نشریه دانش آب و خاک
سال بیست و نهم شماره 3 (پاییز 1398)

The aim of this study was selecting the most suitable interpolation method to estimate the spatial variation of maximum daily rainfall at the Atashgah basin, Ardabil. For this purpose, data of 9 rainfall gauge stations of Ardabil Province Water Regional Company were used. Homogeneity and independence of data were tested. Universal and ordinary Kriging and Cokriging interpolation methods were evaluated by circular, spherical, exponential and Gaussian regression models and Inverse Distance Weighting (IDW), Radial Basis Function (RBF), General and local estimators using Arc GIS software. To compare and evaluate the mentioned methods, statistical parameters of Mean, RMS, ASE, MS and RMSS were used. In each method, the lowest rank was devoted to the lowest statistical error and the highest rank was devoted to the highest statistical error, and then sum of the ranks was used to compare the interpolation methods. Results showed that, in the case of 2 years return period, ordinary Cokriging by circular regression model and for 5, 10, 25, 50 and 100 years return periods, ordinary Cokriging by Gaussian regression model, with the lowest ranks, were the most suitable interpolation methods in estimation of spatial variation of maximum daily rainfall. The weighted average of the maximum daily rainfall of Atashgah basin for the return periods of 2, 5, 10, 25, 50 and 100 years were determined equal to 37.5, 48.19, 49.41, 53.32, 54.14 and 57.69 mm, respectively.

Detention ponds are best management practices designed for the control of urban stormwater and their design objectives are mainly controlling the quantity and quality of urban stormwater at the minimum cost. In this research, long term hourly rainfall data of Kerman and Mehrabad synoptic stations were analyzed and the three rainfall characteristics (rainfall duration, rainfall volume and inter event time duration) were obtained. Analytical probabilistic models (APM) were employed and the model parameters were derived from the closest stations to the study areas. The APM parameters, along with the catchment parameters, were used to develop the optimal combination of the pond volume and outlet capacity. Also, the PSO model led to lower computational   costs in comparison with the APM model. Comparison of the PSO with APM showed that the PSO results were more accurate than the results of APM and there was no need for determination capacity in the forementional model as it did not need outlet size. The PSO model was also found to be more computationally implemented more cheaper and faster.

The increasing in consuming water with good quality and quantity has prompted engineers and designers to plan and present the advanced plans for optimal utilization of water resource systems. Heuristic optimization methods such as particle swarm algorithm that is investigated in this paper are among the latest methods that have been widely used in recent decades. In this study, a developed model of particle swarm algorithm was described and the particle swarm algorithm was evaluated with a nonlinear and constrained single-reservoir optimization equation. For this purpose, at the first step the system was optimized for a period of five years. Lingo software, a non-linear programming model, was used to compare the results. The value of the objective function in the developed algorithm showed only 0.12 differences with the global optimum. After analyzing the sensitivity of the parameters and the efficiency of the algorithm in the five-year period, the ten-year period was selected for optimization. In this case, the objective function had less than 1% difference with the global optimum as well. In both cases, the developed particle swarm algorithm gave better results than the particle swarm algorithm, and sticking in local optimizations value could be removed. Therefore, it could be concluded that the developed particle swarm algorithm had a high ability to solve the complex problems of water resources systems operation.

Existence of heavy metals in water resources and wastewater can cause the environmental problems. Use of low-cost substances as adsorbents has been developed over recent years. The purpose of this study was to investigate the effect of chitosan on sorption of Cd and Cu heavy metals from aqueous solutions using response surface method and Box–Behnken methods.  The batch experiment was conducted to evaluate the effects of independent variables such as pH, metal concentration, and ionic strength on the metal sorption using response surface and Box–Behnken methods. One-way analysis of variance (ANOVA) was applied on data. High values of R2 (0.99) and adjusted R2 (0.99) showed that the removal of Cu and Cd can be described by the response surface method. One-way ANOVA showed (p < 0.001) that quadratic was the best model for determining the interaction variables. The optimal conditions determined for Cu and Cd initial concentrations, pH and ionic strength values were 200 and 168.8 mg L-1, 5.47 and 5.26 and 0.03 M, respectively. The predicted adsorption at these settings for Cu and Cd were 83.68 and 45.07 mg g-1, respectively. Response Surface Method could be useful for optimization the adsorption of Cu and Cd from aqueous solutions by chitosan

