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Soil Erosion Risk Assessment in Nashe Dam Reservoir Using Remote Sensing, GIS and RUSLE Model Techniques in Horro Guduru Wollega Zone, Oromia Region, Ethiopia
Issue:
Volume 4, Issue 1, February 2019
Pages:
1-18
Received:
1 January 2019
Accepted:
14 February 2019
Published:
11 March 2019
Abstract: Soil degradation is wide spread and serious throughout the Ethiopian Highlands. It is also a major watershed problem in many developing countries causing significant loss of soil fertility, loss of productivity and environmental degradation. This research has, therefore, been carried out to evaluate the soil erosion risk and quantify the major land use land cover changes over the past 20 years (1996-2016) in the Nashe watershed. The research integrates the Revised Universal Soil Loss Equation (RUSLE) with a Geographic Information System (GIS) and Remote Sensing (RS) to quantify the potential soil erosion risk and land use land cover changes. Rainfall data, soil data, DEM data and satellite image were used as input data sets to generate RUSLE factor values. Raster calculator was used to interactively calculate potential soil loss and prepare soil erosion risk map. For the land use land cover change calculation two satellite images of two year interval ( Landsat TM 1996 and Landsat 2016) has been utilized. As a result the potential soil erosion risk and land use land cover map of 1996 and 2016 of the study area was generated. The result showed that the potential annual soil loss of the watershed ranges from 0.00 to 243..065ton/ha/yr. and the mean annual soil loss rate is 45.7ton/ha/yr. Concerning the land use land cover change Grass land decline from (8.85%) to (6.85.4%), open forest changes from (47.10%) to (22.75 %) and settlement land changes from (4.42%) to (7.59%). On the contrary farm land changes from (27.18%) to (45.55%), bare lands increase from (5.40%) to (5.55%) and water body changes from (7.06%) to (12.10 %). By the LULC analysis it has been found that the grass land and forest land declined from 1996-2016. On other hand, the rest of the land cover types have increased.
Abstract: Soil degradation is wide spread and serious throughout the Ethiopian Highlands. It is also a major watershed problem in many developing countries causing significant loss of soil fertility, loss of productivity and environmental degradation. This research has, therefore, been carried out to evaluate the soil erosion risk and quantify the major land...
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Reliability of Geotechnical Parameters in the Analysis of Ancient Landslides
Issue:
Volume 4, Issue 1, February 2019
Pages:
19-27
Received:
21 November 2018
Accepted:
26 February 2019
Published:
21 March 2019
Abstract: More than 850 large scale landslides in the two main active seismic zones (Alborz and Zagros) in Iran have been studied over the past nearly four decades. Of these, remedial designs made by the author for major engineering works in the 180 or so landslides encountered in the projects have, to the present, been successful. This work has led me to the conclusion that, regardless of their geotechnical parameters measured on intact samples in the laboratory, the main cause of forming of these landslides has been occurrence of high magnitude recent and historical earthquakes, combined with micro/mega discontinuities existing within the soil/rock masses. In this study, according to the results of geotechnical studies, the stability analysis of ancient landslides in the area of gas transmission lines (IGAT) in Iran, is discussed. Three samples, taken from slip surfaces of ancient landslides of the two main active zones are discussed. The samples were taken from apparently weak soils, but, unexpectedly, they showed good stability strength. The major occurrences of landslides were in the two mentioned active zones (Zagros and Alborz). In the sampling process of the three landslides, samples representative of apparently geotechnically weak rock or poor soil type were the only ones selected for testing and were taken from slip surface/zones with well-defined natural deformation, remolding and slicken siding. Geotechnical and soil shear parameters measured on samples taken from the slip surface showed apparent good results indicating that a landslide should not occur. However this assumption proved to be misleading, for despite these measurements, land sliding did occur. This was especially so in the case of rockslides.
Abstract: More than 850 large scale landslides in the two main active seismic zones (Alborz and Zagros) in Iran have been studied over the past nearly four decades. Of these, remedial designs made by the author for major engineering works in the 180 or so landslides encountered in the projects have, to the present, been successful. This work has led me to th...
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Comparative Study of Consistency Behavior and Shear Strength of Clayey Soils of Rajshahi District, Bangladesh
Ankur Nandy,
Noosrat Rashid,
Md. Ashikuzzaman,
Syed Abdul Mofiz
Issue:
Volume 4, Issue 1, February 2019
Pages:
28-34
Received:
19 February 2019
Accepted:
26 March 2019
Published:
11 May 2019
Abstract: This paper aims at introducing the Fall Cone Test (FCT) to obtain the shear strength of clayey soils and reveals its applicability by comparing the results obtained from that of Unconfined Compression Test (UCT). Furthermore, the liquid and plastic limit obtained from Casagrande method also compared with that obtained from FCT. For these, soils were collected from Godagari, Tanore, and Nauhata from Rajshahi District (RD). At first, Hydrometer analysis was performed in each soil to know the physical properties. Then Atterberg Limit test was carried out by considering Casagrande Method. After that UCT was shown in each land to find the shear strength of the clay soils. Lastly, FCT was conducted to find out the shear strength, LL and PL. FCT shows a lower amount of liquid and plastic limit than the values measured in the Casagrande Method except plastic limit for Tanore for FCT whereas Godagari shows the higher value of shear strength considering FCT. This research can be concluded with further research should be conducted to ensure its accuracy. On the other hand, it can be drawn which soil have more consistency and shear strength considering others.
Abstract: This paper aims at introducing the Fall Cone Test (FCT) to obtain the shear strength of clayey soils and reveals its applicability by comparing the results obtained from that of Unconfined Compression Test (UCT). Furthermore, the liquid and plastic limit obtained from Casagrande method also compared with that obtained from FCT. For these, soils wer...
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Swat Based Soil Erosion Modeling of Nashe, Blue Nile Basin, Ethiopia
Dereje Gizaw Namomsa,
Tamene Adugna
Issue:
Volume 4, Issue 1, February 2019
Pages:
35-41
Received:
29 January 2019
Accepted:
11 March 2019
Published:
27 May 2019
Abstract: In worldwide, soil erosion effect on the water storage structures is significant for proper management of water resource and its use. The effect of soil erosion, improper management system and lack of suitable soil conservation measures have played important role for food production, and global warming problem. For modeling of soil erosion in Nashe watershed a geographical information system (GIS) version-based SWAT has been used to evaluate sensitivities and prone soil erosion area. To predict spatial & temporal soil erosion distribution stream flow calibration and validation of the soil and water assessment tool were applied using the compatible version of SWATCUP against stream flow for Nashe watershed were taken to estimate model performance on monthly basis. Soil erosion involves all parameters are important for feasible conservation of natural, agricultural and built-up environments. To model the soil erosion the analysis was done on over land runoff, soil loss and sediment yield. The model performance(SWAT) has been evaluated by using statistical parameters of (R2) and (ENS) 0.79&0.75 respectively for calibration and validation results 0.71 and 0.65 for R2 and ENS respectively, the results indicate that the best model to forecast hydrological process of the basin or catchment.
Abstract: In worldwide, soil erosion effect on the water storage structures is significant for proper management of water resource and its use. The effect of soil erosion, improper management system and lack of suitable soil conservation measures have played important role for food production, and global warming problem. For modeling of soil erosion in Nashe...
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