6. The Nature of the Sediments Within the Lacustrine Basin

The sediment discharge that ends up in the Red Lake is important, mostly given that the last decades have been characterized by intense deforestations. These have accelerated the erosion and the silting of the lake basin, as well. In order to correctly assess the source areas of the sediments, from the drainage basin, satellite imagery has been used, to accurately identify the areas that have suffered from deforestation in the last decades. Through deforestation, the slopes are severely destabilized, being vulnerable to landslides, high-water waves, etc. Several silt samples from the bottom of the lake were taken in 17 points covering the whole surface of the lake. The thickness of the lacustrine sediments varies extremely, reaching a maximum of over 6 m in the spillway sectors of the two important brooks: Oaia (Oii) and Suhard. The silting process was also measured by comparing bathymetrical transects between the measurements taken by Pişotă and Năstase in 1957 and the measurements taken in 2010 with specialized equipment. Therefore, the silting rate is a very important parameter, associated with numerous processes both natural and anthropic. Silting has also been studied with the help of gravity core samples. Several USLE models have been made, to emphasize the difference between natural erosion and accelerated erosion, due to illegal deforestation. Silting analysis is very important, because, by using different methods, predictions on future silting rates can be made and we can estimate the lifespan of the lake.