The construction of bridges within the river beds often makes changes to the shape and direction of the rivers. These changes take the natural actions of the river, that one of them is the local scouring around the bridges' piers and can cause annually damage. Therefore, many researches have been carried out to control and reduce the scouring. One of the methods presented by researchers is using slot at piers.  In present study, the effect of Pier Opening Area on local scouring around the pier with rectangular section is experimentally investigated. For this purpose, piers with square shape slots and different dimensions were used. The piers were tested at three levels (near the water level, on the bed and under the bed) and four Froude numbers.  The result showed that the maximum scouring depth and the volume of hole scour had a direct relationship with slot level relative to bed and Froude number and an inverse relationship with Pier Opening Area. The best performance belonged to the slot with greater dimensions which was located under the bed level in the minimum Froude number condition that reduced the depth of scouring about 55.4 percent.

One of the regular methods for stabilizing and protecting the riverbanks is use of groyne structure. Groynes alter flow direction to the main axis of the river resulting sediment deposition and stabilization of river sides. Therefore, scour around the groyne and the effect of nose on scour are important parameters in river engineering. It should be noted that change of flow pattern in river side is an affective factor on the rate of scouring around the groyne nose. In this study, the effects of the hockey groyne length (L) on scour in straight channel has been investigated through experimental tests. The results showed that there was a direct relation between scour hole dimensions (including the maximum scour depth (ds), the length of scour hole in up and downstream and the maximum scour width) and hockey groyne length. Also, scour hole distance the from channel wall was longer in hockey groyne comparing to that in straight groyne which prevent from scour in river bank and stabilizing the groyne structure. Thus, maximum scour around the hockey groyne was less than that straight groyne around due to suitable flow direction to the downstream.

One of the experts' suggestions for restoring Lake Urmia is to convert irrigated lands in to rainfed farming in the Urmia lake basin. Rainfed wheat farming might be considered as one of the effective alternatives to the irrigated areas. So, evaluating the soil available moisture as the most important limiting factor of the rainfed wheat farming is necessary. Since the field experiments are costly and time-consuming, application of the crop yield simulating models, e.g. AquaCrop which can estimate the crop yield based on soil water content with high accuracy, would be desirable. In this study, after calibration and validation of the mentioned model for simulating rainfed wheat yield in Tabriz plain during a period of 35-years (1360- 1395 HJ), the meteorological variables of the studied region were predicted for a 5-years ahead prediction interval using Thomas- Fering method. The rainfed wheat yield was then estimated using Aquacrop model for the period between 1396 and 1400 (HJ). Finally, management scenario for increasing the potential of rainfed wheat was proposed. The results of this study confirmed the ability of the conjunctive crop model and time series technique for simulating crop yield and meteorological variables in the studied region. Results showed that despite no significant change will be occurred in rainfall amount, ascending trend of the air-temperatures will cause an increase of about 13% in rainfed wheat yield during the next five years. Also, due to precipitation insufficiency for rainfed wheat farming, predicted supplemental irrigation is recommended equal to 40 mm, to increase the potential yield production.

To evaluate the impact of different irrigation water levels on water use efficiency, yield and yield component of two palm cultivars, a research study was conducted in Behbahan Agricultural Research Station equipped to subsurface drip irrigation system. The study was based on a split plot experiment in randomized complete block design with three replications for two growing season years of 2014 and 2015. The irrigation water was applied in three levels of 75, 100, and 125% of crop water requirement (ETc) as main plot and two palm cultivars of Kabkab and Khasi as sub-main plot. According to the results, there was no any significant difference in weight and length of fruits, number of fruits per cluster, and yield under irrigation water levels and palm cultivars and interaction between them. However, water use efficiency was different significantly between the different irrigation water levels. Accordingly, 75% ETc irrigation treatment by 7545.3 m3/ha water consumption and yield of 6284.2 kg/ha were recommended. Yield of Khasi varieties was 6729.7 kg/ha. Water use efficiency of Kabkab and Khasi cultivars under irrigation treatment of 75% water requirement were 0.804 and 0.862 kg/m3, respectively, which was significantly higher compared to other treatments.

