Wed, Aug 17, 2022: 3:45 PM-4:00 PM
516A
Background/Question/MethodsForest headwater catchments are important source regions for stable and abundant freshwater resources but changing climate is altering forest hydrologic cycling, increasing evapotranspiration (ET) globally, and thus, reducing the portion of the water budget available downslope and in streams. Understanding the rate of these changes and the mechanisms driving them (species composition, landscape position) across forested landscapes has been difficult because of the uncertainty associated with extrapolating ET estimates generated by methods including eddy covariance techniques or coarse resolution remote sensing products. However, recently available remotely sensed (RS) ECOSTRESS data provides the opportunity to estimate ET at high resolution from local to regional scales. Using ECOSTRESS ET from 2019 - 2021, we quantified differences in growing season ET rates across forest types and topographic gradients, including aspect, hillslope, and elevation, in eastern US forested headwater catchments. We further evaluated how these differences correspond to lateral flow by calculating a separate RS based indicator of lateral hydrologic connectivity.
Results/ConclusionsPreliminary results from10 headwater catchments demonstrate ET varies along topographic gradients. We find ET rates on southern slopes are greater than northern slopes. In most watersheds ET rates increased with elevation and in half of watersheds ET decreased along the hillslope, indicating in these watersheds ET was greater at downslope positions. Watersheds with increasing ET along the hillslope (higher ET rates upslope) tend to be located at higher elevations and likely indicate a decrease in lateral flow. These findings suggest topographic components jointly influence ET rates across connected portions of the landscape and highlight the need to consider topography in both understanding ecosystem responses to climate change and managing forests for water resource sustainability.
Results/ConclusionsPreliminary results from10 headwater catchments demonstrate ET varies along topographic gradients. We find ET rates on southern slopes are greater than northern slopes. In most watersheds ET rates increased with elevation and in half of watersheds ET decreased along the hillslope, indicating in these watersheds ET was greater at downslope positions. Watersheds with increasing ET along the hillslope (higher ET rates upslope) tend to be located at higher elevations and likely indicate a decrease in lateral flow. These findings suggest topographic components jointly influence ET rates across connected portions of the landscape and highlight the need to consider topography in both understanding ecosystem responses to climate change and managing forests for water resource sustainability.