Late Holocene Advancements of Denudational and Depositional Fronts in the Higher Himalaya: A Case Study from Chandra Valley, Himachal Pradesh, India

We suggest a set of variables based on documentation of the active denudational and depositional fronts in a segment of Chandra river valley in the Higher Himalaya (India). Convergence and divergence of the denudational front (Dw) with depositional front (S), advancements of lateral valley denudation front (Lw), and the changes in base levels (bn) under the constant valley-accommodation-space earmarks the active geomorphic evolution of the Chandra valley basin through Late Holocene. The cumulative enrichment of stable and metastable sediment mass entrapped into precarious valley spaces, valley floors, and catchments is susceptible to episodic clearance by mass flow through flash floods during extreme conditions like glacial surge, GLOF, cloud burst or river dam and breach activity. Field mapping and scaling of these parameters and sediment masses provide essential database and parametric inputs to long-term predictions and interrelationships of denudation with basin fill and sediment transfer rates. We find that the entrapped sediment mass in proportionately larger denudational catchment area against restricted valley conduits into the Chandra trunk system hampers correct estimation on the rates of sediment production and transfer. Late Holocene regime is further stressed by excessive sediment inputs from largely underestimated colluvial and scree deposition, besides recycling of morainic material. Hence the mapping of advancements of these various fronts (surfaces) as suggested here makes a feasible approach to study the Late Holocene evolution of the glaciofluvial basins in the Higher and Trans Himalayas.