SUSPENDED SOLIDS IN SLOVENIAN RIVERS IN 2021 AND 2022

Abstract

Water flows through the riverbed over sediments that make up the bottom and banks of the river. Bed load moves along the riverbed at increased water velocities, while some of the sediments travel in suspended form downstream with the river‘s flow. In 2021 and 2022, the concentration of suspended solids in rivers was significantly increased multiple times. Typically, this was caused by natural processes in the watershed, especially increased river discharge during intense rainfall events. The most notable increase in the concentration of suspended solids occurred in the Mura river during a high-water event in May 2021, when approximately 39,720 tons of suspended solids were transported through a cross-section of the river in a single day. There was also a significant increase in the concentration of suspended solids in the Savinja river on December 15, 2022, with a daily transport of 15,690 tons of suspended solids. Despite these occasional pronounced increases in the transport of suspended solids, the rivers transported fewer sediments through their channels in the past two years than during the period 2017-2020. The likely reason for this is the longer periods of surface water drought conditions, which were particularly pronounced in the western part of Slovenia in 2022.