November 02, 2017

Introduction to PyQGIS, the Python environment in QGIS

November 02, 2017/ Saul Montoya

QGIS is a great software for the processing/analysis of spatial data, Python is a clear, powerful programming lenguaje; together they can enhance the spatial analysis to solve more complex or more dedicated problems in less time. PyQGIS is the Python environment inside QGIS with a set of QGIS libraries plus the Python tools with the potential of running other powerful libraries as Pandas, Numpy or Scikit-learn. This tutorial shows the main parts of the Python environment and has some practical cases of vector data layers.

October 30, 2017

Tutorial: Georeferencing Historic/Ancient Maps with QGIS

October 30, 2017/ Saul Montoya

Working with spatial data on many environments requires an historic perspective of the land use, urban development and other changes on earth surface. Some times (or most times) the only data available is on printed form with or without a system of reference that makes this data of limited use for a spatial analysis. Afortunately, QGIS can handle the georeferenciation of ancient maps on a smooth and quick way based on the functionality of its tools.

Anyone can overlay an historic map on the map canvas on few steps. This tutorial shows the whole procedure to georeference a map of Lima city from 1856 in QGIS.

October 27, 2017

Tutorial: Wave Barrier Design with OpenFOAM and Salome

October 27, 2017/ Saul Montoya

Coastal structures are subject to tidal and wave related boundary conditions. The design of a wave barrier have to assess the water levels on the inner bay from the impact of a wave and the maximum wave height on the outside part of the structure. This evaluation can be done by the use of dynamic simulations that take into account sea floor geometry, wave barrier height, position and interaction from the water channel and so on. OpenFOAM is an open source software for the simulation of flow in steady and transient states; the software allows us the simulation of the wave interaction with the coastal structure. The tutorial deals with the main parts of mesh construction in Salome and model set up and simulation in OpenFOAM.

October 25, 2017

Tutorial: Determination of Glaciers and Lakes from Sentinel 2 Images with QGIS and SCP Plugin

October 25, 2017/ Saul Montoya

Any object on the earth has a "signature" on a different bands or ranges on the visible and invisible spectrum. Base on the values and trends on this "spectral signature" one can classify different types of land cover as lakes, soils, wetlands, exposed rock and glaciers from many free and available multispectral satellite images as Sentinel 2, Aster, MODIS, and Landsat. QGIS is a very powerful open geographical information system software and its plugin Semiautomatic Classification Plugin gives QGIS many capabilities for the download, preprocess, classification and analysis of satellite imagery without using another desktop software. This tutorial deals with the whole procedure for the supervised classification of lakes and glaciers on a clipped Sentinel 2 image and its vectorization as polygons.

October 19, 2017

Tutorial: Example Problem of MODFLOW with Model Muse

October 19, 2017/ Saul Montoya

This example problem is adapted from the MODFLOW documentation and use to demostrate the use of MODFLOW with Model Muse. The model is implemented without parameters and uses the LPF Package. The model decribes a regional aquifer setup with acuifers and aquitards with the interaction of many boundary conditions as recharge, evapotranspiration, constant head and wells. Groundwater flow simulation was done on steady state conditions.

October 19, 2017

Tutorial: Direct Landsat Imagery Dowload in QGIS with SCP Plugin

October 19, 2017/ Saul Montoya

Based on the review from our followers, we have noticed that the download procedure to download images from the NASA and USGS web servers had changed. It is not clear the current method to download the selected files, even if you have your username and password set up correctly. Luckly there is an alternative way to download those files with QGIS and the Semiautomatic Classification Plugin (SCP). This tutorial covers the whole procedure to sign up, select, previsualize and download a Landsat 8 in QGIS with the SCP Plugin.

October 17, 2017

Tutorial: Intake Channel Design with OpenFOAM and Salome

October 17, 2017/ Saul Montoya

The design of hydraulic structures need the comprehension of water and structure interaction in terms of level, speed, sediment transport, among others. It is important for the hydraulic structure design to take into account the extreme events of flow, pressure and speed, therefore the computational fluid dynamics (CFD) modeling becomes essential in the design stage. OpenFOAM is an open source software for the simulation of flow in steady and transient states; this software allows us the simulation of the hydraulic response from an specific requirement in laminar and turbulent flow conditions, flow velocity calculation, and determination of static and dynamic pressures.

October 15, 2017

Tutorial: Water Surplus Evaluation at Basin Scale with QGIS and Remote Sensing Data

October 15, 2017/ Saul Montoya

The current availability of strong open source GIS software together with remote sensing data and specific data products as high resolution precipitation and evapotranspiration makes possible the assessment at global scale on short processing time of certain parts of the water cycle. Water surplus is the difference in between precipitation and actual evapotranspiration, that can be translated to the difference in between IMERG imagery (precipitation) and MOD16 imagery (actual evapotranspiration). This raster algebra calculation could be implemented in open source software as QGIS with a set of specific procedures as reprojections, temporary files and raster calculators. This tutorial deal with the water surplus calculation for a andean basin for year 2015.

October 13, 2017

Tutorial: Area of Study AsterDEM Download and Basin - Stream Delineation in QGIS

October 13, 2017/ Saul Montoya

QGIS is a open source software for spatial analysis and data representation. There are many tools from QGIS for the hydrological/hydrogeological evaluation and modeling. This time we have made a tutorial with the whole procedure of the download process for a AsterDEM only on the extension of an area of study. The DEM was later reprojected on QGIS and processed to get the channel network and drainage basins. The tutorial has the purpose to show how simple is the process of working with QGIS and Processing.

