IRANIAN JOURNAL OF WATERSHED MANAGEMENT SCIENCE AND ENGINEERING
Year:2018 | Volume:11 | Issue:39 |Papers Count:12

Dust phenomenon has now become one of the emerging natural hazards in the country, a phenomenon that affects its natural and human conditions with its harmful effects on different aspects. Therefore, in this research, the temporal – spatial distribution of dust in west and southwest of Iran and at meteorological stations located in three provinces of Eilam, Khuzestan and Kermanshah were investigated. For this purpose, the statistics of dust days was collected from the Meteorological Organization of Iran for the statistical period of 1986-2008. At first, the necessary data set was considered for normalization, and then the time distribution of this phenomenon at the level of the stations in the study area was determined in a graph. Further, according to the GIS and ArcGIS10. 2 software, the distribution of the annual and monthly spatial days along with dust in west and southwest of the country based on different interpolation methods were determined. The results showed that the number of days with dust in Dehloran, Ahvaz and Dezful stations is at the highest level and in the southern provinces of Eilam and Khuzestan the most critical conditions are observed and from north to south of the region, the number of days of dust increases. Also, the results showed that the distribution of this phenomenon is not affected by regional climate systems due to topographic variation and altitude of the west of the country, and the most days with dust in the southwest are observed in Khuzestan province. In the western regions of the country, there is a high frequency in the middle of the spring. The spatial distribution of this phenomenon is more than the latitude and altitude elevation. According to the results, the criticality of the whole region is important, but in Khuzestan province, conditions are in a more critical situation. Managing a crisis before and during this natural hazard is important for better adaptation to reduce its harmful effects.

The surface soil moisture content has an important and effective role in runoff generation and soil loss, especially in the arid and semiarid regions. For this purpose, an experiment to determine the effect of initial moisture on runoff and soil loss in two soil texture of loamy, sandy clay loam in intact land in the vicinity of the University of Zanjan was performed with four initial moisture levels (one, four, seven and 10 days). Field experiment as factorial in randomized block design was carried out in plot scale (60*80cm) using a rainfall simulator. Twelve plots for each soil were installed on a uniform slope of seven percent and accordingly exposed to simulated rainfall with intensity of 55 mmh-1 for 30 min. The results showed that, significant difference was found in runoff generation (p<0. 01) among initial soil moisture levels in each soil, that this issue was affected by the initial moisture content in the soils. No significant difference was observed in soil loss between the initial moisture levels in loamy soil (p>0. 05), high initial moisture aggregates in this soil resisted versus detachment by raindrops, while these changes were significant among the soil moisture levels of the sandy clay loam soil (p<0. 05), which was associated with a small amount of organic matter and more clay. Contrary to expectation, there was no significant relationship (p>0. 05) between soil loss and runoff generation under moisture levels in soils.

Fast and accurate estimation in Peak flow is one of the major issues in water resources management that have basic role in the design of hydraulic structures and biological activities in drainage basins. So that a proper assessment has a basic role in the success of administrative tasks. In this paper, using artificial intelligence methods (Multi-layer Perceptron Neural Network and the mixture of Multi-layer Perceptron Neural Network with genetic algorithm) to estimate yalfan river, s peak discharge in Yalfan, s sediment and hydrometer local gaging station. For these two models, 8 variables have been considered as the inputs that includes rainfall related to day of peak flow, 5 days rainfall that occurs before of the flooding day, curve number of the basin(CN) and base discharge and finally peak discharge is considered as the output. With artificial intelligence after preprocessing of the data, the optimal structure of the model is determined with input and output data by evaluation criteria and trial and error. In the final, with the mixture of artificial network and genetic algorithm model, the optimum neural network model was determined which results were an input to genetic algorithm model, this has been a good performance in runoff forecasting in Yalfan Basin.

Cylindrical weir is one of the hydraulic structures that was used to measure flow rate and control flood, and is less expensive than similar structures. In this study, the numerical model validation is performed with an accredited experimental model in three different diameters (11, 9 and 6. 35 cm), and in three different angles (45, 90 and 135 degree) toward the wall with Flow-3D software. According to the simulation, in the results with k-ε turbulence model there is a good adaptation than the other turbulence models such as the RNG and LES model, and the correlation coefficient (R2=0. 965), indicated that the k-ε turbulence model is the best. Due to an increasing the length of weir in oblique position and changing the situation of spillway from direct position to oblique position, discharge coefficient will increase, so leads to increasing of discharge. The results show that in models with complementary angles, because of the similarity of these models in the flow pattern, the discharge coefficients will be almost equal to each other. With increasing the diameters of spillway from 6. 35 cm to 11 cm, discharge coefficient reduced up to 50%. Maximum of the correlation coefficient between discharge and discharge coefficient for cylinder with 11 cm diameter is equal to 0. 95 that show high effectiveness of discharge on discharge coefficient.

