Fariba Esmaeili; Mehdi Vatakhah; Vahid Moosavi
Abstract
The current study evaluates the effectiveness of Clark's Instantaneous Unit Hydrograph (IUH) model from the accuracy of different Digital Elevation Models (DEMs) including TOPO, ALOS PALSAR, ASTER, SRTM and GTOPO in the Amameh watershed. For this purpose, at first, 34 rainfall-runoff events were selected. ...
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The current study evaluates the effectiveness of Clark's Instantaneous Unit Hydrograph (IUH) model from the accuracy of different Digital Elevation Models (DEMs) including TOPO, ALOS PALSAR, ASTER, SRTM and GTOPO in the Amameh watershed. For this purpose, at first, 34 rainfall-runoff events were selected. Also, the drainage network, the length and slope of the main river in each of the five DEMs were calculated using Arc GIS software. Then, the 30-minute isochrone map of the watershed was extracted using the spatial distribution of travel time method. Finally, the dimensions of Clark's IUH were estimated for each rainfall-runoff event and DEM. The results showed that with the decrease in the length of the main river following the decrease in DEM spatial resolution, the number of isochrone has been decreased, so that TOPO DEM has estimated the largest number of isochrone with the largest estimate of the length of the main river. The average percentage of the Relative Error (RE) of the runoff volume was estimated as 22.92, 26.68, 27.7, 32.15 and 35.66% respectively for the aforementioned DEMs. Regarding peak flow estimation, there is a significant difference between the average RE values in different DEMs. So that the lowest average value of the RE is related to TOPO DEM with a value of 31.7%. On the other hand, the Root Mean Square Error (RMSE) values also show that TOPO DEM has the lowest RMSE value (3.39 m3) compared to other DEMs. In general, it can be said that the use of TOPO DEM in Clark's IUH model will provide acceptable results.
maryam etehadi abari; a a; a a; meghdad jur gholami
Abstract
Land cover is also important factor for protecting the soil against erosion. A fully forested watershed experiences relatively little surface erosion, but timber harvest alters the canopy cover, exposing the soil to water and wind. Forests provide the maximum amount of soil protection. Reduction of vegetative ...
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Land cover is also important factor for protecting the soil against erosion. A fully forested watershed experiences relatively little surface erosion, but timber harvest alters the canopy cover, exposing the soil to water and wind. Forests provide the maximum amount of soil protection. Reduction of vegetative cover by forest harvesting generally increases the average surface runoff volume and sediment While, the hydrologic response of forest harvesting has been rarely considered. Towards this attempt, the present study has been conducted to investigate the effect of vegetation cover on hydrological components in plot scale (2m*1m) with four replicates in tow slope scale (0-20%, 20-40%) in Kheyrud Forest of Iran during December 2014 until December 2015. The rain depth was measured by using a rain gauge installed in the study area. The runoff volume and sediment yield were also measured through field data collection and lab analyses by weighting and decantation methods. The results of the study showed significant effects of vegetation cover (P ≤0.01) on runoff volume and sediment yield. Natural forest without harvesting, forest with selective harvesting treatments exhibited the lowest amounts of runoff and sediments, with averages of 372.31, 878.96 cc, and 0.08, 0.17 gr m-2 respectively, in comparison to other treatments. Linear regression among mentioned parameters (precipitation, runoff, and sediment) were determined. The results show that there were significant correlation and linear regression among precipitation, runoff and sediment.
Fatemeh Einloo; Ali Salajegheh; Arash Malekian; Mohsen Ahadnejad
Abstract
Urbanization has led to development the impervious surfaces and subsequently changes in urban hydrology. The aim of this study is investigate the effect of land use change and urbanization on the changes of runoff peak discharge in Zanjan City Watershed, Iran. In order to, Landsat Thematic Mapper (TM) ...
