IRANIAN JOURNAL OF WATERSHED MANAGEMENT SCIENCE AND ENGINEERING
Year:2018 | Volume:12 | Issue:41 |Papers Count:13

Evapotranspiration is a major component of the hydrological cycle which shows the amount of water loss. Since the amount of evapotranspiration is directly associated with climate variables and is related with the amount of changes in climate parameters, particularly, temperature plays a key role in this regard. Therefore, in this study, possible impacts of climate change on evapotranspiration rate are estimated in the Lake Urmia Basin as a wet basin in the country. The basin nowadays is faced with drought and reduction of water level. Predictions of the changes in the lake, were examined under scenarios A1B, A2, B1 and B2 using LARS-WG and SDSM Statistical Down-Scaling Models and HadCM3 general circulation model output in the next three periods ( 2011-2030, 2046-2065 and 2080-2099). Using the predicted parameters of climate change, Evapotranspiration rates in the basin in monthly and seasonal periods, was calculated using Hargreaves Samani and Priestley Taylor methods. The results showed an increase in long-term average minimum temperature in the basin between 0. 2 to 3. 4 degrees and a maximum temperature increase of 0. 9 to 2. 9 degrees in future periods compared to the base period (1961-1990). The estimate of evaporation rate shows an increase in monthly and seasonal time series in future affected by the temperature. The increase would be 2. 4 to 15 percent on long-term average in the basin. The results can be used in the management of groundwater and surface water resources, irrigation and drainage projects, estimating crop water requirements, irrigation scheduling and environmental studies and watershed plans.

Dhenedar, Floodwater Spreading plan of about 450 hectares is located in the southeast of Hormozgan. Measuring the electrical conductivity of the affected wells is one of the most important indicators of the effect of artificial recharge schemes. The maps of the electrical conductivity were prepared using the Surfer software. To determine the effect of Floodwater spreading of Aquifer, , wells that were near floodwater spreading with potholes farther away than were floodwater spreading (control wells) were compared. Comparinge the electrical conductivity of the wells showed that the total electrical conductivity increased, but the rate of floodwater spreading area by far less than other locations. Therefore, the electrical conductivity dropped in the well No. 5, which is located near the flood spreading area from 800 to 716 μ m/ cm, respectively before and after the construction of flood spreading system. But that is well No. 11 at the end of the plain and farther distance than floodwater spreading systems, electrical conductivity increased from 710 to 786 micromhos per centimeter.

Culverts are important structures to convey water under roads and rail roads. Blockage or clogging of drainage channels by woody debris is one of the serious problems in the design and operation of road culverts that has not been studied well. In this laboratory study, the entrance blockage of a box culvert model due to the accumulation of woody floating objects is investigated. Also, the influence of hydraulic and geometric parameters such as flow velocity, elapsed time_ and the entrance flow depth in the culvert were studied. Laboratory observations showed that the entrance blockage increases as the interval time between the arrivals of woody floating objects reduces. The maximum blockage occurred in the falling limb of the hydrograph and the last time step. Using the experimental results and dimensional analysis, some dimensionless parameters are reported and their variations against the culvert entrance blockage are evaluated. The most effective parameters are identified using statistical analysis with SPSS software. Finally, a non-dimensional linear relationship is derived to determine the percentage of blockage as a function of the effective parameters.

In each area, watersheds are very important because they are the largest physical and topographic units which contain various ecosystems. Soil, the most important component of these ecosystems, is the third source of carbon storage in the world, playing an important role in global balance of carbon and its sequestration. The purpose of this study is to investigate the role of watershed management projects on carbon sequestration, which it could enrich the soil and improve watershed conditions. In order to estimate the soil sequestration in Fars Kelestan watershed, six different land uses including peanuts planting, grape planting, bush planting, milk vetch, natural almonds and seeding were selected. Soil sampling at two depths (0-20 cm), (20-50 cm) were carried out, in which. 35 samples stratification collected from each depth. The results revealed that the amount of carbon sequestration varies in different land uses. The maximum amount of carbon sequestration in depth (0-20cm) belongs to bush planting which equals to 64. 628 ton/ha. The highest rate of carbon sequestration at depth (20-50cm) belongs to the peanuts planting which is 57. 652 ton/ha. In peanuts planting land use the total carbon sequestration is 119. 150 ton/ha. In purpose of carbon sequestration increasing, biological treatments are recommended with the priority order of the peanuts planting, bush planting, milk vetch, grape planting, seeding, and natural almonds.

Flip bucket is the main part of an energy dissipation structure called ski jump system. In this research, hydraulic characteristics such as jet length, velocity, pressure and Froude Number in four discharges are studied by Flow-3D in two models including spillway with simple flip bucket and spillway with approach channel. For turbulence modeling, RNG and models are used. Validation showed that model is more accurate. The results indicate that the approach channel model has longer jet length and more energy dissipation compared to the other model. In this model, maximum velocity, equal to 2. 30 meter per second, occurs at the beginning of the channel for 20 liters per second discharge. Also, maximum increase percentage in velocity happens in the model of approach channel spillway amounting 32 percent for discharge of 15 liters per second. The results of pressure analysis show that the pressure changes in the two models have no tangible differences. Moreover, maximum pressure is on the toe of the spillway in the first model amounting 2833 Pa for discharge of 25 liters per second. Additionally, maximum Froude Number (4. 5) occurs at jet fall in the simple flip bucket model and in approach channel model it occurs in the channel.

