Applied Water Science (v.8, #8)

The high concentration Fe3+ in sample had interference on the determination of iron species by spectrophotometric method in which 1,10-phenanthroline was used to as a chromogenic agent. The F could mask absolutely the effect of Fe3+ when F/Fe3+ molar concentration ratio was 13.3. The temperature or light did not affect the masking action of F. Low temperature and dark conditions favored the stability of chromophoric complex. This method is suitable for the measure of iron species where the concentration of Fe3+ is far more than that of Fe2+ in samples.
Keywords: Iron species; Spectrophotometric; Fluorine ion; Masking action; Storage condition

In this study, activated carbon (AC) prepared from cork powder was used in synthesis of AC stabilized nano-zero-valent iron (AC/NZVI) composite and evaluated phosphate (PO4 3−) removal efficiency from aqueous solution. The as-obtained AC/NZVI was characterized by scanning electron microscopy (SEM), Brunauer–Emmett–Teller (BET) and X-ray diffraction (XRD) analysis. Response surface methodology based on a three-level, three-factor, Box–Behnken design (B.B.D.) has been employed for determination of optimal combination of three significant process factors or variables such as temperature, solution pH and AC/NZVI dose, for maximum removal of PO4 3− from aqueous solution. Based on B.B.D. experimental design, a limited number of experiments were performed in a cost-effective manner at initial PO4 3− concentration of 211 mg L−1 as a fixed input parameter. A statistically validated quadratic model was developed to predict the responses in the form PO4 3− removal capacity from aqueous solution and adequacy of the model was evaluated using regression analysis and analysis of variance. The model predicted maximum PO4 3− removal capacity of the AC/NZVI was 152.12 mg g−1 under the optimal condition of process variables (temperature 60 °C, pH 3.5, and AC/NZVI dose 0.4 g L−1) which was strictly closer to the experimental value (151.10 mg g−1) obtained in batch experiment under the same optimize condition of process variables. The result of the study inferred that all three factors had a significant impact on removal of PO4 3−.
Keywords: Activated carbon; AC/NZVI; Phosphate removal; Optimization; Box–Behnken experimental design; Quadratic model

In the present investigation, isolated green algae Chlorella vulgaris has been proven to be a very effective and promising adsorbing biomaterial for Cd (II) removal from aqueous solution in batch experiments. Adsorption features of algae were studied as function of time, pH, initial Cd (II) concentration and algal biomass dosages. Kinetics and adsorption equilibrium isotherms of algal biomass were obtained for batch experiments. Kinetic data were best fitted to the pseudo-second-order where adsorption capacity (q e) values agree to experimental values. Langmuir isotherm model which shows the existence of monolayer adsorption under the experimental conditions best fitted to the obtained equilibrium data. The maximum adsorption capacity calculated by Langmuir model was 97.43 mg/g. FTIR, SEM, metal mapping were performed for virgin algal biomass and biomass loaded with Cd (II) to analyze the mechanism of adsorption. The various parameters of thermodynamics viz, ΔH, ΔG and ΔS, show endothermic, feasible and spontaneous behaviour, respectively, in sorption process. Desorption experiments were carried out insight of various parameters which resulted 0.1 M EDTA had commanding recovery of Cadmium metal ions. Recyclability study of algal biomass indicates promising future as it remains unaffected after five cycles with very less adsorption capacity loss (5.8%).
Keywords: Biosorption; Cd (II); Chlorella vulgaris ; Thermodynamics