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Urbanization has led to development the impervious surfaces and subsequently changes in urban hydrology. The aim of this study is investigate the effect of land use change and urbanization on the changes of runoff peak discharge in Zanjan City Watershed, Iran. In order to, Landsat Thematic Mapper (TM) images and Aerial photos of 1956, 2000 and 2012 has been processed by using IDRISI Selva and Geographic Information System software and land use maps prepared in six land use class and the trend of land use changes and urbanization determined. To analysis the hydraulic and hydrology behavior of three periods of land use changes and urbanization on the changes of runoff peak discharge, Stormwater Management Model (SWMM) was used. After the SWMM model calibration based on observation rainfall-runoff events, the results of model calibration and verification, confirmed the accuracy of the model simulation. The results of land use change and urbanization trend of Zanjan City Watershed show that urban areas in 2012 compared to 2000 and 1956, respectively, has increase 22.59 and 923.88 percent and in 2000 compared to 1956 has been increased 543.06 percent. The results of SWMM model show that land use change and urban development has led to increase the runoff peak discharge, so that the average change in runoff peak discharge show that it increase in 2012 compared to 1956 and 2000, respectively, 96.85 and 475.52 percent and in 2000 compared to 1956, 194.288 percent increase in average of runoff peak discharge is observed.
parisa farzi; maryam azarakhshi; ali rasoulzadeh; mehdi bashiri
Abstract
Characteristics of stones forming the earth's surface contribute significantly to environmental changes such as soil erosion and movements of soil particles. This study seeks to investigate the main and reciprocal effects of geological units and slope gradient on runoff and sediment production in Senobar ...
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Characteristics of stones forming the earth's surface contribute significantly to environmental changes such as soil erosion and movements of soil particles. This study seeks to investigate the main and reciprocal effects of geological units and slope gradient on runoff and sediment production in Senobar watershed using rainfall simulator. To this aim, the geological map was created in Arc GIS 10 software and three dominant units i.e. green tuff, sandstone, marl (Et), Orbitolina Limestone (Kl) and Conglomerate, Sand stone (Ngcs) were identified. Besides, to study the effect of slope gradient, the slope map was provided in three classes: 0-10, 10-30 and more than 30%. Then, the rainfall intensity equal to 0.9 mm min-1 (10- years return period) was created by rainfall simulator. Analysis of variance showed significant differences between geological units for runoff, sediment yield and sediment concentration at 5% significant level. It was found out that there is significant difference between different slope gradients in runoff and sediment production; however, there was no significant difference regarding sediment concentration. The results of interaction between geological units and slope gradient for runoff volume was significant at the 95% level of confidence but regarding sediment yield and sediment concentration interaction effects were not significant. Generally, it was found that the type of geological units and slope of the study area impacted on soil erosion process. Also, the impressibility of runoff variable was more than that of the sediment.
yahya Parvizi; mohammad gheitury; Mosieb Heshmati
Abstract
The WEPP physically model is able to dynamically simulate runoff and soil erosion using physical concepts of erosion and hydraulic of overland flow science considering plant growth, residue decomposition, winter process. Determination of the capability of this model in runoff and erosion estimation in ...
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The WEPP physically model is able to dynamically simulate runoff and soil erosion using physical concepts of erosion and hydraulic of overland flow science considering plant growth, residue decomposition, winter process. Determination of the capability of this model in runoff and erosion estimation in different range type with investigation the effects of management were the main objectives of this research. This research was conducted in the Kabode placed across the Gharasoo watershed by installing erosion plot with dimension of 10×3 meter and three replications in three range types at the slopes of 25, 35 and 45%. Climate data including rainfall and air temperature was recorded in the site and additional data including wind velocity and direction, solar radiation and dew point temperature was prepared from Kermanshah synoptic climate station. Event based erosion and runoff was simulated in each plot by the v2008.9 version of the model. Results from model assessment for prediction of runoff indicated that the maximum model accuracy was in 45% slope. Also, mode relative error in runoff in 25 and 35% slope was about 0.61 liter. Overall, model performance in runoff estimation was sought in all three slopes, so that Nash-Sutcliff index was 0.96 to 0.73. Minimum and maximum estimation error in erosion prediction was occurred in 35 and 45% slope, respectively. Model prediction results indicated under-estimation in all the slopes. Negative amounts of Nash-Sutcliff index indicated confirms the low efficiency model especially in conditions prevailing in two slopes of 25 and 35%.
Ali Golkarian; Davoud Davoudi Moghaddam; Seyed Amir Naghibi; Masoud Eshghizadeh
Abstract
Soil erosion is undoubtedly one of the most important problems in natural areas and has a devastating impact on grassland ecosystems. The present study was conducted to assess the ability of Rangeland Hydrology and Erosion Model for estimating sediment yield on rangeland’s hill slopes in dry regions ...
