Mehdi Panahi; Farhad Misagi; Parisa Asgari
Volume 16, Issue 1 , April 2018, , Pages 1-14
Abstract
Introduction: In recent decades, climate change and the lack of adequate and timely rainfall, due to the lack of water supply for irrigated plants, the limitation of renewable land and water resources, the heterogeneous distribution of spatial and temporal distribution of fresh water, as well as the ...
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Introduction: In recent decades, climate change and the lack of adequate and timely rainfall, due to the lack of water supply for irrigated plants, the limitation of renewable land and water resources, the heterogeneous distribution of spatial and temporal distribution of fresh water, as well as the rapid growth of the world population, including Iran, There are increasing problems in providing water resources for various uses. One of the main requirements for meeting the world's food needs is access to sustainable agriculture and its development. In order to achieve such a goal, it should be avoided by adopting appropriate measures to prevent damage to the system of limited resources in each region. Groundwater is always a source of water supplies as a source of fresh water. Underground water management in the first stage requires the identification and operation of aquifers in natural conditions. In most hydrological issues and underground water resources studies, the availability of groundwater resources data and statistics is of great importance. In order to assess the effects of development in existing conditions and provide management methods for groundwater resources, both quantitatively and qualitatively, mathematical and computer simulation of these resources is a powerful tool in optimal utilization of these resources. Maerials and methods: Numerical modeling of groundwater in aquifers is an important tool for the management of water resources. This model can be used to estimate the hydraulic parameters as well as water resources management. The aim of this study was to simulate the fluctuations in groundwater levels in the aquifer by GMS software Zanjan located at a latitude of 47 degrees 50 minutes 49 ° East and latitude 36 degrees 20 minutes north and 37 degrees is located. This model is a combination of code Modflow and GIS using the finite difference method, the underground water level simulation. For this research the information needed to run the model include: Positions border aquifers, at different heights above ground level bed rock aquifer, the amount of withdrawals from wells tapping position, the position and the water level in observation wells, hydraulic conductivity layer and nutrition, were introduced to the model. After preparation of the conceptual model and the determination of initial and boundary conditions, the simulation will be discussed. The flow simulation model was calibrated in a steady flow. Results and discution: The results of the calibration results in a steady state a reasonable balance between the observed and calculated in October 2002 showed. After calibration nutritional value 0/000321 meters per day was that this amount is 1/98 times the amount of power input to the model. The amount of horizontal hydraulic conductivity layers of sand, silt and sand, gravel 28.57 and 40.4 respectively km per day and then unsteady flow model calibration mode for distances between 2002 and 2007, using trial and error to achieve the best balance between the level observed daily and were calculated and projected groundwater levels drop, based on the implementation of the model for 2007 and 2015 and 2022 was performed. The root mean square error, mean absolute error and mean error, respectively, 17/41, 15/22 and -0.6, respectively. After calibration nutritional value 0.000321 meters per day was that this amount is 1/98 times the amount of input supply model. The amount of horizontal hydraulic conductivity layers of sand, silt and sand, gravel 28/57 and 40/4 respectively km per day and then unsteady flow model calibration mode for distances between 2002 and 2007, using trial and error to achieve the best result among the observed daily balance and balance was calculated. The root mean square error and average error with respect to the amount equal to 26/29 and -8/43 showed good accuracy model. The water level calculated for the converter, groundwater flow is from the southeast to the northwest of the current slope correspond area. Conclusion: The model was implemented with the assumption of the rate of groundwater abatement and constant nutrition for a 15-year interval from 2007 to 2022 Maps obtained for the groundwater level in the years reflects a sharp drop in the water level continued indiscriminate harvesting of underground water aquifer Zanjan.
Mehdi Panahi; Farhad Misaqi; Farid Ghanbari
Volume 15, Issue 3 , October 2017, , Pages 19-38
Abstract
Introduction: Groundwater has long been the most ´trusted water source of human beings that is used in the agricultural and drinking sectors. In order to be aware of water condition and its optimized management, it is necessary to carefully examine groundwater level fluctuations and groundwater ...
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Introduction: Groundwater has long been the most ´trusted water source of human beings that is used in the agricultural and drinking sectors. In order to be aware of water condition and its optimized management, it is necessary to carefully examine groundwater level fluctuations and groundwater quality that are influenced by different factors. While carefully monitoring the fluctuations and quality of groundwater, we can have reliable planning in water supply and source management. Therefore, this study aims to determine the trend of changes in quality parameters of groundwater of Shabestar plain in order to understand the quality of groundwater and to specify its application. Material and methods: In this study, in order to understand the quality of Shabestar plain’s groundwater and to specify its application, the chemical results of 15 qualitative variables of groundwater samples belonging to 13 stations located in the study area during the years 1382-1999 were compared while using non-parametric Mann-Kendall test, and then effect of the first-order autocorrelation was eliminated from the data series. Slope of the trend line was calculated by the age method. The qualitative parameters in this study are total anions, total cations, EC, SAR, CL--, , Ca2+, TH, Ph, TDS, , Na%, Na+, Mg2+ and K+ that are measured two times every year. Results and discussion: The results show that time series related to qualitative variables has ascending trend in most of stations (except Ali-shah station, Sefid-kamar station and low water months of Shabestar plain). They show positively significant trend at 5% level with 36 series (18%) in months of high level of water and with 17 series (9%) in months of low level of water. Furthermore, “Ali-shah” and “Sefid-kamar” stations have the highest rank in the highest negative trend in two months with high- and low- levels of water. The comparison of stations suggests that quality of Shabestar plain’s groundwater has critical condition in southern part of plain. Generally we can conclude that the quality of groundwater in the study area has decreased over time. The results achieved from investigating the values of time series correlation coefficients of qualitative variables with normal annual precipitation in the periods (1382-1388) show that none of the qualitative variables have a special significance at the 5% level with the amount of annual precipitation. The overall result of this section suggests the lack of relationship between annual precipitation and qualitative variables, while ground water level has almost steadily dropped with quality variables during common statistical years (1383-1391). Also, climatic variables such as rainfall, temperature and evaporation were not identified as factors in changing the qualitative characteristics of Shabestar plain’s groundwater and we come to this conclusion that their adverse changes were influenced by human factors. Conclusions: According to achieved results, we can say that if the current condition continues, it is not possible to steadily use groundwater source in Shabestar plain. Water quality will be negatively affected by the lack of treatment of urban and industrial wastewater, the release of agricultural wastes at the plains, adjacency to Urmia Lake, and the development of salt marsh.
