  
Abreham Berta Aneseyee

Abstract Background: Information on soil loss and sediment export is essential to identify hotspots of soil erosion for conservation interventions in a given watershed. This study aims at investigating the dynamic of soil loss and sediment export associated with land use/land cover change and identifies soil loss hotspot areas in Winike watershed of Omo-gibe basin of Ethiopia. Spatial data collected from satellite images, topographic maps, meteorological and soil data were analyzed. Integrated Valuation of Ecosystem Services and Tradeoffs (InVEST) of sediment delivery ratio (SDR) model was used based on analysis of land use/land cover maps and RUSLE factors. Result: The results showed that total soil loss increased from 774.86 thousand tons in 1988 to 951.21 thousand tons in 2018 while the corresponding sediment export increased by 3.85 thousand tons in the same period. These were subsequently investigated in each land-use type. Cultivated fields generated the highest soil erosion rate, which increased by 10.02 t/ha/year in 1988 to 43.48 t/ha/year in 2018. This corresponds with the expansion of the cultivated area that increased from 44.95 thousand ha in 1988 to 59.79 thousand ha in 2018. This is logical as the correlation between soil loss and sediment delivery and expansion of cultivated area is highly significant (p<0.01). Sub-watershed six (SW-6) generated the highest soil loss (62.77 t/ha/year) and sediment export 16.69 t/ha/year, followed by Sub-watershed ten (SW-10) that are situated in the upland plateau. Conversely, the lower reaches of the watershed are under dense vegetation cover and experiencing less erosion. Conclusion: Overall, the changes in land use/land cover affect significantly the soil erosion and sediment export dynamism. This research is used to identify an area to prioritize the watershed for immediate management practices. Thus, land use policy measures need to be enforced to protect the hydropower generation dams at downstream and the ecosystem at the watershed.


2014 ◽  
Vol 2 (6) ◽  
pp. 3887-3917
Author(s):  
R. C. Sidle ◽  
M. Ghestem ◽  
A. Stokes

Abstract. Expanding mountain road networks in developing countries significantly increase the risk of landslides and sedimentation, as well as create vulnerabilities for residents and aquatic resources. We measured landslide erosion along seven road segments in steep terrain in the upper Salween River basin, Yunnan, China and estimated sediment delivery to channels. Landslide erosion rates along the roads ranged from 2780 to 48 235 Mg ha−1 yr−1, the upper end of this range being the highest rate ever reported along mountain roads. The two roads with the highest landslide erosion (FG1 = 12 966 Mg ha−1 yr−1 ; DXD = 48 235 Mg ha−1 yr−1) had some of the highest sediment delivery rates to channels (about 80 and 86%, respectively). Overall, three times more landslides occurred along cutslopes compared to fillslopes, but fillslope failures had a combined mass >1.3 times that of cutslope failures. Many small landslides occurred along road cuts, but these were often trapped on the road surface. Given the magnitude of the landslide problem and the lack of attention to this issue, a more sustainable approach for mountain road development is outlined based on an analysis of landslide susceptibility and how thresholds for landslide trigger mechanisms would be modified by road location and construction techniques.


Author(s):  
Akram A. Almohammedi ◽  
Nor K. Noordin ◽  
A. Sali ◽  
Fazirulhisyam Hashim ◽  
Waheb A. Jabbar ◽  
...  

Vehicular Ad Hoc Networks (VANETs) have been developed to improve the safety, comfort and efficiency of driving on the road. The IEEE 1609.4 is a standard intended to support multi-channel in VANETs. These channels include one control channel for safety applications and six service channels for service applications. However, there is still no comprehensive analysis for the average delay and system throughput of IEEE 1609.4 MAC in VANETs considering error-prone channel under non-saturated conditions. In this paper, we propose an analytical models based on 1-D and 2-D Markov chain to evaluate the performance analysis of IEEE 1609.4 MAC in the presence of error-prone channels. Besides, freezing of the back-off timer is taken into consideration to provide an accurate estimation of access to the channel. The simulation results have been carried out to validate the analytical results of our model. The results show that the performance of our model outperforms the existing model in terms of packet delivery ratio and average delay of safety packets over CCH, and system throughput of service packets over SCHs.


