مجله مهندسی آبیاری و آب ایران
پیاپی 41 (پاییز 1399)

Piano key weirs are flow control structure that have more discharge coefficient than classic weir. In the present, study the support vector machine, hybrid of support vector machine and bat algorithm (SVR-BA) and M5 algorithm are used for predicting the discharge coefficient. Overall, 162 expremental data for seven pianokey weir model are extracted from an expremental study. Also, the discharge coefficient is prediction by employing the parameters included ratio of uppstream water hed to high of weir, width of inlet key, width of outlet key, high of weir, shape factor of fillet and shape factor of crest as input data and discharge coefficient (Cd) as output model. The results based assessment cretria shows that all tree used intelegent model can predicted the discharge coefficient of piano key weir. Nevertheless, in test period SVR-BA model has more accurate with value of 0.992, 0.007 and 0.01 respectively for R, MAE and RMSE.

The outflow from dams, due to its huge amount of kinetic energy, can cause damages such as scouring of the riverbed or destruction of the equipment. Stilling basins are structures that dissipate the excess flow energy at downstream of dams. One of the most common methods, which is used in hydraulic structures analysis, is numerical simulation. Most of these methods are based on computational fluid dynamics (CFD. With the capabilities of numerical methods and advanced softwares, complex and diverse modes of action can be investigated. In this research, hydraulic jumps in stilling basin at downstream of a high dam is numerically simulated by using three different turbulence models including the standard K-ε, RNG and LES models and then the results are compared with the experimental data. According to the results, the best turbulence model was LES model for numerical modeling of flow in the stilling basin. In order to evaluate the effect of chute blocks on the performance of stilling basin, a proposed model assuming standard chute blocks of USBR stilling basin type II is considered and this model is compared with the original model. Results showed a decrease of approximately 40% and 4.5% in the flow velocity, respectively, in the beginning of the stilling basin and incident hydraulic jump section on the chute structure, which reflects the high impact of the chute blocks on the improvement of the performance of this dam's stilling basin.

Floods are one of the natural disasters that cause many financial damage and loss of life in worldwide. In general, it could be said that the runoff coefficient is the best indicator which can represent the flooding situation in the watershed. Runoff coefficient is the ratio of rainfall that flows on the ground and its value varies from zero to one. Therefore, providing an appropriate map with most similarity to the reality can be the facilitator of many flood control planning. For this purpose, the runoff coefficient map was compiled by two methods and then was compared. The first method is an experimental and CN-based method that is common among researchers and the second one is using the WetSpa spatially distributed hydrological model. Therefore, the average weight of flooding potential coefficient map which prepared by SCS method was 0.045 and by WetSpa model was 0.714. Finally, for understanding the results of these two methods, the daily average of flooding potential coefficient was compared using daily rainfall and runoff data recorded over a four years period. Since the estimated runoff coefficient was 0.47, which is closer to the results of the WetSpa model, so the WetSpa model performed better. However, due to the fact that each of two methods has unique features (for example, the WetSpa model needs more data and details but on the contrary, SCS model needs less data and details), both of these has different uses which can be effective in certain situations.

Drop manholes prevent excessive flow velocity and provide energy dissipation in steep urban sewer and drainage systems. Poor hydraulic performance of them under Regime R2 was improved by jet-breakers. However, they should be still properly sized to efficiently enhance drop manhole operation. In this study, effects of jet-breaker length, width, sagitta, and angel, as well as inlet pipe filling ratio on drop manhole performance, were investigated experimentally. Dimensional analysis and two-level factorial design were utilized to design experiments and analyze drop manhole air demand. Statistical analysis of the results revealed both significant design factors and regression models. Analysis of result determined the proper levels of significant design factors as 80% filling ratio of the inlet pipe, the jet-breaker angel of 70˚, and the jet-breaker sagitta equal to zero. Nevertheless, neither length nor width of jet-breaker had significant effects.

