Calculating Topographic Wetness Index in ArcGIS | 2023

Welcome to our comprehensive tutorial on calculating the Topographic Wetness Index (TWI) using ArcGIS! 🌊
In this video, we'll walk you through the step-by-step process of deriving TWI, a crucial parameter in hydrology and environmental studies. Whether you're a GIS professional, a student, or someone interested in understanding the science behind terrain wetness, this tutorial has got you covered.
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What is Topographic Wetness Index (TWI)?
Topographic Wetness Index (TWI) quantifies terrain driven variation in soil moisture.
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The Topographic Wetness Index (TWI) was developed by Beven and Kirkby (1979) within the runoff model TOPMOD.
It is defined as ln(a/tanβ) where a is the local upslope area draining through a certain point per unit contour length and tanβ is the local slope.
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Link for Downloading Word Document on TWI:
How to Download SRTM DEM - Video Guide:
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Steps in Calculating Topographic Wetness Index:
00:00 Introduction
00:30 Adding DEM Data
00:46 Project Raster GCS to PCS
02:11 Fill DEM
03:13 Flow Direction
04:03 Flow Accumulation
04:47 Slope in Degree
05:37 Radians of Slope
07:30 Tan Slope
09:14 Flow Accumulation Scaled
10:43 Topographic Wetness Index (TWI)
11:38 Changing Color / Symbology
12:58 Clipping Raster
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Other Important Links:
To know more about Degrees to Radians Conversion visit:
Topographic Wetness Index:
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#topographicwetnessindex #TWI #arcgis #hydrology #geospatial #DEM

[justinquarshie]

Great work, can you use model builder to do this in another tutorial?

[MrSaaf-ulbk]

Hello sir, can tell me please why am I having minus value in my TWI classification? What does that minus value mean?


And one more thing sir, do you have any of reference to TWI Classification based on its value range?