Dissolved oxygen and water temperature dynamics in lowland rivers over various timescales

Abstract

Abstract:The impact of floodplain hydrology on the in-stream dissolved oxygen dynamics and the relation between dissolved oxygen and water temperature are investigated. This has been done by examining the time series of dissolved oxygen and water temperature coupled with meteorological and hydrological data obtained from two lowland rivers having contrasting hydrological settings. Spectral analysis of long-term oxygen variations in a vegetated river revealed a distinct scaling regime with slope '-1' indicating a self-similar behaviour. Identical slopes were obtained for water temperature and water level. The same power-law behaviour was observed for an unvegetated river at small timescales revealing the underlying scaling behaviour of dissolved oxygen regime for different types of rivers and over various time scales. The results have shown that the oxygenation of a vegetated river is strongly related to its thermal regime and flow conditions. Moreover, analysis of short-term fluctuations in the unvegetated river demonstrated that physical factors such as rainfall and backwaters play a substantial role in the functioning of this ecosystem. Finally, the results show that the relation between water temperature and dissolved oxygen concentration at the diurnal timescale exhibits a looping behaviour on the variable plot. The findings of this study provide an insight into the sensitivity of rivers to changing hydro-physical conditions and can be useful in the assessment of environmental variability.

High-frequency monitoring of stream water physicochemistry on sub-Antarctic Marion Island

“…This pattern is further supported by the strong, significant negative relationship between DO concentrations and stream water temperature (r = −0.96, p < 0.0001), which highlights the temperature dependence of diel DO dynamics (Nimick et al, 2011). Such a relationship is consistent with small, shallow and impoverished streams (Rajwa-Kuligiewicz et al, 2015). The night-time maxima and daytime minima in DO observed in the SPR are also found in oligotrophic mountain streams with steep gradients (Nimick et al, 2011).…”

Wavelet Characteristics of Hydrological and Dissolved Oxygen Time Series in a Lowland River

“…As reported by Rajwa-Kuligiewicz et al (2015) Fourier analysis of dissolved oxygen and water temperature time series indicated the existence of one peak in the power spectrum, which corresponds to the daily cycle. Moreover, power spectra of DO, water temperature, and water level time series can be roughly approximated by the "-1" slope.…”

“…Moreover, small individual peaks are visible at the period of one week. In fact, this consistency has not been reported in the ear-lier work of Rajwa-Kuligiewicz et al (2015) since both, the statistical method and Fourier technique, failed to show that. Interestingly, high coherence occurs during flood events, suggesting that extreme events such as floods directly affect the river ecosystems.…”

“…Data used in this study was obtained from the Narew River monitoring station (see Rajwa-Kuligiewicz et al (2015) for a detailed description of the data). The Narew River is located in north-east Poland (see Fig.…”

Laboratory studies on bedload transport under unsteady flow conditions

“…It is hardly surprising that unsteady flows are intertwined with hysteretic behaviour as observed with respect to many variables (see e.g. O'Kane, 2005;Rajwa-Kuligiewicz et al, 2015;Rowiński et al, 2000). Mao (2012) reported a clockwise hysteresis in experimental tests and attributed this type of relation to changes in organization of bed surface grains, which caused smaller bedload transport along the falling limb.…”