One of the most common ways to reduce kinetic energy dissipation is to use a stilling basin. One of the most important parameters of the stilling basin, which has a great impact on its construction costs, is the length of the basin, so it is possible to reduce construction costs by examining and studying it carefully. In this study, the stilling basin was first performed and calibrated using the laboratory data of Chanson and Chachru. Then the spillway of the Chaili dam was investigated using Flow-3D software with RNG turbulence modeling model and flow hydraulic parameters by applying changes along the stilling basin. Studies show that increasing and decreasing the length of the stilling basin and the placement of the end-sill have different effects on the flow characteristics as well as the amount of energy loss. Since increasing the amount of energy consumption is desirable, so among the various modes of the length of the stilling basin, increasing the length of the basin is selected. Increasing the length of the stilling basin increases the energy dissipation and reduces the pressure and force on the end-sill. So that the energy dissipation by increasing the length of the stilling basin to 90 meters and 120 meters compared to the reference model with a length of 75 meters increased by 0.55 and 2.8 percent, respectively, and the force applied to the vertical wall of the end sill, respectively, 5.63 and 3.45 percent decreased. The effect of the placement of the rectangular block on the force and the amount of energy dissipation of the flow was evaluated. The results showed that creating a rectangular block inside the stilling basin reduced the secondary depth of jump and reduced the strength by 7.1% and increased the relative energy loss by 14.31% compared to the stilling basin in the flat state so that the use of blocks They will make the stilling basin than the changes along the stilling basin. Based on this, the results of this research and the methods used in it can be used as an idea to determine the optimal stilling basin.

The nonlinear and complex relationship between the components of a system in hydrological processes and the dynamic behavior between them makes it necessary to use intelligent models for modeling. Usually, in a variety of studies, to increase the accuracy of modeling results, newer models with more computational capabilities are used. In addition to the computational abilities of the models, the use of correct input information is also important to them, and it is necessary to achieve the appropriate accuracy in a variety of modeling methods. Because the error is usually in the hydrologic data, the purpose of this study is to investigate the effect of eliminating possible errors in hydrologic systems in increasing the accuracy of models. In this paper, the monthly flows of Nahandchai, Lighvanchai, and Aharchai rivers have been investigated in two cases the original series and noise reduced time series. Then, for both cases, the runoff predictions with the ANN model have been done. Chaos theory used for the separation of input noise data. The results base on the evaluation criteria shows that this method, providing a possible higher accuracy in data without noise. The amount of Nashatcliff coefficient increased (43.2%, 27.9%, and 5.9%) respectively at the stations of Nahandchai, Aharchai, and Lighvanchai, and RMSE decreased to 65.2%, 65.5% and 7.7% at these stations

Landslide is one of the natural disasters which causes the losses of life and property annually all over the world. One of the solution for decreasing the losses of landslides is to determine susceptible zones for landslide and to zoning its risk through preparing risk-based zoning map of landslide. In this paper, the effectiveness of both information value and area density for zoning the risk of landslide have been evaluated in Neka, Gelevard watershed basin. Therefore, at first, we prepared inventory map of landslide in the basin. Then, 9 effective factors in landslide occurrence and related maps have been prepared. The grade of each layers was measured via area density and information value models and then the risk maps of landslide has been prepared by combining these layers in Ar GIS software. The results showed that slope, direction of slope, fault existence, the efficacy of agricultural and lithology are the most important effective factors for landslide occurrence in the studied area. Quality index (Qs) and Preciseness (P) was investigated to compare the methods and evaluate their efficacy. The higher value of these indexes for information value model shows it has more efficacy than area density for zoning landslide.

Due to the increasing deterioration of river life systems because of human intervention, droughts and climate change, the recognition of the environmental flow in planning water resources development studies to maintain the health of it is necessary. The main objective of in this research is to implementation and assessment the methods of Tennant, Flow Duration Curve, Eco deficit, Aquatic Base Flow, Flow Duration Curve shifting (FDC Shifting) and Desktop Reserve Model (DRM) in estimating the environmental flow of Gharasoo River in different months of the year in the range of studies of Siahab hydrometry station to entrance to Gorgan Gulf in order to conservation and restoring of the above river. In the present study by comparing the results of suggested values of environmental flow in Gharasoo River were determined to be estimate Tennant method 0.57 m3/s for April to September and 0.19 m3/s for October to March, Flow Duration Curve method in conditions of relatively suitable (Q90) and suitable (Q75) was respectively 0.17 and 0.393  m3/s, Aquatic Base Flow method 0.57 m3/s, FDC Shifting method in relatively modest conditions with an annual average of 0.94 m3/s, Eco deficit method 0.88 m3/s and in class B DRM model 0.69 m3/s. Accordingly, by providing the ecological regime of the Gharasoo River, it is possible to maintain proper conditions for maintaining the ecosystem health using FDC Shifting method in C management class (48.5 percent of natural stream of the river).