Developing stage–discharge relationships using multivariate empirical mode decomposition-based hybrid modeling by S. Adarsh; Ajin P. John; R. N. Anagha; Abi Abraham; M. P. Afiya; K. K. Arathi; Aaliya Azeem (1-13).
This paper proposes an alternative method for modeling stage–discharge relationships by accounting significant information from different process scales employing the multivariate empirical mode decomposition (MEMD). First, the multivariate dataset comprising the discharge of current time step and appropriate lagged inputs of stage and discharge are decomposed using MEMD. Then, genetic programming (GP)-based models are developed for each sub-series to predict discharge of current time step, considering the sub-series of predictors at the corresponding timescale as inputs. Finally, the predicted sub-series are recombined to obtain the discharge of current time step. The method is applied for the prediction of the daily discharge from Pattazhy station of Kallada River in the state of Kerala, India. Statistical evaluation based on different performance criteria revealed the substantial improvement in performance of the proposed MEMD-based hybrid model over the popular nonlinear models like GP and M5 model trees. The application of the method for three more stations Ayilam, Thumpamon and Malakkara falling in different rivers in southern Kerala confirmed the robustness of the approach even in handing zero values and extreme flows in addition to the overall improvement in predictability of daily streamflow. The superiority of the proposed method is attributed to its capability in handling multiple causative inputs and capturing significant information from different timescales common to these input variables.
Keywords: Streamflow; Stage; MEMD; Genetic programming; Scale

Stepped spillways are used in the construction of dams, river engineering and soil conservation projects. Energy dissipation in this structure due to the presence of several steps is high, so the construction costs for stilling basin are reduced. The numerical models are new method for flow analysis. This study investigates the flow on the stepped spillway and calculates energy loss caused by it. Also in this study, fluctuation of velocity vectors, shear stress and pressure during the flow on each step is compared. For this purpose, a physical model of the stepped spillway was built with slope at a ratio of 2:1 (horizontal to vertical) and experiments were performed with ten different flow rates. The numerical simulations also were performed under the same conditions using FLUENT software and RNG kε turbulence model. Finally, the results of the numerical model were compared with experimental data. The results indicate that numerical model is in reasonable consistency with the physical model and it can be used in anticipation complex rotational flows in the stepped spillway.
Keywords: Energy dissipation; Velocity vector; Shear stress; Pressure; Stepped spillway; Numerical; FLUENT

Assessment of groundwater quality for irrigation use: a peninsular case study by Kishan S. Rawat; Sudhir Kumar Singh; Sandeep Kumar Gautam (1-24).
The grade of irrigation water available to irrigators has a significant impact on crops as well as yields. Therefore, it is a need to better understand irrigation water quality. The present study mainly focuses on the assessment of the suitability of water of forty-four fixed bore wells of Kanchipuram district, Tamil Nadu, India. The groundwater sample datasets of post-monsoon (2005–2013) and pre-monsoon (2006–2013) season were collected for 9 years. Water quality indices, namely sodium adsorption ratio, exchangeable sodium percent (SSP or %Na), residual sodium carbonate (RSC or RA), Kelly’s ratio, permeability index, chloroalkaline indices (CAI1 and CAI2), potential salinity (PS), magnesium hazard, total dissolved solids and total hardness, have been calculated for separate bore wells. The r 1 and r 2 indices show that groundwater of the study area is Na+–SO4 2− and deep meteoric percolation type. Majority of the wells are fall under moderate to unsuitable category of water for irrigation purposes. Further, wells water has also been classified on the base of meteoric genesis index.
Keywords: Irrigation water quality; Meteoric genesis index; Sodium adsorption ratio; Magnesium adsorption ratio; Geochemistry

The activated carbon from Leucaena leucocephala seed shell was prepared by chemical activation, characterized and used as adsorbent for the removal of hexavalent chromium [Cr(VI)] from aqueous solution via batch mode adsorption. The variables affecting the adsorption process, initial adsorbate concentration, pH, adsorbent dosage and temperature were optimized using central composite design (CCD) of the response surface methodology (RSM) at fixed contact time of 60 min. Equilibrium adsorption isotherm and kinetic were also studied. The analysis of variance (ANOVA) revealed that all the variables studied had significant effects on the removal efficiency of Cr(VI). The obtained data showed that 71.49 mg/L initial Cr(VI) concentration, 4.22 solution pH, 0.57 g adsorbent dosage and 26.2 °C temperature resulted in 95.62% adsorption. Equilibrium adsorption isotherm and kinetic studies showed that Freundlich isotherm and pseudo-second-order kinetic model fitted well to the experimental data. The activated carbon from Leucaena leucocephala seed shell was found to be efficient for Cr(VI) adsorption.
Keywords: Activated carbon; Hexavalent chromium; Characterization; Kinetic; Isotherm

