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[en] This report of the National Institute of Public Health and Environmental Protection (RIVM) contains the results of measurements of radioactivity in the rivers Meuse, Rhine, Roer, in the Westerscheldt, in the Channel of Sas van Gent to Terneuzen, and at some specific locations in the North Sea along the Dutch Coast. The results concern samples taken in 1990. (author). 5 refs.; 8 figs.; 11 tabs
[en] Planning for the capacity expansion of water supply systems requires efficient operation of available water resources and the expansion of existing infrastructure. The need to attend water demand is associated with climate, social and economic uncertainties, increasing the supply costs. Besides, most water supply systems are no longer able to meet increasing demands, resulting in the need to include nonconventional water sources. Previous work applied simulation and optimization techniques through Dynamic Programming (Fraga et al. 2017), Mixed-Integer Programming (Beh et al. 2014) and Genetic Algorithms (Zhang and Babovic 2012) for expansion of urban water systems. This paper proposes a multistage modelling approach to define operation and expansion strategies that reduce the supply costs under risks of water shortage, incorporating reservoir operation and alternative sources. Besides, the impact of climate uncertainty on the system expansion costs will be assessed as well as the efficiency of incorporating alternative sources. The method is applied in Fortaleza Metropolitan Region (FMR), Brazil. FMR consists of eight storage reservoirs and transmission canals that transfer water from the Jaguaribe basin, where is located the largest reservoir of the state (6.2 billion m³). Rainfall variability and recurrent droughts reduce the reliability on the system, that is in a stage of insufficient adaptation to urban and industrial activity growth.
[en] Drought is a very scalar phenomenon due to time affected by many parameters (Potop et al. 2012). Drought indices have been proposed by many researchers for the calculation of drought. Examples include Standardized Precipitation Evapotranspiration Index (SPEI; Vicente-Serrano et al. 2010), the Palmer Drought Severity Index (PDSI; Palmer 1965) and the Reconnaissance Drought Index (RDI; Tsakiris and Vangelis 2005) (Potop et al. 2012; Bamimahd and Khalili 2013; Wang et al. 2014; Hou et al. 2017; Stagge et al. 2015). The purpose of all these indices is to detect drought and minimize the risks that may occur. In this study the advantage of SPEI compared to other indices used is that it combines temperature and precipitation with evapotranspiration capacity. SPEI has been used to determine drought in more than one country (van der Schrier et al. 2013). In Turkey from the past and present has been used many drought indices. These are available in SPEI (Onusluel Gul and Kuzucu 2017). However, the SPEI calculation was applied for in Turkey's the Marmara Region for the first time in this study. The aim is to determine the drought disaster by achieving a more accurate result with SPEI and to minimize the risk by planning drought (Alam et al. 2017; Dai 2011
[en] Cyber-Physical systems (CPS) consist of two layers, one comprised of the physical processes, and one computational and networking layer (Lee 2008). Modern water systems (distribution network, treatment plants, etc.) are CPS, as the physical system is supervised and operated by sensors and actuators through SCADA (Supervisory Control And Data Acquisition) in real-time. Advantages of CPS are automation, increased reliability and efficiency. However, a major disadvantage of the networking, communication and remote control of CPS is the susceptibility to cyber and physical attacks (or combinations) (Rasekh et al. 2016). Indeed, various incidents of cyber-physical attacks have threatened real-world water CPS, making them among the most targeted critical infrastructure (ICS-CERT 2016), e.g. like the 2000 Maroochy Water Services incident. As water CPS are critical for human society, life and health, there is an immediate need of developing robust tools able to assess performance under cyber-physical threat scenarios. Influential work in this new field is implemented by Taormina et al. (2017), with the characterization of cyber-physical attacks in water distribution systems and the development of an EPANET-based modelling environment of such attacks. In this work, we present the development of a stress-testing modelling platform for Cyber-Physical water distribution systems, able to simulate both the cyber layer information flow and the physical processes.
