نشریه دانش آب و خاک
سال سی و یکم شماره 4 (زمستان 1400)

In order to predict the magnitude, velocity, and form of the flood wave with respect to time, the flood routing methods are used. There are several ways to accomplish the flood routing which are divided into two general categories, including hydraulic and hydrological routing methods. Among the various hydrologic routing methods, the Muskingum- Cunge method has been applied more frequently because no need to calibration process of output hydrograph. The accuracy of this method depends on the choice of reference discharge and geometrical parameters. In this study, a new model was proposed for calculating the reference discharge based on the comparison of Muskingum- Cunge method and MIKE11 hydrodynamic model for Dinehvar River, in Kermanshah Province. The results showed that the output hydrograph obtained by the proposed reference discharge was in good agreement with the output of MIKE11 model so that for the 200 years flood hydrograph, the RMSE and E criteria values were equal to 1.64 m3s-1 and 0.99, respectively. Furthermore, comparison of the proposed relationship with other researcher’s findings showed that the proposed relation not only was a function of the peak discharge but also was a function of peak time and base time of the input hydrograph.

Recently, land subsidence has become one of the serious environmental problems due to increased agricultural and industrial activities. Population growth have caused to groundwater over abstraction and land subsidence in some parts of country such as Ardabil plain. Therefore, identifying, control and management of high potential subsidence areas may help to better understand this complex phenomenon and avoiding the possible damages. In this research, a new framework suggested using seven effective parameters on subsidence to determine areas that are vulnerable to land subsidence and its capability is evaluated in Ardabil plain aquifer. In this framework seven effective parameters on land subsidence including groundwater level decline, aquifer media, recharge, pumping, land use, alluvium thickness and fault are prepared in raster layer format and weights and rates assigned for layers to calculate Subsidence Potential Index (SPI). The SPI for Ardabil plain aquifer was obtained from 80 to 154. According to inherently uncertainty of the assigned weights by expert, genetic algorithm adopted to optimize given weights. The results were compared with subsidence value obtained from radar images and it indicated that optimized framework have relatively better results. The southern and southeastern parts of the Plain shows higher SPI.

Applying the studies of resistance to flow in open channels and rivers with specific properties in order to manage them is necessary. An optimum and proper foresight of resistance to flow has a direct impact on the estimation of flow rate, which is important factors in decision about hydro-project developments. This research work tries to identify items which are influencing on the flow resistance by handling properties of the river in specific intervals. In this study, the best Manning’s coefficient of “Shahar-Chay” river by means of hydraulic characteristics and aggregation of river bed has been estimated. Manning’s coefficient by using several methods and using pictures and properties of a river reach with a specific Manning’s coefficient, by comparing to the river conditions with relative pictures and estimating approximate range of the Manning roughness coefficient has been verified. By preparing 3D drawings from region using Arc-GIS and creating lateral sections using Hec-GeoRas, geometric specifications of “Shahar-Chay” river used as input in order to complete hydraulic simulation of HEC-RAS model. By running the software for different values of Manning’s coefficient and hydraulic specifications output from modeling compared to the hydraulic specifications collected from the river reach area. It is found that the most proper value for the Manning coefficient at “Keshtiban” reach is about 0.032. The results of the present research work reveals that three methods, namely “Chaw”, “Coawn” and “comparison of pictures” are more accurate for estimating Manning’s roughness coefficient in rivers, because of introducing several factors taking into account.

