Applied Water Science (v.7, #2)

This research paper focuses on the need of turbulence, instruments reliable to capture turbulence, different turbulence parameters and some advance methodology which can decompose various turbulence structures at different levels near hydraulic structures. Small-scale turbulence research has valid prospects in open channel flow. The relevance of the study is amplified as we introduce any hydraulic structure in the channel which disturbs the natural flow and creates discontinuity. To recover this discontinuity, the piano key weir (PKW) might be used with sloped keys. Constraints of empirical results in the vicinity of PKW necessitate extensive laboratory experiments with fair and reliable instrumentation techniques. Acoustic Doppler velocimeter was established to be best suited within range of some limitations using principal component analysis. Wavelet analysis is proposed to decompose the underlying turbulence structure in a better way.
Keywords: Piano key weir; Turbulence; Acoustic Doppler velocimeter; Principal component analysis; Wavelet analysis

Specific methanogenic activity (SMA) determines the methane-producing capability of the sludge for a specific substrate. Methanogenic activity test can be used to delineate the operating conditions for anaerobic systems and a parameter to assess the system performance by giving a better perceptive of the system and its stability. At the beginning of the start-up period of a new digester, the SMA is of great importance for the determination of proper initial organic loading rate. In different phases, a regular determination of SMA also ascertains the development stages of the sludge. Also, a change in SMA indicates an inhibition or an accumulation of slow degradable or even non-biodegradable organic matter from the influents. This paper reviews the SMA of anaerobic sludge under different operating conditions using different substrates.
Keywords: Biodegradability; Kinetics; Sludge; Organic loading rate; Specific methanogenic activity

Adsorption of dyes using different types of clay: a review by Aderonke Ajibola Adeyemo; Idowu Olatunbosun Adeoye; Olugbenga Solomon Bello (543-568).
Increasing amount of dyes in the ecosystem particularly in wastewater has propelled the search for more efficient low-cost adsorbents. The effective use of the sorption properties (high surface area and surface chemistry, lack of toxicity and potential for ion exchange) of different clays as adsorbents for the removal of different type of dyes (basic, acidic, reactive) from water and wastewater as potential alternatives to activated carbons has recently received widespread attention because of the environmental-friendly nature of clay materials. Insights into the efficiencies of raw and modified/activated clay adsorbents and ways of improving their efficiencies to obtain better results are discussed. Acid-modified clay resulted in higher rate of dye adsorption and an increased surface area and porosity (49.05 mm2 and 53.4 %). Base-modified clay has lower adsorption capacities, while ZnCl2-modified clay had the least rate of adsorption with a surface area of 44.3 mm2 and porosity of 43.4 %. This review also explores the grey areas of the adsorption properties of the raw clays and the improved performance of activated/modified clay materials with particular reference to the effects of pH, temperature, initial dye concentration and adsorbent dosage on the adsorption capacities of the clays. Various challenges encountered in using clay materials are highlighted and a number of future prospects for the adsorbents are proposed.
Keywords: Wastewater; Dyes; Clay; Adsorption; Low-cost adsorbents

Subsurface drainage has been used for more than a century to keep water table at a desired level of salinity and waterlogging control. This paper has been focused on the impact assessment of pilot studies in India and some other countries from 1969 to 2014 . This review article may prove quite useful in deciding the installation of subsurface drainage project depending on main design parameters, such as drain depth and drain spacing, installation area and type of used outlet. A number of pilot studies have been taken up in past to solve the problems of soil salinity and waterlogging in India. The general guidelines that arise on the behalf of this review paper are to adapt drain depth >1.2 m and spacing depending on soil texture classification, i.e., 100–150 m for light-textured soils, 50–100 m for medium-textured soils and 30–50 m heavy-textured soils, for better result obtained from the problem areas in Indian soil and climatic conditions. An attempt has been made in the manner of literature survey to highlight the salient features of these studies, and it is hopeful to go a long way in selecting design parameters for subsurface drainage problems in the future with similar soil, water table and climatic conditions.
Keywords: Subsurface drainage; Salinity; Waterlogging and groundwater table

Semi-aerobic stabilized landfill leachate treatment by ion exchange resin: isotherm and kinetic study by Mohd Faiz Muaz Ahmad Zamri; Mohamad Anuar Kamaruddin; Mohd Suffian Yusoff; Hamidi Abdul Aziz; Keng Yuen Foo (581-590).
This study was carried out to investigate the treatability of ion exchange resin (Indion MB 6 SR) for the removal of chromium (VI), aluminium (III), zinc (II), copper (II), iron (II), and phosphate (PO4)3−, chemical oxygen demand (COD), ammonia nitrogen (NH3-N) and colour from semi-aerobic stabilized leachate by batch test. A range of ion exchange resin dosage was tested towards the removal efficiency of leachate parameters. It was observed that equilibrium data were best represented by the Langmuir model for metal ions and Freundlich was ideally fit for COD, NH3-N and colour. Intra particle diffusion model, pseudo first-order and pseudo second-order isotherm models were found ideally fit with correlation of the experimental data. The findings revealed that the models could describe the ion exchange kinetic behaviour efficiently, which further suggests comprehensive outlook for the future research in this field.
Keywords: Resin; Landfill leachate; Adsorption; Isotherms; Kinetics

The MIKE SHE model is able to simulate the entire stream flow which includes direct and basic flow. Many models either do not simulate or use simplistic methods to determine the basic flow. The MIKE SHE model takes into account many hydrological data. Since this study was directed towards the simulation of surface runoff and infiltration into saturated and unsaturated zone, the MIKE SHE is an appropriate model for reliable conclusions. In the current research, the MIKE SHE model was used to simulate runoff in the area of Sperchios River basin. Meteorological data from eight rainfall stations within the Sperchios River basin were used as inputs. Vegetation as well as geological data was used to perform the calibration and validation of the physical processes of the model. Additionally, ArcGIS program was used. The results indicated that the model was able to simulate the surface runoff satisfactorily, representing all the hydrological data adequately. Some minor differentiations appeared which can be eliminated with the appropriate adjustments that can be decided by the researcher′s experience.
Keywords: Distributed model; Hydrological simulation; MIKE SHE; GIS; Discharge; Water balance

The article contains analysis of the interrelation of circulation processes in the atmosphere with the change of runoff in the basins of rivers. The results of estimates which show the relationship of circulation processes in the atmosphere with the runoff of the zone of formation of one of southern regions of Kazakhstan are discussed. The typification of circulation processes by B. L. Dzerdzeyevskiy and previously made estimates of water resources in the basins of rivers of South Kazakhstan were assumed as a basis. Certain areas were considered in this work: the Ile-Balkash basin, basin of rivers Shu-Talas and basin of the Syrdariya river, each basin is considered separately, since the runoff varies by regions and by the value of fluctuations, it is not permanent, because of the various factors of runoff formation in individual basins of that region. The calculations performed have shown the possibility of using typification of elementary circulation mechanism (ECM) for further researches of climatic changes, including to determine the direction of change of river runoff in other river basins. The created database on annual values of each of the 41 types of ECM can be used in other studies as well.
Keywords: Typification of circulation of the atmosphere by Dzerdzeyevskiy; Elementary circulation mechanism (ECM); Water resources; The basin of river of South Kazakhstan

