A Stable Isotopic Approach to Estimate the Contribution of Evapotranspiration to the Hydrological Cycle Over Lower Gangetic Plain

Josy, Archana (2018) A Stable Isotopic Approach to Estimate the Contribution of Evapotranspiration to the Hydrological Cycle Over Lower Gangetic Plain. Masters thesis, Indian Institute of Science Education and Research Kolkata.

PDF (MS dissertation of Archana Josy (13MS037)) 13MS037.pdf - Submitted Version Restricted to Repository staff only Download (2MB)

Abstract

Evapotranspiration is a significant terrestrial process that greatly contributes to the balance of the hydrological cycle. Though the role played by this land process in recycling moisture has been well understood, its estimation in regional scale still remains undone at many places. Our study uses the stable oxygen isotopic signatures of atmospheric moisture and precipitation to quantify the stable oxygen isotopic composition (δ¹⁸O) of evaporate (δ¹⁸OE), transpired moisture (δ¹⁸OT) and evapotranspiration (δ¹⁸OET) and estimates how much of the total precipitation is recycled back to the atmosphere through the process of evapotranspiration (ET/P) over lower Gangetic plain. To understand the role of dense vegetation in the lower Gangetic plain, partitioning of evapotranspiration has also been done. In the studied region, the δ¹⁸O of atmospheric air moisture (δ¹⁸OA) varied from −24.6‰ to −6.6‰ with an average δ¹⁸OA of −14.2±4.0‰ and the δ¹⁸O of precipitation (δ¹⁸OP) varied from −14.9‰ to 3.0‰ with an average δ¹⁸OP of −3.3±4.3‰. An average relative enrichment of 9.4±2.2‰ can be found in precipitation with respect to the atmospheric air moisture. The average monthly δ¹⁸OET is estimated to be −4.8±4.1‰. Our results show that about 66% of the total annual precipitation is recycled back to the atmosphere through the process of evapotranspiration and out of this 86% is the contribution from vegetation.

Actions (login required)

View Item