Stormflow-hydrograph separation based on isotopes: the thrill is gone--what's next?

January 1, 2002

Beginning in the 1970s, the promise of a new method for separating

stormflow hydrographs using

H, and

Hprovedanirresistible

temptation, and was a vast improvement over graphical separation

and solute tracer methods that were prevalent at the time. Eventu-

ally, hydrologists realized that this new method entailed a plethora

of assumptions about temporal and spatial homogeneity of isotopic

composition (many of which were commonly violated). Nevertheless,

hydrologists forged ahead with dozens of isotope-based hydrograph-

separation studies that were published in the 1970s and 1980s.

Hortonian overland flow was presumed dead. By the late 1980s,

the new isotope-based hydrograph separation technique had moved

into adolescence, accompanied by typical adolescent problems such

as confusion and a search for identity. As experienced hydrologists

continued to use the isotope technique to study stormflow hydrol-

ogy in forested catchments in humid climates, their younger peers

followed obligingly—again and again. Was Hortonian overland flow

really dead and forgotten, though? What about catchments in which

people live and work? And what about catchments in dry climates

and the tropics? How useful were study results when several of the

assumptions about the homogeneity of source waters were commonly

violated? What if two components could not explain the variation of

isotopic composition measured in the stream during stormflow? And

what about uncertainty? As with many new tools, once the initial

shine wore off, the limitations of the method became a concern—one

of which was that isotope-based hydrograph separations alone could

not reveal much about the flow paths by which water arrives at a

stream channel during storms.

Publication Year	2002
Title	Stormflow-hydrograph separation based on isotopes: the thrill is gone--what's next?
DOI	10.1002/hyp.5008
Authors	Douglas A. Burns
Publication Type	Article
Publication Subtype	Journal Article
Series Title	Hydrological Processes
Index ID	70074371
Record Source	USGS Publications Warehouse
USGS Organization	New York Water Science Center

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