modflow

The primary source of water supply in Dasht-e Hengam is groundwater; therefore, it is necessary to study the qualitative and quantitative status of groundwater resources in this area due to its high agricultural use. Groundwater researchers have used mathematical models, MODFLOW and MT3DMS, to simulate groundwater and evaluate their efficiency (Sadeghi Goghari, 2013; Paliz, 2014; Yousefi et al., 2014; Abbasi, 2014).Simulation of groundwater resources shows that droughts and wetlands have little effect on groundwater in Sarvestan plain (Torshizi et al., 2015), and the main reason for declining aquifers Is the uncontrolled extraction of wells from the groundwater aquifer (Torshizi et al., 2015; Jabbari et al., 2015; Runama and Jafari, 2017). In addition, the level of pollution has increased in some plains (Deymehkar, 2016; Fasihi and Zare Abyaneh, 2018; Shahnavaz, 2019). For improving the quality of aquifers, aquifer feeding (Ghafari et al., 2020), a suitable hydraulic system (Ghafari et al., 2020), and (or) reactive-nano-iron barriers have been used (Divya et al., 2020).In this research, with the help of two powerful specialized tools of water resources, MODFLOW and MT3DMS particle transfer model, the plain aquifer during the simulation and the quantitative and qualitative status of groundwater is investigated.

Dasht-e Hengam, with approximately ​​525 square kilometers, is located in 76 kilometers of Qirokarzin city and 220 kilometers south of Shiraz city. Geological conditions, alluvial sediment status, location of available groundwater resources, and observation wells are plain alluvial aquifers (Regional Water Company of Fars, 2012). ‎Fig. 1 shows the geographical location of Hengam Plain (Regional Water Company of Fars, 2012), and ‎Table 1 shows the monthly distribution of rainfall in the plain. Data from ten observation wells in the groundwater aquifer, ‎Fig. 2, were used to calibrate quantitative and qualitative models of the plain. The amount of feed from the surface includes returned water from agricultural and drinking wells, from the river (runoff), drainage, annual rainfall at the aquifer level, and sewage, the information of which is listed in (Regional Water Company of Fars, 2012). Piezometers per month were first interpolated in GIS software and then transferred to the model. The model network cell size for all possible observation wells in the area with a cell size of 150 m was considered. A series of pilot points (Figure 3) were designed at the range level for more accurate and faster calibration.

By calibrating the model over 36 months, the optimal hydraulic conductivity value with an average of 17.3 and a standard deviation of 24.9 m/day was obtained (‎Fig. 5). The highest hydraulic conductivity coefficient is related to the northern and northwestern parts of the plain, and the lowest coefficient occurs at the highest accumulation of exploitation wells. Also, the amount of specific storativity varies between 0.00167 and 0.636, with an average of 0.103 and a standard deviation of 0.117.The slight difference between the computational and observational data, ‎Fig. 6 to ‎Fig. 9, indicates desired modeling in the scope of the study. The correlation between computational and observational values ​​(‎Fig. 10, typically shown for the simulation month 60) also shows this.The quantitative model, MODFLOW, shows that the aquifer volume decreases daily during the 36-month modeling period (‎Fig. 11 and ‎Fig. 12); as a result, the amount of groundwater discharge from the boundary of the plain vanishes due to falling groundwater levels. Also, the volume of groundwater inflow is about 24.4 Mm3/year, the recharge into the aquifer from the surface is approximately 10.97 Mm3/year, discharge from alluvial groundwater and complex formation (often wells) is about 39.43 Mm3/year, and the volume of output due to natural drainage is almost 0.546 Mm3/year. The aquifer storage volume is 12.1, and the reservoir withdrawal volume is about 13.5 Mm3/year (‎Fig. 13); thus, the reservoir deficit is 1.36 Mm3/year.‎Fig. 14 shows the groundwater level of the Hengam aquifer in the last step of the 36 months, which, compared to the beginning of the period, indicates a drop in water after three years of groundwater abstraction. ‎Fig. 15 shows that the water level decreased by about 4.5 m during the simulation period, equivalent to an average annual drop of about 1.5 m.MT3DMS package and chemical quality data related to 10 agricultural wells were used to prepare a qualitative model. Information about the location of sampling wells and initial concentration of qualitative parameters in the aquifer in ‎Table 4 and the calibrated value of qualitative parameters are presented in ‎Table 5 for the last calibration step. The distribution of TDS in Figures 19 to 21 shows that the contamination is constantly expanding during these three years, and ‎Fig. 22 shows that as the groundwater level decreases, the TDS contamination increases during the simulation period.

In this study, using MODFLOW and MT3DMS, the quantitative and qualitative status of Hengam plain was investigated. The groundwater flow model created the slightest statistical deviation on the optimization parameters according to the automated calibration and validation approach. The results showed the nonlinear trend of groundwater level sagging with the final year conditions in an optimistic manner.