Creation of underground dam is a practical cure for the best use of water resources and true ground water management. One of the important and considerable problems for these dams is determining inclined areas for their creation. an Therefore, on this studied study has been determine suitable locations to for construction of subsurface dams has been determined on the Ardestan plain in the north eastern part of Isfahan by using some key criteria and Geographic Information System. In this regard, by considering geological engineering criteria, effective factor on the determining suitable case for construction of subsurface dams were defined. At this time on the basis of some criteria decision technique and by using Analytical Hierarchy (AHP) method problem on the basis of necessary and effective criteria to be divided in small parts and different levels and careful by the expertise judge, calculated importance degree (weight) for any level. Then, at the regard to raise analytical care, velocity and easily calculated weights prepared for any index classes on the vector layer of the above criteria to be recorded on the Arc GIS, 9. 3 environment and cases than most ratio have been determined. The Researches by this method, are suitable alternatives in the slopes and alluvial fans of adjacent mountains in the western and north eastern part of Ardestan with the scale of 1/100000 sheet in order to construct the subsurface dam.

Historically, rivers as a major source to supply drinking water and agriculture are considered in human societies as a very effective in the formation of civilizations. At present, most of the northern rivers that are under the influence of human, cause a variety of changes and destruction of ecosystem. Pollution and human interfaces could be the most important factors to pollution caused by waste water of industrial, urban and rural, pollution resulting from disposal of pesticides used in agriculture, destruction of vegetation, construction of dam, and barriers under bridge, blocking the mouth of the river, illegal fishing. Hence, considering the importance of Talar River for supply agriculture water, and also pour pollution to in, to identify and assess the river water quality and provide the necessary relationship to estimate pollution and water quality. In current study, 72 samples were used during the years of 1391 to 1392 from 6 stations namely, weresk, pole sefid, Shirgah, Talar, Kiakola and Arabkhil. Then, NSFWQI index was estimated. Finally, with applying gene-expression programming and artificial neural network, the obtained models for determination of relation between water quality parameters and water quality index are used with high accuracy. To evaluate the performance of models, statistical parameter such as, root mean square error, mean absolute error, scatter index and correlation coefficient were used. Results showed that the proper functioning of artificial neural networks and planning methods in estimating gene expression index is NSFWQI. The obtained results revealed appropriate performance of that artificial neural and geneexpression programming to estimate NSFWQI index.

Suspended sediments (SS) constitute the major part of river loads. Their grain sizes predominantly are smaller than fine sand. The deposition of SS in the floodwater harvesting systems (FWHS) affects several characteristics such as infiltration rate, aquifers recharging, soil fertility, plant growth and soil water capacity. Although numerous advantages and a few disadvantages were listed for the sediment deposition in FWHS, due to lack of measurements on particle size distribution of SS, inclusive assessment on sedimentations has been impossible up to now. To overcome this limitation, the texture and particle size distribution of more than 100 fine deposit samples taken from 18 sedimentation areas across the country were analyzed. The results showed the dominance of silt (average 46%) followed by very fine sand (average 20%) that totally composes 66-93% (average 83%) of deposited fine sediments. This indicates that coarser (> 2μ ) particles comprise the major partition of the SS. On the other hand, the texture of most samples is loam and silt loam, which represents a medium to coarse texture. Therefore, the infiltration rate of the FWHS reduces to an optimum level without becoming a limiting factor. It seems that some other factors including high deposition thickness at an event, a layered structure with alternating clay layers and failure in plowing and cultivation are responsible for reducing the permeability of FWHS.

Excessive use of fossil fuels, the increasing world population and the ever-increasing of industrial activities accordingly to provide welfare and the needs of humans, thereby has been increased the concentration of greenhouse gases, particularly carbon dioxide in recent decades. This increase in greenhouse gases cause a phenomenon called climate change. The aim of this study was to evaluate the effect of climate change on surface runoff in Caesar's basin (West Iran). The study uses data from a large-scale model HADCM3 under scenario A2, and for small-scale precipitation and average temperature of the climate parameter exponential model SDSM was used. Simulated runoff area for the next period (2021-2050) was simulated by IHACRES conceptual model. The results showed an increase in temperature for all stations. The average temperature of the area for the future compared to the observation period increased by 1. 7 ° C. Simulated rainfall for the next period shows a decrease in precipitation by 24% over the observation period. According to the simulation model of IHACRES, the three hydrometric stations used in this study, all stations showed a reduced rate for the area in the future. This reduction in discharge of 29, 19 and 24 percent in the future period for Rahimabad, Biaton and Cham Zaman stations, respectively was observed compared to base period.