To evaluate the effects of different levels of sewage sludge and sewage sludge-derived hydrochar a greenhouse experiment was performed in a factorial combination based on a completely randomized design with three replications and three factors of organic matter at three levels (control, 10g sewage sludge, and 10 g sewage sludge-derived hydrochar per kilogram), nitrogen at two levels (0, and 250 mg per kg soil as urea), and copper at three levels (0, 10, and 250 mg Cu per kilogram as copper sulfate). The results showed that by applications of sewage sludge and its hydrochar, the dry matters of shoot and root, tillers number, spikes number, leaves number, leaf length, leaf width, plant height, and stem diameter were significantly increased as compared to the control and the amount of this increase in the presence of sewage sludge was greater than that of hydrochar. Also, the using of 250 mg N per kilogram increased the mentioned characteristics relative to the control. The soil contamination Cu significantly reduced the tillers number, spikes number, leaves number, and root dry matter as compared to the control. The use of sewage sludge hydrochar and N fertilizer reduced the Cu toxicity and increased rice tolerance to Cu toxicity by reducing the Cu concentration in rice shoot. To achieve rice optimum growth in both Cu contaminated and non-contaminated conditions, the use of 10 g sewage sludge or sewage sludge-derived hydrochar and 250 mg N per kilogram soil can be recommended at similar conditions.

Soil degradation caused by salinization and sodification is one of major problem in arid and semi-arid regions. To overcome this problem, leaching of accumulated salts from such soils is necessary. In this research, HYDRUS-1D model was used to predict desalination process in saline-sodic soil located in north of Ahvaz. Therefore, Leaching experiments in both with (sulfuric acid) and without reclaiming material was performed in in 11 m2 plots. All experiments were accomplished by applying 100 cm of water in four-25 cm intervals. Desalinization leaching curves were measured. Also, soil texture, field capacity and permanent wilting point water contents, saturated hydraulic conductivity and solute distribution in soil profile were measured. Then, solute transport during leaching process was simulated using HYDRUS-1D by inverse method. The results of the study indicated that all the used amendments showed a pronounced difference in EC compared with control but the difference wasn't significant. Because of, the soils have enough calcium carbonate and gypsum which provide requirement calcium for reclamation. The model predicted solute transport in depths less than 100cm better than other. The simulated results indicated that amount of estimated EC in the first and second period of leaching fit to observed data better than other periods. Over all, the results of solute transport simulation during leaching experiments revealed that HYDRUS-1D provide reasonable description EC distribution in soil profile. So HYDRUS-1D model can be introduced as a suitable tool for prediction solute transport in soil under field condition.

Over the past decades, more than 40 global climate models have been developed in scientific centers around the world to simulate and predict the world climate change. These models are different depending on the initial and boundary conditions, the variables used in the climate, and the structure. Therefore, to use these models to predict future climate in each region, systematically evaluation performance of these models in simulating the time series of observed climatic parameters such as daily, monthly and annually temperature and precipitation will be required. Hence, in this study, an innovative systematic approach for evaluating the performance of 36 global climate models from the Fifth Intergovernmental Panel on Climate Change report on the southern slopes of Alborz Mountains is done. Based on the results, applying the innovative method will have incomparable accuracy in the right choice of general circulation model in each region. The results also indicate the inappropriate accuracy of most models in simulating temperature and especially historical precipitation in the study area (as in other valid studies in the world) and even in the top models of the study area the historical monthly precipitation simulation was not appropriate. Finally based on five statistical properties of Nash–Sutcliffe, bias, correlation, root mean square error and mean absolute error, ACCESS1.0 and GFDL-CM3 models with higher priority and CNRM-CM5 and GFDL-ESM2G models are proposed in the next priority for climate change studies and future temperature and precipitation values prediction.

