Comparative Land Use within the Fourmile Creek Watershed

When considering the watershed as a whole, it is necessary to understand and evaluate the various land uses within to appropriately understand what influences a use may have on the system. Additionally, this will guide us on what metrics we need to obtain to evaluate the watershed and to help us better identify the response to issues pertaining to the watershed. Below I have put together a slideshow that discusses the various land uses with the Fourmile Creek Watershed.

Iowa Flood Information System (IFIS)

 As second part of my previous post on Flood Data for Iowa, I came across the Iowa Flood Information System - IFIS.

This website seems like a one-stop shop for all things weather/flood related for Iowa. It's a more succinct version of what the USGS offers and the user interface seems to be better. You can explore flood inundation maps, flood conditions and forecasts, traffic conditions, a time-adjustable flood risk calculator, rainfall frequencies, weather data, and soil moisture gauges, among a host of other features. They have a downloadable mobile app - download here. 

It seems like a great mobile app to have if you live/work in Iowa and have concerns about flooding/water levels.

Central Iowa flood of 2018

In June of 2018, Central Iowa observed a major flash flood event caused by a storm system that dumped anywhere from 5" to 10" of rain overnight on June 30. The result yielded highly flood creeks, some creeks were destroyed and record water levels were observed in Fourmile and Walnut Creeks (NWS 2018). Flooding caused a water main break, forcing some residents to boil water before using and had residents kayaking through neighborhoods (Des Moines Register 2018a). The boil order was lifted for most residents after locating the break, but some still fell within the order. One duplex townhome actually exploded (Des Moines Register 2018b). No one was harmed in the explosion, but they did narrowly escape.

The same could not be said for 'local legend' Larry Cotlar. Cotlar was an announcer for Drake's basketball team for over 10 years as well as for the Iowa Barnstorms, a professional indoor football team located in Des Moines (We are Iowa 2019).

A twitter feed dedicated to these events can be found here: Des Moines/Ankeny Catastrophic Flash Flooding. Many photos and videos are embedded within that feed.

Below is an aerial video taken 

What has the response been:

After the floods, the follow actions were taken (We are Iowa 2019):

A 1% increase in sales tax was imposed in Polk County. The first 50% was dedicated to property tax relief, and the remaining 50% was dedicated to upgrading infrastructure.

Concrete boxes have been buried beneath the street to help delay storm surges, allowing sewers to catch up with the heavy water flow.

100 homes were identified as being eligible for a flood plain buyout at 110% of their home value. 80 of the 100 homeowners agreed to the buyout.

Here is another video of a neighborhood - St. James Place in Ankeny that borders Fourmile Creek. This youtube channel recorded footage of the creek a week prior to the flooding. 

1. NWS. 2018. June 30, 2018 Central Iowa Major Flash Flood Event. Available from https://www.weather.gov/dmx/20180630_EpicFlashFlood

2. Des Moines Register. 2018a. Ankeny water main break located; most of the city's boil order canceled. Available from https://www.desmoinesregister.com/story/weather/2018/07/01/iowa-flooding-ankeny-under-boil-order-after-major-water-main-break-des-moines-weather-forecast/748927002/

3.Des Moines Register. 2018b. Urbandale couple escapes death in flash flood: 'Next thing I know, we were underwater'. Available from https://www.desmoinesregister.com/story/news/2018/07/01/des-moines-flooding-urbandale-couple-survives-flood-drowning-home-explosion/749441002/

4. We Are Iowa. 2019. Floods of 2018: Lessons Learned. Available from https://www.weareiowa.com/article/news/local/floods-of-2018-lessons-learned/524-504911b7-e5fa-4d4c-a1e8-f681b981778c

Exploring Flood and Drought Data of the Watershed

Using the Advanced Hydrologic Prediction Service from the National Weather Service anyone can look at various information pertaining to a watershed.

The Fourmile Creek Watershed has 7 gauges available to explore (Figure 1)

(All images from https://water.weather.gov/ahps/). 

The symbology of the gauges within the stream indicate:

    6 of the 7 gauges do not have forecasts or probability data available
    5 of the 7 gauges do not have a defined flood category
    1 of the 7 gauges does not have current data available.

Figure 1. Stream gauges within the Fourmile Creek Watershed

Figure 2. Fourmile Creek at Easton Blvd. detailed flood stage information

In Figure 2, a Flood Stage Level of 12.5 feet. Upon double clicking the stream gauge, the image is enlarged and I am given numerous other features to explore. This stream gauge status is updated by past precipitation data as well as forecasted precipitation within 24 hours. I was also able to find more information about multiple flood stage levels (Figure 3).

