Vol 46, No 6 (2019)

The dynamics of Lena delta coastline since the late XX century up to the present time have been studied using Landsat satellite data. The comparison of different-time images of morphologically different segments of the delta coastline has shown the major portion of the delta to be stable. Minimal changes have been recorded near the mouths of the branches carrying a minor portion of the Lena runoff—the Olenekskaya and Tumatskie. In the eastern part of the delta, near the mouths of copious branches Trofimovskaya and Bykovskaya, no changes have taken place, as well as in its western part, which is represented by a part of abrasion marine terrace embraced by the delta. In the southwestern part, in the Olenek delta, the delta coastline has been eroded with the erosion material transported eastward by along-shore current. Near the mouths of the Tumatskaya branch, the forms of marine accumulation are unstable, and the marine terrace in the northeastern part of the delta shows a minor local erosion. The periods of erosion in different delta areas are not synchronous and the eroded zones are not large in size. No increment in the land, nor shore progradation have been seen.

Understanding estuarine characteristics is crucial for managing aquatic ecosystem and aquaculture. A delta is a dynamic area that influence by both sea and river. Research on a micro-tidal estuary remains limited, particularly in Indonesia. To understand the estuarine management in the delta, this research provides an overview about the hydrological characteristics in Wulan Delta Estuary. This research is important to maintain agriculture, aquaculture, and mangrove ecosystem. Morphological data and hydrological were collected in wet season and dry season. The tidal data were collected from 2007–2016. As the results, the river is predominant in the mixing process in the wet season and the tides in the dry season. A low mixing energy causes stratification in the water column, particularly in a depth water depth. In a shallow water depth, salinity circulation is homogenous. In dry season, the sea water can penetrate into the river up to more than 5 km, due to smooth river bed that may harm the agricultural area in surrounding.

Floods are one of the most common natural hazards and as such, they are causing a great loss of human life as well as great economic damages. Flood frequency analysis (FFA) is still an active and popular field of research among geographers. In this study we have performed regional flood frequency analysis (RFFA) using the L-moments method and annual maximum series (AMS) of mean daily discharge data for five stations in Tisza River basin for dependable prediction of flood quantiles. Floods were defined as events over selected threshold level which was set at Q_10%. Based on L-moments ratio diagrams and its goodness-of-fit statistic, the Pearson type III distribution is identified as the best-fit distribution for the Tisza River basin. Results of this paper can be used as guideline for future research on establishing the official FFA distribution for the entire Tisza river basin which will improve international cooperation on the fields of environmental monitoring, water management and flood prevention policies.

The Kuye river watershed is a coal mining watershed in Northwest China. The study analyzed runoff change of year, high flow period and low flow period in the past 60 years based on Mann-Kendall trend test, cumulative anomaly, and continuous wavelet analysis. The contributions of climate change and human activities on runoff variation were assessed by the rainfall-runoff relationship model. The results were obtained: (1) Runoff in year, high and low flow period showed a significant declining trend during 1954–2015, but the trends of decreasing or increasing of precipitation and evaporation were not notable. (2) Runoff in year, highflow period and low flow period exhibited similar abrupt change feature and stage characteristic. (3) The periodic changing characteristics of runoff in high flow period were similar to those in annual runoff, but those in low flow period were different from annual runoff. (4) The effect of climate change on runoff had an significant decreasing trend from 61.73 to 9.19% in year, from 59.76 to 2.68% in high flow period, and from 25.00 to 2.63% in low flow period. Compared with climate change, the impact of human activities increased obviously, the contribution all over 90.00% in 1997–2015. Thus, human activities demonstrated the dominant influence on runoff decline gradually.

Snow cover dynamics play an important role in the hydrological characteristics of Upper Indus Basin (UIB) of Pakistan in terms of seasonal accumulation and depletions. The current study has been carried out to understand the snow cover dynamics, hydrological regime and their inter-relationships. Remote sensing satellite data of Moderate Resolution Imaging Spectro-Radiometer (MODIS) for the period 2000–2016 along with hydro-meteorological parameters was used to study the spatio-temporal changes in snow cover of Hunza basin. Snow cover dynamics were analyzed through temporal analysis of snow cover and its association with hydro-meteorological parameters using Pearson correlation, Principle Component Analysis (PCA) and elevation-based sub zones. The study concluded that 25–40% of the basin area is covered by glacier. Snow covered area may reach up to 90–95% of the basin area due to accumulation of seasonal snow. Hydro-meteorological correlation matrices showed highly significant correlation (R = 0.78) among maximum and minimum temperatures and river runoff while no correlation was observed between river runoff and rainfall (R = –0.03). A highly significant negative correlation was found for River runoff and Hunza mean Snow covered area (R = –0.87). The negative coefficient value shows that river runoff increases with snow cover melting when temperature increases. At sub-altitudinal zones level, river runoff has high negative correlation with snow cover at high altitude zones (Zone 2, 3) (R = –0.84, –0.86) while at lower altitude (Zone 1) there was a moderate correlation (R = –0.6) between snow cover and river runoff. This study reveals that river discharge in Hunza basin is closely associated with its snow cover dynamics. River runoff is associated with basin’s snow melt phenomenon triggered by seasonally increasing temperatures. River discharge increases with active snow melting with start of summer during the months of April and May. Snow melt starts first at lower altitude zones followed by higher elevation zones with higher vertical glacial deposits.

