Friday, April 20, 2012

Thematic Mapping

For this assignment the creation of a Thematic Map using one particular attribute; in this case it is poverty levels in the United States.  Using a closely related color scheme or by using a different saturation of one color scheme.  Both seemed to be effective.  The use of histograms is part of the analysis; specifically the first four listed:

Natural Breaks (Jenks) – Look for groupings the data or breaks where there were large gaps in the data.  With this method the areas of interest really stand out and that is why it is used a lot as like groups.  The color variations change predominately in the southwest; including Nevada all the way to Texas. 

Equal Intervals – This method sets the value ranges in each category equal in size. The entire range of data values (max - min) is divided equally into however many categories have been chosen.  all of the data is equally divided so the data seems rather blurred together.  It does seem to help if only looking at a small portion of the map.

Standard Deviation- The data is highlighted according to how much above or below it is from the mean.

Defined Interval, Geometrical Interval

The first step in the process was downloading the data into ArcMap.
Selecting (highlight), then export the shapefiles of Alaska, Hawaii, and the Contiguous United States; assigning the different projections and giving them a separate data frame.  Your work is done!


Well almost, analyzing the data that you have is now required.  This involves looking for patterns and spatial relationships; I try to look for anything that could possibly have a connection.

I have my histogram charts stored in One Note and have listed a hyperlink; hopefully this will work.  If not, I will be sending them to the drop box. 

http://christine-gisrocks.blogspot.com/2012/04/thematic-mapping.html

Tuesday, April 17, 2012

The purpose of the lab is to generate a watershed sediment transport index value and compare to previously published values.  Channel stability: “is the ability of a stream
First step is to generate the watershed using the DEM downloaded from Michigan CGI.  Next Extract the watershed extent from the flow accumulation surface using the Spatial Analyst Tools/Extraction/Extraction by Mask.  The mask data is the watershed you delineated.
Once the DEM is clipped to the extent of the watershed, run the slope tool and get the slope of the watershed.  Finally, run the sediment transport formula in the raster calculator.  The syntax is:
Power(“FlowAccumulationArea”/22.13,0.6) * Power(Sin(“Slope_Extrac1”/0.0896),1.3)
The Grand Traverse Bay watershed is located in beautiful northwest Michigan’s Lower Peninsula and drains approximately 976 square miles of land. The watershed is one of the larger ones in the State of Michigan and covers major portions of four counties: Antrim, Grand Traverse, Kalkaska, and Leelanau.
Grand Traverse Bay comprises 132-miles of Lake Michigan shoreline from its northwest tip at the Leelanau lighthouse to its northeast tip at Norwood. The bay spans 10 miles at its widest point, stretches a lengthy 32 miles to its base in Traverse City, and has its deepest point at 590 feet.  Grand Traverse Bay is one of the few remaining oligotrophic embayments in the Great Lakes and arguably has the highest water quality of the larger Lake Michigan bays. Oligotrophic is a term applied to lakes that are typically low in accumulated nutrients and high in dissolved oxygen, both of which are characteristics of high quality waters. Lakes such as these are clear and blue and most often cold, much like the Grand Traverse Bay.

Sediment

• Quality is good, typically coarse sand with numerous areas of cobble and gravel; at 100+ft depth the bottom is silt and clay
• Increases in silt and organic detritus along near shore bottom
• Isolated areas that are relatively rich in inorganic matter (i.e., Omena Bay)
• Sediment does not contribute significant concentrations of nutrients to water column; most of the phosphorus in the sediment is organically bound
• There are few rooted macrophyte beds (possibly due to lack of suitable substrate)
• Seiche events (which are large scale periodic movements of water) can re-suspend sediments in deeper portions of the bay. If carried into the water column, they can release contaminants deposited decades ago.