On average, 70 percent of globally exploited water is consumed to produce agricultural crop products. An approach to water resource management in the agricultural sector is to determine the actual amount of water that is consumed in the process of crop production. Virtual water is a measure to estimate actual water use by different crops. In this respect, the actual water use of main agricultural and horticultural crops was estimated by the CROPWAT model in Sistan and Baluchestan Province in the 2016-2017 growing season. According to the results, total water taken from the resources of the area of study was estimated at 780.582 million Cubic meter. Over 49 percent of total water use was related to date production. Average virtual water use for crop production was found to be 1437 m3 ha-1. Tomato and potato had the highest water use efficiencies of 7.850 and 7.344 kg m-3 water use, respectively.

Underground water resources are the largest available water resources available to the earth, and their management and quality control are of great importance. The purpose of this research is to investigate temporal and spatial variations of groundwater quality parameters for drinking and agricultural uses based on Shooler and Wilcox classification in Borujerd-Doroud Plain. In this paper, 55 parameters were used in the years 2001 and 2016 for qualitative parameters such as electrical conductivity, sodium adsorption ratio, acidity, calcium, chlorine, magnesium, sodium and sulfate. Ground maps were used to prepare zoning maps that were better suited for Kriging intrusion detection. The results of this study showed that most of the plain areas in the year 1380 were about 59.78% of the resources in the optimal condition, which improved to 95.79% in 2016. In 2001, more than 74.08% of the area had a good and acceptable quality in agriculture classification, which increased to 85.94% in 2016.

Salmas plain is one of the most important plain in the western Azerbaijan province. In the last decades, speedy population growth coupled with agricultural expansion has extremely increased pressure on the groundwater resources. Irregular increases in water demand and a little recharge ground water have caused to decline in water level in the plain in recent decade. As a result of declining in groundwater levels, land subsidence appears in some parts of plain. In this study, the relationship between the decline in groundwater levels and land subsidence was examined. The land subsidence survey methods were permanent GPS observations and Radar interferometry. The results showed high and linear correlation between the decline in groundwater levels and land subsidence in this plain. The average determination coefficient for GPS and Radar interferometry methods were obtained 78% and 82%, respectively. Maximum rate of subsidence was calculated 11 cm/year using ALOS satellite radar images in 2009. The results of GPS method indicated that one meter decline in groundwater level will be caused 0.078 m land subsidence in the plain studied.

Climate change and its impact on the status of water resources can endanger the various aspects of life and human life on Earth. In this study, single and hybrid-wavelet artificial neural network, Adaptive neuro-fuzzy inference system and gene expression programming were used modeling flow parameter. For this purpose, monthly climatic data with 21-year (1996-2016) statistical period of flow, temperature and precipitation of Tapik station in the Nazluchay River of West Azerbaijan province has been used. In this study, the effects of delayed flow parameters, precipitation, temperature and periodic effect (monthly coefficient) in models have been investigated. The results show the superior performance of wavelet hybrid models compared to single models of soft computing and the positive effect of applying periodic effects on river flow modeling. Also, wavelet transformation by analyzing data and separating the noise enables the ability to upgrade the performance of hybrid models as compared to single models. For the optimal model (i.e. hybrid wavelet-gene expression programing model, the values of correlation coefficient and root mean square error indices were obtained as 0.98 (maximum) and 326.2 (m3/s) (minimum), respectively.

Climate change is one of the most important factors that will affect different parts of human life on earth and will be adverse effects on environmental resources, economic, social and especially water resources. Increasing concentration greenhouse gases in recent decades and increased temperature caused by it, has led to significant changes in meteorological elements. One of the strategies to mitigate climate change effects is to assess its effects on precipitation and temperature in each region. So, climate change effects on temperature and precipitation variables in Birjand Plain have been studied in this research using CanESM2 AR5 model under emissions scenarios 2.6, 4.5 and 8.5 RCPs. Due to the low resolution of general circulation models, SDSM downscaling model was used and climate changes in precipitation and temperature were simulated for future periods (2020-2049). Model simulation results indicate a rise in temperature in future period, so that maximum temperature rise (1.89°C) and the lowest rainfall (0.07 mm) was observed in June. Results can be used in planning water resources management and agricultural sector.

