Croatian Meteorological and Hydrological Service DHMZ

Measurements of river water temperatures

River temperatures are an important indicator of the state of the environment, as water, due to its good thermal conductivity, is a direct indicator of surface and underground temperature of the entire upstream basin, but also beyond.

There are eight river temperature values shown in the table with a three-hour frequency. The displayed values were measured at the specified hour on 20 hydrological stations in different parts of Croatia. Modernization of hydrological stations is in progress so the table will complement as new temperature sensors will be installed on the bathing rivers.

The measurements are carried out with temperature probes which continually measure temperature at a depth of 0.5 to 1 meter. That are the temperature sensors Pt100 (type RTD), OTT PLS pressure probes or OTT Ecolog 500/1000 measuring systems. Measurements are taken uninterruptedly with continuous data records, and hourly temperature values are published in near real time.

At some river gauges measurements are still taken manually. In those cases, a thermometer with lower measurement limits from 0°C to -5°C is used. The thermometer is integrated in the protective metal case which is perforated on the bottom side so that the water can circulate freely around the lower part of the thermometer. Measurement is taken in the middle of the river flow, and the thermometer is kept at the certain depth up to three to five minutes. Such measurements are taken once a day and are not shown in the table. Croatian Meteorological and Hydrological Service (DHMZ) has had data on river temperatures at some hydrological stations since 1948.