فصلنامه علوم و مهندسی آبیاری
سال چهل و پنجم شماره 2 (Summer 2022)

Groundwater vulnerability assessment is an effective tool in the joint management of transboundary groundwater, especially in developing countries where data is scarce, monitoring networks are insufficient, and water is both a cause and a target of conflicts. The Jezira Tertiary Limestone Aquifer Transboundary System (JTLATS) region, which Syria, Iraq, and Turkey share, gives a clear description of the shared water problem in developing countries with arid and semiarid environments. In this study, a comprehensive multidisciplinary Groundwater Vulnerability Index (GVI) was developed as a distributed composite index to assess the groundwater vulnerability in JTLATS by combining different environmental and political socioeconomic datasets and models for three periods between 2003 and 2017. The JTLATS was categorized into five zones: very low, low, moderate, high, and very high vulnerability. The results showed a low vulnerability in the southern regions of the aquifer. In comparison, the areas with high vulnerability are primarily spread in the northern and western parts of the JTLATS and along the Euphrates river. The results showed an increase in the percentage of areas with high vulnerability from 10.45% in (2003-2007) to 13.42% and 20.57% of the aquifer area in (2007-2011) and (2011-2017), respectively. The groundwater vulnerability in the aquifer increased with the spread of political instability in both Syria and Iraq and the increase in cultivated areas in Turkey

Due to the increasing demand for water resources in agricultural, domestic, and industrial sectors, the quality of groundwater resources in Iran is at risk. This is more sensitive for the arid and semi-arid regions of the country where the main supply of water is from groundwater resources. The aim of this study was to investigate the vulnerability of the groundwater aquifer of Sirjan Plain (Kerman province). For this purpose, the DRASTIC model was employed, while the Geographical Information System (GIS) software was used to draw the vulnerability map. In the DRASTIC model, the effective characteristics in assessing the vulnerability of groundwater aquifers including water table depth, net recharge, aquifer type, soil type, topographic slope, the media forming the vadose zone, and hydraulic conductivity were used. They were prepared in seven layers in the ArcMap software and by weighing, ranking, and combining these layers, the final vulnerability map of Sirjan Plain with respect to contamination was produced. The results showed that the DRASTIC index for the mentioned plain was between 69 and 141 and that the southern parts of this plain were more susceptible to contamination. Moreover, the investigation of the nitrate ion on the final DRASTIC map showed that all the points with high nitrate content were in the highly contaminated zone. This can confirm the accuracy of the model.

The purpose of this experiment is the comparison between four different method of irrigation which include: furrow irrigation, drip tape irrigation, sub-surface (t-tape 5 cm under soil) drip irrigation, and 2-hole bottle irrigation. This experiment was carried out in 2 continuous sowing season first was from November to January and the second one was from January to March of 2020-2021. In the first experiment, it is observed no significant difference in any components of radish which may be due to mild weather condition and sufficient rain fall. However, the best treatment for arid areas like Ahvaz, was bottle irrigation treatment with yield of 680.6 kg. ha-1</sup> and water productivity of 0.3 kg.m-3</sup> and the least irrigated water. In this second experiment due to the lack of rainfall and abundance of sunlight the amount of water consumed for treatments increased. In the experiment bottle irrigation yield was 298.24 kg. ha-1</sup> and water productivity was 0.105 kg.m-3</sup>. In conclusion bottle irrigation for poor countries with limited water supply, areas where the cost of assembling a drip system is high or in counties or arid areas which suffer from lack of rainfall can be efficient in producing vegetable for household consumption. For better performance this form of irrigation can be automated which increase system’s productivity. Bottle irrigation is low-cost, easy to operated and doesn’t require manpower which makes it the ideal irrigation for poor countries like Africa and arid areas same as Ahvaz.

