Knowledge space

The article presents the results of investigating the morphological variability of carp (Cyprinus carpio Linnaeus, 1758) in three large reservoirs of the Balkash-Alakol Basin – Lake Balkash, Lake Alakol, and Kapshagay Reservoir. Morphological differences in several features (counting and plasticity) were found in three carp samples. The study included the examination of 24 plastic and 14 counting features. The method of digital image processing (Morpho J) was applied to analyze the differences of the target fish species specimens by body shape. The application of the principal component analysis (PCA) method allowed determining the main loadings on the studied morphological traits of carp. The statistically reliable differences revealed allow to confirm the formation of morphological changes in carp caused by
the duration of adaptive radiation, environmental factors of water bodies and annual artificial stocking of young fish.

This study aimed to examine the efficiency of different drip irrigation regimes in spring film greenhouses for early tomato harvesting. The field (small-plot) experiment included designing and testing the watering technology suitable for rural Tajikistan. Irrigation, soil moisture, and tomato growth were followed for several seasons under four irrigation pilots. The experiments showed that the most effective drip irrigation regime for Elpida hybrid tomato was carrying it out while regulating soil moisture within 75-85%, with the irrigation demand of 4,978 m3/ha and irrigation norm of 99.0 m3/ha, also contributing to better water efficiency. The volume of irrigation water for the production of one unit of tomato crop in the second experiment was 5.73 m3/ha, i.e. 14.18% less than in the control plot. The study showed that the tomato evapotranspiration coefficient tends to increase as the threshold of soil mois-ture before and after irrigation grows. The maximum net yield amounted to 1,342 thou. Somoni/ha – 1.9 times or 52.7% higher compared to the control plot. The research findings can guide individual farmers and production facilities, as well as the overall development of agrarian economies like Tajikistan.

The study was conducted in 2023 and comprised a comparative assessment of the state of Lake Markakol’s aquatic ecosystems in surface and bottom water strata. The analysis of bottom water temperatures showed correlation between this parameter and dissolved oxygen concentrations, indicating that pollution caused by organic impurities leads to lake eutrophication, in turn, pro-pelling the extinction of aquatic life. Although the main water physicochemical parameters of Markakol Lake correspond to the oligotrophic type, the shifts in dissolved oxygen and phos-phate content, as well as growth of aquatic vegetation indicate its transition to the mesotrophic type. Higher phosphate content in water is a consequence of pollution disturbing the biological balance, as well as stimulating the reservoir’s eutrophication and increased biological productivity, i.e. algal bloom. In addition, phosphate ions serve an informative indicator of Hazard Class 3 (organoleptically hazardous) anthropogenic pollution. Based on the correlation factor (r), two statistical models were considered for the target lake: 1) Water Pollution: nutri-ent concentrations depending on surface and bottom water temperatures (Model 1); and 2) changes in Water Pollution Indices (biogenic, heavy metals, mean) because of air temperature growth due to global warming of 0.25°C/decade (Model 2).

The article investigates certain low-cost filtering materials and their filtration efficiency for open well sources in terms of economic access to clean water in Anakapalle, a suburb of Visa-khapatnam, India, during the pre-monsoon period of 2022. The corresponding research aimed to study a selection of filter materials including coconut shell activated carbon, rice husk ash, manganese modified sand, and graphene oxide, as well as assess their performance against selected physico-chemical parameters of water. Considering the basic idea of slow sand and gravity-based filtration, a setup was arranged with a cartridge filled with layers of filtering materials and a ceramic candle filter. Adsorption turned out the most pronounced removal mechanism that took place when utilizing the aforementioned filter materials. The main focus of the study was to reduce pH, TDS, hardness, alkalinity, chlorides and iron content by applying dif-ferent filtration removal mechanisms. The study results show a significant drop in turbidity, pH, TDS and chlorides, and small reduction in hardness when coconut shell activated carbon and rice husk ash were used as filtration media. Whereas the chemically coated medium – manga-nese modified sand – demonstrated a considerable fall in iron concentrations, graphene oxide sand was observed to reduce alkalinity for any sample source.

MAR remains relatively underutilized in Central Asia despite its potential to address water scarcity issues, particularly those related to seasonal fluctuations in water availability. Thus, the objective of this study was to produce a map depicting the potential suitability of managed aquifer recharge (MAR) implementation in Kazakhstan. Employing a multi-criteria decision analysis framework, five distinct physical criteria were integrated and visualized within a Geographic Information System (GIS) to delineate the intrinsic potential for MAR. To demonstrate the practical utility of the generated map, it was applied to the Zhambyl region in Southern Kazakhstan, an area previously afflicted by water scarcity challenges. The intrinsic MAR potential map was overlaid with remote sensing data identifying potential water sources and water utilization patterns. This overlay facilitated the identification of priority areas with potential for further evaluation for MAR implementation. The map developed for Kazakhstan represents the first spatial representation of MAR potential within the region, serving to raise awareness regarding the feasibility of MAR application. It is anticipated that dissemination of this map will enhance understanding among water management professionals, potentially catalysing the integration of MAR methodologies into regional water management strategies.