Depth filtration is a conventional concept for the solid–liquid separation process through granular media, and this technique is very useful in removal of large-sized particle. However, in the case of microparticles smaller than the pore space it does not function well. Accordingly, an effective small particle removal technique is desired. In this research, a carbon fiber felt was introduced as filter media and ± 1.0 V terminal voltage was applied for activating the media to enhance in adsorbing as well as desorbing the fine particles in the filtration and back-washing. Kaolin particles in the range of 0.1–4.0 µm were used as a model of microparticles. The complete kaolin particle removal was observed in pure water, and it decreased to around 50% in the anionic surfactant-contaminated wastewater at the hydraulic loading of 283 L/m2/min. On the contrary, at the back-washing hydraulic loading of 1274 L/m2/min, the kaolin particle washout removal efficiency was found to be around 73% in pure water and it dramatically decreased and found within the range of 5–50% when the kaolin was in contact with anionic surfactant and wastewater. Although the kaolin particle washout removal rate was observed very low in wastewater, this technique would be very useful in enhancing the refreshment of the filter media for extending the production time of the filter.
Keywords: Carbon fiber felt; Depth filtration; Kaolin; Microparticle; Terminal voltage

Quality and degree of pollution of groundwater, using PIG from a rural part of Telangana State, India by N. Subba Rao; B. Sunitha; R. Rambabu; P. V. Nageswara Rao; P. Surya Rao; B. Deepthi Spandana; M. Sravanthi; Deepali Marghade (1-13).
Impacts of geogenic and anthropogenic sources change seriously quality of groundwater. Inferior groundwater quality directly affects the human health, agricultural output and industrial sector. The aim of the present study is to evaluate the groundwater quality for drinking purpose and also to identify the pollutants responsible for variation of chemical quality of groundwater, using pollution index of groundwater (PIG). Groundwater samples collected from a rural part of Telangana State, India, were analyzed for pH, total dissolved solids (TDS), calcium (Ca2+), magnesium (Mg2+), sodium (Na+), potassium (K+), bicarbonate ($$ { ext{HCO}}_{3}^{ - } $$ HCO3- ), chloride ($$ { ext{Cl}}^{ - } $$ Cl- ), sulfate ($$ { ext{SO}}_{4}^{2 - } $$ SO42- ), nitrate ($$ { ext{NO}}_{3}^{ - } $$ NO3- ) and fluoride ($$ { ext{F}}^{ - } $$ F- ). The groundwater is characterized by Na+ and $$ { ext{HCO}}_{3}^{ - } $$ HCO3- ions. The values of TDS, Mg2+, Na+, K+, $$ { ext{HCO}}_{3}^{ - } $$ HCO3- , $$ { ext{Cl}}^{ - } $$ Cl- , $$ { ext{SO}}_{4}^{2 - } $$ SO42- , $$ { ext{NO}}_{3}^{ - } $$ NO3- and $$ { ext{F}}^{ - } $$ F- are more than their threshold limits prescribed for drinking purpose in a few groundwater samples. The computed values of PIG varied from 0.69 to 1.37, which classify the 80% of the present study area into the insignificant pollution zone (PIG: < 1.0) caused by geogenic origin associated with rock-weathering, mineral dissolution, ion exchange and evaporation processes, and the rest (20%) into the low pollution zone (PIG: 1.0 to 1.5) due to influence of anthropogenic source (waste waters and agricultural activities) on the groundwater system, which are proved by ANOVA test. The diagrams (Ca2+ + Mg2+) versus ($$ { ext{HCO}}_{3}^{ - } $$ HCO3-  + $$ { ext{SO}}_{4}^{2 - } $$ SO42- ), Na+ versus (Ca2+ + Mg2+), Na+ versus $$ { ext{Cl}}^{ - } $$ Cl- , Ca2+ versus $$ { ext{SO}}_{4}^{2 - } $$ SO42- and Ca2+ versus Mg2+ support the geogenic origin, whereas the diagram TDS with ($$ { ext{NO}}_{3}^{ - } $$ NO3-  + $$ { ext{Cl}}^{ - } $$ Cl- )/$$ { ext{HCO}}_{3}^{ - } $$ HCO3- confirms the impact of anthropogenic activities on the aquifer chemistry, which substantially proved the explanation of PIG. The characterization of geochemical evolution of groundwater, using trilinear diagram, also further supports the assessment of PIG in the variation of groundwater quality. From this study, the TDS, Mg2+, Na+, $$ { ext{Cl}}^{ - } $$ Cl- , $$ { ext{SO}}_{4}^{2 - } $$ SO42- and $$ { ext{NO}}_{3}^{ - } $$ NO3- are considered as indicators in assessing the groundwater pollution sources.
Keywords: Groundwater quality; Pollution Index of Groundwater; Rural area; Telangana State; India