One of the most important issues discussed in hydrology and flood analysis are flood discharge estimation and the development of its hydrograph, using hydrological models. Today, satellite precipitation products with different spatial and temporal resolutions, have overcome the common problems and constraints in supplying rainfall data. Therefore, the aim of this study is the investigation and application of the TRMM satellite rainfall data as the input for hydrological models used for flood simulation in Gharehsoo watershed. For this purpose, first, the conceptual model of the basin was developed in the HEC-GeoHMS software and the performance of the HEC-HMS software was evaluated in flood hydrograph simulation. The TRMM satellite data was used to estimate the rainfall in parts of the basin lacking a rain gauge station. The accuracy of satellite precipitation data was compared with observation values ​​over the years 2013-2003. The results showed that the HEC-HMS model was suitable for estimating the peak discharge and flood volume for the catchment area, so that the difference between the observational and computational peak discharge was less than 7%, and the difference between the observational and computational flood volume was less than 10%. The examination of TRMM satellite images showed that the highest correlation was observed amongst the monthly data, with correlation coefficient values of 0.25-0.99 and the daily rainfall data was not sufficiently accurate. Also, taking into account the effect of the height of the site, the precipitation values obtained from the TRMM satellite images can be used with acceptable accuracy and an average error of less than 20%.

In multivariate models, the modeling and predicting various parameters can improve by involving other factors. Also Since nonlinear models with conditional variance, the remaining portion of the linear models to adequately model, we expect that the combination of linear and nonlinear models, partly to increase the accuracy of modeling and predictions. In this study, were used the potential evapotranspiration values of stations in the provinces (Birjand, Mashhad, Zahedan and Zabol stations) during the statistical period of 1973-2010 at monthly scale. Since the goal model is multivariable, in addition to potential evapotranspiration data, relative humidity data, wind speed and sunshineare used to modeling the monthly evapotranspiration values. The models studied in this study are MPAR and MPAR-EGARCH models. The results of the verification and validation of the model data showed that both models are highly accurate. In this study, in all cases, the multivariate compilation model with conditional variance was more accurate than the multivariate periodic ARMA model. The results also showed that the MPAR-EGARCH compilation model fitted the minimum and maximum points of the studied data. The average error rate for estimating potential evapotranspiration values by MPAR model at stations of Birjand, Mashhad, Zabol and Zahedan was 0.4, 0.43, 1.05 and 3.04, respectively, and in the MPAR-EGARCH compilation models Respectively is equal to 0.16, 0.19, 0.55 and 0.59 respectively.

Improving the drought quality indicators play an important role in water resources management. In this research, the Effective Reconnaissance Drought Index (eRDI) was used to detect agricultural droughts and present an early warning system in the Jiroft Plain. For this, the reliability of this index was evaluated using the NDVI and its relationship with storage changes of the aquifer was analyzed. According to the findings, the eRDI index shows the same effects in modeling of agricultural drought in different stages of plant growth but its severity is higher in the critical period of vegetation’s growth and therefore this period was considered for the spatial analysis of agricultural drought. The results showed that the occurrence of normal, dry and wet periods are associated with the accessibility or inaccessibility of effective precipitation. The results indicated a significant correlation between eRDI and NDVI in sparsely vegetation areas at the level of 5% (r = 0.87) due to the effective precipitation role in calculating the eRDI, although a weak correlation has been found between the NDVI and eRDI (r = 0.31) in the irrigated area that is probably due to the groundwater pumping and exploitation from the Jiroft dam. As a result, the eRDI-3 and eRDI-7 could be useful for early warning of the agricultural drought and groundwater storage depletion respectively.

Intensity-duration-frequency rainfall curves are one of the hydrological tools for calculating hydraulic design of structures, watershed design, collection and disposal of surface water in cities. In this research, using the empirical formulas for the Ghareman (2004), Vaziri (1991) and Bell (1969), as well as Hyfran-plus hydrologic software, the rainfall intensity and intensity-duration-frequency curves was determined. At first, using rainfall intensities with time duration less than 180 minutes, a run test was performed in SPSS software and manually to ensure the homogeneity of the data. Then, different statistical distributions were fitted to the data to calculate rainfall intensity in different return periods. The chi square (K2) fitness tests was used to determine the optimal statistical distribution. The results showed that inverse gamma statistical distribution compared to other distributions had the highest accuracy in determining rainfall intensity. In the next stage, the intensity of rainfall during different return periods was calculated by empirical formulas using daily rainfall data and maximum daily precipitation. Comparison of the results of the empirical models and the hyfran plus software used in this study showed that the maximum difference of rainfall intensity in long duration is less than 1.6% and in short-term duration less than 20.2%. Also, the difference between predicted rainfall intensity in Vaziri (1991) and Bell (1969) empirical models is less than 19.8 percent.

