Visual Modflow 4.2 Free Download 18
Evangelino Cousteau
Visual MODFLOW Flex brings together industry-standard codes for groundwater flow and contaminant transport, essential analysis and calibration tools, and stunning 3D visualization capabilities in a single environment.
Built and designed on the latest in 3D visualization technology, Visual MODFLOW Flex allows you to effectively present and communicate your data to colleagues and stakeholders with impressive visual renderings of your hydrogeologic model.
Visual MODFLOW Flex provides various grid types from which you can generate your numerical model. Easily experiment with different grid types and choose the one that gives you the best, most stable model.
The key feature of the VMOD-Flex model is the Graphical User Interface (GUI) that allows for pre-processing of data and visualization of outputs. Visual Modflow has three versions: basic, professional, and premium, which vary based on features and price. . The basic version includes general features of MODFLOW, while the professional and premium versions have additional capabilities, such as parameter estimation, different grid size, and inclusion of different groundwater models that account for salinity or pollutants.
Studying the surface and subsurface geological characteristics of the area concerned is vital for detecting the hydrogeological configuration in terms of aquifer properties, water potentiality, and water flow. The geomorphology of El Minya province resembles the prevailing conditions in the Nile Valley. The limestone plateau borders the valley from both sides along its length, causing a steep slope of the earth's surface on both sides of the Nile Valley to the east and west. Three geomorphological units are studied (Fig. 2) (Said 1981):
Limestone Calcareous Structural Plateau (Middle Eocene limestone) is structurally formed and bounds the Nile Valley east and west. The surface lithologic units exposed in the study area range from Middle Eocene limestone to Oligocene-Pleistocene gravel and sand and Quaternary deposits (Fig. 3) (Abdel Aziz 1994; Abu Heleika and Niesner 2009). The subsurface stratigraphic sequence in the study area ranges from the Pre-Cambrian to the Quaternary ages; it is built-up up from the base to the top as follows:
The Nubia Sandstone Sequence rests unconformably on the rugged surface of the basement complex. It comprises all clastic sediments ranging from the Upper Cretaceous to the Pre-Cambrian Basement consisting of alternating sandstone beds, shale, and clay with thickness ranges from 500 to 2500 m in the study area (LaMoreaux et al. 2008).
Tertiary carbonate rocks of the Eocene age consist of limestone dolomitic limestone and cover the plateau area surrounding the depressions of south-Kharga, El-Kharga, El-Dakhla El-Farafra, El-Bahariya, Siwa, and Qattara. Their thickness ranges from 200 to 1200 m (RIGW 1992, 2015).
Four aquifers are present in the study area: Quaternary alluvial deposits, Oligocene sandstone, Eocene limestone, and Nubian sandstone aquifers. The groundwater of the Quaternary and Oligocene sandstone is recorded under unconfined conditions, and Pleistocene sediments overlie the fractured Eocene limestone. In contrast, the Nubian sandstone is registered as a confined aquifer (Yousif et al. 2018). Regionally, groundwater exhibits a northward trending gradient in this area. The recharge of the Upper Eocene water-bearing units may occur by seepage from the Nile and by upward percolation of groundwater in hydraulic charge from the deep NSS through the upper confining Cenomanian shale. No recharge of the upper Pleistocene aquifer is expected to occur from the average 4 mm of the annual rainfall occurring as very limited precipitations and believed to be lost in evaporation (Tantawi et al. 2005). The Middle Eocene aquifer has an isotopic signature of the modern Nile. (Yousif et al. 2018). The investigated groundwater flow pattern in the Eocene aquifer shows the flow direction from the southwest. The total hydraulic head value is 50 m.a.m.s.l. and reaches 30 m.a.m.s.l. northeast (Fig. 4). Figure 5 shows the hydro-stratigraphic cross sections in the study area. The present estimation of groundwater quality of the Eocene aquifer in the new development study area is based on the results of the chemical analysis of groundwater samples collected from the boreholes. The total dissolved solids (TDS) content varies between 2000 and 3000 mg/l (Fig. 6). The spatial extension of the Eocene aquifer in the study area and its approximated thickness is calculated using spatial interpolation inverse distance weighted (IDW) in GIS Tools (Fig. 7).
