17 March 2019 - Soil erosion and the alluvial deposits are natural phenomena, and these soil degradation processes have a significant effect on lakes in Montenegro, especially Lake Plav, Lake Biograd and Skadar Lake. These naturally occurring processes reduce the volume of reservoirs.
When the deposit of alluvial materials is enhanced by eutrophication, which means that a body of water becomes overly enriched with minerals and nutrients which induce excessive growth of plants and algae, this ultimately leads to depleted oxygen levels and generally poor water quality. Eutrophication contributes to fish kills, loss of riparian habitat, the death of beneficial aquatic insects, and taste and odour problems.
In an interview for News Agency Pobjeda, PhD Velibor Spalević from the Department of Geography of the Faculty of Philosophy of the University of Montenegro claims that, based on his research, if the soil conservation measures are not taken, Lake Biograd will be entirely covered by alluvial materials from the Biogradska River in the timeframe of 130 years.
As Professor Spalević assessed, soil erosion and alluvial deposits are mostly influenced by human-made activities (anthropogenic factor), but the problem of climate change has recently become an essential factor as well.
"The research I led at Biogradska Forest in 2004, working with the team of researchers that included Milić Čurović, Arvidas Povilaitis and my colleague Slobodan Radusinović, showed that the production of erosion material in the Biogradska River Basin amounts to 17,179 cubic metres per year, and that the real losses of soil structure from the basin amount to 7.983 cubic meters a year. This amount of soil loss is greater than the deposit of alluvial materials because the amount of soil “produced” in the basin does not fully reach the lake. For this particular river basin the intensity of soil erosion is 282 cubic meters per square kilometre, which indicates that this area has very poor erosion ", explains Professor Spalević.
He further claims that, as a catalyst for these processes over time, the depth of the lake will gradually decrease.
"The surface, i.e., the upper layers of shallow waters can get warmed up in the sun very fast, which further influences the growth of autotrophic bacteria. These bacteria can intensify the eutrophication processes. Also, the waters around Jezerštica gradually reduce the island’s right bank, which is another problem for this ecological gem. Furthermore, the experts from the field of geology are recently initializing the talk about the problem of cracks (caverns) that are noticeable on the north and north-western rim and at the bottom of the Lake Biograd," Spalević points out.
The Professor claims that if special measures for erosion protection are not implemented, such as setting up a gabion or some other stabilization barrier upstream Biogradska River, according to the calculations of the models developed for conditions in Montenegro, Lake Biograd will be covered entirely by alluvial materials from the Biogradska River in the timeframe of 130 years.
"Recent climate changes can also affect this estimate by decade, more or less. One hundred thirty years is a period of “only” two human lives. And while we are discussing whether to take action, nature is acting on its own," Spalević says.