An integrated approach based on the hydrogeochemistry and the isotope hydrology of surface water and groundwater was carried out in the Ellembelle district of the Western Region of Ghana. Measurement of physical parameters (pH, temperature, salinity, total dissolved solutes, total hardness and conductivity), major ions (Ca2+, Mg2+, Na+, K+, HCO3 , Cl, SO4 2− and NO3 ), and stable isotopes (δ2H and δ18O) in 7 rivers, 13 hand-dug wells and 18 boreholes were taken. Na+ was the dominant cation and HCO3 was the dominant anion for both rivers and groundwater. The dominant hydrochemical facies for the rivers were Na–K–HCO3 type while that of the groundwater (hand-dug wells and boreholes) were Na–Cl and Na–HCO3 type. According to the Gibbs diagram, majority of the rivers fall in the evaporation–crystallization field and majority of the hand-dug wells and the boreholes fall in the rock dominance field. From the stable isotope composition measurements, all the rivers appeared to be evaporated, 60 % of the hand-dug wells and 70 % of the boreholes clustered along and in between the global meteoric water line and the local meteoric water line, suggesting an integrative and rapid recharge from meteoric origin.
Keywords: Ellembelle district; Tano basin; Hydrogeochemistry; Isotope hydrology; Hydrochemistry

The present study aims to compare mass transfer-based models to determine the best model under different weather conditions. The results showed that the Penman model estimates reference crop evapotranspiration better than other models in most provinces of Iran (15 provinces). However, the values of R 2 were less than 0.90 for 24 provinces of Iran. Therefore, the models were calibrated, and precision of estimation was increased (the values of R 2 were less than 0.90 for only ten provinces in the modified models). The mass transfer-based models estimated reference crop evapotranspiration in the northern (near the Caspian Sea) and southern (near the Persian Gulf) Iran (annual relative humidity more than 65 %) better than other provinces. The best values of R 2 were 0.96 and 0.98 for the Trabert and Rohwer models in Ardabil (AR) and Mazandaran (MZ) provinces before and after calibration, respectively. Finally, a list of the best performances of each model was presented to use other regions and next studies according to values of mean, maximum, and minimum temperature, relative humidity, and wind speed. The best weather conditions to use mass transfer-based equations are 8–18 °C (with the exception of Ivanov), <25.5 °C, <15 °C, >55 % for mean, maximum, and minimum temperature, and relative humidity, respectively.
Keywords: Calibration; Evapotranspiration; FAO Penman–Monteith; Humidity; Iran

In this study, central composite design at five levels (−β, −1, 0, +1, +β) combined with response surface methodology has been applied to optimize C.I. Reactive Yellow 186 using electro-oxidation process with graphite electrodes in a batch reactor. The variables considered were the pH (X 1), NaCl concentration (M) (X 2), and electrolysis time (min) (X 3) on C.I. Reactive Yellow 186 were studied. A second-order empirical relationship between the response and independent variables was derived. Analysis of variance showed a high coefficient of determination value (R 2 = 0.9556 and 0.9416 for color and COD, respectively). The optimized condition of the electro-oxidation of Reactive Yellow 186 is as follows: pH 3.9; NaCl concentration 0.11 M; and electrolysis time 18 min. Under this condition, the maximal decolorization efficiency of 99 % and COD removal 73 % was achieved. Detailed physico-chemical analysis of electrode and residues of the electro-oxidation process has also been carried out UV–Visible and Fourier transform infrared spectroscopy. The intermediate compounds formed during the oxidation were identified using a gas chromatography coupled with mass spectrometry. According to these results, response surface methodology could be useful for reducing the time to treat effluent wastewater.
Keywords: Electro-oxidation; C.I. Reactive Yellow 186; Response surface methodology (RSM); FTIR; GC-MS

Evaluating the suitability of groundwater for irrigational purposes in some selected districts of the Upper West region of Ghana by Musah Salifu; Felix Aidoo; Michael Saah Hayford; Dickson Adomako; Enoch Asare (653-662).
Groundwater is a very important asset to the people of the Upper West region of the Ghana where majority of them are farmers. Groundwater serves as the most reliable source of water for their domestic and agricultural activities. This study was aimed at assessing the suitability of groundwater for irrigational purposes in some selected communities of five districts where farming activities are very intensive. Twenty-three groundwater samples were collected and analysed for major anions and cations. Physicochemical parameters such as electrical conductivity (EC) and total dissolved solids (TDS) were also measured. From the results of the analyses and measurements, the suitability of the groundwater for irrigation were evaluated based on the TDS, EC, percentage sodium (%Na), sodium adsorption ratio (SAR), permeability index (PI), residual sodium carbonate (RSC), magnesium adsorption ratio (MAR), Kelly’s ratio (KR) and chloro-alkaline Indices (CAI). US salinity laboratory diagram and Wilcox diagrams were also applied. The EC results show that the groundwater in the study area can be classified as none and slight to moderate. According to the US salinity diagram, groundwater in the study area falls within the low salinity-low sodium hazard and medium salinity-low sodium hazard class. The %Na and the resulting Wilcox diagram also classify the groundwater as excellent to good and good to permissible. The groundwater in the study area is generally good for irrigation purposes. However, there are few instances which are problematic and would require special irrigation methods.
Keywords: Groundwater; Upper West region; Irrigation; Farming; Sodium adsorption ratio

Probability distribution functions for unit hydrographs with optimization using genetic algorithm by Mohammad Ali Ghorbani; Vijay P. Singh; Bellie Sivakumar; Mahsa H. Kashani; Atul Arvind Atre; Hakimeh Asadi (663-676).
A unit hydrograph (UH) of a watershed may be viewed as the unit pulse response function of a linear system. In recent years, the use of probability distribution functions (pdfs) for determining a UH has received much attention. In this study, a nonlinear optimization model is developed to transmute a UH into a pdf. The potential of six popular pdfs, namely two-parameter gamma, two-parameter Gumbel, two-parameter log-normal, two-parameter normal, three-parameter Pearson distribution, and two-parameter Weibull is tested on data from the Lighvan catchment in Iran. The probability distribution parameters are determined using the nonlinear least squares optimization method in two ways: (1) optimization by programming in Mathematica; and (2) optimization by applying genetic algorithm. The results are compared with those obtained by the traditional linear least squares method. The results show comparable capability and performance of two nonlinear methods. The gamma and Pearson distributions are the most successful models in preserving the rising and recession limbs of the unit hydographs. The log-normal distribution has a high ability in predicting both the peak flow and time to peak of the unit hydrograph. The nonlinear optimization method does not outperform the linear least squares method in determining the UH (especially for excess rainfall of one pulse), but is comparable.
Keywords: Genetic algorithm; Least squares method; Mathematica; Nonlinear optimization; Probability distribution function; Unit hydrograph