Evaluating the potential health risks of heavy metal pollution in sediment and selected benthic fauna of Benin River, Southern Nigeria by Alex Enuneku; Osaretin Omoruyi; Isioma Tongo; Emmanuel Ogbomida; Ozekeke Ogbeide; Lawrence Ezemonye (1-13).
The potential ecological and human health risk of heavy metal pollution in sediment and Benthic Fauna (Chrysichthys auratus and Tympanotonus fuscatus) of Benin River, Southern Nigeria, was evaluated. Three sampling sites associated with heavy anthropogenic activities along the course of the river were sampled. Heavy metals concentrations were determined in the samples using atomic absorption spectrophotometer (Model 210 VGP, Buck Scientific). In all sediment samples, only Pb exceeded the threshold/probable effect level (TEL). Very high contamination degrees (CD > 24) 181.74, 50.11, and 101.96) for stations 1, 2, and 3, respectively, were observed indicating serious anthropogenic pollution. Geoaccumulation index (i geo) showed slight pollution with Pb and Cd and severely to extremely polluted with Fe across the stations. Cd exhibited moderate individual potential risk ($$E_{ ext{r}}^{i}$$ Eri ), and the other heavy metals showed low $$E_{ ext{r}}^{i}$$ Eri . Potential ecological risk index (RI) showed low risk of contamination for heavy metals in sediment. Human health risk assessment for Co, Cd, Cu, Zn, Mn, Fe, and Ni in C. auratus and Co, Zn, Mn, Fe, and Ni in T. fuscatus indicated no obvious health risk from these heavy metals over a lifetime of exposure. However, hazard quotient (HQ) values for Pb in C. auratus and Cd, Cu, and Pb in T. fuscatus indicated significant health risk. The hazard index (HI) values for both C. auratus and T. fuscatus were > 1 indicating significant adverse health risk of non-carcinogenic effect. Therefore, the consumption of these contaminated fish and shellfish by the people of Koko portends risks of the health of the public. The industries operating in this community should adopt more sustainable and eco-innovative management options in order to attenuate potential ecological and human health risk of metal pollution.
Keywords: Metal pollution; Health risk; Sediment; Fish; Periwinkle

A one-dimensional numerical model is developed to simulate the nitrogen species in wastewater-applied agricultural field to investigate the effect of various isotherms of ammonium nitrogen and nitrate nitrogen. Results suggest that the ammonium nitrogen concentration reaches up to the depth of 40, 25 and 16 cm due to the linear, Freundlich and Langmuir isotherms of ammonium nitrogen, which is corresponding to the reduction in migration depth up to 37% by Freundlich isotherm and 55% by Langmuir isotherm as compared with linear isotherm. Similarly, the peak concentration of 25, 15 and 12 mg/l of nitrate nitrogen is observed during linear, Freundlich and Langmuir isotherms of NH4–N, respectively. Further, the results show that 4% peak concentration reduction is experienced for NO3–N due to the linear NH4–N sorption alone, 7% peak reduction is observed for NO3–N concentration by Freundlich NH4–N sorption alone, and 12.5% peak reduction is monitored for NO3–N concentration due to Langmuir NH4–N sorption alone compared with the combination of Freundlich NO3–N sorption. The numerical results suggest that the combination of Langmuir isotherm of NH4–N and Freundlich isotherm of NO3–N is identified as a best combination of isotherm scenario, which mitigates the NO3–N contamination in groundwater resources.
Keywords: Nitrogen species; Numerical modelling; Linear isotherm; Freundlich isotherm; Langmuir isotherm; Unsaturated porous media