Empowering the local community through localization and based on indigenous knowledge is one of discourses that propounded in new development paradigms. Localization is in relation to dealing community with transformation trend from traditional to modern. In this study, using two questionnaires, asked heads of households view points about the difference between indigenous and formal knowledge in the field of natural resources in rural areas, especially water and soil was investigated. Using the 64 questionnaires in Ghasab Zalekan village, Babol city, Mazandaran province, distinctions of formal and indigenous knowledge were evaluated with two approaches zero and one and low, medium and high ratings. The results show that in this village, 13. 16 percent of voters agree to indigenous knowledge adaptively and 28. 92 percent of voters to formal knowledge scientifically. As well as, other parameters in each knowledge subjects were ranked. Also, with investigating strategies of this two kind of knowledge to conserve soil and water resources, the indigenous knowledge with 48. 056 percent is more efficient and adaptive. The results show 5. 979 percent acceptance rate about innovation and new technologies such as product, achievements and technologies must be adapted with indigenous knowledge and be responsible to rural problems.

Recognizing of critical zones of groundwater quality is one of the most important issues about researches in water fields. The goal of this study is to determine the spatial and temporal variation of groundwater quality factors such as electrical conductivity and chloride ion contents using the best suited geostatistical estimation in Kerman plain on 10 years period (1996-2006). Also, the best variogeram model and parameters related to model of EC and Cl contents will be determined. Findings of variography analysis for Cl contents of groundwater quality data in the beginning and the end of study period showed that the exponential structure is the best spatial model fitted to this parameter. Thus, its effect range increased from 101700 to 106200 meter and sill contents decreased from 2. 246 to 1. 698, during 1996 to 2006. The best model fitted to electrical conductivity spatial structure became exponential in 1995-1996 and spherical in 2005-2006. The results of geostatistical analysis show that effect range and sill contents of EC decreased from 79800 to 37500 meter and 0. 84 to 0. 608, during 1996 to 2006, respectively. Comparing of interpolation methods of groundwater quality data introduced log kriging method as the best approach for Cl and EC zonation maps. Cl zonation maps show an increasing trend of Cl content in all plain areas in 10 years period. Thus, Cl concentration in the input region of plain increased in the range of 3. 03-13. 01 in 2006. Intensity of Cl content occur in north outlet of plain near well numbers 27, 28, and 33, and Cl critical core of western south of plain near well number 19 show an increasing trend. Our findings showed an increasing in EC content, especially its spatial spreading in west and north outlet of Kerman plain and Kerman city in 10 years period.

The basis of land use planning is geomorphological zoning of Earth's surface. The quantitative zoning is conducted using automated and predefined based on zoning criteria. In this study, the quantitative zoning is used to identify areas suitable for artificial recharge in the mountainous area of Gohar and Garbayegan plain, Fars province by fitting a linear fundamental form to the surface. The structures with grade two for triplex windows and the data from the digital elevation model with a resolution of 10 m was used to determine the best fundamental structure fit. The sum of square differences of the surface differences is used as an indicator to determine the degree of fitting the fundamental structures. By fitting the interpretable patterns to the Earth's surface, it can be determined that the earth was similar to which pattern and formation mechanism. Mountain ranges upstream alluvial cones and plains located downstream of the upstream alluvial cones are not linear surfaces. Places which are not at the acceptable slope (gradient less than 0. 002 and higher than 0. 1) allocated to the zero fitting degrees and the fitting degree values are positive in alluvial cones and areas fall in the acceptable range of the slope. The results show that the surfaces located downstream of the alluvial cones and the plains are most suitable areas for floodwater spreading in the Garbayegan watershed.

