Ataollah Kademorasoul; Mostafa Chorom
Volume 1, Issue 1 , May 2009, Pages 1-8
Abstract
Water resources management is one of the most important environment challenges in watersheds. Loosing of soil caused by water erosion is one of dominant geographic processes over the most lands of the world. Nowadays, the feasibility of using mathematics models and advancement software technology has ...
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Water resources management is one of the most important environment challenges in watersheds. Loosing of soil caused by water erosion is one of dominant geographic processes over the most lands of the world. Nowadays, the feasibility of using mathematics models and advancement software technology has made available the quick recognition of erosion and sedimentation processes. In this study, the model of WEPP (version 2006) was provided for simulation and forecast of erosion and sedimentation in the study watershed. The WEEP model is a deterministic model with distributed parameters. In this research, watershed of Imamzadeh Abdollah of Baghmalek which lies in north-east of Khuzestan province is studied. Creation of a climate file is made available as an input file using the model of CLIGN and software of BPCDG as well as preparation of soil, basin management file using Excel and EPIC models. All the parcels of basin were defined for the model and executed using the aerial photos, drainage map, hypsometric map and software of Arc View (version, 3.3). Outputs of the model in the erosion section indicated average soil erosion which was some 22.54 tonha-1. Also, the sediment load was about 3468.2 tons, which indicated a difference of 9 percent in comparison with measured rates. Meanwhile, outputs of the model have well provided the feasibility of distinguishing sensitive hillsides to erosion. Based on outputs and ruling management on the hillsides, the protective recommendations like the proper ways for planting and gabion covering, building traces or groins in course of taking the best management practices were accomplished.
Ali Abdi Nam; Mohammad Mahdavi
Volume 1, Issue 1 , May 2009, Pages 9-20
Abstract
Existing coarse materials produced during surface erosion in the marl watershed basins in tributary beds and impermeable subsurface layers (marl layers) lead to produce a subsurface flow. This subsurface flow can be used in order to develop vegetation cover in order to make the biological stabilization ...
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Existing coarse materials produced during surface erosion in the marl watershed basins in tributary beds and impermeable subsurface layers (marl layers) lead to produce a subsurface flow. This subsurface flow can be used in order to develop vegetation cover in order to make the biological stabilization of tributary beds. This method is very useful in the watersheds basins in which were performed the watershed practices such as Gabion dams and sediment ponds. This paper was the result of the research plan, which was considered as development of vegetation cover to biologically stabilize the tributary beds in Sardehat village areas as a split plot factorial statistical design. The three kinds of trees including: Almond, Elaeagnus, and Acacia as the main treatments, and the mixed of soil with manure and clay, and natural soil as the sub-treatments in three replications were studied in the selected area. During the performance of this study variables like stump diameter, height growth, and canopy cover were measured. Final results showed that considering the planting pattern Almond, Acacia and Elaegnus, and without considering the planting pattern Elaeagnus, Acacia, and Almond were preferred respectively in order to stabilize biologically the marl tributary beds.
Mohammad Hemmati; Davood Nikkami; Hassan Ahmadi; Gholamreza Zehtabian; Mohammad Jafari
Volume 1, Issue 1 , May 2009, Pages 21-31
Abstract
Soil is one of the four elements of life and one of the most important agricultural and rangeland production factors. Soil erosion has impact on fertility of upstream lands and indirectly causes downstream damages. On a global scale, more than 50% of rangelands and about 80% of farmlands are significantly ...
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Soil is one of the four elements of life and one of the most important agricultural and rangeland production factors. Soil erosion has impact on fertility of upstream lands and indirectly causes downstream damages. On a global scale, more than 50% of rangelands and about 80% of farmlands are significantly suffering from soil erosion and sedimentation phenomenon. Despite of agricultural benefits of rainwater, its erosive energy in the primary stages, detaches soil particles and creates surface runoff which has the most severe impacts on soil erosion. The effective energy in this shape of erosion is called rainfall erosivity, which is rainfall erosion potential and depends on rainfall physical characteristics. Some different indices are developed for quantification of rainfall erosivity. Some indices emphasise on the amount of rainfall or rain intensity. Worldwide investigations show that applying a certain index, like EI60 in USLE equation has not sufficient credit and according to climatic condition the best rainfall erosivity index should be determined. In this research, after establishing 21 erosion plots in Kaboudeh Oliya village, Kermanshah city, on two land use types of dry farming of 6, 12, 16 and 17 percent slopes and rangelands on 25, 35 and 45 percent slopes with three repetitions, 15 rainfall events which produced surface runoff were monitored by a recording rain gauge and the amount of surface runoff and sediment were measured. According to the literature, 45 rainfall erosivity indices were chosen to be compared. For facilitating and increasing accuracy of calculations on rainfall erosivity indices, a computer program was developed to analyze and extract necessary factors from each storm. The result showed that in the study area, EI60 is the best rainfall erosivity index and has maximum correlation coefficient of 0.721 with soil loss.
