مجله آبیاری و زهکشی ایران
سال یازدهم شماره 1 (فروردین و اردیبهشت 1396)

Groundwater has been discussed As one of the most important sources of drinking and agriculture water supply in arid and semi-arid especially. Birjand plain by being in the arid region and the use of ground water is as the only source of fresh water ahead. Predict the groundwater level fluctuations can be help in planning and future decision making, to provide long-term drinking water, agriculture and industry. The aim of this study was to compare two methods of MODFLOW numerical modeling and artificial neural network in forecasting of the Birjand aquifer groundwater table. ANN has been one of the smart ways, with the use of intrinsic, non-linear relationships between the thought and generalize the results to other modes. Numerical model receives all information about aquifer GIS layers ,which is able to predict the groundwater level in the future. GMS software uses for the numerical solution of motion equation and of the finite element and finite difference methods. In this study, the finite difference method was used. Numerical models run for steady state, unsteady state and for three scenarios wet, normal and dry were compared. The neural network model inputs were taken from the extraction wells, the amount of input water to each polygon in terms of cubic meters (caused by area rainfall) and the water level in the piezometers, in the step before, and the model, the water level is at the current time step. The results show that using artificial neural network can be predicted with reasonable accuracy the level of underground water for up to 12 months later. Moreover, in a number of piezometers predict the level of groundwater is of sufficient accuracy to 18 months. MODFLOW numerical model predicts with more accuracy than the artificial neural network changes the water level within 24 months.

Soil erosion and effective factor on its rate have been focused in the world wide cover crop is the most important and effective factor on soil erosion. This research was carried out to investigate the relationship between run-off and sediment load with cover crop and crop canopy and to study the effect of cover crop on aggregate stability and water infiltration rate. The experiment was performed as a completely randomized design and factorial arrangement in plots of 1 m2 square (1*1m) at less than 5% slope. The studied treatments include Borago (B), fumitory (F) and flixweed (W) at 0% (without cover crop), 20-30% (low density), 40-60% (medium density), and ˃70% (high density) and 3 replications. At the end of each plots volume of run-off and sediment content due to natured rainfall were measured in spring 2015. Also, mean weight diameter (MWD) of wet aggregate and water infiltration rate were measured. The results showed that. The highest and lowest volume of run-off height were noted in W and B treatments, respectively. The lowest value of sediment content was obtained in B treatment too and by decreasing the crop canopy, the sediment concentration was decreased. There was the highest water infiltration rate and the lowest one was assigned to B treatment, which are due to different root morphology. The comparison of MWD showed that with increasing the crop canopy, MWD increased and the maximum value of MWD was noted in B treatment.

Drought as an inevitable consequence of weather variables is one of the main causes in decline of agricultural yields spatially in rainfed condition. In this study the Agricultural Reference Index for Drought (ARID) including one layer and two layers of soil water balance approaches were used to estimate the yield functions of rainfed wheat and barley in Golestan province. For this purpose the daily metrological variables form 12 weather stations during hydrological years were obtained and then the values of ARID according two mentioned approaches in the growth period of wheat and barley were calculated. In addition to the values of wheat and barley yield production in irrigated (Yp) and rainfed (y) condition for eight city of Golestan province in corresponding time were gathered and by using change point analysis the time series of relative yield for each crop were estimated. By considering six phonological growth period for investigated crops, the average values of ARID droning different years were calculated and by nonlinear solving of relation between relative yield and ARID the sensitivity coefficients to water stresses for each periods and the function of crop yields were determined. Finally evaluated the ability of ARID in two approaches by compared the predicted and observed crop yields according to statist criteria. According to these the results of ARID based on two layer of water soil balance model have a better efficiency in estimating of wheat and barley yields. In addition the accuracy of barley yield function is more than wheat yield function. Investigation the sensitivity coefficients of given crops indicated that the most sensitive period for rainfed wheat and barley in all given stations expect of Ramian Town stations was stem elongation (stage 3) period and the order of sensitivity coefficients for period of initiation stage, booting stage and flowering to water stresses were different according to kind of crops and stations but the two less sensitive periods to water stress were obtained for initiation vegetative and ripping periods.

Studying the processes of runoff generation and assessing the factors affecting it are of the requirements of proper management of the soil and water resources. This study was conducted to investigate the effect of slope on runoff coefficient of surfaces with different materials. For conducting this research, six surfaces of cement, natural grass, asphalt, asbestos cement, pavement and roof insulation, each with an area of 1 square meters in three slopes of 5, 10 and 15 percent, outdoors in research farm of University of Zanjan were prepared. Following three rainfall events on these surfaces, the volumes of the runoffs produced on them were measured. The runoff coefficients of the surfaces and slopes were determined by using the surface area, depth of rain and volume of runoff. Comparison of the result of each surface in the same slope in three different rainfall events did not show significant change in value of the runoff coefficient. The roof insulation and asbestos cement surfaces had the highest runoff coefficients with values of 0.96-0.99 and 0.92-0.97, respectively. The runoff coefficient of the pavement with value of 0.81-.90 was on average 11% higher than that of the cement 0.67-0.82). The results of the various slopes in the grass, cement and asphalt showed that there is a significant difference between the runoff coefficients in the slopes of 5, 10 and 15 percent. In the grass, by increasing the slope, the runoff coefficient increased significantly (about 15%). As well, in the cement and asphalt, increasing the slope increased the runoff coefficient by 7 and 9 percent, respectively.

