The National Center for Atmospheric Research (NCAR) supplies climate forecast data online, with four daily updates. Why not use the power of GRASS-GIS and python to produce animations of predicted rainfall?
Continue reading Precipitation animations with GRASS-GIS and python
Some GIS software has the ability to calculate the upstream drainage area for every stream reach in a stream network. In the streams attribute table there will be a column with the total flow accumulation area upstream of each section (reach) of the stream network. Total flow accumulation is sometimes referred to as "adjoint catchments". GRASS-GIS lacks this capability, but with few quick commands we can overcome this and add total upstream drainage area to each stream reach within GRASS.
Continue reading Upstream drainage areas with GRASS-GIS
Continuing my previous post I’ll now show how QGIS can serve as a front end to Spatialite based tables. We cover styling features with attributes from the database, and how to add new data rows to a non-spatial data table.
Continue reading QGIS fighting bugs – Part 2
Real bugs, agricultural pests, cause damages to food production throughout the world. GIS techniques can help in monitoring pest infestation by collecting and mapping data from traps, baited with pheromone lures. QGIS
when teamed up with Spatialite
makes the ideal combination for pest control programs to maintain and display the distribution of different species of insects. Here’s how it’s done.
Continue reading QGIS fighting bugs
Landsat 8 tiles have been available for more than two years now. In addition to the obvious advantages of these new satellite images: higher (16 bit) radiometric resolution and extra bands, there are some subtle additions to the metadata file that makes image processing easier. Continue reading Get Landsat 8 Reflectance with GRASS-GIS
With the rainy winter season behind us, it’s time to summarize how much precipitation we got this year. The southern Negev desert enjoyed above average annual rainfall (in stark contrast to the rest of the country, where we saw only 60% of the multi-year average)
I wrote about creating isohyetal contours some years ago. This time I’ll try to improve my interpolation by using the powerful, open source R statistics program.
Continue reading Geostatistics and rainfall with R
Grass and ArcGIS use different conventions for the flow direction rasters created when processing a DEM to create watersheds. I need to convert a GRASS flow direction raster to the ArcGIS convention. Here’s how I did it.
Continue reading Flow Direction from GRASS to ArcGIS
We have a large set of LIDAR data, in separate *.las file, each covering a small rectangular area. I wanted to create a polygon shapefile of the coverage of each tile for reference so I know which files to choose when we need a subset of the whole region. Using a bash “one-liner” and a simple function in Spatialite I had my polygon layer.
Continue reading Spatialite helps creating an index of LIDAR tiles
Nearly every new phone or tablet these days comes GPS enabled. And you can choose any of a slew of apps to capture GPS waypoints and tracks. But how do you get these data into a GIS system? Several apps save the GPS data into an sqlite database, so using Spatialite to convert the locations to spatial layers is a piece of cake.
Continue reading Get your phone GPS data into a GIS format
Our regional Drainage Authority prepared a reservoir at the mouth of a small dry riverbed to catch and regulate flood water coming from a mountain canyon. This reservoir was to act as a buffer to prevent flooding of agricultural fields and residential areas further down the valley. After a sudden rainstorm last week, the reservoir bravely fulfilled (pun intended 😉 ) it’s duty. Now we want to know how much water was actually captured, and to create a depth volume curve for the small “lake” that was formed. Here’s how I did this using GRASS.
Continue reading Creating Depth-Volume curves with GRASS-GIS