m.parsinejad

In this study, the Drainmod-S model was used to vary soil salt concentration and the effect of underground drainage on the amount of leaching in a physical model (large lysimeter). A soil extractor was installed at depths of 40, 50, and 70 cm at a distance of 35 cm from the drainage to measure the salinity of the soil solution. In this study, three scenarios were applied including salinity profiles under conventional conditions (mid-season and end-season drainage), soil salinity profiles under different drainage conditions, and prior scenarios with saline irrigation. The second and third scenarios were applied in four drainage stages, respectively. These stages include transplanting and mid-season drainage (days 15 to 20), mid-season drainage (days 35 to 40), mid-season and end-season drainage (days 55 to 60), and end-season drainage (days 75 to 80). The results showed that after simulating the total solute concentration overtime at a depth of 40 cm and comparing it with the measured values, the coefficient of determination (R2) was 0.77 indicating an acceptable Drainmod-S model simulation. This parameter for simulating solute concentration at 50 and 70 cm depth was 0.76 and 0.75, respectively. The mean absolute error parameter (MAE) value was also negligible.

 Surface and groundwater conjunctively interact at different spatial or temporal scales within a plain. In many plain, surface and groundwater resources are used in combination in agriculture. Therefore, it is important to accurately predict the components of groundwater and surface water balance. Despite the rapid expansion of numerical models over the past two decades, there is still a need for comprehensive and integrated assessment of surface and groundwater components. In particular, the interconnection of both surface and groundwater models is important to connect both surface and groundwater, especially the water balance in the unsaturated root zone. In this study the effect of water recharge due to deep percolation from simultaneous supply of irrigation water from surface and groundwater sources, and rainfall from the SWAT model were used to simulate groundwater balance using the combined MDOFLOW-NWT model.

 In this study, the effect of recharge values obtained from the SWAT model was analyzed to simulate the fluctuation of water table, and groundwater balance components using the integrated model of MODFLOW-NWT model in the Mahabad plain. One of the important steps in quantifying the impact of irrigation management, and the change in land-use on the surface and groundwater balance was the simulated recharge due to the deep percolation of rainfall and irrigation water. This was done by the SWAT model, and was used as the boundary condition to the MODFLOW-NWT model. Calibration and validation of groundwater model were also done by trial-and-error and automatic PEST methods. The simulation period was performed for 10 years from the hydrological year of 2009-2010 to 2018-2019, from which 6 and 4 years were used as the period for calibration and validation were from 2009-2010 to 2014-2015 and 2015-2016 to 2018-2019, respectively. Groundwater balance components are naturally different for different years. Therefore, the study was conducted for dry, wet, and normal years. Hydraulic conductivity and specific yield were the used as initial calibration parameters in the MODFLOW-NWT model.

 The results showed a higher hydraulic conductivity and specific yield values for the aquifer was in the southern, central, and northeastern areas of the plain, and the lowest values were in the northern and near the outlet of the plain. After the calibration process, the results showed that an average, 9% of rainfall, and 36% of irrigated water percolate to the aquifer. These observations were confirmed based on a satisfactory and acceptable estimate of the water table level of the model for both calibration and validation periods. The statistical RMSE criteria for calibration and validation periods were 0.35 and 0.34 m, respectively. Also, the results of R2 and NSE criteria were estimated as 0.94 and 0.91 for the calibration period, and 0.93 and 0.89 for the validation period, which indicates that the model was properly calibrated and was well able to simulate groundwater level. The groundwater hydrographs developed from piezometers’ readings, show that the recharge values estimated by the SWAT model, considering the change in land use and irrigation management across the plain, were able to properly simulate groundwater level across the aquifer. Specifically, the studies showed a continuous drop in groundwater level created in the southern and southwestern regions of the aquifer (piezometers of Fakhrighah, Gorg tapeh, and Serah Haji Khosh) due to the presence of high-consumption crops such as apple and alfalfa, and the higher number of operation wells.

The results of this study showed that the recharge values obtained from the calibrated SWAT model was crucial parameters for proper simulation of groundwater, and can significantly improve the model results. The results of the main components of the groundwater balance for different years showed that the amount of recharge due to the infiltration of rainfall, and irrigation were different for each year. Also, interactions between surface and groundwater resources vary from about 30 to 50 million cubic meters between years, indicating a significant interaction between the water resources. In general, the SWAT-MODFLOW-NWT model can be used as a practical tool for proper management of surface and groundwater resources under different management scenarios.