Pollutant or Environmental Stressor
Designated Uses Affected
Sediment
Coldwater Fishery
Other Indigenous Aquatic Life
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That study was followed by an extended Water Quality Study conducted by an independent consulting firm. That analysis considered samples consistently drawn from the lake in the spring and summer each year from 1993 through 2001. The study considered several measures of water quality including temperature and dissolved oxygen, conductivity, total alkalinity, nitrate nitrogen, chlorophyll a, pH and total phosphorous. The results of these individual samples and the trends they indicate are presented in a Lake Water Quality Index which the study authors indicate provides an accepted measure of water quality which can be used for comparative studies. This study confirmed the elevated levels of phosphorous in bottom sediments, but overall gave Long Lake water quality indices ranging from 93 to 100 on a scale of 1 to 100. In fact, the authors indicate that, “Long Lake is the only lake we’ve studied that ever had a Lake Water Quality Index of 100.”4

Thursday, April 5, 2012

Spatial Interpolation

Hi Everyone,
I worked on this a long time today and it was pretty cool how the results turned out depending on what method of Interpolation used.  For this assignment using the IDW and the Spline tool in Spatial Analyst toolbar.



The levels of fecal coliform were evident in the shallow waters of the Galvanston Bay.  I would  hypothesize that the fecal coliform would survive in the warmer, shallow waters without much interference from the wind currents or the water currents - perfect conditions for bacteria to grow!

Saturday, March 31, 2012

Water Delineation

I used the Luce County DEM from the Michigan CGI.  My focus was primarily on the Tahquamenon Fall’s located in the Upper Peninsula.  If you ever get a chance to go there – you’ll find an Upper Fall’s and a Lower Fall’s.  They are both spectacular; however I did the Upper Tahquamenon Fall’s and used a map inset picture of the Falls when the leaves were peak color.
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The Tahquamenon River watershed is located in the north central portion of the Eastern Upper Peninsula. The river originates from the center of three Tahquamenon Lakes which occur about 0.5 miles east of the border between Alger and Schoolcraft counties at an elevation of 880 ft.
From there, the river flows 87 mi to Lake Superior, draining a 790 square mile watershed. Its path is generally south for 10 mi, east for 42 mi, north for 14 mi, and then after the Upper Falls, it meanders with wide curves and high banks easterly 21 mi to Lake Superior.

I used the fill tool for the sinks, generated the Flow Accumulation, and added a new shapefile to create a point on the streams to generate the watershed.


Next, I used “Extract by Mask” tool from the original DEM and the Watershed.  Generated the Slope and finally, used the raster calculator to put the Sediment Transport Index formula in “Power (“watershedFlowAccumulation” /22.13,06) *Power(Sin(“Slope_Extrac1” /0.0896),1.3)
The Upper River segment is the headwater portion of the Tahquamenon River and the area of highest gradient as the river flows across glacial outwash deposits. Total length of this segment is 10.4 mi.

 In profile, the mainstream drainage emerges from a series of steep rolling sand hills, dropping quickly to the three Tahquamenon Lakes. The Tahquamenon Lakes collate drainage from smaller basins higher in elevation, and the river originates from the central lake.

After flowing under County Road 422, the stream falls in a series of gravel riffles and sand-bottomed pools for about 10 mi to County Road 442. Just west of County Road 442, the stream flattens out into a small swampy “spreads,” consisting of braided channel morphology fringed with tag alder and cedar. The river pinches back together at County Road 442, and then opens up again into a spreads flowage. No streams join the Tahquamenon through this section. Water in this section is cold, designated for trout,
with a stable annual flow.





I performed both sediment transport for this area and a watershed delination.  For the watershed delination the steps performed were to download the DEM from the CGI site.  Fill the sink.  Create flow direction map.  Create flow accumulation a map. Digitize pour point. Finally, use watershed tool to generate watershed.

The Water Delineation I completed a couple times, as I ran into problems with the pour point not being exactly on the stream.  Also, the raster calculator did not like the syntex that was put in; so that was another issue.  I just kept plugging along so I will try and post the cartographically pleasing maps to this blog.

Monday, March 26, 2012

Sediment Transport Index

The purpose of the lab is to generate a watershed sediment transport index value and compare to previously published values.  Channel stability: “is the ability of a stream
First step is to generate the watershed using the DEM downloaded from Michigan CGI.  Next Extract the watershed extent from the flow accumulation surface using the Spatial Analyst Tools/Extraction/Extraction by Mask.  The mask data is the watershed you delineated.
Once the DEM is clipped to the extent of the watershed, run the slope tool and get the slope of the watershed.  Finally, run the sediment transport formula in the raster calculator.  The syntax is:
Power(“FlowAccumulationArea”/22.13,0.6) * Power(Sin(“Slope_Extrac1”/0.0896),1.3)

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