[en] Flood risk management moved into the focus of water policies in many European countries. The assessment of flood risk demands the combination of the probability of a flood event with the potential adverse consequences associated with it. Since more than 100 years, we apply the probabilistic concept of return period to specify the probabilities of floods by the exceedance probabilities of their peaks only. Less emphasis is given to the fact that the probability of the harmful event depends on the relationship between load and resistance capacities of the endangered elements. In this context, other criteria of floods, e.g. the flow velocity or the flood volume and the shape of hydrograph, become relevant. To consider the complex failure mechanisms of flood protection structures, multivariate probabilities of hydrological loads are needed. Our statistical tools were refined within the last two decades to provide multivariate statistical relationships. Unfortunately, these methods reached a state where it becomes more and more difficult to apply them in practice. Other problems of flood risk management result from spatial aspects. The local consequences of a flood vary with their event-specific spatial structure and the interplay with the existing structural and non-structural measures of flood protection. Resulting from these and other problems it is no longer sufficient to specify a single design flood at one side of interest. Flood risk management requires a holistic view on flood protection systems to take into account all potential interventions that may alter flood risk in its spatial dimension. The assessments of effectivity and efficiency of interventions in the flood regime depend strongly on the choice of flood characteristics, which are considered or neglected. To select these characteristics, we have to notice the variety of flood events, the different modes of failures of flood protection structures as well as expected and unexpected changes of flood risk in future. Often such a holistic view on flood risk management does not exist and if it would be provided, the decision makers are faced with the problem to make decisions under uncertainty.
[en] Gross α and gross β activities and 238U concentrations were determined in 18 surface water samples collected from Van Lake. The instrumentations used to count the gross α and gross β activities and to determine the 238U concentrations were α/β counter of the multi-detector low background system (PIC-MPC-9604) and Inductively Coupled Plasma-Mass Spectrometry (Thermo Scientific Element 2), respectively. Concentrations ranging from 0.001 to 0.021 Bq L-1 and from 0.111 to 2.794 Bq L-1 were observed for the gross α and β activities in surface waters, respectively. For all samples the gross β activities were higher than the corresponding gross α activities. The results indicated that the gross α radioactive contamination in water samples was lower than recommended values for the guideline of drinking waters and most of the gross β activities in water samples were higher than those in the same procedure. The 238U concentrations ranged from 74.49 to 113.2 μg L-1 in surface waters. The obtained results have showed that 238U concentrations are higher than guideline values for uranium. (author)
[en] Sediment control is one of the key factors considered prior to the design of an irrigation channel. When the channel takes off from its headworks, its slope is usually smaller than that of the parent stream to obtain required head. If the sediment load is heavy then the channel can not maintain equilibrium since the high influx can not be transported fully due to its small gradient. This results in the deposition of part incoming sediment in the channel itself. A typical irrigation intake suitable for small schemes, which consists of a simple settling basin with double orifice: one at the inlet from the river and the other at the outlet to the canal. The basin is provided with a side spill weir near its downstream end, to discharge flows in excess of the maximum canal capacity. This paper deals with the experimental study of such an arrangement. Different flows were run covering a range of levels in the river, from minimum to flood flows to check the hydraulic performance of the layout and in particular to study its effectiveness in settling sediment at low flows and avoiding excessive sediment input to the canal during flood. (author)
[en] The dam break study of this communication uses two interrelated sub-models: a) the dam breach submodel and b) the hydrodynamic routing sub-model. The first sub-model generates the flood hydrograph from the dam which is derived for a specific set of the parameters describing the breach process. This is also the input for the hydrodynamic model, with which simulates the flood wave propagation in the computational domain. Due to complexity, dam breach parameters are characterised by significant uncertainties, which are propagated to the output of the dam-breach sub-model and the consequent hydrodynamic model. Therefore, it is not safe to derive a unique solution for the flood hydrograph, without taking into account the uncertainty of the simulated results. In this study, a forward uncertainty analysis is implemented in order to quantify and propagate uncertainty introduced by the dam breach parameters, in a real-world case study.
[en] Selenium is released in the environment by natural sources and anthropogenic activities that include the use of a wide variety of selenium based materials and runoff drainage (Ma et al. 2018). Regarding selenium in surface and groundwater selenite [SeO3 2- ], and the more soluble selenate [SeO4 2- ] are the most commonly encountered species (Hayashi et al. 2009). Excessive selenium consumption results to neurological and dermatological effects attributed to its toxicity when accumulated (Barron et al. 2009). Many technologies have been studied on selenium removal, while adsorption is considered a very competitive method due to efficient removal and low cost. In the present study adsorbents commercially available GFH and Bayoxide as well as laboratory synthesized FeOOHs were evaluated through batch experiments with the same initial concentration (100 μg/L Se(IV) or Se(VI)). Experiments showed near zero Se(VI) uptake for all the adsorbents studied. Iron oxy-hydroxides (FeOOHs) were evaluated by adsorption isotherms and achieved optimal results on Se(IV) adsorption. The experimental data were better fitted to Freundlich adsorption model and the maximum adsorption capacity of 3.1 μg Se(IV)/mg adsorbent was achieved by the FeOOH synthesized at pH 2.5, which mainly consisted of schwertmannite (oxy-hydroxysulfate (Fe16O16(OH)10(SO4)310H2O). It is noticeable that adsorption of Se(IV) was mainly related with surface charge density and affected by the presence of sulfates and specific surface area.