Optimal operation of reservoirs is one of the ways of dealing with water management issues and encountering with inappropriate spatial and temporal distribution of water. In this research, a metaheuristic algorithm called Water Cycle Algorithm (WCA), has been developed in MATLAB software, with the purpose of optimal operation of a Multi-reservoirs system (Golestan and Voshmgir dams) located at Gorganrood Basin (North of Iran), fora five year period (from 2007-2008 to 2011-2012). At first, the performance of the developed model was investigated through several standard test functions. Next, the developed model is applied for monthly allocation of Gorganrood Multi-reservoirs system. The objective function was defined as the “minimization of the total deficit for the study period”.In order to performance evaluation of the developed model, two criteria of reliability (temporal and volume) and vulnerability have been used. The results of the developed model were compared with those of the other metaheuristic algorithms including Harmony Search Algorithm (HS) and Imperialist CompetitiveAlgorithm (ICA).The WCA, HS and ICA were capable to supply 97.73, 85.57 and 93.17 percent of Golestan dam water demand, respectively. For the Voshmgir dam, the mentioned models could supply 97.06, 86.88 and 93.44 percent of water demand, in same order. The temporal reliability (α=0.9) for WCA, HS and ICA models, was obtained 95, 25and 50 percent for Golestan dam and 91.67, 38.33 and 65 percent for Voshmgir dam, respectively, revealed that the WCA was superior in optimal allocation of Multi-reservoirs system.

Due to the large area of saline and swamp lands throughout the country and the clear need for drainage and also great desire to subsurface drainage systems. It is a top priority to supply materials and specifically select proper drainage envelope. One of the selecting criteria is discharge of pipes. In this study a physical model with dimentions of 4*1*1.3 is used in order to simulate natural conditions and hydraulic conductivity of envelopes. The model as a part of a simulated drainage trench has an adjustable water table. Three kinds of envelopes such as mineral (sand and gravel), organic (rice husk) and synthetic (PP450) ones which are used in the country prepared and the tests performed after installing each envelope around drainage pipes in simulated trench. In all experiments, the discharge through mineral envelope was far more than organic and synthetic ones at different water levels (60, 70 and 80 centimeters from pipe axis). This discharge in mineral envelope was 4-5 times higher compared to synthetic one and the proportion for organic envelope was 3-4 times higher that is due to the higher porosity of the two types of envelopes. While the rice husk cause reduction in discharge compared to sand but can be used as a good choice for envelope in subsurface drainage.

Scouring around bridge piers due to strong storm currents is a main threat to the stability of bridges in rivers. Hence, in this conditions the protection against excessive scouring is required. Attempts have been made by several investigators to reduce scour depth using several devices around bridge piers. One of the successful methods for reduction of scouring was the application of bed sills. In this study, the effect of applying bed sill at the downstream of the pier in reducing the scour around bridge piers under strong storm currents is studied. For this purpose, experiments were conducted by placement of bed sills at the downstream of the pier throughout the flume width with its top position at the bed level and by varying the distance between bridge pier and bed sill. The experimental tests were done under uniform flow with clear water condition and storm currents. Storm currents were simulated by two group of hydrographs with different base time and three different peak flow. A circular pier was installed on the bed with uniform sediments and final scour depth was measured in different flow conditions. The results under uniform flow showed that the efficiency of the bed sill is reduced by increasing the distance between the bed sill and the base of pier. The placement of a bed sill sticking to the pier resulted in the most significant scour reduction of about 36 and 77 % in depth and volume, respectively. This result confirms the findings of previous studies. Under storm flow condition, the placement of bed sill at distances smaller than three times of the pier diameter resulted in the reduction of scour depth and volume. The results show that the efficiency of the bed sill is reduced significantly by increasing the distance from the pier and it results in the increase of scour depth at the distance of three pier diameter. The maximum reduction in scour depth and volume was observed about 25 and 48 %, respectively, at the condition with the bed sill sticking to the pier. Based on these findings, it can be concluded that the efficiency of the bed sill is reduced under storm flow conditions when compared with its efficiency under uniform flow with clear water condition.