Although a dam’s structure has an important role in suppressing floods and providing water for activities such as agriculture, human consumption, industrial use, electricity generation and pisciculture, its break has an immense damage and loss of life when it occurs. In order to reduce the damaging effects of the dam break on the downstream places, it is necessary to provide the flood hazard map. For this purpose, in the first step, the output breach hydrograph of the Alavian dam was computed by the BREACH model under the overtopping scenario. In the next step, the breach hydrograph was routed through the downstream of the river by using HEC-RAS model. Finally, the ArcGISsoftware was utilized to prepare the flood mapping. The results of the present study illustrated that the Alavian dam is breached with the time of failure of 46 min and the peak discharge of about 66000 m3/s. Furthermore, according to the flood hazard map, most of the downstream inundation zones due to Alavian failure dam have been considered as the high hazard area.

In this research, the effects of combined application of nitrogen (N) and iron (Fe) on the chlorophyll index and some growth characteristics of corn were studied using a factorial experiment based on completely randomized design with three replications under greenhouse conditions. The factors were N from two sources including urea and sulfur coated urea (SCU) in 3 levels (0, 100 and 200 mg N kg-1) and the Fe from two sources including commercial Fe-EDDHA and ferrous sulfate (FeSO4.7H2O) in 3 levels (0, 10 and 20 mg Fe kg-1). The results showed that the main effects of both sources of N and Fe on chlorophyll index and growth characteristic of corn plan were significant (p<0.01). Also, the interaction effect of N and Fe on shoot dry weight and leaf chlorophyll index was significant (p<0.05), so that the maximum shoot dry weight of corn was obtained with 200 mg N kg-1 as urea with 10 mg Fe kg-1 as Fe-EDDHA. The maximum leaf chlorophyll index was recorded in treatment with 200 mg N kg-1 from source of SCU with 20 mg Fe kg-1 as FeSO4.7H2O. In the most studied traits the difference between the two nitrogen sources, namely, urea and SCU was not significant.

Diagnosis and Recommendation Integrated System (DRIS) and deviation from optimum percentage (DOP) method are from important methods for interpretation of the results of chemical analysis and diagnosis of nutritional status of plants. In order to evaluate the nutritional status of squash (Lagenaria Vulgaris) through DRIS and DOP and to determine DRIS norms for this crop, 122 leaf samples were collected from squash fields in Khoy and N, P, K, Ca, Mg, Fe, Mn, Zn, Cu and B were analyzed. The squash fields were divided into high and low yielding groups. The DRIS norms were calculated from high yielding fields’ data. The mean of nutrient concentration in high yielding fields were selected as norms for the calculation of DOP indices. Too, Results showed that there were significantly differences between high and low yielding fields in terms of nutrients concentration and their ratios. Sufficiency ranges of nutrients concentration in squash leaves were determined as 2/7-4/0, 0/32-0/46, 3/3-4/6, 1/3-1/9 and 0/53-0/78 for N, P, K, Ca and Mg and 155-206, 116-154, 49/5-66/7, 10/9-15/4 and 57/4-70/8 mg/kg for Fe, Mn, Zn, Cu and B respectively. Based on DRIS and DOP indices, potassium and zinc had the most negative indices among macro and micro nutrients, respectively. DRIS and DOP nutritional balance indices (NBI) in low yielding fields were greater than zero indicating nutritional imbalances in these fields.

