ewce09.azraftaohid.me/L4T1/EWCE 464/TUTORIAL_09/Class notes - 20260825.md

---

share_link: https://notesx.azraftaohid.me/ke09k730 share_updated: 2026-08-26T09:32:20+06:00

1. River Morphology
   1. NDWI
      1. Procedure (2013)
      2. Procedure (2026)
   2. Find out Total Erosion
      1. Find out Unchanged Area or Common Area
      2. Calculate Erosion/Aggredation
      3. Overly Erosion
      4. Overly Accretion
      5. Calculate Erosion/Accretion
   3. Prepare Output on Excel
   4. Bar Computation (Manual Method)
      1. Compute Change in Area
      2. Summerize on Excel
      3. For Exam

---

River Morphology

NDWI

$$\frac{B3-B5}{B3+B5}$$

Procedure (2013)

• Add .TIF files from 2013
• Open ArcToolbox:
  • Spatial Analyst Tools > Math Algebra > Raster Calculator
  • Apply above mentioned formula:

    Float("LC08_L2SP_138043_20131215_20200912_02_T1_SR_B3.TIF"-"LC08_L2SP_138043_20131215_20200912_02_T1_SR_B5.TIF")/Float("LC08_L2SP_138043_20131215_20200912_02_T1_SR_B3.TIF"+"LC08_L2SP_138043_20131215_20200912_02_T1_SR_B5.TIF")
    

  • OK
• Add the .shp file
• Make the added shape file hollow and add boundary
• Select areas of interest from the shape file (hold SHIFT), then export as shape file and add the selected features
• Spatial Analyst Tools > Extraction > Extract by Mask:
  • Input Raster = exported composite file (lc08...)
  • Feature mask data = StudyArea
  • Done
• Hide/remove non-required layers
• Open Properties > Symbology > Stretched of Extract_lc082:
  • Stretch type = Custom
  • OK
• Spatial Analyst Tools > Reclass > Reclassify:
  • Input raster = Extract_lc082
  • Classify > use 2 (rest default)
  • OK
• Change symbology of Reclass_Extr1 with white and blue colors
• Conversion Tools > From Raster > Raster to Polygon:
  • Input raster = Reclass_Extr1
  • Choose an appropriate output name: ...
• Select river by selecting on a point of the river
• Exported polygon > Data > Export; use appropriate name, e.g., ShpRiver2013

Procedure (2026)

• Same as 2013

Find out Total Erosion

• Open Attribute Table of ShpRiver2013
• Add field: Area_2013; type = double
• Calculate geometry: area, hec
• Perform the above three steps for ShpRiver2026

Find out Unchanged Area or Common Area

• Geoprocessing > Intersect:
  • Input Features = ShpRiver2013, ShpRiver2026
  • Rename with UnchangedArea
• Calculate area of generated layer: Unchanged_Area

Calculate Erosion/Aggredation

• Erosion = NextYearArea - UnchangedArea
• Accretion = PrevYearArea - UnchangedArea

Overly Erosion

• Analysis Tools > Overlay > Erase:
  • Input = ShpRiver2026
  • Erase = UnchangedArea
  • Name = Erosion

Overly Accretion

• Analysis Tools > Overlay > Erase:
  • Input = ShpRiver2013
  • Erase = UnchangedArea
  • Name = Accretion

Calculate Erosion/Accretion

• Calculate geometry: Erosion_Area; Accretion_Area

Prepare Output on Excel

...

---

Bar Computation (Manual Method)

• Create new shape file Bar2013 and Bar2026 using Arc Catalog. Use coor of ShpRiver2013.
• Start editing > create features for Bar2026
• Draw by following ShpRiver2026
• Do the same with Bar2013
• Open attribute tables and add B2026_Area, B2013_Area

Compute Change in Area

• Intersect to obtain unchanged
• Erase with unchanged

Summarize on Excel

---

For Exam

• On certain year, whether erosion occurred more or accretion
• Summarize on Excel

...

---

![[Pasted image 20260825090756.png]]

![[Pasted image 20260825090804.png]]