Using automated technologies in irrigation networks in the long time affects network performance and will have an interaction with other factors affecting the performance of the network. The purpose of this study is to identify archetypes associated with automation and providing automation applications model in Qazvin irrigation network. For this purpose, after determining the dynamics of automation in Qazvin irrigation network and developing conceptual model based on the completed questionnaires and interviews, automation application model developed for irrigation network. The dynamics of automation of Qazvin irrigation network is studied, on the basis of irrigation networks indicators such as adequacy, efficiency, equity and flexibility and several improvement policies evaluated, so their effects on utility indices investigated. Then the long-term impacts of improvement policies on system utility are determined and the appropriate policies are suggested. By applying improvement policies such as, earning the trust and participation of farmers in the process of automation, promotion of knowledge and skills of beneficiaries and allocation of budget and finance of automation based on the amount required in the whole network, the utility of the network will improve between 9.5 to 21.13 percent.

It is possible to interpolate rainfall missing data in one synoptic station, using recorded data in the adjacent stations. Inverse Distance Weighting and Kriging methods are the most common geostatistical methods which address this problem. In this paper, we have used modified inverse distance weighting, Ordinary Kriging, and Co-Kriging methods to interpolate weekly rainfall missing data in Sisab station in Northern Khorasan. For this purpose, we have used recorded rain fall data over the last thirty years in 11 adjacent stations. Paired Sample TTest results show there is no significant difference in the significant level 5% between interpolated and actual data through all three used interpolation methods. Paired Sample T-Test results show in the To evaluate the estimation error, and hence, the best interpolation method, statistic indices such as coefficient of determination, root mean square error, mean absolute error, mean bias error and RMSE-observations standard deviation ratio are used. This comparison study shows that although all three methods are capable to interpolate the missing data, but Co-Kriging method has more accurate performance incorporating the altitude data of the stations. In this paper, the best fitted semi variance has been achieved by spherical model and 15 to 25 km range through Kriging methods.

Knowing about plant's water requirement is one of the most important considerations in reforming water productivity in agriculture. So precise estimating of source evapotranspiration is one of the most important factors in improving water management. Penman Mantis FAO is used as a standard formula to estimate the source evapotranspiration. But this detailed and complicated method requires lots of information. Due to the lack of certain required information in all the regions, regional equations for calculating evapotranspiration based on the least of the meteorological data seems necessary. To this end, three experimental equation" Blany Criddle, Hargreaves and Torrent White" was selected and based on Penman Mantis FAO equation for three different climates by the linear regression and nonlinear optimized method was calibrated. A ten year period's data for the three stations of thoroughly humid, semi-arid and dry climate was calculated and divided into two groups: the first 5 years and second one. The data for the first 5 years the equations was calibrated and evaluation of the equations was conducted through F test and RPMSE test, using the second 5 years. Based on the results, using of equations Blany Criddle , and Hargreaves, for the thoroughly humid climate and the Torrent White equation calibrated for semi-arid and dry climate using the regression calibration method is recommended to estimate source evapotranspiration. In the calibrating process of equations, linear regression performed more properly than the optimized non-linear method.

Salinity and nitrate of drainage water are the main reasons of agricultural pollutant. Decentralization of agriculture land, variety of contaminants and the high volume of agricultural waste led to reduce the performance of conventional strategies of nitrate and salinity removal. This study aimed to evaluate the phytoremediation strategy to reduce salinity and nitrate in agricultural drainage, and reduced ability to absorb nitrate salt by three Vetiver, Typha and Reed was investigated in the region of Guilan province in a randomized complete block design with three replications. So 9 cylindrical boxes with 50 cm diameter and 80 cm height and Silty loam soil texture were prepared and after planting, two treatments of nitrate concentrations including of 10 and 20 mg/l nitrate were exposed during testing. Ability of nitrate and salinity reduction in two depths 35 and 70 cm was determined by measuring the amount of nitrate and salinity in soil extracts. Results showed that the highest amount of nitrate uptake of Reed in concentration 10 mg/l and in 70 cm depth was 98.59% and the lowest nitrate uptake in concentration 20 mg/l and in 70 cm depth was 34.96% for Vetiver. In addition, three plants were significant differences in reduction of pH but the salinity reduction was not significant in 5% level.

In this research, flow pattern around T-shaped spur dike located in a 90 degree bend channel by using FLOW-3D software in the conditions of changing spur dike position along the bend (angles: 15, 30, 45, 60 and 75 degrees) with rigid bed was investigated. Accordingly, the numerical simulation results were first compared to experimental results under similar circumstances (45 angle position). The results of this comparison indicated that the numerical and experimental results enjoy rather appropriate correspondence. Therefore, after verification of numerical results, investigation of streamlines, length of flow separation and reattachment zones, and length of vortices under the influence of different positions of placing spur dike was conducted. The results obtained from numerical modeling indicated that at the layers near water surface and bed, for all angles of spur dike placement except position of 75 degrees, at downstream of spur dike a counterclockwise vortex has formed. Moreover, by changing the position of spur dike from the entrance of channel towards the exit of channel, at layer near bed, the maximum vortex length (as long as 4.7 times the spur dike length) for mode of spur dike placement in position of 15 degrees and the minimum vortex length (as long as 1.9 times the spur dike length) in position of 75 degrees have occurred.