Observations show that the space and time heterogeneity of river water composition persists over indefinite time even when the effect of pollutant sources and sinks is minor. The driving forces of such heterogeneity have been supposed and shown to be, among other factors, the stratification of water matrix. Studying the structure of water flow and its effect on pollutant distribution in water was based on a system of fundamental equations of the mechanics of a liquid with a free surface. It has been shown that such effect is due to the fine structure of flows, vortices, waves and high-gradient interfaces (ligaments), which is formed and maintained by the motion of water masses. This conclusion extends our knowledge of the hydrological characteristics of water flow, enables one to better understand the nature of the heterogeneity of natural water composition, and it is of practical significance as such heterogeneity can be taken into account in making water management decisions.

Calculating the regime of waves, in accordance with recommendations of the World Meteorological Organization, requires a database covering not less than 30 years. Continuous measurements for a time interval as long as that are available only for a small number of coastal water areas. Commonly such data are derived from calculations by numerical (spectral) hydrodynamic models of wind-induced waves. The inputs in such cases are data on wind obtained by reanalysis. However, reanalysis cannot be applied to calculations for some seawater areas without pretreatment. Data on the Caspian Sea are used to demonstrate an approach to correcting NCEP/NCAR reanalysis data. The results of the application of this procedure are given.

Microelements in bottom sediments may enter different compounds; however, of greatest interest are their mobile forms as the most bioavailable. The microelements speciation in the pore water and solid phase of bottom sediments were studied in the cooling reservoir of the Kalinin NPP (lakes Udomlya and Pes’vo).

Chlorophyll a concentration, the total abundance of bacteria, the number of bacterial cells with active metabolism, and the abundance of saprotrophic bacteria were studied in the surface and bottom water layers of Lake Beloe in winter and spring 2015–2016. The abundance of sanitary-indicator microorganisms was determined for the first time with the use of Petrifilm test-systems (3M^TM Petrifilm™). In most cases, Lake Beloe water in spring and winter was found to correspond to eutrophic level (in terms of chlorophyll a concentration in water) and polysaprobic status (in terms of microbiological indices). By its sanitary-microbiological characteristics, the lake is clear—the values of the total microbial count, determined with the use of test-systems 3M™ Petrifilm™ Aqua (AQHC), were <1000 CFU/mL, and the abundance of coliform bacteria, determined with the use of test-systems 3M™ Petrifilm™ Aqua (AQСC), varied from 20 to 135 CFU/100 mL. Coliform bacteria were mostly found in the bottom water layer. It was shown that, in the organization of ecological–microbiological studies, special attention is to be paid to the bottom horizons of water bodies.

The taxonomic composition of phytoplankton communities in the Moscow River was studied in the area of Moscow megapolis during 2006–2012. The basic regularities of spatial transformation of river phytoplankton were revealed. The main factors affected the phytoplankton structure are as follows: (1) wastewater inflow carrying nutrients and allochthonic phytoplankton, (2) abnormal high average monthly air temperature (26.1°С) in 2010. The principal regularities of changes in phytoplankton structure under the influence of these factors were established. To analyze the structural transformation we estimated the total number of species and abundance of phytoplankton, and also used the analysis of taxomonic structure of diatom complexes with and without taking into account rare taxa. In the area of the wastewater treatment facilities the species diversity is higher, and taxonomic structure of the phytoplankton community is violated. Natural decline in species diversity on account of dominance of species which are more adapted to natural hydrological conditions occurred at the river section not further than 34 km.

The basic indicators of regional water use have been identified and assessed as a component of a single social–natural–technogenic system. These indicators have been assessed in the case of industrial agglomerations in Siberia: Krasnoyarsk Territory and Kemerovskaya oblast, which are considered as pilot regions for the development of the concept of social–natural–technogenic systems. The choice and assessment of basic indicators is a first stage in solving the problems of risk assessment in sustainable regional development.