In this work, silica fume (SF) is used as a solid-phase extractor for extraction of Zn(II) and Cd(II) from aqueous solutions. Characterization of SF is performed by Fourier transform infrared, X-ray diffraction, transmission and scanning electron microscopy. The optimum experimental conditions for the two metal ions are investigated using batch and column techniques. The maximum adsorption capacity values are found to be 54.13 and 121.28 mg g−1 at the optimum pH 6.0 and 8.0 for Zn(II) and Cd(II), respectively. The equilibrium data are analyzed using the Langmuir, Freundlich, and Temkin isotherms by nonlinear regression analysis. Also, the kinetics analysis revealed that the overall adsorption process is successfully fitted with the pseudo-second-order model. The method is applied for determination of the target metal ions in pharmaceutical and environmental samples using square-wave anodic stripping voltammetry. The limit of detection (LOD) values are 0.102 and 1.43 × 10−3 mg L−1 for Zn(II) and Cd(II), respectively. The percentage recovery values are 98.8–100.5 % which indicate the success of the proposed method for determination of Zn(II) and Cd(II) without interfering effects.
Keywords: Cd(II); Zn(II); Fixed bed column; Pharmaceuticals; Real samples; Silica fume

Accurate and reliable groundwater level forecasting models can help ensure the sustainable use of a watershed’s aquifers for urban and rural water supply. In this paper, three time series analysis methods, Holt–Winters (HW), integrated time series (ITS), and seasonal autoregressive integrated moving average (SARIMA), are explored to simulate the groundwater level in a coastal aquifer, China. The monthly groundwater table depth data collected in a long time series from 2000 to 2011 are simulated and compared with those three time series models. The error criteria are estimated using coefficient of determination (R 2), Nash–Sutcliffe model efficiency coefficient (E), and root-mean-squared error. The results indicate that three models are all accurate in reproducing the historical time series of groundwater levels. The comparisons of three models show that HW model is more accurate in predicting the groundwater levels than SARIMA and ITS models. It is recommended that additional studies explore this proposed method, which can be used in turn to facilitate the development and implementation of more effective and sustainable groundwater management strategies.
Keywords: Groundwater table; Time series analysis; Holt–Winters; ARIMA; ITS

In recent years, delineation of groundwater productivity zones plays an increasingly important role in sustainable management of groundwater resource throughout the world. In this study, groundwater productivity index of northeastern Wasit Governorate was delineated using probabilistic frequency ratio (FR) and Shannon’s entropy models in framework of GIS. Eight factors believed to influence the groundwater occurrence in the study area were selected and used as the input data. These factors were elevation (m), slope angle (degree), geology, soil, aquifer transmissivity (m2/d), storativity (dimensionless), distance to river (m), and distance to faults (m). In the first step, borehole location inventory map consisting of 68 boreholes with relatively high yield (>8 l/sec) was prepared. 47 boreholes (70 %) were used as training data and the remaining 21 (30 %) were used for validation. The predictive capability of each model was determined using relative operating characteristic technique. The results of the analysis indicate that the FR model with a success rate of 87.4 % and prediction rate 86.9 % performed slightly better than Shannon’s entropy model with success rate of 84.4 % and prediction rate of 82.4 %. The resultant groundwater productivity index was classified into five classes using natural break classification scheme: very low, low, moderate, high, and very high. The high–very high classes for FR and Shannon’s entropy models occurred within 30 % (217 km2) and 31 % (220 km2), respectively indicating low productivity conditions of the aquifer system. From final results, both of the models were capable to prospect GWPI with very good results, but FR was better in terms of success and prediction rates. Results of this study could be helpful for better management of groundwater resources in the study area and give planners and decision makers an opportunity to prepare appropriate groundwater investment plans.
Keywords: Groundwater; Frequency ration; Shannon’s entropy; AUC; Wasit; Iraq

This study investigates the adsorptive removal of malachite green (MG) dye from aqueous solutions using chemically modified lime-peel-based activated carbon (LPAC). The adsorbent prepared was characterized using FTIR, SEM, Proximate analysis and BET techniques, respectively. Central composite design (CCD) in response surface methodology (RSM) was used to optimize the adsorption process. The effects of three variables: activation temperature, activation time and chemical impregnation ratio (IR) using KOH and their effects on percentage of dye removal and LPAC yield were investigated. Based on CCD design, quadratic models and two factor interactions (2FI) were developed correlating the adsorption variables to the two responses. Analysis of variance (ANOVA) was used to judge the adequacy of the model. The optimum conditions of MG dye removal using LPAC are: activation temperature (796 °C), activation time (1.0 h) and impregnation ratio (2.6), respectively. The percentage of MG dye removal obtained was 94.68 % resulting in 17.88 % LPAC yield. The percentage of error between predicted and experimental results for the removal of MG dye is 0.4 %. Model prediction was in good agreement with experimental results and LPAC was found to be effective in removing MG dye from aqueous solution.
Keywords: Lime peel; Activated carbon; Malachite green dye; Central composite design; Responses

Physical and isotopic characteristics in peri-urban landscapes: a case study at the lower Volta River Basin, Ghana by E. K. Gampson; V. K. Nartey; A. A. Golow; T. T. Akiti; M. A. Sarfo; M. Salifu; F. Aidoo; A. R. Fuseini (729-744).
The study presents the application of selected multivariate techniques: display methods (principal component analysis) and unsupervised pattern recognition (cluster analysis) in an attempt to discriminate sources of variation of water quality. PCA has allowed the identification of a reduced number of latent factors with a hydrochemical meaning: natural and anthropogenic (domestic and agricultural activities) factors, which also agrees with the R-mode hierarchical cluster analysis (HCA). Q-mode HCA also corroborates the results of the correlation analysis in relation to sampling sites established on hydrochemical parameters, indicating that there are no spatial and temporal characteristics among the sampling sites in the study area. The suitability of river water for irrigation use was assessed in the study area. A plot of the sodium adsorption ratio (SAR) and salinity data on a semilog axis suggests that river water provides good irrigation quality in the area. According to the SAR values plotted in the USSL Staff diagram, 100 % of the river water samples fall in C1–S1 (low salinity–low sodium type) group, which provides good irrigation quality to river water from this area. Also, all the data points showed permeability index values in Class II category which is suitable for irrigation purposes. Recorded magnesium ratio and Kelly’s ratio showed that <50 % of the river water samples were suitable for irrigation purposes. Stable isotope data of water (δ18O and δ2H) obtained revealed that stream waters joining the Volta River were depleted and possibly recharged by rain and waters from the Akwapim Mountains (located at the western part of the Volta River) than the isotopically heavy evaporated waters found within the Lower Volta River. These results would therefore be useful for water balance studies in the study area.
Keywords: Stable isotope; Principal component analysis; Hierarchical cluster analysis; Manya Krobo; Tongu; Lower Volta River Basin; Hydrochemical

