A catchment water balance assessment of an abrupt shift in evapotranspiration at the Hubbard Brook Experimental Forest, New Hampshire, USA. Issue 8 (6th August 2021)

• Record Type: Journal Article
• Authors: Green, Mark B.; Bailey, Scott W.; Campbell, John L.; McGuire, Kevin J.; Bailey, Amey S.; Fahey, Timothy J.; Lany, Nina; Zietlow, David
• Is Part Of: Hydrological processes. Volume 35:Issue 8(2021)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2021-08-06
• Subjects: Hydrology -- Periodicals; Hydrology -- Research -- Periodicals; Hydrologic models -- Periodicals; Hydrological forecasting -- Periodicals; 631.432
• DOI: 10.1002/hyp.14300
• Languages: English
• ISSNs: 0885-6087

Abstract

Abstract: Small catchments have served as sentinels of forest ecosystem responses to changes in air quality and climate. The Hubbard Brook Experimental Forest in New Hampshire has been tracking catchment water budgets and their controls – meteorology and vegetation – since 1956. Water budgets in four reference catchments indicated an approximately 30% increase in the evapotranspiration (ET) as estimated by the difference between precipitation (P) and runoff (RO) starting in 2010 and continuing through 2019. We analyzed the annual water budgets, cumulative deviations of the daily P, RO and water budget residual (WBR = P − RO), potential ET (PET) and indicators of subsurface storage to gain greater insight into this shift in the water budgets. The PET and the subsurface storage indicators suggest that this change in WBR was primarily due to increasing ET. While multiple long‐term hydrological and micrometeorological data sets were used to detect and investigate this change in ET, additional measurements of groundwater storage and soil moisture would enable better estimation of ET within the catchment water balance. Increasing the breadth of long‐term measurements across small gauged catchments allows them to serve as more effective sentinels of substantial hydrologic changes like the ET increase that we observed. Abstract : Water budgets in four reference catchments at the Hubbard Brook Experimental Forest have indicated an approximately 30% increase in the evapotranspiration (ET) as estimated by the difference between precipitation (P) and runoff (RO). This unprecedented change started in 2010 and continued through 2020. While we cannot fully explain what drove this increase, our analysis shows increases in the growing season potential ET play a role, driven partly by increasing atmospheric demand and partly by increasing leaf area index.