Ataolah Kavian; 1 1; 1 1; 1 1; 1 1; 1 1; 1 1
Abstract
Small and portable rainfall simulators are essential tools in study of soil erosion and surface hydrology and it provide to repeat natural rainfall characteristics. In addition to the introduction of this device, calibration tests were performed including nozzles discharge evaluation, uniformity test ...
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Small and portable rainfall simulators are essential tools in study of soil erosion and surface hydrology and it provide to repeat natural rainfall characteristics. In addition to the introduction of this device, calibration tests were performed including nozzles discharge evaluation, uniformity test over the plots and raindrop size distribution. The results of nozzles discharge calibration showed that two nozzles discharge at 20, 40, 60 and 80 KPa pressure are similar and there isn't any significant difference between them. To achieve the optimum uniformity of simulated rainfall over the plot uniformity test was performed with changing nozzle distance (50, 60 and 70 cm) and oscillation of nozzles (30, 45 and 60 degrees) at constant operational pressure of 60 KPa. The results showed that the uniformity coefficient at 2m2 plot obtained from 57% to 61% and rainfall intensity changes from 48 to 101 mm/hr. The results of high velocity photography revealed median diameter of raindrop as 2.4 to 2.6 mm.
Abbas Gholami; Kaka Shahedi; Mahmud Habibneghad; Mahdi Vafakhah; Karim Solymani
Abstract
Present study is aimed at forecasting and comparison of future climate change by using GCM model (General circulation model) under different climate scenarios in Talar watershed of Mazandaran province. Regarding the data of existing stations, to study the climate change phenomenon in Talar watershed, ...
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Present study is aimed at forecasting and comparison of future climate change by using GCM model (General circulation model) under different climate scenarios in Talar watershed of Mazandaran province. Regarding the data of existing stations, to study the climate change phenomenon in Talar watershed, the LARS-WG5 model and 3 climate scenarios i.e. A1B, A2, B1, each in three emission series i.e. 2011-2026, 2046-2061, and 2080-2095, that were extracted from Gharakhayl regional synoptic stations in Quaemshahr, were used and the base year was considered 1992-2007( for a 15- year duration). Since this model is one of the most authentic statistical downscaling methods and its data is produced in three phases of calibration, evaluation and development of meteorological data, it was applied for research in present study. According to the findings, the most precipitaion changes occurred in May and October and the most severe reductive changes occurred in 2080-2095, the result of which warns about seasonal floods in rainy months and drought or water shortage in dry months in the relevant watershed study area. Besides, in future in June, July, August, and September temperature increase will be experienced but in January and February, the minimum simulated tempreture mean will be observed.
Jalal Zandi; Mahmoud Habibnejad Roshan; Karim Solaimani
Abstract
Soil erosion is a serious environmental problem in Vazroud watershed, which is located in the centre of the Mazandaran Province, Iran. Unfortunately, Vazroud watershed like most Iran watersheds don’t have recorded data and erosion and sedimentation gages to research, monitor and model soil erosion ...
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Soil erosion is a serious environmental problem in Vazroud watershed, which is located in the centre of the Mazandaran Province, Iran. Unfortunately, Vazroud watershed like most Iran watersheds don’t have recorded data and erosion and sedimentation gages to research, monitor and model soil erosion at large watershed. In order to assess the soil erosion risk, soil erosion modeling at the watershed scale are urgently needed to be undertaken. This study integrated the Revised Universal Soil Loss Equation (RUSLE) with a Geographic Information System (GIS) to estimate soil loss and identify the risk erosion areas in the Vazroud watershed. Multi-source (map-, space- and ground-based) datasets were used to obtain factors of RUSLE, and an integrated analysis was carried out in raster format of GIS and it was classified into five categories ranging from minimal risk to extreme erosion risk. Extensive field observations verify soil erosion risk map and total accuracy (90%) obtained. The soil erosion map was linked to land use, elevation and slope maps to explore the relationship between soil erosion and environmental factors and identify the areas of soil erosion risk. The slopes between 25 to 45 degree, the altitudes between 1180 to 2180 from sea level and bare lands have the high and extreme erosion risk in this study area. The results allow decision makers to implement management strategies to prioritization area and soil erosion reduction in Vazroud watershed. The integrated approach presented is relatively easy, fast, and straightforward, showing good potential for successful application in other areas.
A Kavian; ALI Azmodeh; K Soleimani; GH Vahabzadeh
Volume 63, Issue 1 , June 2010, , Pages 89-114
Abstract
Globally, soil erosion is one of the most important environmental problems which is threaten soil and water resources. Soil properties are main parameters to affect runoff and soil erosion processes. So, this study was conducted to investigate the effects of some soil properties on runoff and soil erosion ...
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Globally, soil erosion is one of the most important environmental problems which is threaten soil and water resources. Soil properties are main parameters to affect runoff and soil erosion processes. So, this study was conducted to investigate the effects of some soil properties on runoff and soil erosion in the forest lands located in vicinity of Sari city. Rainfall simulator was set in 15 random points in 2 sites to create experimental rainfall. Runoff and sediment yield resulted from each experiment was measured based on field and laboratory investigations. Soil samples from 0-20 cm depth close to the simulation points were collected and analyzed. The results showed that soil initial moisture, percentage of soil organic matter (% SOM), bulk density and sand percent are most effective factors in runoff generation, respectively. Also, the results illustrated that percentage of soil organic matter, soil initial moisture and silt percent affect on soil erosion, respectively. The results of multiple linear models showed that runoff and soil erosion can be predicted based on percentage of soil organic matter, soil initial moisture and percentage of clay with coefficient of determination of 0.638 and 0.752, respectively.