The present study envisages the importance of graphical representations like Piper trilinear diagram and Chadha’s plot, respectively to determine variation in hydrochemical facies and understand the evolution of hydrochemical processes in the Varahi river basin. The analytical values obtained from the groundwater samples when plotted on Piper’s and Chadha’s plots revealed that the alkaline earth metals (Ca2+, Mg2+) are significantly dominant over the alkalis (Na+, K+), and the strong acidic anions (Cl, SO4 2−) dominant over the weak acidic anions (CO3 2−, HCO3 ). Further, Piper trilinear diagram classified 93.48 % of the samples from the study area under Ca2+–Mg2+–Cl–SO4 2− type and only 6.52 % samples under Ca2+–Mg2+–HCO3 type. Interestingly, Chadha’s plot also demonstrated the dominance of reverse ion exchange water having permanent hardness (viz., Ca–Mg–Cl type) in majority of the samples over recharging water with temporary hardness (i.e., Ca–Mg–HCO3 type). Thus, evaluation of hydrochemical facies from both the plots highlighted the contribution from the reverse ion exchange processes in controlling geochemistry of groundwater in the study area. Further, PCA analysis yielded four principal components (PC1, PC2, PC3 and PC4) with higher eigen values of 1.0 or more, accounting for 65.55, 10.17, 6.88 and 6.52 % of the total variance, respectively. Consequently, majority of the physico-chemical parameters (87.5 %) loaded under PC1 and PC2 were having strong positive loading (>0.75) and these are mainly responsible for regulating the hydrochemistry of groundwater in the study area.
Keywords: Varahi; Piper trilinear diagram; Principal component analysis (PCA); Eigen values; Scree plot; Score plot; Loading plot

Continuous discharge of lignin containing colored wastewater from pulp paper mill into the environment has resulted in building up their high level in various aquatic systems. In this study, the chemical texture of kraft lignin in terms of pollution parameters (COD, TOC, BOD, etc.) was quite different and approximately twofold higher as compared to model lignin at same optical density (OD 3.7 at 465 nm) and lignin content (2000 mg/L). For comparative bacterial degradation and detoxification of model and kraft lignin two bacteria Citrobacter freundii and Serratia marcescens were isolated, screened and applied in axenic and mixed condition. Bacterial mixed culture was found to decolorize 87 and 70 % model and kraft lignin (2000 mg/L), respectively; whereas, axenic culture Citrobacter freundii and Serratia marcescens decolorized 64, 60 % model and 50, 55 % kraft lignin, respectively, at optimized condition (34 °C, pH 8.2, 140 rpm). In addition, the mixed bacterial culture also showed the removal of 76, 61 % TOC; 80, 67 % COD and 87, 65 % lignin from model and kraft lignin, respectively. High pollution parameters (like TOC, COD, BOD, sulphate) and toxic chemicals slow down the degradation of kraft lignin as compared to model lignin. The comparative GC–MS analysis has suggested that the interspecies collaboration, i.e., each bacterial strain in culture medium has cumulative enhancing effect on growth, and degradation of lignin rather than inhibition. Furthermore, toxicity evaluation on human keratinocyte cell line after bacterial treatment has supported the degradation and detoxification of model and kraft lignin.
Keywords: Bacteria; Kraft lignin; GC–MS; Toxicity; Cell line

Rooftop level rainwater harvesting system by Hayssam Traboulsi; Marwa Traboulsi (769-775).
Unfortunately, in Lebanon and other countries in the Middle East region, water becomes scarcer than ever before, and over the last decades the demand on domestic water has increased due to population and economic growth. Although rainwater harvesting is considered to be a safe and reliable alternative source for domestic water, the inconvenience or impracticalities related to the cost and space needed for the construction of ground or underground storage tanks makes this practice not widely common in rural areas and rarely implemented in urban cities. This paper introduces a new technique to rainwater harvesting which can be easily used in both rural and urban areas: it collects and stores rainwater directly in tanks already installed on building roofs and not necessarily in special ground or underground ones. If widely adopted in Lebanon, this technique could help in: (1) collecting around 23 MCM (70 % of the current deficit in the domestic water supply) of rainwater and thus increasing the available water per m2 of building by 0.4 m3 per year, (2) saving around 7 % of the amount of electric energy usually needed to pump water from an aquifer well and ground or underground tank, and (3) considerably reducing the rate of surface runoff of rainwater at the coastal zones where rainwater is not captured at all and goes directly to the sea.
Keywords: Middle East; Lebanon; Rainwater harvesting; Climate change; Water shortage

New generalized solutions of linearized Boussinesq equation are derived to approximate the dynamic behavior of subsurface seepage flow induced by multiple localized time-varying recharges over sloping ditch–drain aquifer system. The mathematical model is based on extended Dupuit–Forchheimer assumption and treats the spatial location of recharge basins as additional parameter. Closed form analytic expressions for spatio-temporal variations in water head distribution and discharge rate into the drains are obtained by solving the governing flow equation using eigenvalue–eigenfunction method. Downward and zero-sloping aquifers are treated as special cases of main results. A numerical example is used for illustration of combined effects of various parameters such as spatial coordinates of the recharge basin, aquifer’s bed slope, and recharge rate on the dynamic profiles of phreatic surface.
Keywords: Boussinesq equation; Recharge; Slopes; Ditch–drain; Groundwater mound

Impact of landuse/land cover change on run-off in the catchment of a hydro power project by Deepak Khare; Diptendu Patra; Arun Mondal; Sananda Kundu (787-800).
The landuse/land cover change and rainfall have a significant influence on the hydrological response of the river basins. The run-off characteristics are changing naturally due to reduction of initial abstraction that increases the run-off volume. Therefore, it is necessary to quantify the changes in the run-off characteristics of a catchment under the influence of changed landuse/land cover. Soil conservation service model has been used in the present study to analyse the impact of various landuse/land cover (past, present and future time period) change in the run-off characteristics of a part of Narmada basin at the gauge discharge site of Mandaleswar in Madhya Pradesh, India. Calculated run-off has been compared with the observed run-off data for the study. The landuse/land cover maps of 1990, 2000 and 2009 have been prepared by digital classification method with proper accuracy using satellite imageries. The impact of the run-off change on hydro power potential has been assessed in the study along with the estimation of the future changes in hydro power potential. Five types of conditions (+10, +5 %, average, −5, −10 % of average rainfall) have been applied with 90 and 75 % dependability status. The generated energy will be less in 90 % dependable flow in respect to the 75 % dependable flow. This work will be helpful for future planning related to establishment of hydropower setup.
Keywords: Landuse/land cover change; Run-off; SCS-CN model; Hydro power potential

Aquifer response to recharge–discharge phenomenon: inference from well hydrographs for genetic classification by Arunangshu Mukherjee; Anita Gupta; Ranjan Kumar Ray; Dinesh Tewari (801-812).
The continuous groundwater level data emanating from a high-frequency automatic water level recorder installed in a purpose-built piezometer provides a true hydrograph. Analyses of such hydrographs fairly reflect the aquifer character and can be used to draw inference for genetic classification of hard rock aquifers. The signature shape of annual water level fluctuation curve (annual cycle) of a piezometer is due to the specific character of the aquifer and the way it responds to the recharge–discharge phenomenon. The pattern of annual cycle remains identical year after year, although its magnitude may vary with the annual quantum of recharge–discharge. Lithology of the aquifer does not control the shape of the curve. Based on the crest and trough shape, the hard rock aquifers of Peninsular India, where the monsoonal pattern of rainfall occurs, have been classified into genetic groups. It is also found that the nature of the aquifer can be determined by visual comparison of apparent line thickness of the hydrograph, where thin lines denote unconfined aquifer and the apparently thicker lines correspond to confining condition. The response of an aquifer to a pumping event can be identified and separated by its pattern. Thus, the aquifer classification can be automated by adopting the proposed classification scheme.
Keywords: Well hydrograph; Piezometer; Aquifer response; Genetic classification; Peninsular India

