Abolghasem Bagheri; Alireza Nikooie; Farhad Khodadad Kashi; Mohsen Shokatfadaei
Abstract
Although government’s supportive payments to agricultural activities is fulfilled for the purpose of increasing of social benefits, but it will cause some economic and environmental externalities. So that today the development of agricultural activities lead to decline in groundwater level in most ...
Read More
Although government’s supportive payments to agricultural activities is fulfilled for the purpose of increasing of social benefits, but it will cause some economic and environmental externalities. So that today the development of agricultural activities lead to decline in groundwater level in most of these aquifers. This topic has increased the interest of related governmental sectors in developing and application of water conserving policies in aquifers. The objective of this study was to analyze and evaluate the outcomes of energy subsidies decline as specified water conservation policy alternatives on groundwater consumption and cropping patterns on the aquifer of Mahyar plain in Isfahan province, using non-linear optimization model. A Positive Mathematical Programming (PMP) model was developed and calibrated to land and water usage data for a base period of 2004-2005. The PMP approach produces a constrained non-linear optimization model that mimics the land and water allocation decision facing producers each year. The choice variables in the model are the acreages planted to each of the major crops and the water use by crop. The result showed that water application per acre decreased significantly under the high price scenarios, during the early years of the simulated period. This suggests that high energy prices have a significant effect on the rate of increment of the Mahyar aquifer stability.
Hossein Kheirfam; Seyed Hamidreza Sadeghi
Abstract
Measurment of river sediment transport in different temporal and hydrological conditions is important in hydraulics, hydrology and soil and water conservation science and engineering. Bed load is rarely measured because of difficulties and low efficiency of conventional samplers. The present study was ...
Read More
Measurment of river sediment transport in different temporal and hydrological conditions is important in hydraulics, hydrology and soil and water conservation science and engineering. Bed load is rarely measured because of difficulties and low efficiency of conventional samplers. The present study was carried out in order to design a bed load sampler based on the conditions prevailing in the mountainous rivers flumes. The sampler with dimensions of 120 cm length, 60 cm height and 60 cm width was designed and subsequently fabricated. The accuracy of sampler was evaluated through comparing the bed loads estimations made by the designed equipment and those measured by collecting the whole discharged runoff to a 300 liters water tank installed at the outlet flume and with the help of statistical criteria. The t-test, relative erorr (RE) and relative bias (RBIAS) criteria were then used for statistical analyses. The results showed that the mean mesured bed load by water tank and designed sampler were 0.00635 and 0.0064 gl-1, respectively with no siqnificant differece (p<0.0763). In overall, the designed sampler had a high accuracy and efficiency in river bed load measurement with relative erorr and relative bias of about 8.5% and 0.107, respectively.
Seid Saeid Ghiasi; Faezeh Rajabzadeh; Somayye Najirda; Sadat Feiznia; Aliakbar Nazari Samani
Abstract
Shallow landslide susceptibility assessment by using appropriate methods and determine of effective factors in reduce of its hazards is so effective. The aim of this study is to determine the effective factors on shallow landslide occurrence and investigation of Statistical Index Method (SIM) efficiency ...
Read More
Shallow landslide susceptibility assessment by using appropriate methods and determine of effective factors in reduce of its hazards is so effective. The aim of this study is to determine the effective factors on shallow landslide occurrence and investigation of Statistical Index Method (SIM) efficiency for landslide susceptibility mapping. So, determination of each class of factors’ weights was accomplished by using SIM. That was done by adoption of inventory landslide map and ten initial factors including: slope, aspect, rainfall, altitude, drainage density, plan curvature, land use, geology, geomorphological faces and rock unit sensitivity to erosion in ArcGIS 9.3. Then model efficiency was evaluated by using percentage of area under ROC curve and the results showed high accuracy (0.95) of SIM. Principal Component Analysis (PCA) was used for determination of primary causative factors of shallow landslide occurrence. Results showed that five variables of rainfall, slope, aspect, rock unit sensitivity to erosion and plain curvature are the most effective factors on landslide occurrence, respectively.
Ahmad Fatehi marj; Farzad Hosseini Hosseinabadi
Abstract
Drought is a phenomenon which is not preventable, but its outcomes could be mitigated by a holistic and scientific managerial vision. In order to approach to this goal, some practical frameworks is needed for different parts of the country, in respect to their climates. This paper is introducing development ...
Read More
Drought is a phenomenon which is not preventable, but its outcomes could be mitigated by a holistic and scientific managerial vision. In order to approach to this goal, some practical frameworks is needed for different parts of the country, in respect to their climates. This paper is introducing development of the first agricultural drought risk management plan by experts of Agricultural Drought Management (ADM) for a pilot area. This project lasted for three years from 2009 to 2011. In this project some educational workshops and specialized meetings were held and have helped the plan to be more succeeded. At first, all needed climatic and agricultural information were collected and then a program for agricultural risk assessment in the region were selected. The drought plan was developed with a nine steps proposed method, in respect to advice of experts. Considering the average income of 41 billion Riyals from agricultural and animal husbandry activities, damages costs of poor to very severe drought varied from 3.450 to 10.350 billion Rials. Agricultural drought risk management plan can reduce drought damages from 30 to 47 percent, depended on drought intensity.
