Hossein Hosseini Poor; Jafar Ghaioomeyan; Ahmad Reza Ghasemi; Saeid Choopani
Volume 1, Issue 4 , February 2010, Pages 212-226
Abstract
Hydrologists have paid attention to identify the influential factors on underground water quality to examine the source of salts. In this research, hydrochemistry and the source of underground water salts in Sarchahan plain were examined using ion ratios and the difference between densities of ions of ...
Read More
Hydrologists have paid attention to identify the influential factors on underground water quality to examine the source of salts. In this research, hydrochemistry and the source of underground water salts in Sarchahan plain were examined using ion ratios and the difference between densities of ions of the same source. In a phase in 1998, 49 samples from the aquifer and 13 samples from the surface water of Sarchahan plain were provided. Then some ions with common mineralogy source namely twin ions were identified and the imbalance between them was considered as a sing of subsidiary factors and processes affecting Sarchahan aquifer quality. The examination of the relationship between twin ions with the help of ion differences of CL-Na and So4(ca+Mg) can provide the possibility of identifying the affected region from dissolution of compound such as Manesium in Sarchahan aquifer. Generally, the examination of ion ratios and the difference of twin ions show that the dissolution of Halite and Sulfate salts of alluvium can be the main factor of salinity of underground water in Sarchahan plain. Oppositely, Por Abedin river Causes improvement of Chemical quality of Sarchahan aquifer but Shoor River has no effect on Salinity increase of aquifer due to underground water drainage. Furthermore, natural softening processes and opposite softening affects the quality of this aquifer as well and by extending the salinity toward downstream areas the possibility of occurrence of opposite softening increases. The possibility of Dedolomitization in Sarchahan aquifer is out of question. Additionally, salt domes do not have a clear effect on salinity of underground water too.
Abolghasem Dadrasi; Shahrokh Hakimkhani; Abdolsaleh Ranghavar
Volume 1, Issue 4 , February 2010, Pages 227-239
Abstract
The fact that there are so many erosion models makes it necessary to critically select one of them as all have some limitations. Models are formulations of processes and logics as represented by the modeler. The formulations may be representations of either simple processes or complicated ones as the ...
Read More
The fact that there are so many erosion models makes it necessary to critically select one of them as all have some limitations. Models are formulations of processes and logics as represented by the modeler. The formulations may be representations of either simple processes or complicated ones as the modeler deems necessary to solve a specific problem. These variables must be derived by a procedure of calibration for a specific case. The Soil erosion model of Morgan, Morgan and Finny (1982) from a large list of soil erosion models, have been applied to test the validity of the model in Sanganeh research station, Mashhad, Iran. After a field survey, plots with sheet erosion, were selected and their data was collected. Rainfall, slope and soil data were derived from station archive, vegetation cover and root depths were determined from field observations and some other parameters were tested on site. Soil loss was calculated by using overland flow for each plot after each rainfall and the measured records were compared with model estimations. The results show that in most plots, predictions deviated from the observations and in 28.21% of plots the results seem acceptable. The final result of present research shows that the model performs reasonably well for plots with lower density of vegetation cover (less than 20%), steep area with more than 40 percent, and soil depths of less than 10 centimeter.
Mohammad Shabani
Volume 1, Issue 4 , February 2010, Pages 240-247
Abstract
Estimation of soil erosion and sediment yield in a river is a difficult task and several methods have been suggested for its estimation. One the new methods in river engineering and suspended sediment estimation is application of artificial neural networks which uses the same algorithm of human brain ...
Read More
Estimation of soil erosion and sediment yield in a river is a difficult task and several methods have been suggested for its estimation. One the new methods in river engineering and suspended sediment estimation is application of artificial neural networks which uses the same algorithm of human brain to find out the internal relation between data based on the training process. The objective of current study is to explore the capability of artificial neural networks method for estimation of daily suspended sediment in Kharestan watershed located in the northwest of Fars province, Iran. The study of efficiency is based on the comparison of neural network with regression models. For this purpose, 22 years of water and sediment discharge data of Shoor Kharestan River were considered and tested for outliers. Then the estimation was done based on neural networks and linear regression method (sediment rating curve) and were compared based on RMSE, MAE and R2. The results showed that estimation of neural network is more accurate than that of linear regression (sediment rating curve). The estimations of RMSE, MAE and R2 for neural networks method was 19.27, 12.14 and 0.98 respectively while these values for linear regression were 36.84, 20.75 and 0.74 which showed the lower errors of neural networks method compared with linear regression.
Majid Mohammdi; Hamid Reza Moradi; Sadat Feiznia; Hamid Reza Pourghasemi
Volume 1, Issue 4 , February 2010, Pages 248-258
Abstract
Landside is a natural disaster with great human and economic losses in Iran. In recent year, landslide occurrence due to change of land use and construction of roads, has been on the increasing trend in northern regions of Iran. This phenomenon is more occurring in developing countries due to high rate ...