Denitrification bioreactors for nitrate removal from agricultural water effluents have improved in recent years due to their low cost and ease of use. Scientific results and local experience are required for the optimal use of bioreactors. This study aimed to study nitrate removal efficiency and the effectiveness of each of these factors. Thus, 27 pilot bioreactors had the same volume and depth with different cross-sections in a randomized statistical design. Three geometric shapes of the trapezoid, rectangle, and triangle for the cross-section bioreactors and three organic matters including wood chips, corn stem chips, and wheat straw in 3 replications were used. Nitrate concentration at the inlet of the reactor and their outlet was measured at hydraulic retention times of 3, 6, 12, 16, and 24 hours. According to the average nitrate removal from the effluent, wood chips, wheat straw, and corn stem chips with 31.3, 28.6, and 27%, respectively, were prioritized during the 24-hour hydraulic retention time. Therefore, wood chips are the most suitable organic matter for nitrate removal from drainage water in actual biological reactors compared to other organic materials used in this study. The results demonstrated nitrate removal the 25.6, 30.1, and 35.3% for triangular, rectangular, and trapezoidal geometric shapes, respectively, for wood chips organic matters. Also, reactors with trapezoidal cross-sections have higher efficiency. In sum, this study showed that where there is a limit to the supply of wood chips, wheat straw and corn stalk chips can be used in bioreactors to remove nitrate.

Surface water beside groundwater is dominant in providing water supply in Iran. Hence, for better management of surface water bodies in Iran, the stable isotope technique as an accurate method has been used to study these valuable water resources. The influence of moisture sources on surface water has been reviewed by comparing stable isotope signatures in surface water resources with Iran's MWLs, GMWL, and EMMWL. In addition, the contribution percentage of each air mass (precipitation events originate from each air mass) in the recharge of main rivers across Iran was calculated using the mixing model "Simmr-package" in R. In the Southern Zagros region, the role of cT air mass was dominant, while in the Western Zagros, the role of cP air mass was significant. However, the roles of cP and mP air masses were dominant in the North of Iran. Besides moisture origin, the evaporation effect on surface water resources was also studied. Plotting the average stable isotope content of surface water resources in each mega basin on Iran meteoric water line (IMWL) showed that surface water sources belonging to the Caspian Sea and Urmia lake basins had the most depleted isotope values. However, the surface water resources in the Persian Gulf and the Oman Sea basin as well as the Eastern border basin showed enriched stable isotope values and deviation from IMWL due to the extreme evaporation effect. In conclusion, stable isotopes in surface water resources across Iran were affected simultaneously by evaporation and precipitation moisture source variations.

The main purpose of the present study is to modeling the variation of ground-water quality parameters from 2001 to 2018 and predicting its quality for 2027. To achieve it, we</strong> accessed parameters which included total hardness (TH), total dissolved solids (TDS), sodium (Na), sulfates (SO4</sub>), and chlorides (Cl) which acquired from thirty-four wells in Dehloran Plain, Ilam. Due to the large number of wells, the samples were classified through cluster analysis into six clusters. To determine the number of clusters, a hierarchical clustering method was used. Five time-series models of autoregressive (AR), moving-average (MA), auto-regressive moving-average (ARMA), autoregressive integrated moving-average (ARIMA), and seasonal auto-regressive integrated moving-average (SARIMA) were applied to predict the changing ground-water quality. The best model was selected based on the Autocorrelation function (ACF) and Partial autocorrelation function (PACF), Akaike Information Criterion (AIC), and Coefficient of determination (R2</sup>). The results of the prediction indicated that the average concentration of Cl and Na will increase in all the clusters in 2027. Moreover, the average of the predicted SO4</sub> will increase in all clusters except for the sixth one. The average of TDS also will increase in the first to third clusters, while it will decline in the fourth, fifth, and sixth clusters. The average of the predicted TH in the first, second, third, and fifth clusters will rise, whereas it will be reduced in the fourth and sixth clusters. It can be concluded that the status of ground-water quality is worsening in Dehloran Plain and in 2027 its quality will become lower compared to previous years.

