Volume 19 (2019): Issue 1 (March 2019)

The problematic water situation in Egypt, as one of the River Nile basin countries, has been heightened by the harmful effects of the Grand Ethiopian Renaissance Dam (GERD) on Egypt’s share of the Nile water. In the light of this Egyptian attention was directed towards a study of worldwide transboundary water problems, in order to find the most effective methods for dealing successfully with water shortage problems in basin countries. The present study focuses on the most successful experiences in the management and development of international river basins worldwide, as well as studying the possibility of implementing these experiences in other basins, especially the River Nile basin. The study showed that overcoming the water scarcity problems in Egypt and increasing the Nile water yield for all the basin countries can be achieved, first of all through serious cooperation among all the basin countries for minimizing the huge water losses from the river (more than 1480 Billion Cubic Metres per year which represents roughly 90% of the whole basin income), and secondly to make use of the most successful technical and political experiences that have been implemented in other international river basins mentioned in the present study.

The article describes the characteristics of water circulation in the coastal Lake Gardno. The water cycle is based on water balance data calculated for the period 2003–2007 concerning hydrological years, including the components of horizontal and vertical exchange. Due to the coastal location of the lake, particular attention was paid to the share of the seawater in the lake water cycle. It was found that the inflow of sea water accounts for 10% of the total inflow, while inflow from the land accounts for 86% of the total.

Qualitative analyses of nitrogen and phosphorus loads reaching the lake ecosystem provide a basis for pollution control, which is of paramount importance in shallow lakes due to the rapid turn-over of matter and energy. The studies of both external and internal loading were conducted in Lake Łeknenskie, a very shallow, through-flow lake situated in Western Poland. Strong eutrophication is manifested in rich rush vegetation and a lack of submerged macrophytes as well as nitrogen and phosphorus concentrations (max 13.04 mg N dm⁻³ and 0.32 mg P dm⁻³, respectively). Constant domination of cyanobacteria in the phytoplankton community was noted in almost all seasons with a 98% share in summer, resulting in 20 cm water transparency and 223 μg dm⁻³ of chlorophyll-a. The zooplankton community was dominated by rotifers. The main source of nutrients was the River Nielba. Spatial external nutrient loading was 1.93 g P m⁻² yr⁻¹ and 77.55 g N m⁻² yr⁻¹. An even higher load of phosphorus was released from the bottom sediments, 2.18 g P m⁻² yr⁻¹. A comprehensive action plan is required, aiming at the reduction of both external and internal nutrient loading. A series of solutions regarding local environmental conditions should be applied in the lake catchment, including biogeochemical barriers, denitrification walls, artificial retention basins or wetlands, but most of all – improvement in the functioning of the wastewater treatment plant. Restoration is possible, however, protection measures reducing external loading should be undertaken prior to phosphorus inactivation in the water column and in the bottom sediments, supported by biological methods e.g. biomanipulation.

Interdisciplinary research was carried out on the impact of climate on the diversity and morphology of Stratiotes aloides L. emergent forms’ phenotype in various latitudes. The objectives of the research were: 1. to determine whether the climate influences the diversity of emergent forms, 2. to determine the diversity of morphological and anatomical traits and chemical composition of S. aloides specimens in Poland and Russia, 3. to examine the content of, and determine the correlation between phenols, phenolic acids, flavonoids, anthocyanins, and tannins in S. aloides. The research demonstrated the substantial diversity of 13 morpho-anatomical traits, and 5 phytochemical traits, both between regions, and individual habitats. Principal Component Analysis (PCA) demonstrated different correlation patterns for the analysed substances between regions characterised by different temperature ranges. S.aloides shows substantial abilities to adapt in terms of structure and physiology to the aquatic environment in various climate zones.