Read More
Landside is a natural disaster with great human and economic losses in Iran. In recent year, landslide occurrence due to change of land use and construction of roads, has been on the increasing trend in northern regions of Iran. This phenomenon is more occurring in developing countries due to high rate of population growth and natural resources deterioration. There are several methods for landslide hazard zoning and in this research density area and analytical hierarchy process models were utilized. For landslide susceptibility mapping, field study landslides distribution map and effective factors are required. Prioritization of effective factor was carried out using AHP. Our investigation indicates that lithology, distance from road, slope, distance from drainage network, land use, elevation and aspect are the main land slide controlling factor in the area respectively. Evaluation of these models using QS index showed that density area is a better approach for landslide hazard zonation in the region.
Abdosaleh Rangavar; Gholamali Gezanchian; Hassan Angoshtari; Reza Ghafourian
Volume 1, Issue 4 , February 2010, Pages 259-265
Abstract
The deposition of transported materials by flood water on soil surfaces in warm and arid region causes some changes in texture, structure, depth and fertility of the soil. According to the study of flood water spreading effect on physical and chemical characteristics of the soil, the study field of flood ...
Read More
The deposition of transported materials by flood water on soil surfaces in warm and arid region causes some changes in texture, structure, depth and fertility of the soil. According to the study of flood water spreading effect on physical and chemical characteristics of the soil, the study field of flood water spreading of Jajarm in North Khorasan province was chosen. This area has located on alluvial fan with 0.75- 1% slop, 146.3 millimeter mean annual rainfall, arid and extra arid climate. For the period of 4 years (1995-1999), the soil samples were collected from recognizable A and C horizons and the depth of 0-30 centimeter (plow layer) from 7 profiles at three primary strips. The quantity of effective parameters on soil characteristics was determined in laboratory. This process was repeated after three times flood water spreading. Obtained data were analyzed: I) by t-student test to compare different properties of soil before and after flood spreading. II) by split plot procedure with three replicates to compare the whole effects at flood water spreading. The samples variance analysis showed that flood water spreading was effective on sand ratio, clay, organic matter, bicarbonate (p<0.05) and was effective too on Ca, Mg, Cl, Na, SAR and EC (p<0.01). There was a significant difference between the samples before and after spreading of flood water. Comparing the average mean of factors including soil salinity, Ca and Mg on A, C and plow layer before and after flood water spreading showed only different between plowing layers, also results showed that the sand to clay ratio and silt in a horizon were decreased. Flood water spreading had no more effect on the other soil characteristics.
Mehrdad Safaie; Maryam Fattahi Bandpay
Volume 1, Issue 4 , February 2010, Pages 266-274
Abstract
In order to assess the stability of slopes of the proposed sites for the construction of a composting plant, field studies, laboratory experiments, analysis of geological engineering and geotechnical data of the site location were performed. Results of studies indicate the existence ...
Read More
In order to assess the stability of slopes of the proposed sites for the construction of a composting plant, field studies, laboratory experiments, analysis of geological engineering and geotechnical data of the site location were performed. Results of studies indicate the existence of the phenomenon of occurrences of old landslides at the site. After collecting data, and analyzing the factors affecting the recurrence of landslide using both limit equilibrium stability analysis and Slope / w software, Factor of Safety (FOS) and probability of occurrences (FOS<1) in various conditions based on Bishop method were calculated. Based on the results, the lowest FOS values under saturated conditions and dynamic loading of the probability of earthquakes was found to be (pseudo static analysis) equal to 0.676 which shows in this situation slope is unconditionally unstable. Highest FOS in static conditions was equivalent to 1.30 where it is applied to drainage would increase to 1.50. Accordingly, construction of deep drains and drainage wells is suggested to collect groundwater and subsurface flows in order to reduce degree of saturation and increase FOS and stability while providing safety would be economically justified.
Farzad Bayat Movahed; Davood Nikkami; Hassan Shami
Volume 1, Issue 4 , February 2010, Pages 275-279
Abstract
In arid and semi-arid regions, operating the plough on slope direction, specially, in rain falling with more intensity, results in soil loss and erosion. In such areas, undesirable effects can reduce with operating suitable management. For this purpose, the effect of perpendicular plough to slope direction ...
Read More
In arid and semi-arid regions, operating the plough on slope direction, specially, in rain falling with more intensity, results in soil loss and erosion. In such areas, undesirable effects can reduce with operating suitable management. For this purpose, the effect of perpendicular plough to slope direction and application of straw mulch in 1.8 * 22.1 meter erosion plots on three slope classes of 0-12, 12-20, and 20-40 percent with 3 replicates and RCB design in two different years were tested in Sohrain floodwater spreading research station. In the half of plots in 2003, the perpendicular plough to slope direction and in the others, plough on slope direction were operated. In 2005 at first, the plough on slope direction was done in all of the plots and then, straw mulch were used after wheat cultivation in half of plots. During the study period, the amount of soil loss was monitored after any rain fall by the tanks that located at the end of each plot. The results showed that operating of perpendicular plough to slope direction reduced soil loss about 10.1, 11.5, and 10.4 time relate to parallel plough to slope direction. Also, application of straw mulch reduced 36.9, 10.8, and 55.4 time relate to mulch application in three slope classes respectively. These results show that both perpendicular plough to slope direction and straw mulch application can reduce soil loss and thus, increase the infiltration rate and soil fertility.