The movement of water and solutes have received the attention of many scientific researchers over the past few years. Saline soils contain a high content of salt that is deposited in micropores. Therefore, it is necessary to leaching these soils during a time period when winter ice melting occurs due to the splitting of micropores affected by expansion and contraction resulting from the freezing and melting of water in the soil. The present research studies some different salt leaching methods on soil samples collected from Nazarabad region, Iran in 2016. Two types of saline and conventional water of the region and three different volumes of water in both continuous and alternate modes were used under frozen and non-frozen conditions. The results showed that frozen treatments that were irrigated continuously with conventional water of the region had the best performance as compared to other studied treatments, being feasible during winter in the studied region.

In this study, Site Groundwater Rating (SGR) in the Amirkabir tunnel has been estimated using Radial Basis Function Networks (RBFNs). SGR is the first rating method that by considering the parameters like joint frequency, joint aperture, schistosity, crashed zones, karstification, soil permeability coefficient, tunnel location in the water table or piezometric surface, and the amount and intensity of annual raining in the area, classifies the tunnel path from the risk of groundwater seepage point of view. In this article, using an RBFN, an estimation of SGR along the Amirkabir tunnel path was performed. Field data obtained from primary studies in the tunnel was used to train and test the prepared network. For the testing set, modeling results showed that SGR could be predicted with the mean error of 3.57% and 4.76% using radial basis network and exact radial basis network functions, respectively. A High correlation between the SGR of the tunnel path and the network answers, confirmed the prepared RBFN.

Global warming phenomenon has affected the hydrologic balance, especially in the arid and semi-arid regions of the world. Therefore, it seems necessary to study these effects to achieve better water resources management system. In this study, maximum and minimum temperature information at the period of 1992-2017 of Khorramabad synoptic station were assessed. the changes of these two characteristics and reference evapotranspiration of Khorramabad plain were investigated by time series analysis. MSE, RMSE and R2</sup> indices were used to validate the models. The results has shown that both maximum and minimum temperature series are static and abnormal, so for normalization, the square root for the minimum data and the squared conversion for the maximum temperature data were used. The ACF chart of both series reaches its local peak at time intervals of multiples of 12, indicating a seasonal trend with a period of 12 months. Finally, the ARIMA model (0,0,4) (0,1,1) for the minimum temperature and the ARIMA model (0,0,1) (0,1,1) for the maximum temperature were the best chosen models. The values of R2</sup>, RMSE and MSE for the selected maximum temperature model were 0.971, 1.656 and 0.991, respectively, and for the minimum temperature model 0.965, 1.304 and 0.991, respectively, which indicates the acceptable accuracy of the proposed models. Forecasts indicate an increase in the minimum and maximum temperatures in the whole future period compared to the base period. The peak of this increase occurs in June, July and August for the minimum and maximum temperatures respectively for Tmin: 2.03, 1.54, 1.75, and for Tmax: 1.91, 2.03, 1.77 Celsius. In the next period, the reference evapotranspiration will increase on average compared to the base period, with most of this increase occurring in March, April, and May.

In this study, to investigate the effects of land use changes on hydrological components of the Doroudzan Dam basin for the three periods of 1979 to 1990, from 1987 to 1999, and from 1997 to 2006, three land use maps for the years 1986, 1996 and 2005 were prepared. Then, using the semi-distributed SWAT model, the basin hydrology processes were simulated. After calibration to validate the model, validation was performed for each period. The Nash-Sutcliffe coefficient in calibration and validation of the first period was 0.74 and 0.52, in the second period was 0.88 and 0.61, and in the third period was 0.83 and 0.8, respectively. Also, three scenarios were defined to determine the effect of each land use management application in the study time step (1979 to 2006). All the scenarios were simulated under the same conditions for rainfall and temperature and  different land use maps. The impact of land use change under these scenarios is well observed, with the latter having a 27.7% decrease in surface runoff compared to the control scenario, as rangeland, forest, agricultural cover increased, wasteland decreased. Has found. In the third scenario, surface runoff decreased by 13.5% compared to the control scenario, but increased compared to the second scenario, as rangeland cover decreased and wasteland increased.