Rills are often the major area and source of runoff and sediment in hillslopes. The hydraulic characteristics of flow in the rills can be affected by type and amount of sediment. Knowledge on the flow hydraulic characteristics is essential to find the major mechanism of rill development. The objective of this study was to evaluate the effects of type and amount of sediment on the rill hydraulic characteristics. Laboratory experiments were carried out in a flume with 4m× 0.4 m×0.3m dimensions located at 9% slope steepness under 90 mm h-1 rainfall intensity which was applied on three soil textures of loam, loamy sand and sandy clay loam with four replications. Reynolds number, Froude number, flow depth, Darcy–Weisbach friction coefficient, shear stress and stream power were determined during the rill erosion process. The results showed that Reynolds number and Darcy–Weisbach friction coefficient increased as the sediment load increased in the rills. Froude number decreased as sediment load increased which was attributed with decreasing flow velocity. Shear stress and stream power and flow depth increased with increasing the eroded sediment. Flow depth increased with incease of sediment load, varying from 0.041 to 1mm in loam soil, 0.07 to 1.3 mm in loamy sand soil and 0.06 to 0.7 mm in sandy clay loam soil. Coefficient of determination between sediment load and all hydraulic characteristics were higher than 90% for loam and loamy sand and higher than 60% for sandy clay loam. This study revealed that significant interaction was between sediment load and hydraulic characteristics of flow in the rills.

Providing design hyetograph is an important issue in accurate determination of urban drainage networks. One of the important relevant problems of floods, is its safe transmition without any damage to facilities, farms, habitat buildings and so on. This needs accurate determination of flood quantity and then dimensions of water pass ways, bridges, flash walls, culverts, and so on. The aim of this research is plotting the Huff curves and design storm hyetographs in the six selected stations in upstream of Karkheh dam watershed. In order to design of Huff curves, the recorded date of Kamiaran, Abdanan, Darreh-shahr, Kerned, and Kermanshah were used. For this purpose, the 1191 recorded storms classified in different seasons and in five classes of rainfall durations. The Huff curves were illustrated using the mentioned information for each of the classes as well as the seasons. Furthermore, all the events in a given class and season merged in a universal distinct class and then their Huff curves were plotted too. In order to possibility of comparison of temporal distribution of rainfalls in stations, three new indices denoted by S, I, and Q were defined, each of them shows the ratio of cumulative rain depths received in 25, 50 and 75 percentages of storm durations extracted from the 10 percent Huff curves to the corresponding values obtained from the 50 percent Huff curve.  Results showed that nearly in all the stations the quantity of S-index was greater than I-index, and both of them were greater than Q-index. Results of this study have practical application in surface water management in the watershed area.

Cupper (Cu) is one of the micronutrients and the release rate of this element is an important factor in determining its bioavailability in calcareous soils. In this research, the kinetics of native Cu extraction by DTPA was studied in 21 calcareous surface soils (0-30 cm) and the best kinetics model to describe the data was selected. For this purpose 20 mL of 0.005 M DTPA solution was added to 10 g air dried soil and shacked,then during the 0.16 to 200 hours the concentration of Cu was determined. Furthermore the abilities of  zero, first, second and third order equations, simple Elovich, two constant rate, parabolic diffusion, Lagergern first order and Blanchard equations in description of the kinetics process were evaluated. According to the results, the rate of Cu extraction by DTPA was increased with time then reached a relative equilibrium in 72 hours. The best models for describing kinetics of Cu extraction during 200 hours were the simple Elovich and two constant rates. Also within 0.16 to 20 hours besides these two equations, the parabolic diffusion was one of the best models, too. Lagergern first order and Blunchard equation despite the wide range of correlation coefficients did not have a good fitness with the 21 studied soils. The αsβst product of simple Elovich equation (qt = 1/βs ln(αsβs) + 1/βs lnt ( in initial 15 minutes was larger than 1 for all studied soils. The amounts of constant b in the constant rate equation (qt = atb) were positively and negatively correlated with sand concentration (r= 0.47 *) and CEC values (r=-0.45*), respectively. The highest correlation coefficientsbetween the kinetics parameters of superior equation, was observed between the ab with βs.