Today, with the expansion of communities and their increasing groundwater exploitation, the scarcity of groundwater resources as a serious problem in most arid and semi-arid regions, is the main concern of managers and planners of the country's water sector. In the present study, it is intended to provide practical solutions by modeling the aquifer and applying the scenario of flood distribution to maintain and improve the aquifer condition. Since Salmas plain is located in the semi-arid region and also due to the uncontrolled abstraction, the Salmas aquifer suffers a severe crisis. To study the changes in groundwater level in Salmas aquifer after applying the flood distribution scenario, the MODFLOW mathematical code in GMS was used. The mathematical model was prepared and implemented for both steady and transient states. Then the flood spreading scenario was applied and the results showed that 2.6 million cubic meters is stored in the aquifer, which is equivalent to 44.7% of the total water fed to the aquifer. Applying the scenario, the water level increased on average by 13 cm at the end of October 2012, and the change in groundwater level was in the southern and middle part of the aquifer.

In recent decades, increasing water demand in Iran has resulted in excessive water usage, specially groundwater. Due to the increase in aquifer water usage, groundwater management should considerate to meet consumers needs and achieving a fair benefit in addition aquifer sustainability and future needs. This study aimed to manage and reduce water usage of Haji Abad aquifer in Hormozgan province. first, Groundwater simulation model was calibrated and validated by MODFLOW software and then, the new operation wells discharge values were calculated by using the cooperative method (bankruptcy) and these values were entered into the simulation model and the results were compared with the current situation. In this study, five bankruptcy methods proportional (P), Constrained Equal Award (CEA), Constrained Equal Loss (CEL), Talmud (Tal) and Piniles (Pin) are used to manage operation wells discharge, The annual discharge values of the operation wells are claimer demand and the amount of groundwater recharge which calculated by the simulation model in each polygon are the available water. In these five methods, groundwater head increased and overall aquifer status improved relatively well. Finally, the Bankruptcy Allocation stability index (BASI) for five methods was calculated and compared.compared.

Monitoring the quantity and quality of groundwater is a non-separable part of the environmental information system. There are several ways to design a groundwater monitoring network. In the present study, we attempted to develop a new method for flexible design. Flexible means that the results of this study allow the decision maker to select a limited number of high-priority wells, taking into account the budget level allocated to the project. It is also possible to use this method easily for wells under study or construction. Also, in this design method, monitoring is not limited to just one parameter (in the present study, EC concentration) and one or more parameters can be easily replaced. The DRASTIC model was used to calculate the aquifer vulnerability, which consists of seven layers of aquifer, including groundwater depth, net recharge, aquifer media, soil type, topography, impact of vadose zone, and the hydraulic conductivity of aquifers. The layers were optimized using differential evolutionary algorithm (DE) to find the highest correlation between the vulnerable points and the points with the highest concentration of EC. As a result of this optimization, the amount net recharge (the actual infiltration of water into the aquifer) had the highest correlation, which was confirmed by comparing net recharge and EC maps. With the help of WhAEM2000, 10-year capture zone of existing wells was calculated. The final priority of the wells was calculated by linking of these models.

In order to ensure sustainable water management, a thorough understanding of the hydrological conditions and the interactions between surface and ground water. In this paper used from corrected multifunctional and integrated hydrologic model SWAT-MODFLOW to simulation quantitative processes of surface and ground water and simultaneous exchanges between them at the Shazand catchment. After the calibration, results of calibration SWAT surface water model to Duab bridge hydrometrical station that located at the Shara river and the basin's output, shown coefficient value of R2 and Nash-Sutcliff 0.64 and 0.63, respectively. At the groundwater part, the amount of RMSE for 19 observational wells calculated 1.72 m that is an acceptable level. With regard to the results obtained in the two surface and ground water sections, the performance of the model with regard to the integrity and consideration of all exchanges of the two models is concurrently and in a wide area acceptable and can recommended use from integrated SWAT-MODFLOW model In integrated simulation of the hydrological conditions of the catchment in a comprehensive manner. To evaluate the application of SWAT-MODFLOW integrated model at the basin level, the model was used to estimate the impact of a 10% reduction in water resources scenario using an index on the existing water resources system, the results obtained from the water index. The availability of WAI used in this study indicates an improvement in the value of the indicator and thus an improvement in the status of the water resources system compared to the status quo.

In most areas, much of the drinking water supplies from groundwater resources are constantly threatened by various pollutants. In this paper, the groundwater quality protection zone is defined using MODFLOW, WhAEM2000 and DRASTIC models. In this research at the beginning, the conceptual model of Rudan plain aquifer has been made by MODFLOW model. The model is calibrated for the year of 1389-90 in the steady state with the root mean square error about 1.49 m error. Also, the model is calibrated for the period 1389-91 with the root mean square error about 2.32. Then, the groundwater quality protection zone is determined by using WhAEM2000 model in both constant radius and analytical methods. Finally, the vulnerability level of the aquifer was identified by using the DRASTIC model and considered for determining the protection zone area.Results showed that most of the wells are located in the highly vulnerable zone with agricultural land use. So, Because of the high risk of groundwater pollution, extra travel time for groundwater (about 10 years) must be considered for determination of protection zone. Also, for less vulnerable areas and other land use areas, a smaller protection area can be applied, since the application of greater zone in these areas will lead to a lot of social and economic costs.