Soils in arid and semi-arid regions are strongly affected by the accumulation of salts, especially carbonates and gypsum. The soils are inherently low in organic matter content and in consequence unstable in the structure which declines the soil’ s resistance to water erosion processes. Moreover, the soils are weakly covered with natural vegetation cover which exposes surface soil to erosive factors, particularly raindrop impact. Therefore, this study was conducted to investigate the splash erosion rate in relation to slope gradient in the soils with different properties. Toward this, twelve soil texture classes were exposed to simulated rainfalls with 40 mm per hour in intensity for 10-min in four slope gradients (0, 10, 20, and 30%). A total of 144 experimental soil boxes with 25 cm ×35 cm in dimensions were investigated using the completely randomized block design. The results of this study showed that significant difference was found among the soils in splash erosion (P<0. 001). Among the soils, the highest splash erosion rate was observed in Silt (244. 20 gram m-2), while sand showed the lowest value (65. 71 gram m-2). Splash erosion rate was significantly affected by slope gradient. Splash erosion showed a decreasing trend from 0 to 10 slope degrees and increasing trend from 10 to 30 slope degrees. Significant correlations were found between splash erosion and sand, clay, geometric mean particle diameter, bulk density, saturated hydraulic conductivity, organic matter, calcium bicarbonate equivalent and gypsum. Multiple linear regression analysis indicated that the splash erosion was significantly related to the Organic matter, Calcium Carbonate Equivalent and gypsum with a coefficient of determination of 0. 75. The soil’ s susceptibility of arid and semi-arid regions to splash erosion can be initially estimated using a regression equation based on these variables.

Some methods of erosion control in the steep slope of the lateral sidewall of the earth's structures include the use of biological mulch and natural remedies were investigated in this study. In this paper, with the aim of determining the type and the most suitable aggregate of these materials on soil erosion resistance parameters, on the lateral wall of irrigation and drainage channels of Arayez plain of Khuzestan, the required experiments were carried out in the rain simulator lab of the Soil Conservation and Watershed Management Institute. So that, using at least 290 experiments on soil samples of the studied region, using 15 types of modifying agents and biological mulch, as well as the most appropriate combination of them, were carried out. In the following, experimental treatments on a flume with lateral slope of 1 to 1. 25 similar to normal slope of drains, were simulated using 30 and 80 mm / h rain intensity. The results showed that all of mulch treatments and cement mortar treatments, anti-sulfate cement, cement grout and lime and clay mixtures had a significant effect on sediment yield reduction in comparison with control treatment, and confirmed that these treatments have an effective role in controlling erosion from lateral walls of drainage canals. It was shown that mulch No. 1 had the greatest effect on decreasing the erosion rate of drainage channel walls (up to about 89%). In treatments of soil reformers, antisulfate cement slurry treatment had the best effect on sediment deposition of up to 98%. Therefore, polypropylene fiber melt treatment and lime saturation treatment not only do not decrease sediment, but the combined application of these materials in comparison with control treatment can increase the sediment by about 15 times.

This paper has been developedis to discuss and analyze the stability of the city of Garmsar with a focus on integrated watershed management by understanding the factors affecting the sustainability of upstream watershed and analyze the relationships of cause and effect of urban sustainability in action with persistent factors of Hablehroud Basin. The issue of urban development without attention to its margin is meaningless. The twenty-first century faced with the controversial issue of sustainable development will be a priority for sustainable urban development. The issue of sustainability in urban planning is dependent on natural resources and biological capacity which does not paid sufficient attention. Urban strategies for the implementation and execution of static follower of the school of modernism and the need to interact, sustainable and vital urban watersheds that feed the city's vessels have not been addressed. The research is based on the descriptive analytical method and is based on observations and the field data. In this study, the DPSIR model that is an environmental assessment model and the evaluation analytical hierarchy process method is used to better determine the answers and options resulting from environmental assessment model. The results showed that Garmsar city as a city dependent on urban watershed is not sustainable, but the city of Garmsar watershed sustainability through the implementation of strategies appropriate to the natural resources is possible.

Natural phenomena could be recognized through the selection and then produce the appropriate scale. The critical subject in this way that have been less studied in Iran is identifying the multi-scale algorithms and distinguish them from simplification algorithms. In this research, operation of each multi-scale algorithms at certain scales has supposed, then implementation of structural simplifying algorithms-low pass filter and simple average-have evaluated in order to identify the flood process using three Digital Elevation Models at 1: 25000, 1: 50000, and 1: 1000000 scales in ArcMap software and HEC-HMS model. Results demonstrated that different approaches of map production make different results as the generalization and the best approximation of spatial data. Comparing the result of flood simulation proved sensitivity of such algorithms with respect to scale of basic map. It has been specified that the effect of generalization algorithms does not necessarily conform the hierarchical structure of scale of input data. Finally, we suggested to investigate the flood phenomena of Jamash watershed, we should use low pass filter and simple average algorithms to simplify DEMs at 1: 25000 and 1: 1000000 scales but using these algorithms at 1: 50000 scale has have not suggested.