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Application of GIS to explore the effects of land use on stream water
quality: Watershed delineation, sampling point identification and
hypothesis development
John E. Petersen, Assistant Professor of Environmental Studies and Biology
John.Petersen@oberlin.edu W: (440) 775-6692 H: (440) 776-0005
1) the effect of spatial components in the landscape - watershed boundaries, land use and
population density – on stream water quality
Background:
Objectives:
Experience working with GIS to analyze spatial data
Understand how land use activity affects water quality
Delineate watersheds
The objective of this exercise is to lead you through the process of quantifying and evaluating the
effect of spatial pattern on ecological process.
Watersheds and ecology:
The field of systems ecology is increasingly concerned with the effects of landscape
configuration and the spatial arrangement of resources on ecological dynamics.
Oberlin College is situated on the West Branch of the Black River watershed, a 175 square mile
basin dominated by farms, patchy forests and industrial land that ultimately drain into Lake Erie
west of Cleveland. The Vermilion River watershed, immediately to our west, is of similar size
but is more forested. In the proposed exercise, students would learn to delineate watershed
boundaries and would identify sub-watersheds in both basins that drain areas of similar size, but
have substantially different land use. They would develop hypotheses regarding water quality
and flow magnitude and identify stream sampling sites that would allow them to test these
hypotheses. The class would then travel to these sites to verify land use, collect and process
water samples, and compare predictions with observations.
Something about the history of the use of paired watersheds as an approach to studying the
impact of land use in ecology.
Explain how land uses effect the quantity and quality of water in rivers. Effect of vegetation type
on evapotransporation. Effect of impervious surfaces on stormwater flow. Urban vs. Rural
hydrograph. Effects of
GIS:
GIS, which stands for “Geographic Information System”, can be defined in a number of
different ways. For our purposes, we can think of it as an approach to storing,
analyzing and displaying spatial information…..
Type important types of layers, raster and vector files are. In a raster (also known as
grid) layer, a value is given to each individual grid cell. So, for instance in a layer
representing land use, each cell might be given a different numerical value based on
presence of forest, open water, wetland, building, paved surface, etc.
Conventions used in this handout
Terms in bold are the names of files or folders
Terms in italics are menu options, buttons of features of the GIS software
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Terms in Courier font are the names of data sets, also know as themes in GIS
Terms that are underlined are choices that you can make from lists of options
Develop hypotheses regarding how land use might affect stream water quality
Identify small sub-watersheds in black basins that drain areas of similar size, but have
substantially different land use
Description of the files
Layer name:
Old Layer Name
Description
Source
USGS Roads
VermilionRvr
vermilion_nhd
BlackRvr
ErieTribs
black_nhd
erie_tribs_nhd
http://seamless.usgs.gov
/
USGS http://seamless.usgs.gov
/
Tributaries of the
southern portion of
Lake Erie
OhioStateBoundaries ohio_state_boundary
DEM
bv_dem
OHWatersheds
Digital elevation
map
watersheds_11_digit_huc Watershed
boundaries
Procedures
Open the map file WatershedData which contains links to all of the data that you will use in this
exercise. In GIS you typically work with multiple different “layers” of geographic information.
Each layer represents a different piece of geographic information – for instance, one layer for
roads, another for rivers, another for elevation, another for land use, etc. Each layer exists as a
series of files on the desk top that you can add and delete from your map, but I have added
everything you will need into the WatershedData file. [indicate directory]
View files
Lead students through looking at the data and turning layers on and off
Display each of the watersheds as a different color
Right Click on OHWatershed layer name: Properties  Symbology  unique values
 Under Value Field select Name  Click “Add Values” button  Click OK
Under the Display tab, check the box that says, “Show Map Tips (Uses primary display
field)” and click OK
This displays the watershed name when you hover over the map
Turn on spatial analyst extension
Right click anywhere in the upper menu area of ArcGIS and add the Spatial Analyst tool bar
Under the tools menu, click the check box next to spatial analyst
(need to do both of these to get it to work)
Turn on the Hydrology Modeling tool
Right click on the top menu and click the appropriate box
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Burn streams in each watershed
Merge together the Tools GeoProcessing Wizard  Merge layers together and Black River stream files.
