Showing 7 results for Modflow
S. Dowlatabadi, S. M. A. Zomorodian,
Volume 19, Issue 71 (6-2015)
Abstract
One of the most essential and appropriate groundwater model components is accurate information of the recharge values among input data often introduced to the model as the percentage of rainfall of aquifers. The recharge values are influenced by many temporal and spatial factors. Firoozabad plain is one of the suitable plains for agriculture in the Fars province in which utilization of groundwater resources has been banned since 23 September 2002, due to the declining water level and negative balance. The main purpose of this study was to estimate the recharge values of groundwater aquifer by using SWAT in the MODFLOW model. Firstly, surface water was simulated via SWAT model, and sensitivity analysis, calibration, validation and uncertainty analysis of results were performed by SWAT-CUP software. After extraction of aquifer recharge values from the calibrated model, the groundwater of basin was simulated via MODFLOW model in both steady and unsteady conditions. Following the model calibration, the hydrodynamic coefficients of plain were determined and sensitivity of model was checked in terms of hydraulic conductivity and discharge rate of pumping wells. As for the confidence, the model was revalidated, which proved in simulating the behavior of the aquifer very well.
J. Abedi Koupai, M. Golabchian,
Volume 19, Issue 72 (8-2015)
Abstract
Nowadays, due to the high potential of advanced simulation models for groundwater, these models are comprehensively applied in the management and exploitation of groundwater resources. The aim of this study was to investigate and simulate the groundwater resources in Kouhpayeh-Segzi watershed and in particular estimate the hydrodynamic coefficients of unconfined aquifer. After preparation of input layers, efficient parameters in modeling, boundary conditions and aquifer gridding were determined. Then, based on the available data, the model was run and calibrated in a steady state for the water year 2002 and in a transient state for water years between 2002 and 2004. The simulation outputs were confidently verified for the water year 2005. The results indicated that the hydraulic conductivities and storage coefficients were ranged on sub-basin from 15.26 to 19.87 m/day and 0.0107 to 0.0186, respectively. From aquifer's hydrograph for a period from 1995 to 2012, water level dropped about 25 cm. This may be due to two irrigation networks (green area). This leads to rising water level. By ignoring these recharge areas, water level declined up to 80 cm per year. With sensitivity analysis in transient state to evaluate the efficacy of each parameter, the accuracy of the results of calibration model was confirmed. In addition, the hydraulic head values computed by MODFLOW were in good agreement with those that were collected from all piezometers.
M. Goodarzi, J. Abedi Koupai, M. Heidarpour, H. R. Safavi,
Volume 19, Issue 73 (11-2015)
Abstract
Due to the time and space changes of hydrological events in the arid and semi-arid regions, recharge measurement in these areas is very difficult. Hence, groundwater recharge is a complicated phenomenon for which there is not a fixed method to determine. The aim of this research was to develop a method for estimation of groundwater recharge based on a hybrid method. In this study, a hybrid method for calculating recharge was presented by combining empirical methods with a mathematical model, MODFLOW, and AHP analysis. The results showed that the most important parameters affecting groundwater recharge are soil properties, unsaturated thickness, land cover, land slope, irrigation and precipitation, from which the soil properties and precipitation are most important. The results showed that the overall impact of small changes in precipitation and temperature significantly affect the groundwater recharge, and heavy soils are much more sensitive to these changes than light soils. By changing 10% precipitation, the recharge rate is changed between 16% and 77% and by changing 1ºC temperature, the recharge rate is changed between 6% and 42%. Also, results showed that precipitation and evapotranspiration changes in four months including December, January, February and March had significant effects on annual recharge rate. Using the results of this research, the vulnerable areas of the plain, appropriate places and time for artificial recharge could be identified. Overall, the results of this study can be useful in various aspects of groundwater management.