Bahram Saghafian; Saman Mohammadi; Baghe Ghermezchshme
Volume 1, Issue 1 , May 2009, Pages 32-45
Abstract
Calculating low flow characteristics is very important for planning of water diversions; providing water for hydropower, water quality threshold in streams, water supply for cities and industries and estimate of sewerage discharge threshold. The objective of this research is analyzing low flow with different ...
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Calculating low flow characteristics is very important for planning of water diversions; providing water for hydropower, water quality threshold in streams, water supply for cities and industries and estimate of sewerage discharge threshold. The objective of this research is analyzing low flow with different duration and return periods and extracting low flow regional models for locations without hydrometric station. This research was carried out in Gilan province where 35 hydrometric stations with long-term and reliable daily discharge data were selected. Low flows of durations 10, 30, 60, 90 and 180 days were estimated. Using frequency analysis, several statistical distributions were examined and log Parson Type 3 was found the best distribution for flow duration over 60 days and log normal best fitted flow durations shorter than 60 days. Then low flows of different return periods including 2, 5, 10, 25, 50, 100 and 200 year were calculated. Independent factors were identified using factor analysis that included basin area, mean annual rainfall, slope, average elevation, and drainage density. Cluster analysis divided the basins in two homogeneous regions. In each homogeneous region, multivariate regression through step-by-step method determined basin area, mean annual rainfall and slope as independent influential parameters in low flow regional models. Regional models were extracted for low flow with various durations and return periods.
Seyed Masoud Soleimanpour; Majid Soufi; Hassan Ahmadi
Volume 1, Issue 1 , May 2009, Pages 46-52
Abstract
Fars province has experienced gully erosion in six climate zones based on deMartonne classification method. After selecting one region from each climate zone, 15 active and representative gullies were investigated using morphometric characteristics and watershed area, slope gradient above gully heads, ...
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Fars province has experienced gully erosion in six climate zones based on deMartonne classification method. After selecting one region from each climate zone, 15 active and representative gullies were investigated using morphometric characteristics and watershed area, slope gradient above gully heads, linear advancement, form factor, particle size analysis, vegetation cover, gravel content and bare grounds were measured and sediment production was calculated. Effective factors on sediment production due to gully erosion were determined using Stepwise method provided in the SPSS software package. The results of this research revealed that four factors including slope gradient, maximum 24 hours rainfall, sand, and form factor had significant impact on sediment production with 99 percent of confidence. Slope gradient above the gully head was the most important factor on the sediment production. Slope gradient and form factor had positive relationship and maximum 24 hours rainfall and sand had negative relationship with gully development. The most important impact of slope gradient on the sediment production implies the velocity of surface runoff concentrated above gully heads. Alternative controls to decrease slope gradient would be effective on the reduction of gully development and sediment production.
Akram Mirzaei; Ziaoddin Shoaei; Nader Jalali; Alireza Eslami
Volume 1, Issue 1 , May 2009, Pages 53-60
Abstract
In this research, Hydro-physical model was used for estimating of potential sediment yield in sub- basin of Karaj watershed. In this model limited field survey is required and five main factors as vegetation cover, rainfall, erosion ability, topography and area were used. The results of comparison made ...
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In this research, Hydro-physical model was used for estimating of potential sediment yield in sub- basin of Karaj watershed. In this model limited field survey is required and five main factors as vegetation cover, rainfall, erosion ability, topography and area were used. The results of comparison made between the observed sediment yields in the gauged station of Siera with the estimation made by the model were highly correlated. Factor analysis by SPSS software was used for determining the role of those factors on erosion and sediment yield. The results showed those factors covered about 92% of sediment changing in sub-basins.
Alireza Eslami; Majid Montaseri; Reza Sokooti Oskoei
Volume 1, Issue 1 , May 2009, Pages 61-69
Abstract
Due to flood damage of most watersheds in the country, the necessity of forecasting systems, zoning and flooding are more consideration. Now with the increasing availability of digital information and computer analysis, geographic information systems (GIS), play important role in the hydrological and ...
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Due to flood damage of most watersheds in the country, the necessity of forecasting systems, zoning and flooding are more consideration. Now with the increasing availability of digital information and computer analysis, geographic information systems (GIS), play important role in the hydrological and hydraulic modeling. WMS Software, including new software that zoning flood explored. In this research a part of the Glaz River that passes the Oshnavieh city and has the potential to high flooding potential and damage of the infrastructure the city has selected. The main objective of this research is flood zonation in the region. In order to estimate the flood, according to historical data available and hydrometric stations and the maximum instantaneous flood, normal statistical distribution of, log normal two parametric, log normal three parametric, log Pearson type III and Gamble used. To determine the distribution of superior Test PPCC was used. For zoning depth of flooding, after calculation of the hydraulic profile of the water surface by the model (HEC-RAS) and Then the water surface profile model (HEC-RAS) for the return periods of 25 and 50 and 100 per year was calculated. Finally, flood hazard zonation maps defining the risk function, in the city was prepared. Results showed that the river within the Oshnavieh city limits Glaz River due to improper management, and more has become a channel and the ability to cross the river passing through floods with return periods of 25 years and more. Similarly flood damages with high return periods will be irreparable in the city. According to these maps, high-risk positions and can be identified and prioritized in urban planning.
