samira bayati

Water balance looks like a simple function, but its estimation at the watershed level is a complex process. For this purpose, water balance models could be a useful tool for simulating water balance components. The aim of this study was to simulate the surface water balance of the Karun 4 watershed using a model with minimum input data, because one of the problems in mountainous areas is lack of data. Many water balance models have been used in Karun watershed. Therefore, the Exp-Hydro model, which has not been used in Iran so far and has a simple structure and minimum input data, was selected. Exp-Hydro is one of the watershed-scale daily hydrological models that make use of daily data including precipitation, air temperature and potential evapotranspiration as input and simulates the daily streamflow at the watershed outlet. Due to its simple structure in this study, the open-source model, written in Python was used to simulate the daily runoff of the Karun 4 watershed.

In this study, the spatially lumped version of the Exp-Hydro model was used to simulate daily runoff. The script code of the model was written in Python. Python software, NumPy, SciPy, and Matplotlib library functions were installed to run this model. The input data of the model were prepared in separate files in text format. Then the results of Exp-Hydro model were compared with a daily water balance model that was developed in this study. This model was prepared in Excel software. The statistical period of this study was from 2000 to 2020, where two-thirds of the data were used for the calibration period and one-third for the validation period. The WHAT software and recursive digital filter method were used to separate the baseflow from the observed daily flow data. The Exp-Hydro model was calibrated automatically using PSO optimization algorithm and the daily water balance model that developed in this study was calibrated using Goal Seek method. The efficiency of the models were evaluated in this study by means of Kling Gupta criteria (KGE), Nash-Sutcliffe efficiency coefficient (NSE), Correlation coefficient (R), Root Mean Square Error (RMSE) and Mean Absolute Error (MAE).

In the separation process of the base flow values from the total flow of Armand hydrometric station, was done in such a way that in the minimum flows, the separated flow rate corresponds to the minimum values, which in this case, the values of the two constant parameters of the filter parameter and base flow index (ratio of baseflow to the total flow) was chosen as 0.9 and 0.36, respectively. Evaluation of the developed daily water balance model's performance using the KGE, NSE, R, RMSE and MAE showed that these objective functions were 0.76, 0.69, 0.83, 0.25, and 0.11 respectively during the calibration and 0.76, 0.62, 0.85, 0.19, and 0.09 respectively during the validation period. This means the developed daily water balance model in this study has produced good and satisfactory outputs. Also, the evaluation of Exp-Hydro model's performance using the KGE, NSE, R, RMSE and MAE showed that these objective functions were 0.69, 0.37, 0.69, 0.35, and 0.14 respectively during the calibration and 0.6, 0.19, 0.71, 0.28, and 0.11 respectively during the validation period. This means the developed daily water balance model in this study has produced good and satisfactory outputs. This means the Exp-Hydro model has an intermediate performance according to the KGE coefficient in both calibration and validation periods. In addition, the developed daily water balance model in this study estimated the low flows with higher accuracy and both models had underestimated regarding flood flows. Sensitivity analysis of Exp-Hydro model was done manually by changing each parameter of the model and comparing the changes between observation and simulation runoff hydrographs, and the value of efficiency coefficients was also controlled. In this analysis, it was found that since f is the parameter that controls the reduction of runoff depending on the reserve, this parameter has an inverse relationship with simulation runoff value; So that by decreasing the f value, the simulation runoff values increase and become more than the observation runoff values. Also, this parameter was the most sensitive parameter in the Exp-Hydro model. In the developed daily water balance model in this study, m in calculating maximum runoff generated in the catchment bucket using the Reservoir performance exponential function and e in calculating snow melt were the most sensitive parameters. These parameters were the most sensitive parameter in this model; so that by reducing their values, the simulated runoff values of the model decrease and become lower than the observed runoff values. In general, the performance of the developed daily water balance model in this study was better than Exp-Hydro model.

