High-frequency monitoring for the identification of hydrological and bio-geochemical processes in a Mediterranean river basin

Summary A telemetric high-frequency hydrologic and water quality monitoring network was deployed to obtain data for the characterization of the hydrologic and bio-geochemical processes of a complex Mediterranean watershed of Koiliaris River, Crete, Greece. The network measures water level, water temperature, pH, dissolved oxygen (DO) and nitrate. Analysis of the hydrologic data suggests the existence of four hydrologic processes that operate in the watershed with distinctive characteristic response times. The response of the flow hydrograph of the upper reservoir of the Karstic system to a precipitation event had a characteristic time of 10 d while the characteristic time of the lower reservoir was 38 d. The flash flood events of Keramianos temporary river (tributary to Koiliaris) had a characteristic response time of 29 h while the diurnal variation of flow had a characteristic response time of 18 h. The diurnal fluctuation of the chemical parameters had a characteristic response time of 8 h for pH, 83 h for DO and 13 h for nitrates while the nitrate flush from the Neogene deposits to the river had a characteristic response time of 2.7 h. The diurnal fluctuation is related to in-stream biological activity. The results illustrate the importance of high-frequency sampling for accurate parameterization of processes operating in complex environmental systems with varying process response times.

[1]  R. Drysdale,et al.  The influence of diurnal temperatures on the hydrochemistry of a tufa‐depositing stream , 2003 .

[2]  S. Capelo,et al.  In situ continuous monitoring of chloride, nitrate and ammonium in a temporary stream Comparison with standard methods. , 2007, Talanta.

[3]  J. Lee,et al.  Inorganic chemicals in an effluent-dominated stream as indicators for chemical reactions and streamflows , 2002 .

[4]  Filippos Vallianatos,et al.  Estimation of aquifer hydraulic parameters from surficial geophysical methods: A case study of Keritis Basin in Chania (Crete - Greece) , 2007 .

[5]  S. Seitzinger,et al.  Diurnal patterns of denitrification, oxygen consumption and nitrous oxide production in rivers measured at the whole‐reach scale , 2004 .

[6]  Y. Azov.  Effect of pH on Inorganic Carbon Uptake in Algal Cultures , 1982, Applied and environmental microbiology.

[7]  Li-qing Li,et al.  First flush of storm runoff pollution from an urban catchment in China. , 2007, Journal of environmental sciences.

[8]  C. Fassoulas.  The structural evolution of central Crete: insight into the tectonic evolution of the south Aegean (Greece) , 1998 .

[9]  Charles N Haas,et al.  The WATERS Network: an integrated environmental observatory network for water research. , 2007, Environmental science & technology.

[10]  Erik A. Smith,et al.  Diurnal and seasonal water variations of temperature, pH, redox potential and conductivity in gnammas (weathering pits): Implications for chemical weathering , 2008 .

[11]  O. Tzoraki,et al.  In-stream biogeochemical processes of a temporary river. , 2007, Environmental science & technology.

[12]  S. R. Parker,et al.  Biogeochemical controls on Diel cycling of stable isotopes of dissolved O2 and dissolved inorganic carbon in the Big Hole River, Montana. , 2005, Environmental science & technology.

[13]  A. Baumann,et al.  The nappe pile of eastern Crete , 1976 .

[14]  F B Green,et al.  Seasonal and diurnal variations of temperature, pH and dissolved oxygen in advanced integrated wastewater pond system treating tannery effluent. , 2004, Water research.

[15]  A. Spacie,et al.  Dissolved oxygen dynamics of streams draining an urbanized and an agricultural catchment , 2003 .

[16]  Ourania Tzoraki,et al.  A generalized framework for modeling the hydrologic and biogeochemical response of a Mediterranean temporary river basin , 2007 .

[17]  L. Turk.  Diurnal fluctuations of water tables induced by atmospheric pressure changes , 1975 .

[18]  M. Masson,et al.  Seasonal variations and annual fluxes of arsenic in the Garonne, Dordogne and Isle Rivers, France. , 2007, The Science of the total environment.

[19]  C. Kendall,et al.  Assessing the sources and magnitude of diurnal nitrate variability in the San Joaquin River (California) with an in situ optical nitrate sensor and dual nitrate isotopes , 2009 .

[20]  Philippe Van Cappellen,et al.  Kinetic modeling of microbially-driven redox chemistry of subsurface environments : coupling transport, microbial metabolism and geochemistry , 1998 .

[21]  Michael K Stenstrom,et al.  First flush in a combined sewer system. , 2008, Chemosphere.

[22]  Poul Harremoës,et al.  Oxygen and pH fluctuations in rivers , 1978 .