Current Issue : January - March Volume : 2018 Issue Number : 1 Articles : 5 Articles
This study focuses on the return period evaluation for design hyetographs, which is\nusually estimated by adopting a univariate statistical approach. Joint Return Period (JRP) and\ncopula-based multivariate analysis are used in this work to better define T-year synthetic rainfall\npatterns which can be used as input for design flood peak estimation by means of hydrological\nsimulation involving rainfall-runoff (RR) models. Specifically, a T-year Design Hyetograph (DH)\nis assumed to be characterized by its peak H, at the chosen time resolution Dt, and by the total\nrainfall height W, cumulated on its critical duration dCrit, which has been a priori fixed. As stated\nin technical literature, the choice of the expression for JRP depends on which event is deemed as\ncritical for the investigated system; the most important cases are: (i) all the variables must exceed a\ncertain magnitude to achieve critical conditions; or (ii) at least one variable must be greater than a\nthreshold; or (iii) critical conditions are induced by all the events with a joint Cumulative Density\nFunction (CDF) overcoming an assigned probability threshold. Once the expression for JRP was\nchosen, the relationship among multivariate T-year design hyetographs and T-year design flood peak\nwas investigated for a basin located in Calabria region (southern Italy). Specifically, for the selected\ncase study, a summary diagram was obtained as final result, which allows the main characteristics\nof T-year DHs to be estimated, considering both the univariate and the copula based multivariate\nanalysis, and the associated T-year design flood peaks obtained through the simulation with a\nRR model....
Environmental isotope tracers have been a useful tool in providing new insights into hydrologic processes. In Mexico, there have been several studies reporting different values for Ã?´18O and Ã?´2H for certain geographical areas. The objective of this study is to achieve the isotopic characterization of rainfall and groundwater and to report the comprehensive understanding of groundwater flow processes around and within the Calera aquifer and, consequently, its potential recharge sites. The samples used for the stable isotope analysis ( Ã?´18O,Ã?´2H ) were measured using a GV-Isoprime isotope-ratio mass spectrometer at the Isotopy Laboratory of the Water Center for Latin America and the Caribbean. The Ã?´D of precipitation ranged between âË?â??110.20ââ?¬Â° and 10.11ââ?¬Â°, with a mean of âË?â??55.67ââ?¬Â° Ã?± 27.81ââ?¬Â°. The Ã?´18O ranged between âË?â??17.80ââ?¬Â° and 2.74ââ?¬Â°, with a mean of âË?â??9.44ââ?¬Â° Ã?± 4.74ââ?¬Â°. The Ã?´D of groundwater ranged between âË?â??81.92ââ?¬Â° and âË?â??36.45ââ?¬Â°, with a mean of âË?â??66.05ââ?¬Â° Ã?± 8.58ââ?¬Â°. The Ã?´18O ranged between âË?â??18.26ââ?¬Â° and âË?â??8.84ââ?¬Â°, with a mean of âË?â??12.35ââ?¬Â° Ã?± 2.12ââ?¬Â°. The local meteoric water line of the Zacatecas state is Ã?´D=âË?â??2.03+5.68Ã?´18O . The groundwater samples were clustered into four groups. The clustering of the samples led to the finding that streamflows play a significant role in the hydrological balance as a source of local recharge to the aquifer....
Reuse of water is necessary in Organized Industrial Zones (OIZ) due to excessive use of groundwater in semi-arid Turkey. Membrane treatment of the OIZ wastewater treatment plant (WWTP) effluents should be explored for new treatment options. In this study, three different UF membranes with variable molecular weight cutoff (MWCO) values (4, 10, and 250 kDa) were used to treat the effluent of an OIZ WWTP at laboratory scale. Six different nanofiltration (NF) and reverse osmosis (RO) membranes were used for the effluent of UF membranes to evaluate the difference in the membrane filtration performance and the water quality. Effluent electrical conductivity (EC) values of NF membranes were 1.77 �± 0.17, 3.73 �± 0.27, and 4.20 �± 0.23 ms/cm for NF (NF90, NF270, and TM610) membranes, respectively while they were 0.83 �± 0.47, 1.17 �± 0.47, and 1.13 �± 0.57 ms/cm for RO (XLE, AD90, and BW30) membranes, respectively. Scanning electron microscope (SEM), energy dispersive X-ray Spectroscopy (EDS), and confocal laser scanning microscope (CLSM) images showed severe biofouling in UF 4 kDa and UF 10 kDa membranes whereas UF 250 kDa membrane showed larger metal precipitates and little bacterial fouling. The results indicated that OIZ WWTP effluent could be reused as irrigation water according to Turkish regulations with UF 250 kDa and RO-XLE membranes, effectively....
The present study was investigated the physico-chemical characteristics along the coastal waters of Puthupattinam, Southeast coast of India. The atmospheric and surface water temperature was maximum of 35.4±1.43 and 33.1±1.69°C during the summer season and minimum of 30.3±1.78 and 29.7±1.29°C during post-monsoon season. The maximum turbidity was 6.98±1.23 NTU during monsoon season and minimum of 5.03±0.88 during summer season. The salinity and pH of the coastal waters showed maximum of 36.0±1.96ppt and 8.3±0.35 during summer season and minimum of 31.9±1.53 ppt and 7.7±0.33 during monsoon season. The ammonia level was maximum of 0.5±0.1 mg/l during summer season. The DO, BOD and COD level of the coastal waters showed the maximum of 7.02±0.54 mg/l during monsoon, 0.99±0.04 mg/l during premonsoon season and 89.3±1.21mg/l during summer season. The nitrate, nitrite, phosphate, silicate, total nitrogen and POC level of the coastal waters showed the maximum of 8.2±1.00, 1.7±0.20, 0.64±0.02, 7.3±0.40, 10.1±0.69 and 2.2±0.76 mg/l during monsoon season....
Abatement of sulfides in sewer systems using iron salts is a widely used strategy. When dosing at the end of a pumping main, the reaction kinetics of sulfide precipitation becomes important. Traditionally the reaction has been assumed to be rapid or even instantaneous. This work shows that this is not the case for sulfide precipitation by ferric iron. Instead, the reaction time was found to be on a timescale where it must be considered when performing end-of-pipe treatment. For real wastewaters at pH 7, a stoichiometric ratio around 14 mol Fe(II) (mol S(âË?â??II))âË?â??1 was obtained after 1.5 s, while the ratio dropped to about 5 mol Fe(II) (mol S(âË?â??II))âË?â??1 after 30 s. Equilibrium calculations yielded a theoretic ratio of 2 mol Fe(II) (mol S(âË?â??II))âË?â??1, indicating that the process had not equilibrated within the span of the experiment. Correspondingly, the highest sulfide conversion only reached 60%. These findings differed significantly from what has been demonstrated in previous studies and what is attained from theoretical equilibrium conditions....
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