Critical assessment of discharge measurements in challenging headwater streams: conventional vs. hot-water injection thermal imaging

Schubert CM, van Geldern R, Gossel W, Visser AN, Barth J (2026)

Publication Type: Journal article

Publication year: 2026

Journal

Hydrological Sciences Journal-Journal Des Sciences Hydrologiques Taylor & Francis: STM, Behavioural Science and Public Health Titles / Taylor & Francis

DOI: 10.1080/02626667.2025.2594631

Abstract

Varying flow and morphology challenge precise discharge evaluations in spring-fed headwater streams. This study compared the site-specific suitability of conventional methods (dye, salt tracers, floating spheres, current meters, and bucket-and-stopwatch gauging) with an innovative hot-water-injection thermal imaging technique across four hydro-morphologically challenging sites. Statistical analyses showed thermal imaging is a reliable option in small turbulent or non-turbulent sites under the condition of complete mixing (width <1.2 m, depth <0.2 m, 0.9–64 L s−1), offering chemical-free applications and fast deployment. Limitations included incomplete mixing at large sites (>2 m, >0.3 m, >136 L s−1) and reduced thermal contrasts (thermal masking) under warm conditions. Salt and dye tracers performed comparably. Floating spheres overestimated discharge in shallow or high flows, impellers underestimated under turbulence and required depths >0.05 m, and gauging underestimated discharge in shallow, turbulent sites. These findings highlight that careful site-specific method selection remains essential to minimize errors in hydro-morphologically challenging headwater streams.

Authors with CRIS profile

Robert van Geldern Lehrstuhl für Angewandte Geologie Anna-Neva Visser Lehrstuhl für Angewandte Geologie Johannes Barth Lehrstuhl für Angewandte Geologie

Involved external institutions

Martin-Luther-Universität Halle-Wittenberg (MLU) DE Germany (DE)

How to cite

APA:

Schubert, C.M., van Geldern, R., Gossel, W., Visser, A.-N., & Barth, J. (2026). Critical assessment of discharge measurements in challenging headwater streams: conventional vs. hot-water injection thermal imaging. Hydrological Sciences Journal-Journal Des Sciences Hydrologiques. https://doi.org/10.1080/02626667.2025.2594631

MLA:

Schubert, Christina M., et al. "Critical assessment of discharge measurements in challenging headwater streams: conventional vs. hot-water injection thermal imaging." Hydrological Sciences Journal-Journal Des Sciences Hydrologiques (2026).

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