The present study on geochemical evolution of groundwater is taken up to assess the controlling processes of water chemistry in the Western Delta region of the River Godavari (Andhra Pradesh), which is one of the major rice-producing centers in India. The study region is underlain by coarse sand with black clay (buried channels), black silty clay of recent origin (floodplain) and gray/white fine sand of modern beach sediment of marine source (coastal zone), including brown silty clay with fine sand (paleo-beach ridges). Groundwater is mostly brackish and very hard. It is characterized by Na+ > Mg2+ > Ca2+:HCO3  > Cl > SO4 2− > NO3 , Na+ > Mg2+ > Ca2+:Cl > HCO3  > SO4 2−, and Mg2+ > Na+ > Ca2+ > or < K+:HCO3  > Cl > or > SO4 2− facies. The ionic relations (Ca2+ + Mg2+:HCO3 , Ca2+ + Mg2+:SO4 2− + HCO3 , Na+ + K+:TC, Na+ + K+:Cl + SO4 2−, HCO3 :TC, HCO3 :Ca2+ + Mg2+, Na+:Cl and Na+:Ca2+) indicate that the rock weathering, mineral dissolution, evaporation and ion exchange are the processes to control the aquifer chemistry. Anthropogenic and marine sources are also the supplementary factors for brackish water quality. These observations are further supported by Gibbs mechanisms that control the water chemistry. Thus, the study suggests that the initial quality of groundwater of geogenic origin has been subsequently modified by the influences of anthropogenic and marine sources.
Keywords: Geochemical evolution; Groundwater; Western Delta region; River Godavari; Andhra Pradesh; India

Artificial intelligence modeling of cadmium(II) biosorption using rice straw by Mahmoud Nasr; Alaa El Din Mahmoud; Manal Fawzy; Ahmed Radwan (823-831).
The biosorption efficiency of Cd2+ using rice straw was investigated at room temperature (25 ± 4 °C), contact time (2 h) and agitation rate (5 Hz). Experiments studied the effect of three factors, biosorbent dose BD (0.1 and 0.5 g/L), pH (2 and 7) and initial Cd2+ concentration X (10 and 100 mg/L) at two levels “low” and “high”. Results showed that, a variation in X from high to low revealed 31 % increase in the Cd2+ biosorption. However, a discrepancy in pH and BD from low to high achieved 28.60 and 23.61 % increase in the removal of Cd2+, respectively. From 23 factorial design, the effects of BD, pH and X achieved p value equals to 0.2248, 0.1881 and 0.1742, respectively, indicating that the influences are in the order X > pH > BD. Similarly, an adaptive neuro-fuzzy inference system indicated that X is the most influential with training and checking errors of 10.87 and 17.94, respectively. This trend was followed by “pH” with training error (15.80) and checking error (17.39), after that BD with training error (16.09) and checking error (16.29). A feed-forward back-propagation neural network with a configuration 3-6-1 achieved correlation (R) of 0.99 (training), 0.82 (validation) and 0.97 (testing). Thus, the proposed network is capable of predicting Cd2+ biosorption with high accuracy, while the most significant variable was X.
Keywords: Artificial intelligence; Cadmium(II) ions; Factorial design; Rice straw biosorbent

Prevalence of indicator and pathogenic bacteria in a tropical river of Western Ghats, India by M. V. Vincy; R. Brilliant; A. P. Pradeepkumar (833-844).
The Meenachil, the only river that flows through the heart of the Kottayam district of Kerala state, India was selected for the study. The present study has been carried out with an objective to systematically examine the prevalence of indicator and pathogenic microorganisms and to compare the microbiological quality of the river water during the pre-monsoon and post-monsoon seasons. Water samples from 44 different sites during pre-monsoon and post-monsoon seasons were collected for the analysis. During the pre-monsoon period, the faecal coliform count ranged from 230 to 110,000 MPN/100 ml while there was a variation from 200 to 4600 MPN/100 ml during the post-monsoon period. When the faecal streptococci count was analysed, it ranged from 140 to 110,000 MPN/100 ml during the pre-monsoon and 70 to 4600 MPN/100 ml during the post-monsoon seasons, respectively. All the samples collected were found to have total viable count (TVC) higher than those prescribed by Bureau of Indian Standards (ISI 1991). Total viable counts were found in the range of 1.1 × 102 to 32 × 102 cfu/ml in the pre-monsoon and 1.0 × 102 to 26 × 102 cfu/ml in the post-monsoon. The presence of faecal indicator bacteria, Escherichia coli and potentially pathogenic bacteria, Vibrio cholerae, Vibrio parahaemolyticus and Salmonella enterica in the Meenachil River indicates that the bacteriological quality of the Meenachil River is poor. Moreover, it sheds light to the fact that raw sewage is being dumped into the Meenachil River. Urban runoffs and effluents of rubber factories appear to be the important sources of faecal contamination in the river. From this study, we conclude that these water bodies pose significant public health hazards. Adequate sanitary infrastructure will help in preventing source water contamination. Besides this, public health education aimed at improving personal, household and community hygiene is urgent.
Keywords: Pathogenic bacteria; Tropical rivers; Western Ghats; Surface water contamination; Meenachil river

Assessment of groundwater quality by unsaturated zone study due to migration of leachate from Abloradjei waste disposal site, Ghana by Courage Davidson Egbi; Tetteh Thomas Akiti; Shiloh Osae; Samuel Boakye Dampare; Gibrilla Abass; Dickson Adomako (845-859).
Leachate generated by open solid waste disposal sites contains substances likely to contaminate groundwater. The impact of potential contaminants migrating from leachate on groundwater can be quantified by monitoring their concentration and soil properties at specific points in the unsaturated zone. In this study, physical and chemical analyses were carried out on leachate, soil and water samples within the vicinity of the municipal solid waste disposal site at Abloradjei, a suburb of Accra, Ghana. The area has seen a massive increase in population and the residents depend on groundwater as the main source of water supply. Results obtained indicate alkaline pH for leachate and acidic conditions for unsaturated zone water. High EC values were recorded for leachate and unsaturated zone water. Major ions (Ca2+, Na+, Mg2+, K+, NO3 , SO4 2−, Cl, PO4 3− were analysed in leachate, unsaturated zone water, soil solution and groundwater while trace metals (Al, Fe, Cu, Zn, Pb) were analysed in both soil and extracted soil solution. Concentrations of major ions were high in all samples indicating possible anthropogenic origin. Mean % gravel,  % sand,  % clay, bulk density, volumetric water content and porosity were 28.8, 63.93, 6.6, 1 g cm−3, 35 and 62.7 %, respectively. Distribution of trace elements showed Kd variation of Al > Cu > Fe > Pb > Zn in the order of sequential increasing solubility. It was observed that the quality of groundwater is not suitable for drinking.
Keywords: Municipal solid waste; Leachate; Soil properties; Piezometer; Distribution coefficient; Unsaturated zone