Soil evolution is the result of a combination of geomorphological and pedological processes. In this study to investigate the spatial variation of soil characteristics and determine the relationship between soil evolution and different geomorphic surfaces of epandage pediment, erosion pediment, slope surfaces, smooth surfaces, horst, lake deposits, alluvial fan, mountain ridge and circgue in an elevation-climatic profile in the Southeast of Ardabil 12 soil profiles were dug. After digging and field studies, physicochemical and clay mineralogical experiments were performed on the samples. The results showed that variations in weathering intensity and the types of soil forming processes at different geomorphic surfaces, had significant effects on soil properties and evolution and vertisols, mollisols, inceptisols, and entisols orders were identified. Smectite, vermiculite, kaolinite, and illite have formed the composition of evolved soil minerals, respectively and the relative amount of smectite varies from 78.5% at the epandage pediment to 12.3% at the mountain ridge. Also statistical comparison of the mean confidence interval of crystalline iron (Fed-Feo) by Bootstrap method showed that there were significant differences between geomorphic surfaces in terms of soil evolution and the highest amount of crystalline iron with mean of 6.372 g kg-1 was observed in epandage pediment with vertiolsols and the lowest value with average of 0.913 g kg-1 in alluvial fan with entiolsols. According to Spearman correlation test, crystalline iron had a direct relationship with clay percentage, calcium carbonate equivalent, pH and cation exchange capacity, but inversely with sand and organic carbon.

The main objective of this project was to measure water consumption of silage maize under farm management. Thus, the volume of water consumed for Silage maize in Behbahan was measured in sprinkler and surface irrigation systems and various water resources during one season (2016-2017). The measured values of the net water requirement were estimated by the Penman-Monteith method and also compared with the national document values. The average yield in surface and sprinkler irrigation systems was 58329 kgha-1. Water productivity varied from 3.91 to 13.71 kg per cubic meter in all fields. The average of application efficiency in sprinkler irrigation systems was 73.3%. The average amount of water consumed by Silage maize in surface irrigation farms was 9778 and in farms irrigated by sprinkler systems was 6991 cubic meters per hectare. Comparison of the average of net water requirement calculated by the Penmann-Montieth and those obtained from the national water document using the T test showed a significant difference being 440 and 582 mm, respectively. Comparison of the Pearson correlation coefficients showed that the trend of changes in water productivity with trend of changes in maize yield was significant at 5% level. Obviously, by increasing the application efficiency, water productivity has increased.

The purpose of soil management is maximizing the supply of water and nutrients to the plant and minimizes the soil erosion, improve soil fertility and soil physical conditions. Using in-site water harvesting methods reduces runoff from the area and increases the water stored in the soil profile. Rainwater harvesting is not a new concept, but it requires the combination of native methods with modern knowledge. Because the used technology was inappropriate for special conditions of the region, some water harvesting projects have been unsuccessful or even led to the loss of the whole crop. The suitability of an area for rain water harvesting depends on its ability to supply the technical and basic needs of the system. This study introduces a method for rain water harvesting in the area with little slope or no slope, which can be Mechanized Construction for large-scale. On the other hand, a computer simulation has been preparation and introduced for precise and scientific designing of a water harvesting system, which there has not been much effort in this case. The results of simulation indicated the reduction of concentration ability of water by Kajaweh system with decreasing the size of structure. In addition, in relatively smaller sized structures under high intensity rainfall, reduction of water concentration ability by Kajaweh system was predicted by simulation. Such trend is also expected for long time rainfall times (especially in low rainfall intensity).

As the world's population continues to increase and fresh water decreases, the need for desalination of sea water is increasing. Therefore, the desalination process has become a new challenge as the earth's resources must find sustainable solutions through renewable energies. Condensation irrigation (CI) combines desalination and irrigation, which can produce required energy by solar power. This research was conducted for feasibility study in Research Station of Ahvaz University. The air flow was saturated by passing over the saline water surface in the solar still. Then the saturated airflow was driven into buried drainage pipes (25 m), where the humid airflow cools gradually, and the humidity condenses along the inner pipe surface. This condense water penetrates the soil via drainage pipe perforations, and irrigates the surrounding soil. During the field test, changes in the daily production of condensation water were observed due to the surrounding environment influenced on the input temperature but the average daily fresh water production was 6 L day-1. In addition, a laboratory model was built to identify the effective two entrance temperatures on the performance of condensation irrigation. The result showed that changing the flow temperature has a great impact on the performance of condensation irrigation.