The Topographic Wetness Index (TWI) is a steady-state wetness index that attempts to quantify the water movement on landforms and landscapes. The conventional Topographic Wetness Index is created in a Geographic Information Systems and defined as ln(a/tan β), the logarithm of the area divided by the tangent of the local slope. The conventional TWI is an index that correlates water movement on similar sloped landforms that have the same TWI index value. It is an interpretation of USGS digital elevation model (DEM) slope, and the upstream area used in its analysis. Any estimate of water accumulation is based on the finite areas determined within the calculation area. Slope and upstream surface area are the only two derivatives used in defining TWI. TWI performs best on sloping uplands but deteriorates in flat landscapes.

Purpose: The TWI is a valuable index for understanding the relationship between topography and hydrology before making a field visit. It can help identify areas that are prone to water accumulation and can be used to assess the potential for wetland development. However, the standard TWI has design limitations that has been overcome with the development of the Climate Enhanced Topographic Wetness Index.

Creation Date: 20240507

Publication Date: 20240507

Revision Date:

Refresh Cycle: Updated periodically as new imagery becomes available

Version: 1.0.0

Change Log: Service Deployed

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The Topographic Wetness Index (TWI) is a steady-state wetness index that attempts to quantify the water movement on landforms and landscapes. The conventional Topographic Wetness Index is created in a Geographic Information Systems and defined as ln(a/tan β), the logarithm of the area divided by the tangent of the local slope. The conventional TWI is an index that correlates water movement on similar sloped landforms that have the same TWI index value. It is an interpretation of USGS digital elevation model (DEM) slope, and the upstream area used in its analysis. Any estimate of water accumulation is based on the finite areas determined within the calculation area. Slope and upstream surface area are the only two derivatives used in defining TWI. TWI performs best on sloping uplands but deteriorates in flat landscapes.

Purpose: The TWI is a valuable index for understanding the relationship between topography and hydrology before making a field visit. It can help identify areas that are prone to water accumulation and can be used to assess the potential for wetland development. However, the standard TWI has design limitations that has been overcome with the development of the Climate Enhanced Topographic Wetness Index.

Creation Date: 20240507

Publication Date: 20240507

Revision Date:

Refresh Cycle: Updated periodically as new imagery becomes available

Version: 1.0.0

Change Log: Service Deployed

Report Service Errors