Create a file called, “BlackAndVermilion”
2) From the Spatial Analyst menu choose Options. In the General tab set the working directory to
\WatershedDeliniationEx. In the Extent tab set the analysis extent to Same as Layer “DEM.” In the Cell Size tab
set the analysis cell size to Same as Layer “NED.” Click OK.
[NOTE: Can’t have any spaces in the entire file name]
3) From the Spatial Analyst menu choose Convert  Features to Raster. For the input features select
BlackAndVermilion. Set the field to RHH_. Save the output raster in the \WatershedDeliniationEx\Data
directory as BAndVSTRMGRD. Click OK. The new raster layer, BAndVSTRMGRD will be added to the map.
4) From the Spatial Analyst menu choose Reclassify. Set the input raster to BAndVSTRMGRD. From the
Reclass Field, select “<value>”. Reclassify the old values of 0 to New Values of 1 and the values of NoData as
new values of NoData. Save the output raster in the \HydroMod\Data directory as BAndVstrmgrd2. Click OK.
The new raster layer, BAndVstrmgrd2 will be added to the map.
5) From the Spatial Analyst menu choose Raster Calculator. Enter the following expression:
con([BAndVstrmgrd2] == 1, [DEM], [DEM] + 1000). Click evaluate. A new raster layer Calculation is added to
the map session. Right click on Calculation layer choose Save as Layer File. Save the raster layer in the
\WatershedDeliniationEx\ Data directory as DEMburn. Remove the Calculation layer from the map session and
add nedburn.
Fill sinks
Most DEM maps will have sinks, or cells that are lower than all surrounding cells. Some sinks are natural parts
of the landscape (ponds), while others are due to errors present in the DEM. In order to model flow all sinks in
the DEM must be filled.
6) From the Hydrology menu choose Fill Sinks. Select DEMburn as the input surface. Save the output raster as
DEMfill. Click OK.
7) The raster layer DEMfill will automatically be added to the map session.
Flow Direction
Flow direction is determined by finding the direction of steepest descent from each cell. Flow direction is what
is ultimately used to compute the watershed for a given outlet. Each cell in the flow direction layer has its flow
direction coded according to the D8 model.
8) From the Hydrology menu choose Flow Direction. Select DEMfill as the input surface. Save the output raster
in theDEMFlowDir. Click OK. The raster layer DEMFlowDir will automatically be added to the map session.
Flow Accumulation
Flow accumulation creates a grid of accumulated flow to each cell, by accumulating the weight for all cells that
flow into each down slope cell. Flow accumulation is not a step in delineating watersheds, but it does aid in
ensuring that the outlet used to compute the watershed falls on cell that receives a substantial amount of flow
from upland cells.
9) From the Hydrology menu choose Flow Accumulation. Select DEMFlowDir as the direction raster. Save the
output raster in the \WatershedDeliniationEx\Data directory as DEMFlowAcc. The raster layer DEMFlowAcc
will automatically be added to the map session.
Generate map of flow accumulations at each point in the river
Under spatial analyst, choose Raster Calculator.
Type: con([BAndVstrmgrd2] == 1,[DEMFlowAcc])
This expression selects only those cells that are in the river and returns a null value for all other cells
Right click on Calculation layer
Select “Make Permanent”
Save as FlowAccRiver
Delete Calculation
Add FlowAccRiver
Right Click, choose properties, Under display tab, check the box for “Show map tips (uses primary
display field)”, Under symbology tab, select white to black Color Ramp, and histogram equalize
View the land use data layer
Compare land use densities in Black and Vermilion river watersheds
What fraction of the landscape is urbanized in each?
What percentage is covered by impervious surfaces?
Of land that is within 100 of a stream, what percentage is in each?
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Based on differences in land use, how would you expect the hydrograph to differ following a storm event in
Black and Vermilion rivers?