In this research, prediction of precipitation and temperature values using general circulation models of the atmosphere in the period 2021-2050 were carried out. Climate data such as rainfall and average temperature were obtained from the Meteorological Organization. For future climate scenarios, the output from general circulation model HadCM3 under the A2 emissions scenario was used. Due to the low resolution of general circulation models, downscaling model of SDSM4. 2 was used and climate changes in precipitation and mean temperature were simulated for future periods. In this study, for SDSM model calibration, among the 26 large-scale climatic parameters (NCEP), an average of 3 parameters most correlated with mean temperature and 6 parameters are most correlated with average rainfall in Seymare drainage basin. The results showed that the predicted climatic parameters for the simulation of climate parameters with high accuracy for the average temperature, but with less accuracy for rainfall. This is due to lack of normal and unconditional situation of rainfall data. The results indicate that the average temperature of the area in the period 2050-2021 compared to the observation period (2008-1979) showed an increasing of 1. 7 ° C and average rainfall showed a decrease of 47%.

InDebris floods are high concentrated flow that occurs in steep mountain areas. Slit dam is one of the structures designed for controlling these kinds of floods. A two dimensional model is proposed for simu lation of debris flow in slit dam reservoirs. In this model, the finite difference MacCormack explicit scheme is used for discretization of governing equations, and a formula is proposed for the slit dam boundary condition. Due to the lack of observed data of debris floods in slit detention dam reservoirs, the numerical model is compared with an experi mental model. The model results show that the applied scheme using the proposed initial and boundary condition is capable to simulate the two dimensional movable hydraulic jump in slit dam reservoirs. Finally, the com-parison of numerical results and experimental data confirms that the numerical model is fairly capable to simulate the outflow hydrograph of slit dam.

Drought is an insidious environmental phenomenon. This phenomenon causes water shortage for some activities, communities or environment. Drought should be compared with average climate and hydrological Conditions for Long period of time. Hydrological drought is detected by reduced water storage in lakes, underground water levels drawdown and reduced river flow and often will affect a large area. The most common definition of a hydrological drought is to define a threshold limit, such that if the river is less than that, a hydrologic drought is considered. In this study, the fixed threshold limit of Q70 was used in Karaj drainage Basin. Results showed that Q90 of year 1998 was the driest year. The results show that 1377 year was one of the driest years in this area and in Karaj station 284 days and for Gachsar station 255 days were dry. Also, the results show a total lack of water in Gachsar station Q70 threshold equal to 68/11 million cubic meters, Kalavan stations equivalent to 75. 2 million cubic meters and for Karaj station equal to 44/42 million cubic. The general extreme value (GEV) best fit the parameters of the drought. The results can be used in water resources management and planning necessary to prevent or mitigate the effects of drought in the area.

In order to achieve the objectives of this study, among 80 River Watershed of North Shore (covered Mazandaran Province), 17 stations were selected in three western, central and eastern sections. Based on period of records, the 44 water years from 1966-19767 to 2010-2011 were selected as a common period. To evaluate the existence of trends, the most common nonparametric time series called Mann-Kendall test was used. And if there is a trend to assess for ascending or descending time series, Sen test was used. According to the results of the three stations in the western part of the province, there is not a clear trend in the annual series. But for winter and autumn seasonal series, some stations showed positive trends and the rest of stations with no trend, which is an indication of the impact of climate change, particularly in cold seasons. Based on six stations in central part of province, stations in region of plain Mazandaran; Mahmoodabad, Haraz and Miandasht and Babol show ascending winter trend. Namaerstaq-Namarestagh mountainous stations show summer ascending trend and also Babolrood-Qarantalar stations show ascending autumn and winter trend. The only station in the eastern parts, the Arab Khayl-Talar of annual rainfall and summer trend is upward and the rest of the stations show no clear trend.

Knowledge of initiation of soil runoff is important in estimating surface runoff, volume of runoff and losses from a rainfall event over soil surfaces. Many parameters in the beginning of runoff are effective which topography is a major influencing parameter. The plan shape is an important parameter which affects the run-off initiation which has been investigated in this research. In order to investigate the effect of the plan shape, a three dimensional geometric model is required. Calculating the run-off appearance in hillslopes leads to measuring the time that the run-off starts, as well as surface water flow and the amount of runoff and sediment movement. A laboratory research is conducted to investigate the effects of plan shape which are divergent, parallel, and convergent on time of run-off initiation. The results showed that the nine complex hillslopes have a different runoff initiation threshold. As well, when the plan shape changes from convergent to divergent, the time of runoff initiation of surface and subsurface flow increases. This means that in the convergent hillslopes, runoff starts later. Also, the effect of plan shape is more important than profile curvature for starting runoff. Thus, in the divergent and concave hillslopes, runoff is started posterior than convergent and convex hillslopes.