Are diurnal fluctuations in streamflow real?
| Autor: | Jaime G. Cuevas, Christian Little, Matías Calvo, Paul Dassori, Mario Pino |
|---|---|
| Rok vydání: | 2010 |
| Předmět: |
Fluid Flow and Transfer Processes
Meteorology Mechanical Engineering stream and air temperatures Diurnal temperature variation methodological artifacts Front (oceanography) TA Engineering (General). Civil engineering (General) Hydraulic engineering metodologické artefakty Atmospheric sciences Diurnal fluctuation južné dažďové pralesy Amplitude Streamflow Air temperature Weir inštrumentálna analýza Environmental science southern rainforests instrumental analysis Underwater TC1-978 teploty vzduchu a vody Water Science and Technology |
| Zdroj: | Journal of Hydrology and Hydromechanics, Vol 58, Iss 3, Pp 149-162 (2010) JOURNAL OF HYDROLOGY AND HYDROMECHANICS Artículos CONICYT CONICYT Chile instacron:CONICYT |
| ISSN: | 0042-790X |
| DOI: | 10.2478/v10098-010-0014-0 |
| Popis: | Diurnal variations in streamflow (DVS) have been studied in detail by underwater pressure loggers. Some of this equipment requires barometric compensation with a logger or sensor located outside the water. Studies related to this topic have not offered a critical report of the validity of patterns inferred with these instruments. While studying a forested watershed in Southern Chile (40° S), we detected a DVS when the external logger was placed 1.5 m above ground, under a marked diurnal fluctuation in air temperature (amplitude 12.4 °C) and a dampened fluctuation in stream temperature (amplitude 1.4 °C). Synchronization was apparent between air and stream temperature in a direct relationship, but the synchronization between air/stream temperature and streamflow was negative, with some hours of lag time. In laboratory experiments, when the external logger is considerably warmer than the water-level logger, depth measurements can be underestimated by up to 1.5 cm. When the opposite occurs, water depths can be overestimated by up to 0.9 cm and are large instrumental/methodological artifacts compared to the field water diurnal variation of 1.3 cm. Finally, we relocated the external logger in front of the water-level logger and inside a weir, but exposed to the air. Results confirmed the pattern previously detected in the field, but streamflow fluctuations were 19% less accentuated. We conclude that the incorrect placement of the external logger, along with an instrumental artifact, can intensify a DVS pattern. |
| Databáze: | OpenAIRE |
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