October 11, 2017

Multiple Well Configuration in MODFLOW with Model Muse Tutorial

October 11, 2017/ Saul Montoya

Modflow with Model Muse are a powerful set of softwares developed by the USGS for groundwater modeling. Model Muse is very handy when working with GIS files but sometimes there are some specific requirements about the hydrogeologic features to conceptualize. This time we have prepared a tutorial about the multiple well configuration on a regional groundwater model. The tutorial deals with the model construction and configuration of 182 pumping wells on a 84km x 54km area in the north of Mexico.

September 22, 2017

How to insert a Geological Fracture on a Hydrogeological Model with MODFLOW and Model Muse

September 22, 2017/ Saul Montoya

Model Muse is a software for the pre and post data processing of hydrogeological 3D model in MODFLOW. Both Model Muse and MODFLOW are developed by the USGS (usgs.gov). Model Muse is designed to work with objects and datasets, a powerful model construction methodology that allows the quick setup of boundary conditions, a simple way of progressive refinement and interesting features as inserting geological fractures on the numerical model.

This tutorial show the whole procedure for the conceptualization of several fractures based on some known fracture information as a point on the fractures, the azimuth and elevation. The tutorial deals with the theorethical determination of the fracture plane equation, the construction of a dataset with the desired equation plus the implementation of object that represents the fracture with the relevant hydrogeological features.

August 16, 2017

Tutorial Infiltration Gallery for Water Supply Modeling with MODFLOW and Model Muse

August 16, 2017/ Saul Montoya

Tutorial for the simulation of filtration galleries close to a river. Modeling done with MODFLOW, Model Muse and QGIS.

August 03, 2017

Tutorial of a Cross Seccion of Water Quality with MODFLOW, MT3DMS y QGIS

August 03, 2017/ Saul Montoya

Groundwater flow modeling depends on GIS data, and its output is compatible with a sort of GIS tools. In order to do analysis or representation from contaminant transport modeling it is needed a sort of commands, formats, tools and plugins from a stack of programs as ModelMuse and QGIS.

This tutorial is not only a example of water quality representation, it is as well a discussión on the main parts of modeling construction and simulation.

July 16, 2017

How to insert a Geological Contact in MODFLOW with MODEL MUSE

July 16, 2017/ Saul Montoya

Model Muse and QGIS makes possible to deal with geological data for the groundwater flow model cocntstruction. A diverse group of tools are required to process and insert geological features as contacts or faults. This tutorial show the whole procedure from the ground up to build the model geometry and insert a geological contact as the interfase within two layers.

July 02, 2017

Tutorial to Georeference Google Searches with Python and QGIS

July 02, 2017/ Saul Montoya

To carry out a series of studies and investigations we have to know both name and location of certain places. This may be available through some web pages, however the use of data is limited and advance geoprocessing tools on softwares as QGIS can not be used. There are several services or APIs that can bring you the spatial location of Google searches. In this tutorial we will use the Google Maps API for the location of Hospitals in a radius of 5 kilometers from a point in Miraflores, Lima. Only open source software tools have been used for this tutorial.

June 24, 2017

Recharge Estimation by Daily Precipitation with MODFLOW UZF and Python

June 24, 2017/ Saul Montoya

The processes of the superficial and groundwater water cycle are related to the precipitation (shape and intensity) and the dynamic of soil moisture. This dynamic of soil moisture is determined by the type of soil and the root zone in a daily, or even hourly, temporal scale. These phenomena have not been considered or studied in conventional hydrogeology text books, maybe because of their intensive use of modeling tools and complex conceptualizations and validations.

June 19, 2017

Modeling of Soil Erosion with Landlab in Python – Open Source Software

June 19, 2017/ Saul Montoya

Soil erosion is the movement of the upper soil layers caused by processes related to water or wind. Soil erosion can occur slowly on the surface, however, soil alterations caused by human activity can increase this rate in 10 to 40 times. The evaluation of soil erosion is important to estimate the impact of human activities and the planning of remediation plans.

This article introduces the Landlab environment, which is developed in Python, as well as a practical example of soil erosion modeling on slopes over time.

June 12, 2017

Development of Web Maps with Open Source Software and Free Repositories – Case Study: Geological Risks of Peru

June 12, 2017/ Saul Montoya

The problems and challenges in water resources management, the environment protection, risk prevention and many subjects related to the human activity require transmitting data in a practical and updated way. The web maps are a good solution since many of these data are associated to a location and the Internet is a great tool available for many. The development of web maps is relatively new but necessary to implement for many uses like data diffusion, the understanding of problematic and decision making.

June 09, 2017

Using GRIDGEN V 1.0 to Generate Unstructured Grids

June 09, 2017/ Saul Montoya

GRIDGEN is a program developed by the United States Geological Survey (USGS) to create unstructured grids to be used in numerical models such as MODFLOW-USG.

The use of unstructured grids has advantages, like the capacity of refining specific areas. However, its design and manipulation is more complicated than in structured grids. The most complex step is the creation of input data, specifically the ones related to cell connectivity. For this reason, GRIDGEN is an useful tool that helps to simplify the process.

June 08, 2017

Modeling of Air Pollution caused by Atmospheric Effluents (Chimneys) with OpenFOAM

June 08, 2017/ Saul Montoya

The preservation of air quality requires the characterization and evaluation of impacts produced by point sources that emit contaminants and its interaction with wind, climate conditions and zone geometry. Current evaluation tools as AERMOD only offer 2D evaluation with Gaussian dispersion, while the nature of air contaminant dispersion is a 3D phenomenon with thermodynamic components and interactions with terrain geometry.