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Abstract Warming temperatures and precipitation changes are expected to alter water availability and increase drought stress in western North America, yet uncertainties remain in how concurrent changes in the amount and seasonality of precipitation interact with warming to affect hydrologic partitioning. We combined over a century of streamflow (Q) and climate observations with two decades of tree growth data and remotely sensed vegetation activity to quantify how temperature and precipitation interact to control hydrologic partitioning in the Front Range of Colorado, Boulder Creek Watershed. Temperature and precipitation significantly increased over the last five decades, with precipitation increasing primarily in winter (11.2 mm decade−1) and temperature increasing primarily during the growing season (0.12°C decade−1). In response to wetter winters and warmer summers, streamflow decreased −9.8 mm decade−1, with largest declines occurring during summer and autumn baseflow (−8.4 mm decade−1). Spring warming was associated with increases in episodic, short spring melt events, earlier and slower snowmelt and an increase in fraction of precipitation available to plants (catchment wetting or W). Warming during the growing season resulted in an increase in the fraction of W lost as evapotranspiration (ET), earlier and lower peaks in remotely sensed normalized difference vegetation index (NDVI) and lower tree ring width index (RWI). These analyses highlight that vegetation is becoming increasingly water limited even as increases in precipitation and slower melt increase plant water availability. Further, catchment‐derived metrics like the Horton Index (ET/W) provide insight in to how simultaneous changes in temperature, precipitation and melt impact vegetation across complex watersheds.
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Tracking changing water budgets across the Bahamian archipelago
Freshwater resources on small island nations are already at risk from sea level rise and groundwater pumping however, increasing aridity due to climate change further stresses water availability. The amount of freshwater availability on small island nations is delicately balanced by incoming precipitation (P) and outgoing evapo- transpiration (ET). As climate changes, some island nations may see increasing aridity (ET > P) which can have implications for long term freshwater sustainability. Understanding how P and ET are changing allows small island nations to make more informed planning decisions regarding sustainable management and to adapt contemporary strategies to accommodate future change. The Bahamas is one such nation made up of over 700 small islands, many of which rely on freshwater lenses for potable water and irrigation. We use precipitation obtained from the TerraClimate reanalysis dataset and satellite derived actual evapotranspiration (ETa) to analyze how seasonal and yearly water budgets have changed over the last 16 years. We show that ETa is increasing across the Bahamas at a higher rate than global averages. The cause of ETa increases is driven by both increases in temperature and water availability form shifting precipitation patterns, ultimately driving decreases in the amount of available water to recharge the freshwater lens.
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- Award ID(s):
- 1930451
- PAR ID:
- 10555106
- Publisher / Repository:
- Elsevier
- Date Published:
- Journal Name:
- Journal of Hydrology
- Volume:
- 598
- Issue:
- C
- ISSN:
- 0022-1694
- Page Range / eLocation ID:
- 126178
- Subject(s) / Keyword(s):
- Carbonate Island Hydrology Freshwater lens Remote sensing Water budgets Reanalysis data
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1016/j.jhydrol.2021.126178