Based on differences in land use, how would you expect water quality to differ in Black and Vermilion rivers?
Delineate watersheds
Watersheds are delineated from an outlet based on a flow direction grid. Outlets can either be existing cells or
defined interactively. If the outlet you are computing the watershed for falls on a stream in the real world, it is
important that it lies on a nearby cell with high flow accumulation.
From the Hydrology menu choose Interactive Properties. Set the flow direction to flowdir and the flow
accumulation to flowacc. Uncheck the snap on for watershed tool option. Click OK
14) Select the Watershed button from the Hydrology Modeling toolbar, and click on the cell with the highest
flow accumulation closest to point #24 (zoom in if necessary). The watershed is defined based on this point, and
appears as a new layer – Watershed1.
Questions
If you wanted to compare the effects of different land use on the magnitude and quality of water flow you need
to adjust for the different sizes of the two watersheds. Identify a pair of sampling locations, one in each
watershed, that meet the following criteria:
Capture as much of each watershed as possible, including the land uses that dominate
Are easily accessible for sampling from a road
Drain similarly sized areas
A problem with comparing the properties of streams that drain large areas with multiple land uses is that it is
difficult to determine the specific effects of particular land uses. It is also difficult to measure stream flow in
rivers that receive substantial runoff. In order to assess the effect of
Identify two sub-watersheds that meet the following criteria:
Are less than ___ in size
Contain distinct land uses that can be used to test your hypothesis
Are easily accessible for sampling from a road
Drain similarly sized areas
Appendices:
Terms
Metadata: data that describe data.
Issues/problems/things to do:
AB: How do we compare relative dominance of different land use within the two watersheds?
AB: How do we compare relative dominance of different land riparian land uses within the two watersheds?
AB: How do we compare sizes of watersheds?
AB: Get all data in consistent and defined coordinate system
AB: New data layers that could be useful
Roads maps (so that we can accessible sample locations)
Demographic data
JP: Because DEM and stream data are not exactly on top of each other, the cells in the streams in the burned in
version of the DEM do not necessarily flow down gradient. As a result, the final river system flows backwards in the
Vermilion watershed.
JP: Figure out how to use watershed file as a mask to prevent flow accumulation calculations from extending into
Lake Erie
JP: Take useful sections of watershed delineation exercise
JP: Review exercise on VT watersheds as a template for our exercise
JP: Figure out how to display river names on map
JP: Capture screen shots and get them into exercise
USEFUL CONTACTS:
Case Western Biology department
Joe Koonce is chair of biology (216) 368-3557 <joseph.koonce@cwru.edu>
Great Lakes fisheries researcher
Developing GIS models for evaluating impact of land use on stream water quality
Ann Marie Gorman (216-368-3579) amg24@case.edu
Joe’s GIS technician
Put together most of the data we will use for watershed delineation exercise
DEMS
Stream maps
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Watershed boundaries
Land use data
All data they provided is in UTM17 format (Universal Transverse Mercater for zone 17)
Alternate to State plain coordinate system
Most of Ohio is in zone 17
“NAD1927” = North American Datum from 1927
“NAD1983”
Watershed delineation is conducted on DEM (digital elevation maps)
University of Texas has developed software for ESRI that works with for 3.2 (and probably 8.3) that does
watershed delineation, she calls it “Arc-hydro”
You need to copy this into ArcView and use it with Spatial Analyst
She says there is an online tutorial
Has a tool for watershed processing
You feed it with a digital elevation map (DEM)
DEMs for both 10m x 10m are available from Ohio EPA
Stream data
Medium resolution and is from National Hydrography Dataset (NHD USGS)
Can be downloaded offline
Land use data
1992 NLCD (National Land Cover Data) USGS (http://edc.usgs.gov/geodata/)
2004 data should be available some time
Aerial photos
Are in slightly different projection than other stuff: UTM17, but for NAD1983 instead of for
NAD1927 like other data
There is a 60 meter or so shift when it is overlayed on other data
Email from Ann Marie regarding her data sets:
This file includes (in projection UTM 17, NAD1927):
* bv_dem - Digital Elevation Model (brian gara email) at a 10m x 10m pixel size for the Black and Vermilion rivers
region. Elevations are in meters. This is a grid/raster, so you will need spatial analyst
* lulc_1992 - Landuse Landcover clipped to the same region. Comes from the NLCD. 30m x 30m
pixel grid
* black_nhd - National Hydrography Dataset map for the Black River. This is the coarser resolution
map (considered med-res on the NHD website). I've found that my higher-res data for that region is
not complete.
