QUANTITATIVE CONSIDERATIONS CONCERNING THE SOURCE-AREAS FOR THE SILTING OF THE RED LAKE (ROMANIA) LACUSTRINE BASIN

Andrei Enea, Gheorghe Romanescu, Cristian Stoleriu
Alexandru Ioan Cuza” University of Iasi, Romania

Abstract

The Red Lake is part of the natural barrage lakes category, and has been a major part of the landscape since 1837. The silting is specific to hidrographic basins and can be accelerated in specific conditions, which are associated to the negative, anthropic intervention. The long lifespan of the like is due to a very low silting rate and the durity of the body of the landslide. A very important static factor that reduces the quantity of solid material, that is transported in the lake, is represented by the small area of the hydrographic basin, from which the lake recieves its sediments. Through our work, we have analysed the source-areas for the sediments and the origin of the transported material. The origin of the sediments varies, depending on the distribution and size of the areas with differentiated land use, the granulometric size of the particles, the type of plants and their size, soil types etc. The hydrologic network of the Red Lake concentrates the sediments, from the 41 km2 of the drainage basin, therefore generating maximum silting rates which vary between 1cm/year and 3.77 cm/year, while the overall average for the entire lake is recorded at 1.23 +/- 0.6 cm/year. A special attention has been given to the deforestation processes that take place in this drainage basin, which lead to the exposure of the soil towards greater erosion, because of the vegetation that has been cut down. In this case, we can talk about an accelerated erosion and silting process, which are well differentiated along the drainage basin, therefore the human factor intervening decisively in shortening the lifespan of the Red Lake.