Two approaches to hydrograph separation of the glacial river runoff using isotopic methods

Abstract

Application of the stable isotope method in the balance equations used to calculate separation of the runoff hydrograph from the Djankuat Glacier basin is demonstrated. Simultaneous solution of equations of water, isotope and ion balances is applied to estimate contributions of different components and processes to formation of the Djankuat River runoff regime. For June 2014, we made calculations for the purpose to separate contributions of the spring (isotopically weighted) snow and winter (isotopically depleted) snow. Field works in the glacial basin Djankuat were performed during two ablation seasons, i.e. from June to September of 2013 and 2014. Two approaches were used when calculating separation of the runoff hydrograph by means of solution of systems of equations for isotopic and ion balances: 1) taking account of the isotope fractionation during snow melting, and 2) with no account for the fractionation. Separation of the hydrograph for June 2014 have shown that about 15–20% of the Djankuat River runoff is formed by spring snow melting, sometimes increasing up to 36%. Contribution of spring meltwater to the total runoff increases when the isotope fractionation during the snow melting is taken into account for the calculations. In this case, the contribution of spring snow changes from 30 to 50%.

Isotopic Composition of Glacier Ice and Meltwater in the Arid Parts of the Altai Mountains (Central Asia)

“…with R 18 O 1 -isotopic content of the first component, f 1 -share of the first component, R 18 O 2 -isotopic content of the second component, f 2 -share of the second component, R 18 O-resulting isotopic composition [1].…”

“…This separation is carried out using the isotope balance formula, which generally has the form: R 18 O1f1 + R 18 O2f2 = R 18 O with R 18 O1-isotopic content of the first component, f1-share of the first component, R 18 O2-isotopic content of the second component, f2-share of the second component, R 18 O-resulting isotopic composition [1].…”

“…In Russia, stable isotopes research of glacier river runoff and glacier ice has been carried out for several years in the Central Caucasus, using examples of runoff from the Dzhankuat glacier (mainly by the Moscow State University) [1][2][3].…”

The Components of the Glacial Runoff of the Tsambagarav Massif from Stable Water Isotope Data

“…where subscripts refer to glacial (g) and snow/firn (s) component of the total runoff (r), and fg and fs are the fractions of these two components (fg + fs = 1) [8].…”

“…In Russia, isotope separation of meltwater was carried out for several years near the Dzhankuat glacier in the Central Caucasus. The authors estimated the contribution of winter and spring snow to the runoff [6][7][8].…”