Lab 10: Flood Hazards in Manhattan, Kansas (Data taken from Spatial Analysis of
Geohazards Using ArcGIS8 by William Harbert)
Synopsis: We are going to analyze flood hazards in Manhattan, Kansas. We will analyze a subdivision, businesses, and utility data which will be affected by the hazard. We will be creating a report, as well as creating a map using a map template.
Points: 20 points, 10 for questions, 10 for map
Exercise Steps:
1. Copy all of the data over from the class drive onto your h: Open the Manhattan1.mxd.
There are two data frames, Flood Zones and Overview. We will be working with Flood
Zones for much of the exercise. The Overview will be used for the map creation.
2. The map contains two data frames. The active data frame, Flood Zones, shows the extent of the 100 and 500 year flood zones, as well as rivers and parcels in the city of
Manhattan, KS. The overview data frame will be used in the map.
3. We want to determine the population affected from the 100 and 500 year flood plain.
Choose parcels which intersect the 100 year flood plain. Open the attribute table and observe the fields LANDVAL (land value), BLDGVAL (building value), and
TOTALVAL (total value). Next we want to also look at the parcels which intersect the
100 and 500 year flood plain. Add to the current selection parcels which intersect the 500 year flood plain (hint: use the dropdown menu to choose add, in select by location). The
500 year flood plain is shown to not include the 100 year flood plain (check this by turning the 100 year off), but the 500 year flood plain does include both the 100 and 500, therefore we need to select both to represent the entire 500 year flood plain. Not how many more parcels are in the 500 than the 100 year flood plain. When done viewing close the attribute table and clear selected features.
4. Next we want to analyze a specific subdivision to determine affected parcels. Using the select by attribute dialog, from the parcels layer choose the SUB field with A04 as the value. Be sure to see all unique values. A04 is the code for the Maplewood Subdivision.
Once selected zoom to the selected features. Export the selection and save it as
Maplewood in the Manhattan_KS.mdb (choose personal geodatabase from the dropdown at the bottom). Click yes to add the exported data to the map. Move Maplewood below the 100 year flood layer, clear selected features, and symbolize with a 30% gray color.
From the labels tab check “label features in this layer” and verify that PID is in the label field. Click Ok.
5. Next we want to add a field which will show the flood probability for a given area. A
100 year flood has a 1% chance of occurring every year, a 500 year flood has a 0.02% chance of occurring every year. Open the attribute table for Maplewood, add a new field

called Flood_Prob and make the type text. Click Ok. Using select by location choose
Maplewood parcels that intersect a 100 year flood plain. In the attribute table for
Maplewood calculate values for the Flood_Prob field and choose yes when asked to calculate outside of an edit session. Type “1%” including the text, and choose String as a
Type on the right. Click Ok. Close the attribute table and clear the selected features
6. Next we want to choose Maplewood parcels which are only intersected by the 500 year flood plain, not the 100 year flood plain. First choose all of the Maplewood parcels.
Now using select by location, remove Maplewood parcels which intersect the 100 year flood plain. You are now left with 2 parcels highlighted, which are only those in the 500 year flood plain and not the 100 year flood plain. Open the Maplewood attribute table and calculate the values again for the Flood_Prob field. Now type “0.02%” and choose string on the left. Click Ok. Now the Flood_Prob field should be populated with either 1% or
0.02% for each parcel based on the flood zone each are in. Close the attribute table when finished.
7.
Next we are going to create a report with the PID, Owner_1, and the Flood_Prob fields. The PID is a parcel identification field and is created for each parcel. This is very common in the U.S. with local governments. The agencies I worked for created these numbers based on the coordinates of the center point of the parcel. From the tools menu create a report. Make sure Maplewood is selected as the layer. Include PID, OWNER_1, and Flood_Prob as the report fields. On the Grouping tab, group the report items by
Flood_Prob, then on the Sorting tab, choose to sort them ascending by PID. On the display tab, check the box next to title. Click Report Title on the right and rename
Maplewood Subdivision: Flood Hazard. Expand fields on the left and click
Flood_Prob. Change the text to Probability. Click OWNER_1. Set the width field to 2.5 and change the Text to Owner. Click Generate Report. If you are pleased with the report, in the report viewer click Export. Save as a pdf named FloodHazard on your h:/lab10 folder. Close the Report Viewer and do not save. Turn off the Maplewood subdivision and zoom to full extent.
8.
Add the Flood93extent layer from the Manhattan_KS geodatabase. The flooded area shows the Great Midwest Flood of 1993. During the summer of 1993 severe flooding in the upper Mississippi River Basin causing an unprecedented amount of disctuction to many communities, including Manhattan, KS. Notice that the Flood of 93 does not agree with the 100 or 500 year flood zones. The 100 and 500 year flood zones represent areas that have a certain probability of becoming flooded, therefore a real flood may be very different. Turn off the 100 and 500 year flood layers.
9.
We want to determine the flooded area of the parcels affected by the 1993 flood. In
ArcToolbox expand Analysis Tools> Overlay> and choose Intersect. We will now create a feature class that will show all of the parcels which intersect the 1993 flood zone. For the input features add Flood93extent and Parcels. Name the output feature class
Parcels93 and save in the Manhattan_KS geodatabase. Leave everything else as is and click Ok. Zoom to the Parcels93 layer. Open the attribute table for Parcels93, the table contains data for acres, owner name, total value land and buildings, etc. Close table when done. Turn off Parcels93 and zoom too full extent.

