Comparing two tools for ecosystem service assessments regarding water resources decisions

Area of Science:

• Ecohydrology
• Ecosystem Services Assessment
• Land Management Modeling

Background:

• Hydrologic ecosystem services are crucial for land management decisions.
• Ecohydrologic models like SWAT and InVEST are commonly used for assessing these services.
• Understanding model performance across different watershed characteristics is essential.

Purpose of the Study:

• To compare the Soil and Water Assessment Tool (SWAT) and the Integrated Valuation of Ecosystem Services and Tradeoffs (InVEST) annual water yield model.
• To evaluate the utility of these models and new indices for guiding land management decisions related to hydrologic ecosystem services.
• To develop a framework for selecting appropriate models for specific decision contexts.

Main Methods:

• Comparative analysis of SWAT and InVEST models at two US watersheds (Wildcat Creek, Indiana; Upper Upatoi Creek, Georgia).
• Assessment of model performance in estimating spatial water yield distribution.
• Evaluation of model guidance for environmental flows, potable water supply, and rainfed irrigation.

Main Results:

• InVEST and SWAT showed similar water yield estimates in Wildcat Creek.
• Significant differences in water yield estimates were observed between InVEST and SWAT in Upper Upatoi Creek.
• InVEST's accuracy may be limited in watersheds where baseflow significantly contributes to total water yield due to unmodeled storage dynamics.

Conclusions:

• Model performance in estimating water yield varies significantly across different watershed types.
• The choice of ecohydrologic model is critical for accurate assessment of hydrologic ecosystem services.
• A framework is proposed to aid in selecting the most suitable model or index for specific land management decision-making contexts.