Figure 3. Scale to Flood categories at Easton Blvd. in the Fourmile Creek Watershed

In 2018, this stream crested at 17.51 feet, the highest on record for this location. There is an option to turn on a FEMA flood layer (Figure 4). When I change the basemap, you can see how the flood plain overlaps with residential neighbhorhoods. Taking this one step further, I looked at the next upstream gauge. While this gauge doesn't have up-to-date forecast data, it's important to note that many agricultural lands are within the floodplain. As such, Polk County Conservation has begun purchasing land from homeowners (both residential and agricultural lands) to restore flood plains and stream channels to their natural channels. One of the main considerations for purchasing lands is to increase storm water management efforts, reducing the effects of erosion and flood waters.

Figure 4. FEMA National Flood Hazard Layer

Figure 5. FEMA National Flood Hazard Layer with Satellite Imagery Basemap

As I stated above, flooding in Fourmile Creek reached an all time high in 2018. During this period, a major flash flood event occurred as a result of thunderstorms stalling out over central Iowa, resulting in 5-10 inches of rain, streams flooding over their banks, and record water levels in both Fourmile Creek and Walnut Creek. A follow-up post will go over this event in depth.

Dendrology of the Fourmile Creek Watershed

Here, I've created a slideshow of the most common trees within the watershed that I came across while visiting the area in September of 2020. I biked a 15 mile loop from Copper Creek Lake Park along the Chichaqua Valley Trail to Mally's Weh-Weh-Neh-Kee Park. Weh-Weh-Neh-Kee is a Meskwaki people term for 'a good place'. The Meskwaki people inhabited Iowa in the mid-1800s. For more information on this tribe, you can visit their website. Fourmile Creek bordered the Chichaqua Valley Trail for a good portion of the 15 mile ride.

 

The image on the left is from my starting point (Copper Creek Lake Park, bottom) to Mally's (top). The image on the right shows a zoomed in section of the trail. Here you can see where Fourmile Creek butts right up against the trail.

Anyway, without further ado, here's my presentation:

Fourmile Creek Watershed Map

Below is a slideshow with some specs on the Fourmile Creek Watershed. I chose to use Arcmap, as I'm more familiar with that than I am Google My Maps, plus I like to keep my GIS skills sharp as I use the program at work as well. I'm a firm believer (mainly from experience) in: "If you don't use it, you lose it".

I initially used a webpage through Iowa DNR (Iowa Elevation Tools - LiDAR elevation profile) to determine the stream elevation change. With this webpage, I selected two points (Image 1), headwaters and mouth, approximately and came up with an elevation change of 273.3 (Image 1). I then attempted to download a Digital Elevation Model (DEM) raster in Arcmap and couldn't figure out how to accurately assess elevation change. After doing some research, I found a study done by an engineering firm on this watershed, listing the elevation change specifically at 310 feet.

Image 1. Point Selection for elevation profile using LiDAR.

Image 2. Elevation Profile using LiDAR.

Why I'm exploring the Fourmile Creek Watershed

Recently, my significant other took a job in Iowa as a Conservation Ecologist. We were torn on the decision whether or not she should take the job, but ultimately we think it was the best decision for her, and for us. As such, I think choosing to study a watershed out in this area and become familiar with some of the conservation practices out there will help me become familiar with the projects they have going on and hopefully increases my chances of employment out there. I'm currently a Wildlife Biologist in Northern Virginia - see my About Me section above for more info on this.

One really neat thing for me is I was actually able to visit this watershed at the end of August/beginning of September. We hiked around a bit in the area and made sure bike one of the trails associated with the watershed. I've included some photos with descriptions below.

I'm thoroughly looking forward to exploring and learning about the various aspects of this watershed and watershed management in general.

Photo Credit: Me.

The above photo depicts and overview of the watershed and various measurements taken within the watershed itself. These measurements are updated periodically to reflect current conditions.

Photo Credit: Me

This photo shows part of a modified kayak/canoe launch at Mallys Weh-Weh Neh-Kee Park, which is also adjacent to a biking trail.

Photo Credit: Me.

This photo is adjacent to the above boat launch. An old railway was repurposed as an extensive part of Polk County Conservation's Biking Trails. This is one of the old railway bridges. Polk County manages trails ranging from just under 4 miles to over 25 miles.

Photo Credit: Me

This photo depicts a revetment/riprap used as mitigation strategy for bank stabilization during high water events. This helps prevent erosion along the banks.

Photo Credit: Me

This photo shows I believe a water retention area to control runoff from impervious surfaces (roads/sidewalks). This too helps reduce erosion, prevent flooding and helps to control water flow into larger streams.

Photo Credit: Me

Both of the photos above and below are views from the plane of the Des Moines River just southeast of Des Moines and the Fourmile Creek Watershed.