WATERSHED ANALYSIS (WEST ANTIGONISH)

Conducting a watershed analysis to provide valuable insights about the health vital water source etc of the province area

Marion Jay Bernabe

Watershed analysis is a crucial aspect of environmental management and planning. It involves the study of a specific land area defined by topographic divides from which water flows into a common outlet. This analysis can help in understanding the health of an ecosystem, pinpointing water contamination sources, predicting geologic hazards due to flooding events like landslides and changing river patterns, and extreme erosion. A healthy watershed sustains ecosystem function and provides for human well-being and livelihood.

Choosing to conduct a watershed analysis in West Antigonish, Nova Scotia, can be particularly beneficial. The region is home to the James River Watershed, which supplies water to the Town of Antigonish and its surrounding service area. This watershed is protected under the James River Watershed Protected Water Area Regulations and encompasses an area of just less than 40 km².

Conducting a watershed analysis here would provide valuable insights into the health of this vital water source. It could also contribute to the development of strategies for sustainable water management, ensuring the long-term availability of clean water for the community. Furthermore, such an analysis could help identify potential threats to the watershed and propose mitigation measures.

In conclusion, conducting a watershed analysis in West Antigonish, Nova Scotia, would not only contribute to scientific understanding but also have practical implications for local water resource management and conservation efforts. It’s an opportunity to make a significant impact on both the local community and the environment.

Area of scope are the following

o Mattie Settlement

o Merland

o Monastery

o Pirate Harbour

o Tracadie Road

o North Intervale

o Port Shoreham

o Moose Point

PREPARING, CREATING AND AGGREGATING MY DATA

Step 1: Creating shapefile for my polyon- study area and river polyline

using the feature class to start creating the study area. Use Antigonish Spatial Reference

NOTE:

Make sure that the Coordinate System is based from the selected Study Area.

If Nova Scotia- -->NAD 1983 UTM Zone 17N

If Antigonish ---> NAD 1983 UTM Zone 20N

Step 2: Creating the Study Area

Step 3: Creating the river polyline baseline

Creating my polyline baseline for AREA OF SCOPE/STUDY AREA WATERSHED ANALYSIS

Uploaded my data for the river polyline baseline creation

Started populating my map to get my river polyline using feature class

STUDY AREA + RIVER POLYLINE BASELINE CREATED

Step 4: Spatial Reference Validation

Validating Spatial Reference for both study area. UTM Zone should be under Antigonish Area.

Converting Study Area ( Feature Layer) into a NAD 1983 UTM Zone 20N.

Validating the Projected Coordinate System is now NAD 1983 UTM ZONE 20N

Step 5: Creating Water Pour Points

Created two points for my watershed analysis pour point later

**Final Location of Pour Point 1 and Pour Point 2**

DIGITAL ELEVATION MODEL PREPARATION

Step 1 : DEM Raster Data Exportation

Exported my raster data for ANTIGONISH AREA in the cataglog pane

Dragged the dem020hy to the contents pane

Changed my symbology for my outline color

Step 2: Clipping Process

Clipping my RASTER DEM Data to the Study Area

Step 3: Fill Spatial Analysis Process

Geoprocessing Fill Spatial Analysis. See validation message if succeeded

Using FILL SPATIAL ANALYSIS TOOL to remove small imperfections in the data

Step 4: Spatial Reference Validation

Validating Spatial Reference for both DEM_Clip and DEM Original. UTM Zone should be under Antigonish Area.

WATERSHED ANALYSIS PRE-PROCESSING

Step 1: Flow Direction Spatial Analysis and Map

Using the flow direction to create a raster of flow direction from each cell to its downslope neighbor, or neighbors, using the D8, Multiple Flow Direction (MFD), or D- Infinity (DNF) method.

Make sure it is D8 and it is saved inside my GEODATABASE Project

Validating that the flow direction is properly executed and successfully applied to the DEM_filled

Step 2: Flow Accumulation Spatial Analysis and Map

Using the flow accumulation spatial analysis tool to create a raster of accumulation flow into each cell . A weight can optionally be applied.

Validating that the flow direction is properly executed and successfully applied to the DEM_Flow Direction

Step 3: Raster Calculator Spatial Analysis

Builds and executes a single map algebra expression using python syntax.

Double click DEM FLOW Accumulation then decide a parameter value that should go along with it. In my case it is 500. Make sure that the output raster name is saved in the geodatabase as " STREAM EXTRACTION "

Confirmation message that the process succeeded

OPTION 1 ---> STREAM EXTRACTION MAP @ DEM Flow_Accumulation> 500

OPTION 2 ---> STREAM EXTRACTION MAP @ DEM Flow_Accumulation> 1000

Step 4: Raster to Polyline Conversion

Converts a raster dataset to polyline features

Be sure to select the stream extraction 1000 map

Step 5: Adjusting the pour points

Adjusting the pour points from River Polyline Baseline Map to River Polyline Processed Map

From River Polyline Baseline Map Created at the very beginning

Moved to the desired location based from ACTUAL RIVER POLYLINE MAP PROCESSED

Step 6: Watershed Spatial Analysis

Determines the contributing area above set of cells in a raster

Step 7: Vector Format- Raster to Polygon Conversion

Vector Format Conversion for Pour point 1---> Named as Watershed 1

Vector Format Conversion for Pour point 2----> Named as Watershed 2

Step 8: Watershed 1 and 2 Specs Checking

Checking the Shape length and shape area

Conclusion

Conducting a watershed analysis in West Antigonish, Nova Scotia, would not only contribute to scientific understanding but also have practical implications for local water resource management and conservation efforts. It’s an opportunity to make a significant impact on both the local community and the environment.

biggest take away of that I have learned so far for this project is that, I dont really need the baseline river polyline during the the first phase. The Digital Elevation Model, point of flow is sufficient enough for me to analyze the watershed of the area.

Another one would be making sure that I am always using the right coordinate system based from the area of study. I made a mistake at first and used 17N instead of 20N while creating my shapefile for my polygon. that is why I added SPATIAL REFERENCE VALIDATION as my process for my project. This is for me to convert the coordinate system to the correct one if ever I made a mistake.

Lastly, the pour point is a critical component of the watershed analysis. It is basically used to define the outlets of watershed. They help ensure that all water within a watershed drains to a specific point, facilitating accurate watershed analysis.

As per checking of the watershed 1 and watershed 2 specs. The stream of water in Antigonish area is so small. This is because area is controlled by James River, the area will not be easily gotten flooded. It may store water in areas but flood won’t be as so severe based from the pour point 1 and pour point 2 that was set during the analysis.

GEODATA REFERENCES

· Nova Scotia Mountain Data --->à Click here

· NOVA SCOTIA - data resources --->à Click here

· For DEM Data --> à Click here

· Dp055 data --->à Click here

Other References

· https://gisresources.com/giswatershedwatershed-analysis/

· https://storymaps.arcgis.com/stories/ccb399d1eae64ed49e4c4c2c2f697e6b:

· https://extension.msstate.edu/publications/watersheds-role-importance-stewardship

· https://www.townofantigonish.ca/sewar-water.html