December 04, 2017

Tree / Crop Counting and Classification with Python and Scikit-Image - Tutorial

December 04, 2017/ Saul Montoya

Lately there has been a wide source of spatial photogrametry available for agriculture. Available submetric images can be found in Google Earth, and drone images can increase the ortophoto resolution to the order of centimeters. Most of this data gives us a new perspective of the spatial distribution and stage of the crops, however a real spatial analysis of crop metrics have not been widely performed due to limitations on the images and software involved.

We tried to make this tutorial with the popular library OpenCV, however the installation process was tedious in Windows. Then we shifted to Scikit-Image, a image processing library in Python that comes already installed on the Anaconda software. The process for image analysis required intermediate Python and GIS skills, but most important a strong criteria of the algorithm inputs, options and results.

December 02, 2017

How to join tables in QGIS - Tutorial

December 02, 2017/ Saul Montoya

QGIS is a powerful open source software for spatial analysis and management of spatial data. User experience with QGIS is great and most users find QGIS easier to use than other free and commercial GIS software. This time we will show how simple is the process to join tables in QGIS. Spatial data of sanitary quality of beaches in Lima was used to show the join table process.

November 29, 2017

Example of Zone Budget Package in MODFLOW with Model Muse

November 29, 2017/ Saul Montoya

MODFLOW is the code developed by the USGS for the simulation of groundwater flow in steady and transient flow conditions. MODFLOW can represent a wide variety of physical process related to the groundwater flow regime as recharge, evapotranspiration, wells, among others. Latest development in MODFLOW allow the simulation of flow and transport in the unsaturated flow zone with the UZF and MT3D packages. From the beginning of the MODFLOW development the water balance on the groundwater models was a strong part of the modeling process with high accuracy in between the balance of water going in and out of the system. On any groundwater flow model build on MODFLOW there absolutely control over the water coming from the specified boundary conditions and the discrepancies are minimal.

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: 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.

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 08, 2017

Determination of Mining Projects Areas with Satellite Imagery and QGIS

June 08, 2017/ Saul Montoya

Our current working conditions require access to spatial information in short periods of time. Work planning tasks or quoting of services require data of distances, areas, proximities, medium elevations, among others. The data can be given by clients, organizations or by field monitoring, but they may not be available at the required moment. The use of geoprocessng tools of satellite imagery reduces the required time to have this information. Since QGIS is open source and the Landsat, MODIS and Aster images are free, this type of geoprocessing is versatile, economic and friendly for any user with basic/intermediate QGIS knowledge.

May 29, 2017

Tutorial: How to convert MODFLOW-2005 files to MODFLOW-6 format

May 29, 2017/ Saul Montoya

The United States Geological Survey (USGS) has just released a new MODFLOW version: MODFLOW-6. This one comes with new functionalities to make it easier to create input files and perform simulations. Among the downloaded MODFLOW-6 files, there is an executable file to convert MODFLOW-2005 files to the new MODFLOW-6 format. In this tutorial we will show you how to do this.

May 29, 2017

How to generate a legend on map canvas in QGIS with PyQGIS - Tutorial

May 29, 2017/ Saul Montoya

QGIS is a powerful and user friendly GIS software. The user can represent points and style them according to the measured values. This tutorial deals with the legend representation on map canvas for a better geospatial data analysis.
Legend representation is done with just 6 lines of code on PyQGIS, the Python tool of QGIS.

May 17, 2017

Tutorial to Generate Orthophotos from Drone Images with WebODM

May 17, 2017/ Saul Montoya

Drone imagery is a powerful for geospatial analysis on small scales and high resolutions. The availability to take drone images and the open source tools available allow the user to generate orthophotos with resolutions of less than 1 meter and fully compatible with SIG softwares as QGIS.

This tutorial show the procedure to make an orthophoto with WebODM based on drone images from a pinneapple field.