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The study evaluated the effect of environmental conditions and morphometric parameters on lake water temperature changes. The analysis was carried out on the basis of 14 lakes located in northern Poland. The assessment was based on the daily water and air temperatures from 1972 to 2016. It took into account the location of lakes (latitude, longitude, altitude) morphometric parameters (surface area, maximum and mean depth, volume), hydrological processes (rate of water exchange, course of ice phenomena), and trophic status (water transparency) as factors that can modify lake water temperature changes. Direction and rate of air and water temperature changes were analysed by means of Mann–Kendall’s and Sen’s tests. Cluster analysis (CA) was applied to group lakes characterised by similar water temperature changes. The effect of climatic and non-climatic parameters on a lake’s water temperature was assessed on the basis of principal component analysis (PCA). Water temperatures in the lakes in the years 1972–2016 were characterised by a higher rate of increase of 0.43 °C·dec−1 than the air temperature decrease of 0.34 °C·dec−1. The analysis showed a faster rate of heating of waters in western Poland. This can be explained by shorter duration of ice cover. Moreover, the changes of water temperature were affected by other factors, including the location of the lakes, their morphometric parameters, wind speed, water transparency and water exchange time.

The conversion of chemical energy contained in organic matter into electricity has become an object of interest for many scientists worldwide. This technology is used in microbial fuel cells (MFC). Apart from generating electrical energy, these cells can be used simultaneously for wastewater treatment. Although the technology is constantly being improved, currently functioning microbial fuel cells cannot provide appropriate output parameters to use on an industrial scale. One of the barriers is so-called extracellular electron transfer, which in turn depends on the electrode type used, its material, shape, and size. According to current literature, carbon, graphite, stainless steel, and ceramics are the most frequently used electrode materials. However, more and more often, scientists are turning to other, unusual materials, the production of which uses the newest technologies, and one of them is graphene. This material is modified in different ways and connected with other materials, and the results of this seem to be very promising. Scientists manage to get a higher level of extracellular electron transfer and, hence, higher output parameters of the whole system. This article describes chosen technologies and attempts made by scientists worldwide to use graphene in MFC and their results.

Aim of the study: The current paper aims to give a detailed evaluation and analysis of some extreme rainfall events that happened in the last decade in terms of spatial and temporal rainfall distribution, intensity rate and exceedance probability. Moreover, it examines the effects of each analysed aspect on the resulting flash floods in the study area. Material and methods: American Meteorology Society (AMS) in their glossary of meteorology divided rainfall intensity types into four groups (light, moderate, heavy, and violent). Also, for estimating the exceedance probability, Lognormal distribution was applied as a statistical model of the precipitation probability distribution function. Results and conclusions: Out of six episodes, five of the analysed events were classified as heavy rainfalls. However, the duration of heavy rainfalls was not more than two hours. Four events of maximum daily rainfall (for a 39-year dataset) were rated from 1 – 10% of exceedance probability. To conclude, the current study can be an initial step in modelling hydrological events in the study area and in the process of transforming precipitation into the outflows of urban basins in the future.

Construction of the Włocławek Barrage on the Vistula River in 1970 became an important source of energy; however, it discontinued sediment transport in the Vistula River. This phenomenon resulted in accumulation before and erosion below the barrage; a similar problem can be expected due to the planned construction of the Lower Vistula Cascade. This study is dedicated to finding an effective and feasible solution to sediment transport management, acceptable to a wide group of users (e.g., navigation, energy producers, and ecologists). A numerical 1D model was applied to carry out analysis of hydrodynamics and sediment transport in the river section from Włocławek Barrage to the Vistula River mouth in the Baltic Sea. For calibration, historical data describing the accumulation and erosion created by the Włocławek Barrage were used. The proposed model allowed incorporation of new barrages chronologically, in accordance with the proposed time schedules. Analysis was carried out in a 50-year horizon, using a set of historical flow data. For sediment flushing, it was proposed to use natural flooding events exceeding Q10% discharge and to control sediment management of the adjacent barrages. To use this method in practice requires verification.