Access to reliable and sustainable water resources is increasingly threatened by increased needs of developing community in a region. The inter-basin water transfer option is considered as an “uncommon” alternative to overcome limitations of fresh water. The purpose of this study is to investigate various aspects in decision making and planning of inter-basin water transfer projects. At the same time, positive and negative challenges, implications and limitations of the economic, social, environmental, hydrological, technical, and political aspects of such decisions in the origin and destination basins are being discussed and compared. According to projects considered in this study composition and role of various aspects in the evaluation and justification of water transfer plans vary with every specific situation. The complexity of the problem is that the contribution and effectiveness of these factors are not necessarily coordinated and cannot be generalized for other situations. Negative feedbacks from an inter-basin water transfer project can end up to be positive for another project. In general, the efficiency of inter-basin water transfer projects depends on a comprehensive approach based on integrated water resources management. A detailed understanding of the needs of the target basin should be coordinated with identifying the existing conditions and predicting future and long-term consequences of the project in the origin basin. All economic, social, cultural, hydrological, environmental, political and technical aspects of a project rely on the concept of sustainable development.

Using plants for the remediation of soils contaminated with heavy metals is an economical, cheap, and effective strategy. The goal of this research was to study the effect of sewage sludge and drought stress on the remediation of cadmium in soil, root uptake by corn plant. This study was carried out on corn in factorial design experiment based on completely randomized design with three replications in three soil pollution levels, namely B1(control soil), B2 (Cd with soil, 20 mg.kg-1), B3 (Cd with sewage sludge with soil treated, 20 mg.kg-1), and two different irrigation regimes, including A1 (full irrigation) and A2 (limited irrigation). The research included two irrigation treatments at two levels of irrigation: 100% of field capacity (A1) and deficit irrigation at 80% of field capacity (A2). The results showed that the soil treated with cadmium and sewage sludge decreased dry and fresh wet weight plant. Sewage sludge increased the amount of cadmium concentration in shoot almost 21% toward the soil treated with cadmium (soil without cadmium); however, it could not increase cadmium uptake due to the decrease in shoot and root dry matter. In limited irrigation, cadmium concentration in shoot and root was reduced by 46 and 16% toward control treatment, respectively. With increasing irrigation and in the soil treated with sewage sludge, the transfer factor of cadmium from root to shoot dry matter increased. The translocation factors were 0.65, 0.5, and 0.13 for sewage sludge contaminated treatments, cadmium-contaminated treatments, and control treatments, respectively. Based on the results, growing plants at an irrigation level of 100% offered nest advantages in terms of higher biomass and efficient Cd removal.

In this study, evaluation of SWAP model in simulating crop yield, water and salt movement in soil were investigated in the wheat- fodder maize cultivated units. The research was conducted in the Voshmgir network, Golestan province. The crop yield, soil humidity and moisture data in different times of agriculture year of 2007-2008 were measured. The measured and simulated data were analyzed. The statistical comparison which was done base on the root mean square error (0.49 ton/ha), correlation coefficient (0.85) and modeling efficiency (0.84), for estimating the total crop dry matter of wheat and fodder maize showed that the estimated crop yield by SWAP agree well with observed values. Suitable values of statistical indexes obtained for estimating soil moisture and soil salinity by SWAP, indicated that considering suitable bottom boundary condition in SWAP which has important role on water and solute balance in soil, has affected on estimation of soil moisture and salinity considerably.

Evaluating drainage systems, exploring their strengths and weaknesses, provides a comprehensive perspective to designers and organizers for optimum design and implementation of guidelines for the future. This study was conducted at an experimental site consisting of three plots on a subsurface drainage network under operation in Behshahr, a coastal region in northern Iran. To evaluate system performance,discharge rates from laterals and the depth of water table between laterals were monitored for a period of three months during the autumn. A second degree equation similar to the Hooghoudt formula was developed to show the relation between the hydraulic head and discharge rate. This equation was used to estimate the hydraulic conductivity (K) and equivalent depth (d) of the impermeable layer. The obtained K for the three plots ranged from 1.4 to 2.4 md-1, which was greater than the design value. This analysis also showed that the laterals were placed on the permeable layer. The Glover-Dumm equation was used to show the rate of water table fall and to calculate the specific yield () S y and reaction factor (α). Based on these results, the actual α was 8%, which is greater than the design value of 4%, and the average S y obtained was 5.7%, compared to the design value of 7.7%. From these results, it can be concluded that the lateral spacing was overestimated.

By evaluating the performance of the current drainage systems and exploration of their strengths and weaknesses a comprehensive perspective can be given to designers and organizers for optimum design and implementation of drainage systems for future plans. This study was conducted to evaluate the performance of subsurface drainage systems using rice husk as envelope in Behshahr, a coastal region in the northern part of Iran. For this purpose, eleven piezometers were installed between two subsurface drains designated as S3PD14 and S3PD15. Subsurface drainage system was monitored during rainfall seasons in 1383 and 1385. Parameters such as daily water table fluctuations and drain discharge rate were recorded. The overall conclusion was that subsurface drainage system performance was not satisfactory due to poor control of water table depth and low water discharge, which was mainly because of the drain envelope clogging. Therefore, the Hooghoudt’s equation should not be used for evaluation of design parameters, due to the fact that this equation is only valid for normal conditions (envelope without clogging).