* vermilion_nhd - same as above but for the Vermilion River
I included some more for reference:
* erie_tribs_nhd - All of the NHD files for the US portion of the Lake Erie Basin
* ohio_state_boundary - This is a pretty high resolution state boundary file...sorry can't remember
where I got it, but ODOT, the GeoCommunity and ESRI are possible sources
* watersheds_8_digit_HUC - Watersheds at the scale of the 8-digit Hydrologic Unit Codes (EPA
designates these codes).
* watersheds_11_digit_HUC - Watersheds at the scale of the 11-digit HUCS. Finer res than the 8digit. See below for the breakdown.
8-digit HUC# = 04100012 - Huron-Vermillion
11-digit HUC#'s
4100012050 - Vermilion R. (headwaters to above East Branch)
4100012060 -Vermilion R. (above East Branch to Lake Erie)
8-digit HUC# = 04110001 - Black-Rocky
11-digit HUC#'s
4110001020 - West Branch Black R. (headwaters to Black River)
4110001030 - East Branch Black R. (headwaters to below Coon Cr.)
4110001040 - E.Branch Black R. (below Coon Cr. to Black River)
4110001050 - Black R. (below E.Branch to Lake Erie ) and Lake Erie tribs. (below
Black R. to above Porter Cr.)
OK.First thing tomorrow morning, I am going to look into the exact hydrologic analysis tools that
I have and how to install them. For now, here are 2 resources:
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http://support.esri.com/index.cfm?fa=downloads.dataModels.filteredGateway&dmid=15
I think the package I have is under Hydro Tools and documentation
* http://www.crwr.utexas.edu/giswr/
-
-
ArcGIS Hydro Data Model
Let me know as questions arise...OH, and any mention of ArcGIS (I believe!) includes the ArcView 8.x with which
you are working.
Ann Marie Gorman
Research Assistant, Department of Biology, Case Western Reserve University, 10900 Euclid Ave., Cleveland,
Ohio 44106
Ph: 216.368.3579
Fax: 216.368.4672
Email: amg24@cwru.edu
Marti Row = GIS person for Lorain County, Lorain County auditors office (referral from Laura Moore)
m_rowe_GIS@Hotmail.com (440) 329-5553
Brad Flam (referral from David Beach)
did GIS component of EcoCity Cleveland’s Bioregional plan now in Berkeley did GIS stuff
NODIS (Northern Ohio Data Information Services) at Cleveland State college of urban affairs
Mark Salling (216) 687-3716
Referral from David Beach
These folks do extensive GIS work in NE Ohio
e.g. mapped extent of urban sprawl
1980, 2000, 2020 layers of sprawl
Potential sources of data (referral from David Beach)
Ohio State has repository for GIS
Ohio EPA
ODNR
Akron
Kent State
USGS provides downloadable access to land use/land cover data (21 different land use types) for
Ohio region at 30 m resolution.
http://water.usgs.gov/GIS/metadata/usgswrd/landuse.html
Sean M. Quigley
Contact_Voice_Telephone: (614) 430-7753
Contact_Facsimile_Telephone: (614) 430-7700
Contact_Electronic_Mail_Address: squigley@usgs.gov
Resources at Oberlin
Geology has “erdas imagine” program
Have higher education kit
Laura uses this in GIS course with ArcView 3.2
Allows conversion of orthofotograph
A vector GIS system
Allows lots of transformations among interfaces
Installed in Kettering 100
Nicely linked with ESRE products