Water2014, 6(8), 2255-2277; doi:10.3390/w6082255 (doi registration under processing) - published online 31 July 2014 Show/Hide Abstract
Abstract: The “Scansano-Magliano in Toscana” area is characterized by a morpho-structure chiefly made-up by sandstone and shelly-calcareous lithologies. Generally, these complexes host minor aquifers in Tuscany, since they have medium to medium-low permeability. In the area under examination, a sandstone outcrop develops with continuity along the ridge of the structure for several kilometers and above a shelly substratum. Consequently, this hydrostructural context suggested the possibility that a significant groundwater body was hosted in the sandstones. In order to verify this assumption, an isotopic study was carried out taking into account several wells and springs sited on the sandstone outcrop and its surrounding area; the samples collected over a period of two years were analyzed to obtain δ18O‰, δ2H‰ and 3H. A study of the hydrostructural and morphological condition was also performed, and minor springs were selected. The analyses of this spring-water resulted in the characterization of the isotopic features of the infiltration water in the studied area, which represents a fundamental base of work for the interpretation of the data of groundwater points which drain long flow paths. By means of this approach, the groundwater framework was defined and the presence of a significant and continuous groundwater body within the sandstone complex was verified. A preliminary conceptual hydrogeological model was also proposed.
Water2014, 6(8), 2233-2254; doi:10.3390/w6082233 - published online 30 July 2014 Show/Hide Abstract
Abstract: Spawning market squid lay embryo capsules on the seafloor of the continental shelf of the California Current System (CCS), where ocean acidification, deoxygenation and intensified upwelling lower the pH and [O2]. Squid statolith geochemistry has been shown to reflect the squid’s environment (e.g., seawater temperature and elemental concentration). We used real-world environmental levels of pH and [O2] observed on squid-embryo beds to test in the laboratory whether or not squid statolith geochemistry reflects environmental pH and [O2]. We asked whether pH and [O2] levels might affect the incorporation of element ratios (B:Ca, Mg:Ca, Sr:Ca, Ba:Ca, Pb:Ca, U:Ca) into squid embryonic statoliths as (1) individual elements and/or (2) multivariate elemental signatures, and consider future applications as proxies for pH and [O2] exposure. Embryo exposure to high and low pH and [O2] alone and together during development over four weeks only moderately affected elemental concentrations of the statoliths, and uranium was an important element driving these differences. Uranium:Ca was eight-times higher in statoliths exposed to low pHT (7.57–7.58) and low [O2] (79–82 µmol·kg−1) than those exposed to higher ambient pHT (7.92–7.94) and [O2] (241–243 µmol·kg−1). In a separate experiment, exposure to low pHT (7.55–7.56) or low [O2] (83–86 µmol·kg−1) yielded elevated U:Ca and Sr:Ca in the low [O2] treatment only. We found capsular effects on multiple elements in statoliths of all treatments. The multivariate elemental signatures of embryonic statoliths were distinct among capsules, but did not reflect environmental factors (pH and/or [O2]). We show that statoliths of squid embryos developing inside capsules have the potential to reflect environmental pH and [O2], but that these “signals” are generated in concert with the physiological effects of the capsules and embryos themselves.
Water2014, 6(8), 2212-2232; doi:10.3390/w6082212 - published online 25 July 2014 Show/Hide Abstract
Abstract: This hydrogeological study assessed the quality of phreatic water supplies across the semi-arid, traditional agricultural region of the Yinchuan region in northwest China, near the upper reaches of the Yellow River. We analyzed the chemical characteristics of water collected from 39 sampling stations before the 2011 summer-autumn irrigation period, using multivariate statistical analysis and geostatistical methods. We determined which factors influence the composition of groundwater, using principal component analysis (PCA) and two modes of cluster analysis. PCA showed that the most important variables in the study area were the strong evaporation effect caused by the dry climate, dissolution of carbonate minerals and those containing F− and K−, and human activity including the treatment of domestic sewage and chemical fertilization. The Q-mode of cluster analysis identified three distinct water types that were distinguished by different chemical compositions, while the R-mode of analysis revealed two distinct clusters of sampling stations that appeared to be influenced by distinct sets of natural and/or anthropogenic factors.
Water2014, 6(8), 2195-2211; doi:10.3390/w6082195 - published online 25 July 2014 Show/Hide Abstract
Abstract: There is a growing requirement to generate more precise model simulations and forecasts of flows in urban drainage systems in both offline and online situations. Data assimilation tools are hence needed to make it possible to include system measurements in distributed, physically-based urban drainage models and reduce a number of unavoidable discrepancies between the model and reality. The latter can be achieved partly by inserting measured water levels from the sewer system into the model. This article describes how deterministic updating of model states in this manner affects a simulation, and then evaluates and documents the performance of this particular updating procedure for flow forecasting. A hypothetical case study and synthetic observations are used to illustrate how the Update method works and affects downstream nodes. A real case study in a 544 ha urban catchment furthermore shows that it is possible to improve the 20-min forecast of water levels in an updated node and the three-hour forecast of flow through a downstream node, compared to simulations without updating. Deterministic water level updating produces better forecasts when implemented in large networks with slow flow dynamics and with measurements from upstream basins that contribute significantly to the flow at the forecast location.
Water2014, 6(8), 2175-2194; doi:10.3390/w6082175 - published online 25 July 2014 Show/Hide Abstract
Abstract: In the Mekong Delta (MD) in Vietnam, piped-water supply stations are being intensively built to reach the millennium development goal (MDG) to provide safe and clean drinking water resources to communities. However, studies focusing on the effectiveness of supply stations in reaching these goals are scarce to date. Water samples from 41 water supply stations in the MD were collected between June and October 2012. Water samples were analyzed for general parameters, salinity, nutrients, metal(loid)s and microbial indicator bacteria and compared with World Health Organization (WHO) and Vietnamese drinking water guidelines. In addition, 542 household interviews were conducted to investigate the connection rate to piped-water and people’s perceptions regarding piped-water supplies. The results show that water guidelines were exceeded for pH (min. 6.2), turbidity (max. 10 FTU), Cl (max. 1,576 mg·L−1), NH4 (max. 7.92 mg·L−1), Fe (431.1 µg·L−1), Hg (11.9 µg·L−1), and microbial indicator bacteria (max. total coliform 50,000 CFU 100 mL−1). Moreover, more than half of the interviewed households with access to a piped-water supply did not use this supply as a source of drinking water due to (i) high connection fees; (ii) preference for other water sources; and (iii) perceived poor quality/quantity. Our study shows that the maintenance and distribution of water supply stations should significantly improve in order for piped-water to become a reliable drinking water source. Additionally, alternatives, such as rainwater harvesting and decentralized treatment facilities, should also be considered.
Water2014, 6(8), 2164-2174; doi:10.3390/w6082164 - published online 24 July 2014 Show/Hide Abstract
Abstract: Floating objects designed to divert woody debris—known as debris diversion devices—can protect hydrokinetic turbines deployed in rivers; they also change the hydrodynamic conditions of a river, at least locally. Modifications associated with velocity adjustments in both magnitude and direction would be expected. Thus, one could assume that extra macro-turbulent levels would be found immediately behind a device and downstream of that location. This article presents a set of cross-sectional and longitudinal velocity measurements carried out to quantify these effects. Results show important changes in the velocity components. In addition, significant changes in the vorticity field, calculated along cross-sectional profiles, demonstrate the role of a submerged chain used to maintain the debris diversion device in place. More importantly, findings suggest that hydrokinetic turbines should not be installed in a river’s central area behind a debris diversion device, due to the additional turbulence created by the submerged chain.