A morphometric analysis of Shanur basin has been carried out using geoprocessing techniques in GIS. These techniques are found relevant for the extraction of river basin and its drainage networks. The extracted drainage network was classified according to Strahler’s system of classification and it reveals that the terrain exhibits dendritic to sub-dendritic drainage pattern. Hence, from the study, it is concluded that remote sensing data (SRTM–DEM data of 30 m resolution) coupled with geoprocessing techniques prove to be a competent tool used in morphometric analysis and evaluation of linear, slope, areal and relief aspects of morphometric parameters. The combined outcomes have established the topographical and even recent developmental situations in basin. It will also change the setup of the region. It therefore needs to analyze high level parameters of drainage and environment for suitable planning and management of water resource developmental plan and land resource development plan. The Shanur drainage basin is sprawled over an area of 281.33 km2. The slope of the basin varies from 1 to 10 %, and the slope variation is chiefly controlled by the local geology and erosion cycles. The main stream length ratio of the basin is 14.92 indicating that the study area is elongated with moderate relief and steep slopes. The morphometric parameters of the stream have been analyzed and calculated by applying standard methods and techniques viz. Horton (Trans Am Geophys Union 13:350–361, 1945), Miller (A quantitative geomorphologic study of drainage basin characteristics in the clinch mountain area, Virginia and Tennessee Columbia University, Department of Geology, Technical Report, No. 3, Contract N6 ONR 271–300, 1953), and Strahler (Handbook of applied hydrology, McGraw Hill Book Company, New York, 1964). GIS based on analysis of all morphometric parameters and the erosional development of the area by the streams has been progressed well beyond maturity and lithology is an influence in the drainage development. These studies are very useful for planning of rainwater harvesting and watershed management.
Keywords: Morphometric analysis; Digital elevation model; Slope map; Geographical information system; Geoprocessing

Multivariate statistical techniques, cluster and principal component analysis were applied to the data on groundwater quality of Suri I and II Blocks of Birbhum District, West Bengal, India, to extract principal factors corresponding to the different sources of variation in the hydrochemistry as well as the main controls on the hydrochemistry. For this, bore well water samples have been collected in two phases, during Post-monsoon (November 2012) and Pre-monsoon (April 2013) from 26 sampling locations spread homogeneously over the two blocks. Excess fluoride in groundwater has been reported at two locations both in post- and in pre-monsoon sessions, with a rise observed in pre-monsoon. Localized presence of excess iron has also been observed during both sessions. The water is found to be mildly alkaline in post-monsoon but slightly acidic at some locations during pre-monsoon. Correlation and cluster analysis studies demonstrate that fluoride shares a moderately positive correlation with pH in post-monsoon and a very strong one with carbonate in pre-monsoon indicating dominance of rock water interaction and ion exchange activity in the study area. Certain locations in the study area have been reported with less than 0.6 mg/l fluoride in groundwater, leading to possibility of occurrence of severe dental caries especially in children. Low values of sulfate and phosphate in water indicate a meager chance of contamination of groundwater due to anthropogenic factors.
Keywords: Groundwater quality; Fluoride; Correlation analysis; Hierarchical cluster analysis; Principal component and factor analysis; Suri I and II

Performance of aquatic plant species for phytoremediation of arsenic-contaminated water by Shivakshi Jasrotia; Arun Kansal; Aradhana Mehra (889-896).
This study investigates the effectiveness of aquatic macrophyte and microphyte for phytoremediation of water bodies contaminated with high arsenic concentration. Water hyacinth (Eichhornia crassipes) and two algae (Chlorodesmis sp. and Cladophora sp.) found near arsenic-enriched water bodies were used to determine their tolerance toward arsenic and their effectiveness to uptake arsenic thereby reducing organic pollution in arsenic-enriched wastewater of different concentrations. Parameters like pH, chemical oxygen demand (COD), and arsenic concentration were monitored. The pH of wastewater during the course of phytoremediation remained constant in the range of 7.3–8.4, whereas COD reduced by 50–65 % in a period of 15 days. Cladophora sp. was found to survive up to an arsenic concentration of 6 mg/L, whereas water hyacinth and Chlorodesmis sp. could survive up to arsenic concentrations of 2 and 4 mg/L, respectively. It was also found that during a retention period of 10 days under ambient temperature conditions, Cladophora sp. could bring down arsenic concentration from 6 to <0.1 mg/L, Chlorodesmis sp. was able to reduce arsenic by 40−50 %; whereas, water hyacinth could reduce arsenic by only 20 %. Cladophora sp. is thus suitable for co-treatment of sewage and arsenic-enriched brine in an algal pond having a retention time of 10 days. The identified plant species provides a simple and cost-effective method for application in rural areas affected with arsenic problem. The treated water can be used for irrigation.
Keywords: Phytoremediation; Water treatment for arsenic removal; Water hyacinth; Algae

Heavy metals and microbiological contamination were investigated in groundwater in the industrial and coastal city of Thoothukudi. The main sources of drinking water in this area are water bores which are dug up to the depth of 10–50 m in almost every house. A number of chemical and pharmaceutical industries have been established since past three decades. Effluents from these industries are reportedly being directly discharged onto surrounding land, irrigation fields and surface water bodies forming point and non-point sources of contamination for groundwater in the study area. The study consists of the determination of physico-chemical properties, trace metals, heavy metals and microbiological quality of drinking water. Heavy metals were analysed using Inductively Coupled Plasma Mass Spectrometry and compared with the (WHO in Guidelines for drinking water quality, 2004) standards. The organic contamination was detected in terms of most probable number (MPN) test in order to find out faecal coliforms that were identified through biochemical tests. A comparison of the results of groundwater samples with WHO guidelines reveals that most of the groundwater samples are heavily contaminated with heavy metals like arsenic, selenium, lead, boron, aluminium, iron and vanadium. The selenium level was higher than 0.01 mg/l in 82 % of the study area and the arsenic concentration exceeded 0.01 mg/l in 42 % of the area. The results reveal that heavy metal contamination in the area is mainly due to the discharge of effluents from copper industries, alkali chemical industry, fertiliser industry, thermal power plant and sea food industries. The results showed that there are pollutions for the groundwater, and the total Coliform means values ranged from 0.6–145 MPN ml−1, faecal Coliform ranged from 2.2–143 MPN ml−1, Escherichia coli ranged from 0.9 to 40 MPN ml−1 and faecal streptococci ranged from 10–9.20 × 102 CFU ml−1. The coastal regions are highly contaminated with total coliform bacteria, faecal coliform bacteria and E. coli. This might be due to the mixing of sewage from Thoothukudi town through the Buckle channel and fishing activity.
Keywords: Groundwater; ICP-MS; Heavy metals; MPN; WHO; Thoothukudi