Fire occurrence may lead to a significant impact in many terrestrial ecosystems. This basin scale study attempted to evaluate the effects of fire on the water balance components in the Central Zagros, Iran in 2019. Two modeling frameworks including WetSpass-M spatial model and Bayesian Belief Networks were used to investigate the effect of fire on the amount of runoff, groundwater recharge and evapotranspiration. The first part of the study was water balance simulation at a monthly scale. In addition, the Bayesian belief networks were applied to explore and understand key issues effect on water balance after the fire. Calibration and validation of the WetSpass-M model were performed without considering the effect of fire (2000-2014) and then, the model was run again for the fire scenario by reducing manning roughness coefficient and increasing the θ coefficient. Subsequently, the water balance components of each class, i.e. sparse forest, sparse, semi- dense and dense rangelands were calculated. The percentage of changes in the water balance components was used for comparison. Calibration and validation were performed before finalizing the simulation. A Nash-Sutcliff coefficient of 0.61 and 0.58 was obtained during the calibration and validation, respectively. The analysis of the water balance components results depicted that fire had increased the amount of runoff (13.5%) and it has reduced the amount of groundwater recharge (2.52%) and reduced the amount of actual evaporation (4.45%). The highest increase in runoff belonged to the sparse forest (15.8%), followed by dense (14.5%), semi- dense (13.7%) and sparse rangelands (12.5%), respectively. The results showed that runoff acts as the major factor affecting soil water balance (50.36%) followed by land use (10.49%), and infiltration (10.12%).

The examination of the quality of surface water, which is crucial for water supply, has attracted the interest of numerous researchers for a long time. Various indicators are employed to evaluate the quality of water in rivers, and among these indices is the Iran Surface Water Quality Index (IRWQISC).

In this study, water quality changes of Zayandehroud River located in Chaharmahal va Bakhtiari and Isfahan provinces were evaluated using IRWQISC yearly. Physicochemical parameters including BOD5, COD, DO, pH, EC, nitrate, phosphate, ammonium, temperature and total hardness were used to calculate the IRWQISC index in 7 selected stations for 12 years (2004-2015).

 Comparison electrical (EC) values in the stations showed that, EC increased from the upstream to the downstream of Zayandehroud River, and the concentration of parameters in the first station (Kouhrang tunnel) was much lower than the other stations in most years. The results of IRWQISC index showed that values was relatively good in all stations. The best and lowest water quality according to this index were good and moderate in 2006 and 2010 with the values of 73.2 and 49.6, respectively.

Overall, based on the twelve-year average of IRWQISC index, in the selected stations water quality was moderately good in Gharaghush, Cham-nar, Zamankhan Bridge, Kouhrang tunnel, Sudegan and Horeh stations, and was medium in Azadegan station. Identification of pollution sources and controlling inputted pollutants is necessary to protect and prevent the water quality decreasing of the Zayandehroud River.

Management has become an important environmental issue in the last century. This study was conducted to evaluate the knowledge and attitudes of people regarding urban waste management in Shahrekord in 2013. In order to do this study, the city was divided into three districts and randomly, 50 questionnaires (n=150) were distributed randomly. The results showed a significant relationship between the level of education of people and their knowledge about solid waste management (Chi-Square, p<0.05). There was no relationship between the awareness of people and their age and gender (Chi-Square, p<0.05). These results indicated that in a society with a high level of culture, it is easier to manage solid waste. The mean score of awareness of people in this study was 31.88 ± 0.98 (mean ± SD) of 68 score. According to these results, awareness of people in shahrekord was estimated as medium. Therefore, there is a need for planning to change the behavior and attitudes of families and implement programs to increase people's knowledge based on the social and cultural context of the study area. Therefore, in order to improve solid waste management, it should be used to appropriate educational media to promote public culture in relation to solid waste management.

Various indices are used to assess the suitability of water quality for drinking and agricultural uses. The aim of this study is to investigate the water quality of rivers in Beheshtabad watershed for irrigation purposes. Some water quality parameters were measured in 4 selected stations monthly during spring and summer 2013 and 2019 with using the standard methods. Then, SAR, RSC, SSP, KR, PI and MAR indices were calculated. According to the results, the water quality of the stations was in good condition in terms of PI with values less than 80 mg/l, was in good condition in terms of KR with values less than one and in terms of SSP with values less than 200. The water of the studied rivers was hard in terms of total hardness, sweet in terms of total dissolved solids, and had a good condition in terms of permeability index, residual sodium carbonate, soluble sodium percentage, Kelly’s Ratio, magnesium adsorption ratio indices. According to water quality indices, water quality did not change in 2019 compared to 2013. According to the Wilcox diagram, the water of these rivers were in class C2S1, suitable for agricultural use, and according to the Piper diagram were located in Bicarbonate-Magnesium-Calcium group, in the category of water with temporary hardness. In general, evaluation of water quality of these rivers showed that the water of these rivers did not have limitation in terms of agriculture and were almost acceptable and suitable for irrigation.

