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Water budget and run-off response of a tropical multispecies “reforest” and effects of typhoon disturbance


Zhang, Jun; Bruijnzeel, L Adrian; Tripoli, Rogelio; van Meerveld, H J (2019). Water budget and run-off response of a tropical multispecies “reforest” and effects of typhoon disturbance. Ecohydrology, 12(2):e2055.

Abstract

To examine claims that reforesting degraded Imperata grassland in Leyte (Philippines) made streamflow perennial again, we studied the hydrological behaviour of a 23‐year‐old mixed‐species “reforest” between June 2013 and May 2014. Typhoon Haiyan, one of the strongest events ever, caused major damage to the site in November 2013. Average daily apparent water use (ET) was 5.0 mm day−1 pretyphoon and 3.2 mm day−1 after disturbance. Corresponding ratios of period total quickflow Qq to precipitation were 16% and 44%. Quickflow volume and peak discharge increased rapidly once a threshold value of ~250 mm for soil water storage in the top 60 cm was exceeded. Before disturbance, quickflow consisted predominantly of lateral subsurface flow due to high soil hydraulic conductivities down to 60 cm. After disturbance, shallow groundwater rose regularly to within 10 cm of the surface on foot slopes, and saturation overland flow was observed during several large storms. Comparing estimated annual ET and Qq for undisturbed conditions for the reforest and a nearby degraded Imperata grassland microcatchment suggested that the extra infiltration following reforestation (~240 mm year−1) exceeded the extra ET by the reforest (100–185 mm year−1), implying a net positive trade‐off (55–140 mm year−1) and tentatively confirming local claims of improved dry‐season flow.

Abstract

To examine claims that reforesting degraded Imperata grassland in Leyte (Philippines) made streamflow perennial again, we studied the hydrological behaviour of a 23‐year‐old mixed‐species “reforest” between June 2013 and May 2014. Typhoon Haiyan, one of the strongest events ever, caused major damage to the site in November 2013. Average daily apparent water use (ET) was 5.0 mm day−1 pretyphoon and 3.2 mm day−1 after disturbance. Corresponding ratios of period total quickflow Qq to precipitation were 16% and 44%. Quickflow volume and peak discharge increased rapidly once a threshold value of ~250 mm for soil water storage in the top 60 cm was exceeded. Before disturbance, quickflow consisted predominantly of lateral subsurface flow due to high soil hydraulic conductivities down to 60 cm. After disturbance, shallow groundwater rose regularly to within 10 cm of the surface on foot slopes, and saturation overland flow was observed during several large storms. Comparing estimated annual ET and Qq for undisturbed conditions for the reforest and a nearby degraded Imperata grassland microcatchment suggested that the extra infiltration following reforestation (~240 mm year−1) exceeded the extra ET by the reforest (100–185 mm year−1), implying a net positive trade‐off (55–140 mm year−1) and tentatively confirming local claims of improved dry‐season flow.

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Additional indexing

Item Type:Journal Article, refereed, original work
Communities & Collections:07 Faculty of Science > Institute of Geography
Dewey Decimal Classification:910 Geography & travel
Uncontrolled Keywords:Earth-Surface Processes, Ecology, Aquatic Science, Ecology, Evolution, Behavior and Systematics
Language:English
Date:1 March 2019
Deposited On:16 May 2019 15:15
Last Modified:19 May 2019 05:55
Publisher:Wiley-Blackwell Publishing, Inc.
ISSN:1936-0584
OA Status:Closed
Publisher DOI:https://doi.org/10.1002/eco.2055

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