Variability of the water availability in a river lake system – A case study of Lake Symsar

Abstract

It is predicted that climate change will result in the diminution of water resources available both on global and regional scales. Local climate change is harder to observe and therefore, while counteracting its effects, it seems advisable to undertake studies on pertinent regional and local conditions. In this research, our aim was to assess the impact of a river and its catchment on fluctuations in the water availability in a natural lake which belongs to a post-glacial river and lake system. River and lake systems behave most often like a single interacting hydrological unit, and the intensity of water exchange in these systems is quite high, which may cause temporary water losses. This study showed that water in the analyzed river and lake system was exchanged approx. every 66 days, which resulted from the total (horizontal and vertical) water exchange. Also, the management of a catchment area seems to play a crucial role in the local water availability, as demonstrated by this research, where water retention was favoured by wooded and marshy areas. More intensive water retention was observed in a catchment dominated by forests, pastures and wetlands. Wasteland and large differences in the land elevation in the tested catchment are unfavourable to water retention because they intensify soil evaporation and accelerate the water run-off outside of the catchment. Among the actions which should be undertaken in order to counteract water deficiencies in catchment areas, rational use and management of the land resources in the catchment are most often mentioned.

Influence of Cascading River–Lake Systems on the Dynamics of Nutrient Circulation in Catchment Areas

“…Weather conditions are also important for water exchange [29]. Smaller amounts of precipitation may result in lower water levels and a consequent decrease in the water table level, thus reducing the reservoir surface area.…”

“…Weather conditions affect the heating, cooling, mixing and circulation of lake waters [37]. They do not directly influence the lake water pollution, but they indirectly influence the hydrological conditions in river-lake systems [29,38] by regulating water levels in river beds and lakes, influencing dilution and accumulation of nutrients in waters and influencing the intensity of water flow in river beds. For example, lower water abundance in individual hydrological years, resulting from lower precipitation sums, contributed to the occurrence of periodic water depletion in some watercourses in the catchment area of the river-lake system under study, especially in summer, during intensive plant vegetation and increased water demand [29].…”

“…The retention of water in catchment areas is desirable because it allows its use during periods of its shortage, which is facilitated by the proper use of the catchment area [33]. Forest use and the presence of pastures and green areas are conducive to water retention, but large differences in altitudes may be conducive to its faster outflow [29]. In typically agricultural catchments, with arable…”

“…The retention of water in catchment areas is desirable because it allows its use during periods of its shortage, which is facilitated by the proper use of the catchment area [33]. Forest use and Water 2020, 12, 1144 5 of 18 the presence of pastures and green areas are conducive to water retention, but large differences in altitudes may be conducive to its faster outflow [29]. In typically agricultural catchments, with arable land dominating, even half of the water per one hectare of area can be retained compared to forest catchments [29], which was explained in a study by Schüler et al [39] by the higher intensity of field evaporation with such land use.…”

“…Forest use and Water 2020, 12, 1144 5 of 18 the presence of pastures and green areas are conducive to water retention, but large differences in altitudes may be conducive to its faster outflow [29]. In typically agricultural catchments, with arable land dominating, even half of the water per one hectare of area can be retained compared to forest catchments [29], which was explained in a study by Schüler et al [39] by the higher intensity of field evaporation with such land use. All measures aimed at water retention in river basins, as in river-lake systems, could improve water conditions in the landscape.…”