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Soil erosion is undoubtedly one of the most important problems in natural areas and has a devastating impact on grassland ecosystems. The present study was conducted to assess the ability of Rangeland Hydrology and Erosion Model for estimating sediment yield on rangeland’s hill slopes in dry regions at Shahid Noori paired watershed of Kakhk. RHEM is a mathematical, distribution and physical model that is capable to simulate hydrological and erosional processes with climatic data and hill slope’s characteristics. Measuring of sediment yield performed on 18 erosion plots in both disturbed and undisturbed rangeland conditions. In order to implement the model, the parameters of climate, soil texture, slope length, slope steepness, canopy cover and ground cover were measured and entered into the model to estimate amount of runoff and sediment yield in each year. The analysis showed no significant difference between observed and estimated values at 5% level in both all erosion plots and the average of measured values of all three different aspects. The results indicate that the model is capable to determine the quantity effects of rangeland conservation practices in hydrological and soil erosion processes. Overall, the present study suggested good potential for application of the model in the same rangelands of dry regions.
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.
S. H. Hosseini; S. Feiznia; H. R. Peyrovan; Gh. R. Zehtabian
Volume 62, Issue 2 , October 2009, , Pages 215-228
Abstract
In Iran, fine grained formations (Neogene's units) are very susceptible to erosion. Also, they are the units producing runoff and causing soil loss in watersheds. The objectives of this study is to assess the effect of physical - chemical and mechanical properties of these formations on sediment and ...
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In Iran, fine grained formations (Neogene's units) are very susceptible to erosion. Also, they are the units producing runoff and causing soil loss in watersheds. The objectives of this study is to assess the effect of physical - chemical and mechanical properties of these formations on sediment and runoff rates at different rainfall intensities, based on using field simulator in Taleghan Basin. For this purpose, Neogene's units were separated into five sub-units including Halite siltstone (NgSiH), Siltstone (NgSi), Mudstone (gy1C), Gypsum mudstone (gy1CG) and Halite clay stone (gy2CH), based on physical and chemical properties. Then, runoff and sediment rates were determined in each sub-units at two different intensities (30 and 60 mm/h) using rainfall simulator. Analysis of variance and Duncan's tests showed that NgSiH sub-unit has produced the highest amount of runoff and sediment rates and then the runoff and sediment rates of other subunits in decreasing order are as follows: NgSi, gy2CH, gy1CG and gy1C are 5% significant level. The trend of induced runoff and sediment rates at different times showed that in NgSiH and NgSi sub-units, runoff amounts were fixed rapidly at second ten minutes. Also, on the other sub-units, runoff amounts were fixed at third ten minutes but sediment yield was increased rapidly at third ten minutes.
N. Noura; A. Kabir
Volume 62, Issue 1 , June 2009, , Pages 153-166
Abstract
In this paper the utilization of GIS for the parameterization of rainfall- runoff process, physically based hydrological model components is described. The hytrogeneity of soil and vegetation in a catchment can be expressed with distribution functions of infiltration and soil storage capacities which ...
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In this paper the utilization of GIS for the parameterization of rainfall- runoff process, physically based hydrological model components is described. The hytrogeneity of soil and vegetation in a catchment can be expressed with distribution functions of infiltration and soil storage capacities which derived efficiently by an overlay of a soil map with land use characteristics. These distribution functions are used to consider the non-linear distribution of actual saturation within a catchment with regard to their impacts on generation of excess rainfall and deep percolation during a storm event. The newly developed infiltration model components and its parametrization by GIS was successfully applied to Kechik catchment. To obtain the nesessory information a simple digital soil map of the catchment was constructed by discretizing the watershed into 1×1 km2 grid cells, and combined with the land use classification to estimate for each cell in a soil texture class the areal distribution function of infiltration model parameters consist of surface soil moisture content, maximum and minimum infiltration capacity rate (Sm, fo, fc), coefficients of model (K1, K2, K3 & K4) and excess rainfall. The results of the model application are shown that the rainfall-effective runoff relationships during storm events in catchment, by application of GIS technology, a new generation of hydrological model for micro and macro scale can be developed under consideration of catchment characteristics and their spatial heterogeneity.
