A practical approach to lake water density from electrical conductivity and temperature

Abstract

Abstract. Density calculations are essential to study stratification, circulation patterns, internal wave formation and other aspects of hydrodynamics in lakes and reservoirs. Currently, the most common procedure is the use of CTD profilers and convert measurements of temperature and electrical conductivity into density. In limnic waters, such approaches are of limited accuracy, if they do not consider lake specific composition of solutes, as we show. A new approach is presented to correlate density and electrical conductivity, using only two specific coefficients based on the composition of solutes. First, it is necessary to evaluate the lake-specific coefficients connecting electrical conductivity with density. Once these coefficients have been obtained, density can easily be calculated based on CTD data. The new method has been tested against measured values and the most common equations used in the calculation of density in limnic and ocean conditions. The results show that our new approach can reproduce the density contribution of solutes with a relative accuracy of 10 % in lake waters from very low to very high concentrations as well as in lakes of very particular water chemistry, which surmounts all commonly implemented density calculations in lakes by far. Finally, we provide a web link for downloading the corresponding density calculator.

Quantifying, assessing and removing the extreme gas load from meromictic Guadiana pit lake, Southwest Spain

“…We found coefficients ofλ 0 ¼ 1:73 kg=m 3 mS=cm , which was to our knowledge the highest value reported for limnic waters (see Moreira et al, 2016), and λ 1 ¼ −0:0025 kg=m 3…”

“…We used the Moreira et al (2016) form for a density formula to connected density with electrical conductivity:…”

Instability of a dense seepage layer on a sloping boundary

“…Nevertheless, equation (22) is acknowledged to be a simple idealized representation of the density behaviour in real lakes, and particularly as no allowance is made here for temperature variations. Detailed experimental studies of the effects of temperature and electrical conductivity upon water density in several European lakes and reservoirs are discussed by Moreira et al (2016).…”

Assessing Aquatic Ecological Health for Lake Poyang, China: Part I Index Development

“…Phosphorus and nitrogen were the drivers of eutrophication that could lead to the disaster of harmful algal blooms [30]. EC represented the concentration of water-soluble inorganic salts and indirectly reflects the intensity of industrial production [31]. Nutrition conditions were represented by the nutrient indictor of trophic level indices (TLI).…”