The first streamflow reconstruction from blue intensity

Keywords: streamflow reconstruction, blue intensity, tropical dendrochronology
Session Type: Virtual Paper Abstract
Day: Monday
Session Start / End Time: 2/28/2022 11:20 AM (Eastern Time (US & Canada)) - 2/28/2022 12:40 PM (Eastern Time (US & Canada))
Room: Virtual 40

Abstract

Using the first blue intensity record from the tropics—from Fokienia hodginsii in Quang Nam, Vietnam—we produce a 430-year reconstruction for the nearby Vu Gia River. We use delta blue intensity (ΔBI) to overcome the color changes from heartwood to sapwood. The reconstruction targets the peak flow season (October to December) of the prior year. Interestingly, the reconstruction from ΔBI is skilful while that from ring width is not (ΔBI: R² = 0.58, RE = 0.55, CE = 0.35; ring-width: R² = 0.29, RE = 0.30, CE = -0.23). The skill scores suggest that ΔBI captures well winter monsoon strength in the region. The well-known Strange Parallels Drought in the mid-eighteenth century is prominent in the reconstruction, together with a prolonged pluvial that lasted through most of the nineteenth century. Importantly, while instrumental data show an increasing trend in the calibration period (1977–2006), the reconstruction reveals that the river is in fact recovering from a three-decade drought that started in the mid-twentieth century. This information must be taken into account in water management, as the river feeds a large irrigation district downstream. Our results also demonstrate that BI is a promising proxy for the hydroclimate, and water management in the region could benefit from more BI chronologies.