Assessment of spatial distribution of aridity indices in Raya valley, northern Ethiopia by Mewcha Amha Gebremedhin; Gebrerufael Hailu Kahsay; Hailemariam Gebrewahed Fanta (1-8).
Aridity is a risk with the threat of desertification because of erratic precipitation and prolonged droughts. Aridity indices are often used for the climate-based land classification and monitoring droughts. Hence, this study aimed at analysis of the spatial distribution of aridity indices in Raya valley, northern Ethiopia. Meteorological data from eight meteorological stations located throughout the study area were used to compute the three aridity indices employed: the De Martonne aridity index (I DM), the Pinna combinative index (I P), and the Food and Agriculture Organization aridity index (I FAO). Each aridity index value was computed at each station. Then, once the statistical properties of each aridity index at each station were assessed, inverse distance-weighted geographic information system interpolation technique was used for the spatial estimation of the aridity indices. The three indices indicated a high coefficient of determination which in common revealed the area prone to dry and semi-dry risk. However, I DM was found more appropriate for the considered area since it defines more the climate of each location using seven classes, and it can be computed at specific season and month. The annual, seasonal, and monthly aridity indices of I DM showed high spatial variability of aridity index. The spatial distribution of the I DM underlined irrigation requirements in the northern east part of the study area. This analysis may be helpful for the utilization of water resources and irrigation systems of the study area.
Keywords: Aridity indices; Raya valley; Spatial distribution

The quality of groundwater is poorly understood in the arid northwest part of Rajasthan, whereas it is the only source of drinking and irrigation and the residents consume it without any prior treatment. This study illustrates the qualitative analysis of groundwater and its suitability in the bulk samples collected from three different canal catchment areas. Most of the samples were identified for higher values of EC, TDS, TH and fluoride, therefore considered posing restriction to drinking use. The abundance of major ions was found in the order of Na+ > Ca+2 > Mg+2 > K+ = Cl> HCO3> SO4−2 > NO3> F. The irrigation quality parameters such as sodium adsorption ratio, %Na, residual sodium carbonate, residual sodium bicarbonate, Kelley’s index, potential salinity, magnesium hazard, Mg/Ca ratio and permeability index were calculated and discussed thoroughly in combination with Wilcox, USSL and Doneen diagrams. Most of the samples belong to predominant Cl and Na+ in hydrogeochemical studies. According to USSL diagram, majority of the samples fall under C4S1 class. Furthermore, groundwater chemistry was found mainly influenced by evaporation–crystallization in Gibbs variation diagram. This study suggested that groundwater is unsafe for drinking purpose without purification and quality measures should be considered while cropping in its irrigation use.
Keywords: Groundwater quality; Canal catchment area; Drinking; Irrigation

The present paper aims at determining the status and trends of groundwater quality of 12 aquifers situated in Northwestern Algeria, especially under conditions of last drought that has affected the region using water quality index (WQI) over a period of 4 years. Multivariate statistical methods have been used jointly with conventional graphical methods, to classify the samples according to plausible levels of groundwater evolution. The computed WQI values range from 67 to 588 and therefore can be categorized into four categories: “good water” to “water unsuitable for drinking.” Overall, 36% of groundwater sites sampled in the study area had good water quality, while 53% were poor. Unfortunately, 6% of the samples indicate “very poor water quality” and 5% represent water “unsuitable for drinking purposes.” Results show that the majority of groundwater of Tafna basin fell under good water quality. Groundwater of poor and medium quality characterizes the majority of the studied aquifers of Macta basin. The result showed that the water quality at monitoring station “Ain Skhouna” fell under good water quality (Chott Chergui aquifer). Results also show that groundwater of Coastal Oranais basin showed poor water quality, very poor at some monitoring stations of Mléta Plain aquifer. It has been demonstrated that the water of some aquifers has degraded under water scarcity conditions and will continue to degrade given the ongoing and projected development in the study area. The analysis reveals that the water of some aquifers needs treatment before it is used for human consumption. The influence of salt water on the some freshwater aquifers in the study area needs special attention in terms of monitoring and for sustainable management.
Keywords: Coastal Oranais basin; Drought; Groundwater quality; Northwestern Algeria; Water quality index; Tafna