Author(s):  
Nirbhay Kumar Chaubey ◽  
Dhananjay Yadav

<span>Vehicular ad hoc network (VANET) is an emerging technology which can be very helpful for providing safety and security as well as for intelligent transportation services. But due to wireless communication of vehicles and high mobility it has certain security issues which cost the safety and security of people on the road. One of the major security concerns is the Sybil attack in which the attacker creates dummy identities to gain high influence in the network that causes delay in some services and fake voting in the network to misguide others. The early detection of this attack can prevent people from being misguided by the attacker and save them from getting into any kind of trap. In this research paper, Sybil attack is detected by first applying the Poisson distribution algorithm to predict the traffic on the road and in the second approach, analysis of the network performance for packet delivery ratio (PDR) is performed in malign and benign environment. The simulation result shows that PDR decreases in presence of fake vehicles in the network. Our approach is simple and effective as it does not require high computational overhead and also does not violate the privacy issues of people in the network.</span>


Author(s):  
A. Alhassan ◽  
W. A. Agyare ◽  
C. Y. Asante

Sediment delivery from the Tono Reservoir watershed in the Upper East Region of Ghana is of major concern, necessitating the need to estimate the rate of siltation of the reservoir. This study determined the current volume of silt in the reservoir, mapped landcover changes using Landsat images and employed Water Erosion Prediction Project (WEPP) model, to simulate hydrology and sediment dynamics for three landuse/landcover scenarios. The Geo-spatial interface for WEPP (GeoWEPP) was used to characterize upland overland flow elements based on their landuse/landcover, soil, and slope profiles. Using characteristics obtained from GeoWEPP as inputs for the WEPP model runoff fluxes, soil loss rates, and sediment delivery ratio (SDR) for three environmental scenarios: landuse/landcover with agricultural lands under fallow tilled management (Scenario 1), landuse/landcover with agricultural lands under corn, soybean no till management (Scenario 2), landuse/landcover with non-agricultural lands under shrub-perennial (Scenario 3) were estimated. Over the simulated 29-year period; runoff depth, soil loss rate and SDR were estimated to be 118.4 mm, 22.8 t/ha, and 0.68 for Scenario 1; 94.6 mm, 2.8 t/ha, and 0.31 for Scenario 2; and 57.7 mm, 0.6 t/ha, and 0.92 for Scenario 3. Shrubland had decreased by 8 %, bareland area had increased by 9.1 %, and the reservoir area had also decreased by 3.7 %. The study indicates landuse/landcover change impacts significantly on land degradation and hydrology of the Tono reservoir and subsequently accounts for the reduction in reservoir capacity by about 1.74 % on annual basis observed through the bathymetric survey.


2019 ◽  
Vol 7 (2) ◽  
pp. 70-84
Author(s):  
Bayu Oktasandi ◽  
Endang Setyawati Hisyam ◽  
Indra Gunawan

DAS Pompong merupakan salah satu DAS yang termasuk dalam klasifikasi DAS yang dipulihkan di Provinsi Kepulauan Bangka Belitung dengan luas 7.701,192 Ha. Kerusakan DAS Pompong diakibatkan oleh perubahan tataguna lahan serta kurangnya kesadaran masyarakat terhadap pelestarian DAS serta aktifitas pertanian dan penambangan yang semakin tak terkendali yang menimbulkan dampak sangat besar terhadap tanah diatasnya, berupa pengikisan (erosi) dan pengendapan (sedimentasi). Penelitian ini bertujuan untuk mengetahui besar erosi dan hasil sedimentasi serta memberikan rekomendasi upaya konservasi lahan pada DAS Pompong. Pada penelitian ini menggunakan Metode USLE (Universal Soil Loss Equation) untuk menghitung besarnya erosi yang terjadi, dan Metode SDR (Sediment Delivery Ratio) untuk menghitung besarnya sedimentasi. Berdasarkan hasil analisis yang dilakukan diperoleh besarnya erosi total pada DAS Pompong sebesar 260,038 ton/ha/thn atau 2.002.603,816 ton/thn, dan jumlah sedimentasi sebesar 278.361,930 ton/thn. Hasil analisis menunjukkan bahwa besar erosi yang terjadi pada DAS Pompong masuk klasifikasi bahaya erosi  Kelas IV (Berat). Arahan konservasi lahan yang dapat direkomendasikan adalah dengan melakukan tidakan konservasi tanah secara vegetatif dan mekanik.


