Application of tree rings in understanding long-term variability in river discharge of high Himalayas, India

Abstract

River water supply has an important bearing on socioeconomic developments. Changes in water availability in the past are known to have affected the human civilizations that flourished along with watercourses/river systems. The Himalaya, the world's highest and most dynamic mountain system, is perennial source of water for large number of rivers and streams that directly benefit human societies downstream. Because of high significance of the Himalayan rivers to human society, it is important to understand natural variability in river discharge in the long-term perspective. However, the observational records of river discharge, largely spanning over the past few decades, do not provide sufficient time window to understand its natural variability on interdecadal to centennial scales. Precisely dated, high-resolution tree-ring chronologies developed from moisture stressed sites from river basins provide valuable proxy to extend available short river discharge records back to the past several centuries/millennium. The principle behind this lies in that the precipitation, which directly affects the growth of trees on moisture stressed sites, also controls river discharge. Taking a case study of tree-ring-based river discharge reconstruction of the Sutlej river, the easternmost tributary of the Indus river system, we present here the potential application of tree rings in hydrological studies from the Himalaya.