F. Mohammadmirzaei, M. Zakerinia, A. Hezarjaribi,
Volume 24, Issue 2 (7-2020)
Abstract
Increase in population, agricultural development, and the reduction of surface water resources have resulted in an untapped harvest of ground water. On the other hand, the lack of attention to the balance between the exploitation and recharge of aquifers has led to a drop in water level in the aquifer. To understand the behavior of the ground water system and the status of resources and uses in the basin, as well as the situation of water exchange in these two parts, it is possible to connect reliable groundwater and surface water models The purpose of this study was to simulate Gorganroud aquifer flow by using using the groundwater model to understand the behavior of the aquifer system in different hydrological conditions and to provide a management solution to improve the supply and demand conditions. First, the status of the aquifer under study was simulated by using the information available in the area by Modflow; then the groundwater model results were transferred to the Water Evaluation and Planning model (WEAP) by the LINK KITCHEN Software. Then different management scenarios including increased irrigation efficiency in agriculture, the use of refinery effluents and the reduction of river flow due to climate changes were considered as two combinations of the above scenarios to alleviate water demand under this scenario; so, projections for a period of 20 years water resources of the basin were studied. The results of modflow calibration showed that there was a good agreement between observation and simulated water table, such that the RMSE for Steady and Transient condition was 0/972 and 0/97, respectively. The results also showed that simultaneously applying multiple water management strategies seems to be better than any of its individual states, thereby reducing water withdrawal on various resources.
Sh. Nasiri, H. Ansari, A.n. Ziaei,
Volume 25, Issue 3 (12-2021)
Abstract
Reducing surface water resources and successive droughts and consequently excessive use of groundwater resources, especially for agricultural purposes, have caused irreparable damage to the natural resources of the country. In the meantime, knowing the status of the water balance of the plain can help to effective management of water resources in the region. Samalqan plain is located in a semi-arid climate in North Khorasan Province. Since the surface water resources for water supply are not very reliable, so, the main source of water supply in the region is
well. Due to the existence of rivers in the plain, the low thickness of the alluvium, groundwater level fluctuations, and the high uncertainty in the calculation of hydrodynamic coefficients, the need for careful hydrogeological studies and determining the role of each parameter affecting groundwater is necessary. This study was conducted to simulate the Samalqan aquifer and analysis of water balance for the years 2003 to 2013 using the MODFLOW model. To identify the groundwater recharge rate, this component was estimated by the SWAT model. Calibration and validation of the model with an error of 1.1% and 1.2%, respectively, indicated that an appropriate estimation between the simulated and observed heads. Assessment of the groundwater hydrograph in the observation wells showed that the groundwater level in most places has many monthly and seasonal fluctuations. After drawing the potential lines of the plain, the inputs and outputs were identified, and using the reserve volume changes, the water balance was determined. The results showed that the water balance of the plain was negative and the reservoir deficit was estimated at 9.14 million cubic meters. Therefore, this model can be used to predict the future situation of aquifer and the management of
water resources in the region.
Sh. Nasiri, Hossein Ansari, A.n. Ziaei,
Volume 26, Issue 1 (5-2022)
Abstract
Hydrological models are useful tools in water resources planning, but some of them do not have satisfactory performance on a regional scale. Hydrological models are appropriate for a specific spatial scale and the lack of input data is a limiting factor in the modeling. One way to overcome this limitation is by using a flexible comprehensive model in different watersheds. Since surface and ground water have dynamic interaction in environmental ecosystems and form a combined water resources system so, the application of two general methods including fully integrated and coupled regions has been evaluated in this research. An investigation of these methods showed that the major focus in most studies is on increasing the accuracy of recharge and evapotranspiration rates in simulation. The results showed that the simultaneous use of SWAT and MODFLOW models to understand the hydrological conditions in a region has been able to cover the defects associated with the semi-distributional and distributive constraints of two models, simulating the surface-groundwater and the interaction between the aquifer and river. This method can provide useful information about the water balance of the basin and help to plan water resources more accurately
G.m. Samadi, F. Mousavi, H. Karami,
Volume 26, Issue 3 (12-2022)
Abstract
The impact of different management options on the region and the existing conditions can be evaluated with minimal cost and time to select the most practical case using various tools including mathematical models. In this study, the SWAT hydrological model was performed from 2009 to 2019 using climatic, hydrological, and hydrometric data in the Malayer catchment, and the final model was validated by SWAT-CUP. To reduce the amount of uncertainty in the input parameters to the MODFLOW model, using the values of surface recharge from the implementation of the SWAT hydrological model, quantitative modeling of Malayer aquifer was performed more reliably in GMS software by using MODFLOW model. After modeling the study area in the 2009-2018 period and calibrating the model in the years from 2018 to 2019, the mean values of absolute error (MAE) were 0.35-0.65 m, and root means square error (RMSE) was 0.62-0.94 m, which seems acceptable considering computational and observational heads equal to 1650 m. Results of water level changes in observation wells located in the Malayer region indicate that the groundwater level in the aquifer has decreased by an average value of 9.7 m in the 10-year study period.
