Reconstructing discharge of Beas river basin, Kullu valley, western Himalaya, based on tree-ring data

Abstract

Tree-ring data of Cedrus deodara (Deodar) growing within the Beas river basin, Kullu valley, Himachal Pradesh in western Himalaya, have been analyzed in relation to streamflow reconstruction. The correlation between Deodar tree-ring chronology and river discharge data from various gauge stations of the Beas river basin showed positive relationships with early summer months (March–April). Streamflow of these months has been reconstructed using a simple linear regression transfer function model which goes back to AD 1834. Explained variances during the calibration period are 43.7% and 60.6% for two gauge stations, Bhuntar and Thalout, respectively. In the reconstructed data (AD 1834–1984) the periods of highest streamflow were during AD 1840–1843, 1893–1897, 1922–1926, 1935–1940 and 1942–45; and lowest were during the years AD 1847–1851, 1863–66, 1927–1929, 1960–1962 and 1972–1974. Spatial coherence analysis between the reconstructed series with regional gridded precipitation and nearby longest instrumental precipitation records showed coincidence with drought and wet periods. Through the spatial correlation analysis between reconstructed March–April runoff and gridded Palmer Drought Severity Index (PDSI), a common regional moisture variation was identified.