1. B Y : S A R A H S A N S O N E
M E N T O R : D R . C H O W D H U R Y
Ground Water Flow Model of
“Gate Site” at Warner Creek
2. NYC Water
Supply
• Provides 1
billion gallons
of daily drinking
water to more
than 8 million
residents of
NYC
• Provides 110
million gallons
of daily drinking
water to people
within
Westchester,
Putnam, Ulster,
and Orange
counties
Provides
40% of
NYC
Water
Supply
3. Focused View
of Studied
Watershed
Stony Clove Creek
is the highest
contributor of
sediment into the
Esopus
Esopus Creek
leads into the
western end of the
Ashokan
Reservoir
6. Causation of
Slope Failure
Failure caused by
interchanging
sediment layer
Interchanging
sediment layers
have different
hydraulic
properties causing
high pressure
areas and plane
failures
Sand
Clay
9. Goal
Build a Visual Model to display how Hydraulic
Conductivity effects slope failure
10. Steps to Obtain Goal
1. Obtain the slope of the area of interest.
2. Study the sediment types of the area of interest.
3. Make a simple model that is both homogeneous
and isotropic.
4. Create a model that is heterogeneous and
anisotropic to mimic field conditions.
14. Steps to Obtain Goal
Obtain the slope of the area of interest.
Study the sediment types of the area of interest.
Make a simple model that is both homogeneous and
isotropic.
Create a model that is heterogeneous and anisotropic
to mimic field conditions.
17. Steps to Obtain Goal
Obtain the slope of the area of interest.
Study the sediment types of the area of interest.
Make a simple model that is both homogeneous and
isotropic.
Create a model that is heterogeneous and anisotropic
to mimic field conditions.
24. Steps to Obtain Goal
Obtain the slope of the area of interest.
Study the sediment types of the area of interest.
Make a simple model that is both homogeneous and
isotropic.
Create a model that is heterogeneous and anisotropic
to mimic field conditions.
28. Acknowledgments
SUNY New Paltz Summer Undergraduate Research
Experience (SURE) Award
Mentor: Dr. Chowdhury
Peipei Lee and James Woodberry
Don Hodder and Dr. Rayburn
Bill and Keegan
Editor's Notes
The circled area is our main concern for our research.
The circled area is the area we’re working in.
Reason being, it provides the most sediment into the esopus creek, and is the main cause for the increase in turbidity
The esopus enters in the west
Obviously provides the increase in sediments
First circled area displays slope failure
Second circled area displays large amounts of sediment travel into the water
Displayed in the photo are interchanging beds of sand and clay
Due to high differences in “hydraulic properties” water pressure builds up between the layers and clay will start to “liquefy” and travel into the creek.
On the left there is a picture of a site near our “Gate Site” of major slope failure
On the right is the same location after the DEP restore the major slope failure
Both of these pictures were taken a year after the DEP restored the site.
The attempt to restore the site didn’t last long
A major cause of this is the interchanging layer of clay and sand reacting to major storm events
These major storm events cause many contact springs and mud boil
*definition of contact spring and mud boil
Read from slide
Here are the steps that are going to help us achieve our goals.
We used a meter stick, a clinometer, and a level
Before going out into the field we measured everyone’s eyesight height. We chose a flat area of land with close to 0⁰ slope.
One person would stand with the meter stick and the level and the other would hold the clinometer.
The person with the meter stick would use the level to make sure it was perfectly vertical before recording measurements.
The person with the clinometer would stand tall and look straight ahead. The clinometer has a level in it so you can check weather or not you are looking straight ahead.
Then the person holding the meter stick would move the marker till it was where the person with the clinometer was looking and we would record that measurement.
An inclinometer or clinometer is an instrument for measuring angles of slope (or tilt), elevation or depression of an object with respect to gravity.
When Bill Dan and… started this project they collected elevation heights of 7 places along a certain at something NW. We used the same markers they created to continue with our research. We could not simply take the slopes they found because the slope failure in this region is moving constantly at a fast pace. This means that its constantly changing.
We started at the highest elevation which happens to me their 7m mark.
The person with the meter stick stood at that mark holding it so that it was level and had the marker at the persons eyesight. This was as the person with the clinometer walked down slope we can measure the angle from that “0” point.
We would measure the angle at that point and then move the meter stick to where the person with the clinometer was standing.
We did this for the rest of the meter marks except we always had to correct for error in the elevations. The elevations along this longitudinal line was not always the same. So we had to calculate the difference between that mark and the 7m mark. And then use that difference to move the “0” meter mark to its correct location.
All we needed to do was use some simple trig and manipulate the equation so that we can solve for our slope.
We collected samples from different locations along stony clove creek which we called Wright Rd, a difficult slope and, gravel pit
We collected both sand and clay sediments
Collecting the sediments were not easy
It involved crossing rivers and climbing deep slopes
It also involved us using Dr.Rayburn’s knowledge of the area to make sure we were collecting the correct sediment.
These characteristics were of the most important when were studying the different sediment types.
After collecting we would bring the sediment back to lab allow them to air dry and then study them closely under the microscope.
Slow hydraulic conductivity consisted of sediment types that were extremely angular, poorly sorted, small in size and closely compact.
Faster hydraulic conductivity is consisted of sediment types that were well rounded, well sorted, bigger in size and less compact.
This is why clay’s hydraulic conductivity is so much slower than sands hydraulic conductivity.
This is a 2D contour map of the site we surveyed
Using past and our new updated data we were able to create this map
This is the simplest and first model we were able to create of our model.
The picture above shows one of the columns. This column represents the 10M mark we surveyed. The top left of the column is the top of the slope and the bottom right is where the stream is.
The picture above is one of the rows. The most left is the 0M mark we surveyed and the most right is the 7M mark we surveyed. This picture represents how some areas were affected more by the slope failure than others.
This is a 3D representation of the 2D map displayed before
Using the same data we were able to create the different layers shown in the green and purple sections at the right of the model *model is not aligned up right
Due to lack the data we were unable to get the model to run but we conducted further research this past fall and spring.
We realized in the fall and spring that we need to add constant heads to the sample to make it run
The layers of different hydraulic conductivity while being homogeneous and isotropic.
The 2 red rectangles seen above show the constant head boundaries of the area of interest.
The stream and the top of the slope both act as constant head boundaries.
A constant-head boundary occurs where a part of the boundary surface of an aquifer system coincides with a surface of essentially constant head. (The word “constant,” as used here, implies a value that is uniform at all points along the surface as well as through time.)
Layer 1 of the visual flow model.
The green boxes represent a no flow path zone.
The arrows indicate the path of water flow.
This picture is layer 2 of the visual modflow.
It demonstrates the convergence of water in the middle of the slope and no flow of water on the outside.
This holds true to our observations in the field that most of the slope failure happens in the middle of our area of interest.
The picture above is of layer 4.
Its hard to see because the path-lines are so small but they are heading down gradient.
They are so small because its hard for water to penetrate through the thick layers above it. So a minimal amount of water is getting through to this layer.