Parviz Abdinezhad; Parviz Moradi
Abstract
In this research, some effective factors on stability and sedimentation of woven-wire check dams within marly areas were studied. For this pupose, data of 380 light-weight metallic dams were collected during field study and Pearson correlation coefficients and regression analysis of variance of SPSS ...
Read More
In this research, some effective factors on stability and sedimentation of woven-wire check dams within marly areas were studied. For this pupose, data of 380 light-weight metallic dams were collected during field study and Pearson correlation coefficients and regression analysis of variance of SPSS statistical software were used in analysis procedures. The results showed that there were significant relation between width, length and volume of dams with stability at confidence level of 99% and according to correlation coefficients, width of dam showed a higher correlation in comparison to two other variables, but length of dam holds the second place. On this respect, dimensions of dams were among the effective factors on their stability. The stability of dams also represents an inversely linear relationship (correlation coefficient of 0.24) with volume of sediment accumulated behind them. The link between length and width to volume of accumulated sediment favors a direct linear relationship, and based on their correlation coefficients (0.69 and 0.23 respectively) the impact of length of dams is greater. In general, to reach a desired stability of these dams, their dimension must be in accordance with standards and must be determined using respective equations.
Hamidreza Peyrowan; Mohsen Shariat Jafari; Dadvar Lotfollahzadeh
Abstract
The study performed to determine the relationship between landslide and increasing sediment load in Latian dam watershed. Sediment yield of six sub-basins were estimated with by two methods of MPSIAC and hydrometric station . More than 150 landslides were mapped by ETM+ and Google Earth image processing. ...
Read More
The study performed to determine the relationship between landslide and increasing sediment load in Latian dam watershed. Sediment yield of six sub-basins were estimated with by two methods of MPSIAC and hydrometric station . More than 150 landslides were mapped by ETM+ and Google Earth image processing. Comparing the observed data with MPSIAC output in Lavasanat and Kond-Afjeh sub-catchments, it became clear that Lavasanat has less sediment yield. But, despite of this subject, observed sediment yield in Lavasanat hydrometric station is about two times in Kond–Afjeh, while the landslides area in Lavasanat and Kond–Afjeh sub-basins are 1.8 and 0.7 percent of the area. Based on the estimated sediment yield of MPSIAC model, the weighted average of specific sediment yield for Kond-Afjeh and Garmabdar sub–basins with landslide area of 0.7 and 2.4 percent are 387.02 and 431.39 m3km-2y-1 respectively, which means that increasing the relative percentage of landslide area from 0.7 to 2.4 percent, specific sediment yield increases by 11.5 percent. Based on data analysis in Roodak hydrometric station in Jajrood basin, average sediment discharge of the river in the first nine months of 1383 before Hajyabad landslide was 6.17 tons per day that increased to an average of 16.9 tons per day at nine months after landslide. This amount is equivalent to 170 percent increasing of sediment load in nine months after mentioned event. The interesting point is that this increasing of sediment yield was in the period of about 30% decrease in water debit . This means that not only increasing sediment yield of the river is not related to the water debit, but also, about 30% reduction of water debit is should reduce sediment yield. So, regarding to the area of 20.45 ha of Hajabad landslide zone, each hectare of landslide area could increase more than 8% of the sediment load in the river.
Zahra Faghfouri; Nasim Arman; Mohammad Faraji; Zohreh Khorsandi
Abstract
Whereas investigation of effective factors in soil erosion and sediment yield, we can`t introduce specific factors basically as a main factors in water erosion. In fact, erosion condition in an area is a result of contract effect of impressive factors collection in erosion. In order to identify the effective ...
Read More
Whereas investigation of effective factors in soil erosion and sediment yield, we can`t introduce specific factors basically as a main factors in water erosion. In fact, erosion condition in an area is a result of contract effect of impressive factors collection in erosion. In order to identify the effective factors in soil erosion and sediment yield in Seied Abad Basin, interrill erosion was determined by average intensity (30 min, 10 year: 40 mmhr-1) using rain simulator in 33 plots. Also, factor analysis, multivariate regression, logistic and Scalogram model were used. Using factor analysis (principal component analysis), between 15 effective variables in sediment ratio, six factors were selected. They were runoff coefficient, sand, rocks susceptibility, soil texture and land use that illustrate %82.009 of variation of data (KMO=0.53). The results of multivariate regression model were almost the same with factor analysis and the results of the Scalogram model confirmed this. Finally, runoff volume (0.02), rock susceptibility (0.001) runoff coefficient (0.00005), and sand percentage (0.00002) were effective factors in soil erosion and sediment yield. In this regard, regarding to these factors, we can conduct policy and planning for decreasing soil erosion and sediment yield.