Adsorption studies of cadmium ions on alginate–calcium carbonate composite beads by Zahid Mahmood; Athar Amin; Uzma Zafar; Muhammad Amir Raza; Irfan Hafeez; Adnan Akram (915-921).
Alginate–calcium carbonate composite material was prepared in the form of beads and characterized using Fourier transform infra red (FT-IR) spectroscopy and scanning electron microscope (SEM) techniques. The adsorption of Cd2+ ions was studied through batch experiments. The adsorption parameters such as contact time (120 min), adsorbent dose (1.5 g), initial metal ion concentration(10 mg/L), pH (6) and agitation speed (150 rpm) were optimized at room temperature. Langmuir and Freundlich isotherms were applied to the data and it was noted that the adsorption of Cd2+ ions is better explained by Freundlich model. The kinetic studies showed that the adsorption of Cd2+ ions followed pseudo-first order kinetics. Thermodynamic parameters like ∆G 0, ∆H 0 and ∆S 0 were calculated and on the basis of these values it was established that the adsorption process is feasible and endothermic in nature. It was concluded from the study that the composite material of alginate and calcium carbonate can effectively be used to recover Cd2+ ions from wastewater.
Keywords: Alginate; Calcium carbonate; Composite beads; Cadmium adsorption

Temporal water quality response in an urban river: a case study in peninsular Malaysia by Renjith VishnuRadhan; Zaki Zainudin; G. B. Sreekanth; Ravinder Dhiman; Mohd. Noor Salleh; P. Vethamony (923-933).
Ambient water quality is a prerequisite for the health and self-purification capacity of riverine ecosystems. To understand the general water quality situation, the time series data of selected water quality parameters were analyzed in an urban river in Peninsular Malaysia. In this regard, the stations were selected from the main stem of the river as well as from the side channel. The stations located at the main stem of the river are less polluted than that in the side channel. Water Quality Index scores indicated that the side channel station is the most polluted, breaching the Class IV water quality criteria threshold during the monitoring period, followed by stations at the river mouth and the main channel. The effect of immediate anthropogenic waste input is also evident at the side channel station. The Organic Pollution Index of side channel station is (14.99) ~3 times higher than at stations at river mouth (4.11) and ~6 times higher than at the main channel (2.57). The two-way ANOVA showed significant difference among different stations. Further, the factor analysis on water quality parameters yielded two significant factors. They discriminated the stations into two groups. The land-use land cover classification of the study area shows that the region near the sampling sites is dominated by urban settlements (33.23 %) and this can contribute significantly to the deterioration of ambient river water quality. The present study estimated the water quality condition and response in the river and the study can be an immediate yardstick for base lining river water quality, and a basis for future water quality modeling studies in the region.
Keywords: Dissolved oxygen; Biochemical oxygen demand; Organic pollution index; Urban river; Peninsular Malaysia

The present work aims at evaluation of the potential of cyanobacterial biomass to remove Cu(II) from simulated wastewater. Both dried and carbonized forms of Lyngbya majuscula, a cyanobacterial strain, have been used for such purpose. The influences of different experimental parameters viz., initial Cu(II) concentration, solution pH and adsorbent dose have been examined on sorption of Cu(II). Kinetic and equilibrium studies on Cu(II) removal from simulated wastewater have been done using both dried and carbonized biomass individually. Pseudo-second-order model and Langmuir isotherm have been found to fit most satisfactorily to the kinetic and equilibrium data, respectively. Maximum 87.99 and 99.15 % of Cu(II) removal have been achieved with initial Cu(II) concentration of 10 and 25 mg/L for dried and carbonized algae, respectively, at an adsorbent dose of 10 g/L for 20 min of contact time and optimum pH 6. To optimize the removal process, Response Surface Methodology has been employed using both the dried and carbonized biomass. Removal with initial Cu(II) concentration of 20 mg/L, with 0.25 g adsorbent dose in 50 mL solution at pH 6 has been found to be optimum with both the adsorbents. This is the first ever attempt to make a comparative study on Cu(II) removal using both dried algal biomass and its activated carbon. Furthermore, regeneration of matrix was attempted and more than 70% and 80% of the adsorbent has been regenerated successfully in the case of dried and carbonized biomass respectively upto the 3rd cycle of regeneration study.
Keywords: Lyngbya majuscula ; Copper; Adsorbent; Response Surface Methodology; Optimization; Regeneration

Surface water samples from three stations in the Bonny/New Calabar River Estuary were analyzed for the physicochemical characteristics and trace metal level in 2011 and 2012, respectively. Results show pH ranged from 7.56 to 7.88 mg/L; conductivity, 33,489.00 to 33,592.00 µScm−1; salinity, 15.33 to 15.50 ‰; turbidity, 4.35 to 6.65 NTU; total dissolved solids, 22111.00 to 23263.00 gm−3; dissolved oxygen, 4.53 to 6.65 mg/L; and biochemical oxygen demand, 1.72 mg/L. The level of some trace metals (Ca, Mg, K, Zn, Pb, Cd, Co, Cr, Cu, Fe, Ni, and Na) were also analyzed by Atomic absorption spectrometry with K, Zn, and Co being statistically significant (P < 0.05). The results were compared with USEPA and WHO Permissible Limits for water quality standards. It was observed that the water quality parameters in the Bonny Estuary show seasonal variation with higher values for pH, DO, BOD, temperature, and salinity during the dry season than wet season. Concentrations of trace metals such as Pb, Cd, Zn, Ni, and Cr were higher than stipulated limits by WHO (2006). The result of the Metal Pollution Index suggests that the river was slightly affected and therefore continuous monitoring is necessary to avert possible public health implications of these metals on consumers of water and seafood from the study area.
Keywords: Water quality; USEPA; Pollution metal index; Spectrophotometer; Bonny; Estuary

Hydrochemistry of surface water and groundwater in the shale bedrock, Cross River Basin and Niger Delta Region, Nigeria by T. N. Nganje; A. S. Hursthouse; Aniekan Edet; D. Stirling; C. I. Adamu (961-985).
Water chemistry in the shale bedrock of the Cretaceous-Tertiary of the Cross River and Niger Delta hydrological basins has been investigated using major ions. To carry out a characterization of the water bearing units, 30 and 16 representatives surface and groundwater samples were collected. The evolution of the water is characterized by enhanced content of sodium, calcium and sulphate as a result of leaching of shale rock. The spatial changes in groundwater quality of the area shows an anomalous concentrations of ions in the central parts, while lower values characterize the eastern part of the basin covering Ogoja, Ikom and Odukpani areas. The values of total dissolved solids (TDS) and ions increases down gradient in the direction of groundwater flow. The dissolution of halite and gypsum explains part of the contained Na+, Ca2+, Cl and SO4 2−, but other processes such as ion exchange, silicate weathering and pyrite oxidation also contribute to water composition. The assessment with contamination indicators such as TDS, hardness, chloride, nitrate and sulphate indicates that the water in area is suitable for human consumption in some locations. Modelling using MINTEQA2 program shows that the water from all the shale water bearing units are under saturated with respect to gypsum.
Keywords: Geochemistry; Shale terrain; Surface water; Groundwater; Southeastern; Nigeria