In this study, for study the effect of rainfall changes on groundwater quality in dry and semi-arid climate of Isfahan province, six basins with high concentration of wells and meteorological stations were selected. Data from 72 meteorological stations of Isfahan province during the statistical period of 2003-2013 and data from 350 wells were used to study the changes in groundwater quality. Subsequently, data with the lowest quality of EC, Ca, Mg, pH, Na, Cl parameters were recorded in Excel software, and ArcGIS software and the changes were zoned. In studying the meteorological drought, rainfall of September as the representative of the driest months of Isfahan, DIP software, analysis of time series 6, 12, 18 and 24-month and the time series with the highest correlation in the zonation were used. Then a correlation time series was zoned in different sections of the six study basins in ArcMap software. The results of Pearson statistical method showed a positive correlation between the drought of meteorology and groundwater quality in the 18-month time series. In summary, with the negative trend of precipitation, the positive trend of salinity, calcium, magnesium, acidity, chlorine and sodium in groundwater was observed from the western areas to the eastern regions. The results show that the minimum variation of millimeters in rainfall from a basin to another basin in Isfahan province affects groundwater quality in each of the six basins and leads to a downward trend in groundwater quality following drought events.

Water distribution networks are critical infrastructure that should be protected against deliberate and accidental attacks. The quality of water is investigated in the treatment plant; however, it can be significantly changed during transmission from the treatment plant to consumers. The contamination entry place is unpredictable and contamination can be entered from several locations simultaneously. Water quality sensors and the pollution warning system can detect the contamination. The alarm system function is depends on the number of sensors installed on the network and their location. In this research, contamination is entered in one or two nodes and the number of sensors installed in the network is one to four. In addition, four objective functions were considered to optimize the locations and the number of sensors. The network was analyzed dynamically. For each sensor placement, the consumed contamination water and the contaminated area are evaluated.  The method was able to identify the best location for the different objective function.

< p >Rice production in northern region of Iran which is strategically and economically very important, requires irrigation management changing with traditional irrigation method (flood irrigation). Plant models that can simulate crop yield in different irrigation management and different conditions will be very beneficial in terms of time and cost. The latest version of the AquaCrop model was used in this study. In this regard, a research was conducted in summer of 2018 to investigate the effect of different levels of irrigation on water consumption, rice yield and water productivity in paddy field of Babolsar, Mazandaran, Iran. The experiment was performed in the field in a randomized complete block design with three replicates and four treatments in 12 plots. The treatments were TI (Traditional/flood Irrigation), AI1, AI3 and AI5 (Alternative Irrigation one, three and five days after disappearance of water from the soil surface, respectively). After applying different irrigation practices and recording the amount of cumulative water given to the treatments, grain yield and water productivity were also determined. To quantify and verify the effects of different water management on rice yield, calibration, validation and sensitivity analysis of the model was performed based on field measurements. After calibration, the model was performed for the four treatments and the results showed that the model could simulate the yield of the product for irrigation management with high accuracy (0.81).

Deficit irrigation has different effects on growth, metabolism and plant performance, which has a major impact on photosynthesis. The goal of this study was to investigate the effect of different irrigation levels on yield and water productivity of sweet pepper (Capsicum annuum L.) in greenhouse condition. Five irrigation levels are evaluated on yield and yield components of Sweet pepper. The research was done based in completely randomized design including 3 replications as pot planting in Gorgan University of Agricultural Sciences and Natural Resources during 2016. In this study, five irrigation regimes existed of (70, 85, 100, and 125% of water requirement). The results inducted that the effect of different irrigation regimes on fruit number, fruit fresh weights, and water productivity was highly significant (p < 0.01), but fruit dry weights and yield were significant at 5 percent levels (p < 0.05). In conclusion, the results showed that the highest of Yield and water productivity in 100 percent of the requirement. the results showed that sweet pepper plants are sensitive to the deficit and over irrigation, increasing of irrigation levels from 100 to 125 percent of water requirement has resulted to the redaction of yield and water productivity to 7.1 and 42.6 percent, respectively. However, increasing irrigation levels from 100 to 85 percent of water requirement has resulted in the redaction of yield and water productivity to 69.6 and 63.9 percent, respectively. The results showed that with decreased and increased in water irrigation level, fruit fresh and dry weights and Fruit number were significantly decreased