In order to maintain the ecological and biological sustainability of wetlands, it is necessary to have a proper understanding of their physical, biological and chemical environment and to investigate the status of heavy metals in them. The purpose of this study was to investigate the contamination of Choghakhor wetland with arsenic, copper, chromium, lead, zinc and cadmium using MI, HPI, HEI, Cd and IRWQIST indices during autumn 2018. Surface water sampling was performed in 10 stations and the concentration of metals was measured by ICP-MASS. The results of calculation of water pollution indices also showed that the wetland water was within the danger threshold class in terms of drinking according to MI index in all of the stations with a value of 1.04 and within the low pollution class according to HEI index with a value of 0.46. Cd index showed low pollution with a value of -4.96 and HPI showed that wetland water was not polluted with heavy metals with a value of 34.73. Also, according to the results of IRWQIST index, water quality was within the good condition of this index in all studied stations in terms of toxic pollutants with the lowest value of 76.4 in station 1 and the highest value of 80.4 in station 10. Therefore, the water quality of Choghakhor wetland was within the low pollution condition in terms of heavy metals in the water, which requires special attention to the water quality of this wetland in order to prevent further pollution.

Variations in the type of storms, distribution of rainfall over the basin and other influencing factors such as soil texture, land use types and slope classes leads to significant differences in the spatial distribution of water components. In this study, using the monthly scale data, including rainfall, groundwater depth, temperature, evaporation and wind speed, WetSpass-M model was used to analyze the spatial distribution of water components at the basin of interest in the south-east of the Karun Basin. The modeled results were calibrated to simulate the monthly streamflow. Considering the fact that the Vanak Basin is a mountainous area, the snow cover maps were introduced to the model in order to include melting process. Evaluation of the model's performance using the Nash-Sutcliff coefficient of 0.61 and 0.54 during the calibration and validation period, respectively showed that this objective function was acceptable. This means the model has produced acceptable outputs. After this step, the spatial distribution of runoff and groundwater recharge in relation to various land use and slope classes were studied. Analysis of the monthly spatial distribution of runoff and groundwater recharge maps showed that due to change in slope and land classes, the runoff coefficient has a significant impact on both groundwater recharge and runoff. In such a way that the forest areas and mild slopes have generated an average 138 mm annual runoff and 596 mm annual recharge accordingly, it means a lower runoff coefficient and higher recharge values. The highest montly recharge value was in February (82 mm in thin forests with the slops of less than 10˚). This may be used to provide a better understanding of the factors affecting the distribution of water balance components or help in the maintenance, management and planning of surface water and groundwater resources.

Surface water, especially rivers, are the important sources for drinking water, agricultural and industrial uses. These reservoirs are easily affected by pollution and various activities. The vulnerability of surface water is greater than that the groundwater. Therefore, the importance of water quality evaluation, especially for drinkable water, has increased due to the reduction in its quality and quantity in recent years. Optimal use and conservation of water resources in terms of quantity and quality are the principles of sustainable development of any country. Water quality indices are among the useful tools in water quality assessment and management. The aim of this study was to evaluate the water quality of the Beheshtabad River in Chaharmahal and Bakhtiari Province, Iran by using the Liou Pollution Index and selecting the most important parameters based on Principal Component Analysis (PCA).

In this study, 7 water quality parameters including temperature, dissolved oxygen, biological oxygen demand, ammonia nitrogen, electrical conductivity, total suspended solids, and potential hydrogen were measured by standard methods along the river in 7 selected stations for 6 months (April to September 2016). Some of these parameters were measured at the sampling site and others in the laboratory. Then, the values of the Liou Pollution Index were calculated to evaluate the water quality of the Beheshtabad River in different stations. In this study, SPSS software was used to analyze the principal component. In the next step, the appropriateness of the statistical universe was assessed using the Kaiser-Meyer-Olkin test.