Mahbobeh Kiani Harchegani; Seyed Hamidreza Sadeghi; Hossein Asadi
Abstract
Water erosion comprises major processes of the detachment, entrainment, transport and deposition. Sediment washed out from the watershed is composed of different particle sizes. The particle size distribution of sediment is a significant factor influencing detachment and transport processes. However, ...
Read More
Water erosion comprises major processes of the detachment, entrainment, transport and deposition. Sediment washed out from the watershed is composed of different particle sizes. The particle size distribution of sediment is a significant factor influencing detachment and transport processes. However, the changeability variables of particle size distribution under different flow conditions have been less considered. Accordingly present study was therefore planned to evaluate the changes in particle size distribution of effective sediments by laser diffraction in initial unsteady and mature steady flow conditions in laboratory scale for a type of soil that was collected from Koudir region in Mazandaran Province. Towards this attempt, rainfall simulation experiments with intensities of 30, 60, and 90 mm h-1were conducted in a set of 1 × 6 m plot with varying slopes of 5, 15 and 25% based on governing condition in the north region of the a soil type and in three replications. The results showed that the sediment concentration is influenced by the slope more than by the rainfall intensity in runoff different conditions. In addition, the results explained significant levels of (p<0.05) for particle of 10 in slope of 5% and in rainfall intensities of 60 and 90 mm h-1 in steady and unsteady flow conditions. While particle of >2 micron had a significant different (p<0.05) in slope of 5% and in rainfall intensity of 30 mm h-1. In this regard, variable of D50 had very complex behavior in slopes and different rainfall intensities but D90 was not influenced by slopes and rainfall intensities in confidence level of 90% in steady and unsteady flow conditions because of inability flow in moving particles of >63 micron and especially variable of D90.
Ata Amini
Abstract
In basins where the water demands surpasses the available resources, water shortage crisis occurs and the deficiency balance is essential to be reciprocated. In such basins, inter-basin water transfer has been announced as a method to supply new water resources. In such projects the potential of donor ...
Read More
In basins where the water demands surpasses the available resources, water shortage crisis occurs and the deficiency balance is essential to be reciprocated. In such basins, inter-basin water transfer has been announced as a method to supply new water resources. In such projects the potential of donor and recipient basins are not assessed properly. In this study, the inter-basin water transfer project from Sirwan to Sefidrood and Karkheh basins was evaluated. The assessment is based on the ability of donor basin to meet current needs and maintain water resources for future development. For this purpose, while the areas prone in the basin were identified, different scenarios were defined for agricultural development and water consumption in the Sirwan basin. In determining agricultural development scenarios the quantitative criteria with the utmost impact on the development of agricultural land were identified as maps in the GIS software. Water consumption scenarios were determined based on estimated net irrigation requirement for agricultural crops using Cropwatt software. The results showed that the basin enjoys a high potential for agricultural development. So that the annual water restoration will be less than the future water needs in the basin. These results advocate the need to reassess the inter-basin water transfer projects in Iran.
Puria Asiaban; Manoochehr Fathi Moghadam; Sajad Kiani; Ahmad Hosseini
Abstract
Rectangular orifices are considered as a common structure for discharge measurement in hydraulics. The purpose of the present research is to investigate the effect of the ratio of length to width of rectangular orifices with same surface area on discharge coefficient. Different rectangles are examined ...
Read More
Rectangular orifices are considered as a common structure for discharge measurement in hydraulics. The purpose of the present research is to investigate the effect of the ratio of length to width of rectangular orifices with same surface area on discharge coefficient. Different rectangles are examined as orifice while the aspect ratio in one of them is equal to 1.618 (golden ratio). Golden ratio is a special number which can be frequently existed in nature and this study attempts to find the probable specialty of this ratio in hydraulics. So, the experiments were carried out on five rectangle orifices that the ratio of length to width of ones varied from 1 to 16. Also, a comparison between the discharge coefficient of rectangular and circular orifices is performed. Therefore, the number of 94 tests was conducted on the orifices in the discharge range of 0.136 - 0.637 L/s. A mathematical relation is developed as pressure distribution coefficient in order to account the effect of non-hydrostatic pressure distribution under low head condition. Results of the experiments showed that the increasing of aspect ratio generally leads to increase discharge coefficient so that discharge coefficient of orifices with variation of the ratio of length to width changes about 11.7%. Furthermore, it is illustrated that golden ratio doesn’t have any specialty in flow evacuation and the discharge coefficient of circular orifices is equal to minimum discharge coefficient of rectangular orifices.
