Showing posts with label GIS. Show all posts
Showing posts with label GIS. Show all posts

Friday, May 11, 2012

Analysis of Impervious Cover’s Spatial Placement and its Impact on Watershed Quality

Research Questions:
  • How placement of impervious cover in a watershed affects the health of the watershed?
  • Does the spatial arrangment of Impervious cover matter in relationship to the watershed's outlet or the watershed's streams?
Study Site:
The Analysis Plan with the starting inputs of a 5 meter DEM, NHD Flowlines, delineated watersheds with the outlet points, and an impervious surface cover raster. 


 With over 2000 watersheds in the state the analysis required a model created in ArcGIS's Model Builder to iterate through all of the watersheds to create a set of Euclidean distance to the outlet rasters and a set of Euclidean distance to the streams rasters.
A second model was necessary to multiply the two sets of rasters by the impervious surface cover raster.



Each of the cells in each watershed would be weighted inversely to their distance to the outlet points and to the streams.  
 In Watershed Sample ID: 1000

  • The unweighted percentage of impervious surface cover was 2.91%
  • The IDW value for Distance to the Outlet was 6.72%
  • The IDW value for Distance to the Streams was 2.74%
The shows that the impervious surface cover is clustered closer to the outlet. It also shows that the impervious surface cover is clustered slightly farther away from the streams than an even distribution would be. 

Using a  sample of 15 watersheds the IDW value for Distance to the Outlet was on average 15.86% higher than the unweighted percentages. The IDW value for Distance to the Streams was on average 3.19% lower than the unweighted percentages. 
In the future other measures of distance such as flow length and flow gradient will be used to see if they produce a better result than Euclidean distance.  In addition, the results of this study need to be compared to an indicator of watershed health to see if any trends develop.
 

Wednesday, October 26, 2011

ArcGIS for the Android Market


ArcGIS for the Android market has just been released.
I just downloaded it to my Samsung Galaxy S. I hope that it will be as smooth as I have heard the iPad app is. At least it is free so we really can't complain either way.
This is what ESRI says about their app:
Use ArcGIS to discover a community of hosted maps from ArcGIS Online
ArcGIS is a great way to discover and use maps. Maps come to life in ArcGIS. Tap on the map or use your current location and discover information about what you see. You can query the map, search and find interesting information, measure distances and areas of interest and share maps with others.
Find community hosted maps from ArcGIS Online – Esri’s online GIS. Alternatively you can use the authoring tools on ArcGIS.com to create your own maps that can be used in ArcGIS.
Features:
Features
- Navigate map galleries in just a few taps
- Use maps authored in ArcGIS.com
- Access your own GIS data
- Display and zoom to current location
- Data Collection and Editing
* Use your GPS or the map to collect and update GIS data
* Attach photos and movies to what you collect
* Intelligent form-based data entry driven by ArcGIS data models
* Includes a set of hosted industry specific collection sample maps so you can test drive these capabilities. Look for them inside of the new Gallery entry on the Find Maps tab.
- Magnify your Identify and Editing experience
* When interacting with the map, tap and hold to accurately locate a position on the map using a Magnifier
- Perform linear and area measurements based on your current location or by interacting with the map.
- Retrieve detailed map metadata
- View feature attribute information
- Perform keyword search and get access to relevant information
- Change the visibility of layers
- Access popular maps faster by adding them to your favorites list
Let me know whether you recommend this or not.

Sunday, October 23, 2011

First Post

This is my first post ever on Blogger.com. I am just trying to figure out the basics of the site. I would like to be able to write long post about maps and cartography techniques that I find interesting or useful.  I am a Geography major at The University of  Maryland, Baltimore County and I am also trying to get my Geographic Information Systems certificate.  I recently started an internship with the Citizens Housing and Planning Association in Baltimore City.  I have a real passion for maps. I am fascinated with all aspects of them. From their earliest forms when they where more of an art than a science to today with all the applications mapping has in today's interconnected world.  Through this blog I hope that I will be able to spread my passion for cartography with others and interact with individuals with similar interests as me.