10.
Add the following layers: b80k100, Rivers, Streets, HistoricalSites, and manholes from the Manhattan_KS geodatabase. Manhattan, KS plans for many different flood situations. The b80k100 layer represents a flood scenario with the Big Blue River
(flowing north-south) carrying 80,000 cfs (cubic feet/second) and the Kansas River
(flowing west-east) carrying 100,000 cfs. The b80k100 layer represents the extent of this flood scenario. If an event like this were anticipated many different departments within the city would need specific information to plan for this hazard. For example the emergency services department might want the address and phone number of everyone affected, public works may want the streets that are expected to be flooded so they can be closed, and the fire department may want to know which businesses have hazardous materials etc.
11.
We want to determine the total length of streets which would be affected by the new flood scenario. Use the intersect tool under Analysis>Overlay. This tool is different then the intersect option in select by location. By choosing intersect in select by location a street segment may be chosen outside of the flood zone, because part of that street segment might be inside the flood zone. Using Intersect under the Analysis tools you are clipping the streets to the extent of the flood, therefore only those street segments in the flood zone are shown. Using the Intersect tool, add b80k100 and streets and name the output StreetsBF (streets big flood). Now we have the streets which are affected by the flood.
12.
Use the same procedure as above for hazmat sites and sewer manholes for the flood scenario.
13.
Zoom in to the Maplewood Subdivision. We are going to make a map of this area.
Go into layout view. On the layout toolbar click on the tool for Change layout button.
The button shows two pages and has an arrow, this will be located on the far right, or the bottom, depending on where you put your layout toolbar. Once clicked on, open the file called Flood.mxt in the template folder. Click Ok. For the data frame order make sure
Floods are first and Overview is second. Click Ok. Templates can be created and used for any map. This helps keeping all of your data in the same format. Go to the Insert menu and insert picture. Insert the geologo.tif located in the Template folder. Move the logo underneath the inset map. This is a great way to add company logos to maps. In the main map you should include the subdivision parcels, the flood plains, as well as the streets.
Label the streets using the FULLNAME, and label the parcels using ADDRNUM.
14.
Double-click the legend to open the legend properties. Click the items tab. In your legend include Maplewood, 100 and 500 year flood plains, and streets. Select all 4 legend items, then click the style button. In the legend items selector, scroll down about two thirds and choose the Vertical Single Symbol Label Only Style. Click Ok. Select the 4 items again, and check the place in new column box, and specify 4 columns. Click Ok.
Adjust your legend and move it into the box below along with the scale. Adjust the scale if necessary. The title of the map should be Manhattan, KS and the subtitle is Flood
Hazards. Beneath the overview map change the text to Maplewood Subdivision. Enter

the subdivision number A04 in the lower left portion of the map. Be sure to include your name and date. Print out the map and include with the lab. Save your Manhattan.mxd on your h: and close the project.
Questions:
1.
What is the total value of parcels affected by a 100 year flood plain?
2.
What is the total value of parcels affected by a 500 year flood plain?
3.
What is the total parcel area inundated by the 1993 flood? (Give your answer in acres).
4.
What is the total value of parcels affected by the 1993 flood?
5.
What is the average (mean) total value of the parcels affected by the 1993 flood?
6.
What is the total length of streets in the flood zone of the Big Blue/Kansas River flood? (Hint: use the Shape_length field). Be sure to include units.
7.
How many historical sites are in the Big Blue/Kansas River flood zone? List them
8.
How many Hazmat sites are in the Big Blue/Kansas River flood zone?
9.
How many manholes are in the Big Blue/Kansas River flood zone?
10.
If this flood scenario happened, how would you use the above information to prepare for it? What would you do for the streets which may be flooded?, the hazmat sites?, the historical sites?, and the manholes?