The procedures of this work are based on applying and integrating two techniques, the visual MODFLOW USGS 2005 software groundwater model and multi-criteria decision analysis (MCDA) model. The operational steps and modeling processes are illustrated in a flowchart (Fig. 8).
Groundwater flow models are used to calculate the rate and direction of groundwater movement through aquifers and confining units in the subsurface; these calculations are referred to as simulations (Mandle 2002). The model is also used to simulate possible future changes in hydraulic head or groundwater flows due to future changes in aquifer system constraints. MODFLOW 2005 is used as a numerical model. It is a standard USGS software developed by McDonald and Harbaugh (1988) and Harbaugh (2005). The integral finite difference method is employed to resolve the transient flux equation. There are virtually no hydrological studies specifically focused on the study area. Currently, the drilling of test wells is being carried out under the Ministry of Water Resources and Irrigation (MRWI) supervision. Available and updated field data from wells in the Eocene aquifer are collected and organized by integrating the attributes and spatial databases with GIS tools. Arc GIS is used to manage the model's spatially distributed input parameters and outputs. The database constructed in the GIS technique is imported into the conceptual model, including the ASTER (Dem) 1-ARC resolution with 30 m, the measured potentiometric water levels, hydraulic properties, and recharge and discharge components.
When studying the dynamic behavior of the aquifer to determine the amount of change in groundwater levels, it is necessary to decide on the initial conditions of the groundwater levels. Due to the lack of available data for the study area, current static groundwater levels of the investigated wells have been used as the initial distribution head for the model (Fig. 10).
The present estimation of aquifer characteristics, including transmissivity, hydraulic conductivity, and storativity, is based on step-drawdown, constant discharge, and recovery tests for the investigated wells in the modeled area. Six wells were selected to represent field measurement data; their locations are shown in Fig. 4. The data of step drawdown tests are plotted on a linear scale (Fig. 11) to estimate the general well equation using Jacob (1947) and Rorabaugh (1953) techniques.
The objective of model calibration is to assure that it can produce field-measured heads, which are calibration values. The calibration process has been carried out for the boundary conditions and the hydraulic conductivity spatial distribution modification to match the observed and simulated groundwater heads (Figs. 13, 14). The following basics and assumptions were considered during the model verification:
Transient simulation is needed to solve time-dependent groundwater problems. The calibrated steady-state model is run under transient calibration for one year of pumping to adjust the storativity values (Fig. 15). The model is subjected to sensitivity analysis to quantify the uncertainty in the calibrated parameters. It revealed the high sensitivity of the model toward the boundary conditions, hydraulic conductivity, and storativity, respectively. The new agricultural development project in the study area covers 4000 acres. Proposed pumping wells were distributed with a spacing of 1000 m to decrease the pressure on the aquifer and reduce the interference between the wells. Virtual observation wells were distributed among the extraction wells to monitor the groundwater levels under the impact of each development plan.
Based on the obtained results of the optimal scenario for groundwater sustainability of the applied visual MODFLOW model, multi-criteria decision analysis (MCDA) model technique (Malczewski 1999, 2000) is used to assess the impact of groundwater consumption by detecting the groundwater suitability zones after long run reclamation in the concerned development area. The (MCDA) model is not a substitute for cost-benefit analysis; it is a complement analysis it gives a range of decisions. In this work, the MCDA model integrates geospatial data of the most effective parameters in the groundwater potentials both for aquifer hydraulic characteristics and groundwater quality by merging all multi-criteria layers into one perspective layer for groundwater exploitation. The contributing criteria are groundwater levels (GWL) which are obtained from the outputs of the optimal simulated scenario (second scenario) of the groundwater flow model, groundwater salinity (TDS), aquifer transmissivity (T), and aquifer storativity (S). ArcGIS is used to generate a thematic map for each criterion. All-controlling criteria thematic maps are reclassified in ARC-GIS to use in the model as a layer (Fig. 18). Each criterion is ranked according to its priority in the groundwater assessment and integrated into a GIS database model using the weighted overlay method. Weighted-sum overlay analysis provides the ability to obtain weight for each ranked criterion. It combines all inputs by overlaying all rasters, multiplying each by its given weight, and summing them together to calculate the overall suitability of each cell and create one output raster layer that defines the appropriate groundwater zones. The ranks, rates, and attributes of input criteria are indicated in Table 2. The equation used in this method is defined as the following:
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