Forest cover mitigates the impacts of rainfall variability on streamflow in Puerto Rico
Abstract
Climate warming is changing rainfall regimes, placing additional stress on burgeoning human water demands. Therefore, it is crucial to identify how land use management and rainfall fluctuations influence downstream processes. Puerto Rico is a topographically rugged island with high sedimentation rates in surface water reservoirs, so it is particularly vulnerable to droughts and rainfall extremes despite receiving enough rainfall to support its water demands. The island has high forest cover, offering an opportunity to study the role of conservation of native vegetation in regulating streamflow. We used mean daily streamflow values from 60 stations between 2005 and 2017 across a rainfall gradient in Puerto Rico to assess how short-term and antecedent rainfall and forest cover proportion influenced streamflow and baseflow dynamics. Baseflow was calculated from mean daily streamflow using the Hysep local minimum method. Using generalized linear mixed effects models to predict streamflow and baseflow, we assessed the individual and interactive effects of daily rainfall, 2-week antecedent rainfall and forest cover. The resulting models accounted for 69% and 78% of streamflow and baseflow variability, respectively. Although forest cover alone is not a significant streamflow predictor, watersheds with high forest cover had greater baseflow. Forest cover also plays a large role in determining both streamflow and baseflow through interactions with rainfall. Compared to watersheds with little forest cover, heavily forested watersheds yielded slightly more streamflow under low daily rainfall and less streamflow under high daily rainfall. Forest-dominated watersheds also had significantly higher baseflow at low antecedent rainfall conditions and lower baseflow during periods of high antecedent rainfall. Our results show that forest cover regulates how both daily rainfall and antecedent rainfall influence flow dynamics in a tropical island setting. Further work will examine how forest cover alleviates the impacts of extreme rainfall on flood risk and regulates water provision by decreasing vulnerability to drought conditions.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFM.B41F..04H
- Keywords:
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- 3305 Climate change and variability;
- ATMOSPHERIC PROCESSES;
- 0414 Biogeochemical cycles;
- processes;
- and modeling;
- BIOGEOSCIENCES;
- 1631 Land/atmosphere interactions;
- GLOBAL CHANGE;
- 1813 Eco-hydrology;
- HYDROLOGY