2010 ◽  
Vol 2 (2) ◽  
pp. 275-306 ◽  
Author(s):  
E. V. Taguas ◽  
P. Cuadrado ◽  
J. L. Ayuso ◽  
Y. Yuan ◽  
R. Pérez

Abstract. Soil loss is commonly estimated using the Revised Universal Soil Loss Equation (RUSLE). Since RUSLE is an empirically based soil-loss model derived from surveys on plots, the high spatial and temporal variability of erosion in Mediterranean environments and scale effects mean that it is necessary to evaluate the model in other spatial units such as the microcatchment. In this study, a series of topographic and soil surveys was carried out on a microcatchment of 6.7 ha in a mountainous area under no-tillage farming with bare soil in order to examine spatial and temporal results produced by RUSLE. GPS measurements of the microrelief height differences were used in a control area in the microcatchment to compare observed erosion and deposition with RUSLE predictions. Erosion points located in certain areas correlate very closely with RUSLE predictions, while the distribution of deposition points showed no correlations with RUSLE predictions. Secondly, a time series of daily rainfall data was used to calculate annual erosivity values, which were fitted to an appropriate distribution function. It was determined that the rainfall distribution best fitted the Pearson type III distribution function. Next, efforts were made to quantify the long term erosion and to check the suitability of the land-use and management under different thresholds of tolerance. It was found that values of erosivity in the study area with a return period of 10 years generate a mean annual erosion of 5 t ha−1 yr−1. On the study scale, RUSLE allowed us to locate the most erosive areas and to combine the suitability of the soil land-use and the management with the frequency of the annual erosivity. In addition, an annual sediment delivery ratio of approximately 47% was estimated for the period 2005–2006.


RBRH ◽  
2018 ◽  
Vol 23 (0) ◽  
Author(s):  
Carina Barbosa Colman ◽  
Karina Mendes Pinheiro Garcia ◽  
Rodrigo Bahia Pereira ◽  
Enio Arriero Shinma ◽  
Fernanda Ely Lima ◽  
...  

ABSTRACT Several Sediment Delivery Ratio (SDR) models have been used to estimate Sediment Yield (SY), mainly in data-scarce and ungauged basins, such as in many regions of Brazil. However, it is difficult to choose the most suitable SDR model, mainly because of the lack of investigations of this approach using observed data. Here, we investigated the performance of five widely used SDR models (SDREST) to estimate sediment yield values (SYEST ) based on observed data in a tropical watershed. We used observed sediment yield values (SY OBS) during September 2011 to July 2017 in three sub-basins of the Guariroba Basin, Midwestern Brazil. To estimate the average annual soil loss, we used the Revised Universal Soil Loss Equation. The SDROBS and SYOBS ranged from 5.56 to 10.54% and 940.76 to 5,400.32 t yr-1, respectively. The Williams and Berndt (1972) method presented the best performance, with a percent bias ranging from -2.34 to 3.30% in SRD estimation. Therefore, this model provided suitable SDR and SY estimates, and may be useful to estimate SY in other tropical data-scarce and ungauged basins.


2019 ◽  
Vol 11 (7) ◽  
pp. 1840 ◽  
Author(s):  
Valter Marques ◽  
Marcos Ceddia ◽  
Mauro Antunes ◽  
Daniel Carvalho ◽  
Jamil Anache ◽  
...  

The use of the Universal Soil Loss Equation (USLE) and the Sediment Delivery Ratio (SDR) facilitates sediment yield (SY) estimates in watersheds. However, the soil loss predictions are frequently unrealistic because of the methods used to estimate the USLE’s factors. Here, we evaluated the performance of methods to estimate the soil erodibility (K-factor) and the influence of its estimation in the SY predictions. K-factor values were obtained from three widely used equations and using a portable rainfall simulator. These values were used to compute annual average soil loss and SY in a tropical watershed. We compared SY estimates with a 15-month observed sediment discharge dataset sampled in the catchment outlet. The most reliable method for the K-factor estimating was the USLE nomograph. Furthermore, our results indicate that the use of a portable rainfall simulator to estimate the K-factor tends to underestimate soil loss and sediment delivery.


Sign in / Sign up

Export Citation Format

Share Document