In this work, we developed a new method to assess the impact of climate change (CC) scenarios on land subsidence related to groundwater level depletion in detrital aquifers. The main goal of this work was to propose a parsimonious approach that could be applied for any case study. We also evaluated the methodology in a case study, the Vega de Granada aquifer (southern Spain). Historical subsidence rates were estimated using remote sensing techniques (differential interferometric synthetic aperture radar, DInSAR). Local CC scenarios were generated by applying a bias correction approach. An equifeasible ensemble of the generated projections from different climatic models was also proposed. A simple water balance approach was applied to assess CC impacts on lumped global drawdowns due to future potential rainfall recharge and pumping. CC impacts were propagated to drawdowns within piezometers by applying the global delta change observed with the lumped assessment. Regression models were employed to estimate the impacts of these drawdowns in terms of land subsidence, as well as to analyze the influence of the fine-grained material in the aquifer. The results showed that a more linear behavior was observed for the cases with lower percentage of fine-grained material. The mean increase of the maximum subsidence rates in the considered wells for the future horizon (2016–2045) and the Representative Concentration Pathway (RCP) scenario 8.5 was 54%. The main advantage of the proposed method is its applicability in cases with limited information. It is also appropriate for the study of wide areas to identify potential hot spots where more exhaustive analyses should be performed. The method will allow sustainable adaptation strategies in vulnerable areas during drought-critical periods to be assessed.

A multistage reverse electrodialysis system was studied at the REDstack research facility (the Afsluitdijk, the Netherlands) for over 30 days to describe the performance of such configuration under natural water conditions. The experiments were done with two 0.22 × 0.22 m2 stacks in series comprising 32 cell pairs (3.1 m2 of membrane area) for stage 1 and 64 cell pairs (6.2 m2 membrane area) for stage 2. The total gross power density at the available salinity gradient was stable at around 0.35 W•m􀀀 2. The total net power density, corrected for the initial pressure drop of the stacks, was 0.25 W•m􀀀 2 at an energy efficiency of 37 %. Throughout the operation, due to increased stack pressure drop, the actual total net power density lowered to 0.1 W•m􀀀 2. A distinct behaviour was found for multivalent ions in each stage. For stage 1, Ca2+ and SO42􀀀 were transported from the river water to the seawater side, so-called uphill transport. For stage 2, uphill transport was not found, in line with Donnan potential calculations. Stack autopsy revealed microorganisms with sizes ten times larger than the cartridge filter nominal pore size (5 μm) and biofilm covering part of the spacer open area, both contributing to the increasing pressure drop in the stacks. This study showed that stable gross power densities and high energy efficiencies were obtained from feeding natural waters to a multistage reverse electrodialysis system, independent of fouling. In addition, it emphasized the importance of maintaining pumping power losses low for a viable deployment of the technology.

Underground Pumped Storage Hydropower (UPSH) is an alternative to manage the electricity production in flat regions. UPSH plants consist of two reservoirs of which at least one is underground. For this last reservoir, abandoned mines could be considered. UPSH related activities may induce hydrochemical variations, such as the increase of the oxygen (O2) partial pressure (pO2), which may entail negative consequences in terms of environment and efficiency, especially in coal mined areas where the presence of sulfide minerals is common. This work assesses the main expected environmental impacts that UPSH using abandoned coal mines may induce. © 2017 The Authors. Published by Elsevier Ltd. E. Pujades and A. Jurado gratefully acknowledge the financial support from the University of Liège and the EU through the Marie Curie BeIPD-COFUND postdoctoral fellowship programme (2014/16 and 2015/17 fellows from “FP7-MSCA-COFUND, 600405”). This research has been supported by the Public Service of Wallonia – Department of Energy and Sustainable Building. Peer reviewed