Inland valley agro-ecosystems which are a category of wetlands have potential for sustainable crop production relative to uplands. A major challenge to their utilisation in the study area is their heterogeneity in hydrology, morphology, soil types and agro-economy. The study assessed the surface water quality of three typologies of the agro-ecosystems—amphitheatre-like valley-heads (Am), valley-side (VS), and low depression (LD)—for cropping. Surface water of six sites were sampled during the wet and dry seasons. The physicochemical properties and metal concentrations of the samples were analysed. Descriptive statistics and water quality indices were used to assess the suitability of the waters of the agro-ecosystems for cropping. Results showed that the valleys have neutral to slightly alkaline waters. Values of physicochemical parameters are generally within the acceptable range for cropping. The concentration of major cations varied across the inland valley types, but exhibited similar characteristics within each valley. The dominance of the major cations is in the order of Na > Ca > K > Mg. ANOVA results indicated that there is no significant difference in the concentration of heavy metals across the valleys (F = 2.044, p = 0.138, α = 0.05). Generally, most of the physicochemical parameters and trace metals have low concentrations and are non-toxic to plants. Values of water quality indices (sodium adsorption ratio, soluble sodium percentage, total dissolved solids and permeability index) indicated that the concentrations of minerals in waters across the valley typologies are generally within permissible limits for cropping.
Keywords: Inland valley; Irrigation; Wetland; Water quality indices; Agriculture; Food security

Soil and water quality determines the health of an aquatic ecosystem. Rajakhali Canal, a tributary of Karnaphuli River estuary, flowing through Chittagong City (the commercial capital of Bangladesh) receives a huge amount of domestic and industrial wastes and sewages. Monitoring the environmental status of Karnaphuli River and its tributaries is very important for their ecological and economical services provided to city areas. This study evaluated some environmental characteristics of water and soil in the Rajakhali Canal as it affected the environment, and ultimately the life and human beings of Chittagong City. The mean concentrations of physico-chemical parameters were pH (8.5), DO (0.1 mg/L), TA (47.6 mg/L), TDS (631.8 mg/L), TSS (280 mg/L), SO4-S (2.3 mg/L), NH3 (1.1 mg/L), NO3-N (0.2 mg/L) and PO4-P (0.1 mg/L) in the dry season. During the rainy season, the mean concentrations of physico-chemical parameters were pH (7.01), DO (0.55 mg/L), TA (65.9 mg/L), TDS (653.6 mg/L), TSS (300.3 mg/L), SO4-S (1 mg/L), NH3 (0.6 mg/L), (NO3-N (0.3 mg/L) and PO4-P (0.5 mg/L) in water. In case of soil, the mean concentration of physico-chemical parameters in dry and rainy seasons was represented respectively as follows: pH (6.8), OM (4.5 %), sand (71.7 %), silt (3.1 %), clay (25.2 %), organic nitrogen (45.4 ppm) and phosphorus (9.6 ppm); and pH (6.7), OM (4.5 %), sand (74.4 %), silt (2.4 %), clay (23.2 %), organic nitrogen (35.3 ppm) and phosphorus (7.6 ppm). The result revealed that water and soil quality of this canal became deteriorated and that the total environment of the water body became polluted due to the anthropogenic activities such as industrial, domestic and irrigation effluents. Statistical analyses also supported that water and soil parameters were strongly correlated (1-tailed 0.05 level and 0.01 level significant) with each other at all stations during all seasons. The result of this study will be useful for management and planning for water quality monitoring in this estuary. To protect this vital estuarine region, the government agencies, private agencies and scientists should work with proper attention.
Keywords: Karnaphuli River; Rajakhali Canal; Chittagong City water quality; Soil quality; Pollution

Assessment of fluoride contaminations in groundwater of hard rock aquifers in Madurai district, Tamil Nadu (India) by C. Thivya; S. Chidambaram; M. S. Rao; R. Thilagavathi; M. V. Prasanna; S. Manikandan (1011-1023).
The fluoride contamination in drinking water is already gone to the alarming level and it needs the immediate involvement and attention of all people to solve this problem. Fluoride problem is higher in hard rock terrains in worldwide and Madurai is such type of hard rock region. Totally 54 samples were collected from the Madurai district of Tamilnadu with respect to lithology. The samples collected were analysed for major cations and anions using standard procedures. The higher concentration of fluoride is noted in the Charnockite rock types of northern part of the study area. 20 % of samples are below 0.5 ppm and 6 % of samples are above 1.5 ppm exceeding the permissible limit. The affinity between the pH and fluoride ions in groundwater suggests that dissolution of fluoride bearing minerals in groundwater. The higher concentration of fluoride ions are observed in the lower EC concentration. The isotopic study suggests that fluoride is geogenic in nature. In factor scores, fluoride is noted in association with pH which indicates the dissolution process.
Keywords: Groundwater; Fluoride; Lithology; Weathering

Surface water contains natural pollutants humic acid (HA) and fulvic acid at ppm level which form carcinogenic chloro-compounds during chlorination in water treatment plants. We report here synthesis of ZnO–chitosan (CS) nano-composites by simple hydrothermal technique and examined their application potential as fluorescent probe for monitoring ppm level HA. These ZnO–CS composites have been characterized by HRTEM, EDX, FTIR, AFM and Fluorescence Spectra. HRTEM images show the formation of ZnO–CS nano-composites of average diameter of 50–250 nm. Aqueous dispersions of these nano-composites show fluorescence emission at 395 nm when excited at 300 nm which is strongly quenched by ppm level HA indicating their possible use in monitoring ppm level HA present in surface water.
Keywords: ZnO nano-rods; Monitoring HA in surface water; Fluorescent probe

Probability analysis for consecutive-day maximum rainfall for Tiruchirapalli City (south India, Asia) by R. Mani Sabarish; R. Narasimhan; A. R. Chandhru; C. R. Suribabu; J. Sudharsan; S. Nithiyanantham (1033-1042).
In the design of irrigation and other hydraulic structures, evaluating the magnitude of extreme rainfall for a specific probability of occurrence is of much importance. The capacity of such structures is usually designed to cater to the probability of occurrence of extreme rainfall during its lifetime. In this study, an extreme value analysis of rainfall for Tiruchirapalli City in Tamil Nadu was carried out using 100 years of rainfall data. Statistical methods were used in the analysis. The best-fit probability distribution was evaluated for 1, 2, 3, 4 and 5 days of continuous maximum rainfall. The goodness of fit was evaluated using Chi-square test. The results of the goodness-of-fit tests indicate that log-Pearson type III method is the overall best-fit probability distribution for 1-day maximum rainfall and consecutive 2-, 3-, 4-, 5- and 6-day maximum rainfall series of Tiruchirapalli. To be reliable, the forecasted maximum rainfalls for the selected return periods are evaluated in comparison with the results of the plotting position.
Keywords: Rainfall; Return period; Probability distribution; Chi-square test