The results of this study showed that the water quality was good during the study period at sampling stations\, according to the Liou Pollution Index. The value of Liou Pollution Index was in the slightly polluted class in March in station 4. Then, the average of Liou Pollution Index in the Beheshtabad River was compared to different rivers. The result showed that the average of Liou Pollution Index in the studied river is higher than rivers outside Iran. In addition, according to the statistical technique of PCA, two components were introduced as the main component. The first component expressed 57.26% of the total variance and included dissolved oxygen, ammonia nitrogen, biological oxygen demand, electrical conductivity, total suspended solids and potential hydrogen parameters. The second component, temperature, expressed 21.3% of the total variance. Furthermore, the result of comparing the measured quality parameters with the standard value of surface water showed that biological oxygen demand, electrical conductivity, and total suspended solids parameters in some stations were within the standard range and in some others were higher, which indicated a negative result. The best and worst water quality in terms of biological oxygen demand was observed in May and June, respectively. The electrical conductivity in April and May in all stations was within the standard range. However, electrical conductivity was higher than the standard level in June in stations 4 and 5, higher again in July and August in stations 4 to 7, and higher as well in September in stations 2 to 7. The fish farming workshops, industrial pollution and geological survey may be the reasons. The value of potential hydrogen in all of the stations was within the standard range of 6.5 to 9.5. The value of dissolved oxygen was high because of increasing rainfall and stream flows due to the snow melting.

The results of this study showed that the water quality in the Beheshtabad River did not change during the last 6 months (April to September 2016), and water quality was good. In addition, PCA plays an important role in prioritizing the importance of each parameter in the pollution. Therefore, PCA places more important parameters in the first component and less important parameters in the subsequent, respectively. On the other hand, the measurement of physicochemical parameters is important for the study of water quality. This research demonstrates the usefulness and efficiency of the multivariate statistical technique of PCA and the use of indicators for effective management of surface water quality. Therefore, using water resources in the future is possible, and does not endanger their management based on sustainable development

Base-flow can be considered as a part of stream-flow which is connected to discharged flow from aquifers. Due to high variations in rainfall values and other hydrological components in arid and semi-arid areas, watershed scale simulation of the flow is very important. Hydrological models are generally employed as an appropriate tool in this field of study. This work makes uses of use a distributed model called WetSpass-M to investigate water balance and estimate the total flow for Vanak watershed. This model was developed with the aim of simulating water balance in arid and semi-arid regions. Since the model focuses on spatial variations of hydrological components for a desired watershed, all inputs of this model are in the form of raster maps with an ascii format. The temporal resolution for grid inputs was set on a monthly scale except the number of rainy days. The performance of the model for total flow was measured with the Nash-Sutcliff coefficient, the values of 0.57 and 0.56 in both calibration and validation periods were obtained respectively. It also shows an efficiency coefficient of 0.52 for simulated baseflow in both periods. Thus the model result could be regard as an acceptable accuracy for both total flow and base-flow for Vanak watershed. Also a visual comparison of observed and simulated hydrograph demonstrated that model performed better in the case of total flow than filtered base-flow. The other conclusion that we draw from this visualization was low flows simulation were simulated slightly better than high flows. Additionally the results of simulation of water balance components in the study area has demonstrated that the highest portion of annual rainfall in water balance components of the watershed belongs to groundwater recharge.

Unit Hydrograph is a method for flood hydrograph simulation resulting n response to a unit of excess rainfall on the basin. The theory for unit hydrograph is based on two systematic principles called superposition and proportionality. So far several methods of unit hydrograph has been developed which show different responses and functionalities under local conditions of the basin. In this study we used a continuous hydrologic simulation from HEC-HMS model to compare the performance of three unit SMA algorithm and linear reservoir were selected as loss and base-flow functions of the basin, respectively. The flood hydrograph and its specifications including peak discharge and runoff volume were derived using three ways of Snyder, Clark and SCS methods. To compare the performance of models the Nash - Sutcliffe Efficiency was considered as as the objective function. Parameterization and validation of the hydrological parameters were done by changing parameters manually and a applying a trial-error method. Results showed for all three methods the percent of differences between the simulated and observed volumes for runoff was quite very close to each other. While in term of peak flows, the Clarke unit hydrograph method showed the best agreement between the simulated and observed peak discharges.