The present study envisages the application of multivariate analysis, water utility class and conventional graphical representation to reveal the hidden factor responsible for deterioration of water quality and determine the hydrochemical facies of water sources in Jia-Bharali river basin, North Brahmaputra Plain, India. Fifty groundwater and 35 surface water samples were collected and analyzed for 15 parameters viz pH, TDS, hardness, COD, Ca2+, Mg2+, Na+, K+, Fe, HCO3 , Cl, SO4 2−, NO3 , PO4 3− and F for a period of 3 hydrological years (2009–2011) in six different seasons (three wet and three dry). The results were evaluated and compared with WHO and BIS water quality standards. Except Fe (> 0.3 mg/L), all parameters were found well within the desirable limit of WHO and BIS for drinking water. Ca2+ and HCO3 were dominant ions among cations and anions. The piper trilinear diagram classified majority of water samples for both seasons fall in the fields of Ca2+–Mg2+–HCO3 water type indicating temporary hardness. Varimax factors extracted by principal component analysis indicates anthropogenic (domestic and agricultural runoff) and geogenic influences on the trace elements. Hierarchical cluster analysis grouped water sources into three statistically significant clusters based on the similarity of water quality characteristics. This study illustrates the usefulness of multivariate statistical techniques for analysis and interpretation of complex datasets, and in water quality assessment, identification of pollution sources/factors and understanding temporal/spatial variations in water quality for effective water quality management.
Keywords: Shallow aquifer; Multivariate statistical techniques; Hierarchical cluster; Principal component; Hydrochemistry

The present study focused on the synthesis of magnetite nanoparticles in the removal of copper from aqueous solutions. Magnetite nanoparticles were developed by co-precipitation method for the adsorption of copper from aqueous solution. The characteristics of the synthesized nanoparticles were assessed using Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), field emission scanning electron microscope (SEM) and energy-dispersive X-ray (EDS) analyses. Batch adsorption experiments were performed by varying the solution pH, contact time, stirring speed, adsorbent dosage and concentration of the effluent. The magnetic nanoparticle showed an excellent performance in removing copper under the following optimized conditions: pH 2, contact time = 75 min, initial concentration of copper = 100 ppm, adsorbent dosage = 0.6 g and stirring speed = 150 RPM. Thus, the developed magnetic nanoparticle has the potential to be used for the removal of copper from aqueous solution.
Keywords: Biocompatibility; Co-precipitation; Fourier transform infrared spectroscopy; Heavy metal pollution; Magnetic nanoparticles; Scanning electron microscopy

The negative effect of high concentration of heavy metals in the environment on living species prompted this research. A study of adsorption of zinc on synthesized magnetite (MG), baobab fruit shell (BB) and magnetite–baobab composite (MB) was carried out. The adsorption of Zn(II) ions was examined using batch equilibrium technique. The effects of initial metal ions concentrations (15–150 mg/L for zinc), adsorbent dose (0.05–0.3 g), contact time (5–150 min), pH (2–8) and temperature (303–343 K) on the sorption capacity of these adsorbents were investigated. The Zn(II) ions at a solution concentration of 150 mg/g gave maximum adsorption capacity of 38.25, 33.95 and 29.20 mg/g for MB, MG and BB, respectively. The adsorption of Zn(II) metal ions was modelled using Langmuir, Freundlich and Temkin isotherms. The highest correlation coefficient (R 2) value was obtained from Freundlich model for Zn(II) adsorption on MG and MB as 0.986 and 0.973, respectively, while that of Zn(II) on BB was obtained from Langmuir model as 0.993. The kinetic and thermodynamic studies revealed that the adsorption processes followed pseudo-second-order kinetics and were endothermic in nature. Desorption experiments were conducted on the spent adsorbent using 0.1, 0.2, 0.5, 1.0 and 2.0 M HCl to determine the reusability potentials of the adsorbents. There was an decrease in the amount of Zn(II) ions adsorbed after each stage of desorption process varied between the different acid concentrations. The 0.1 M HCl gave the highest degree of adsorption for Zn(II) on BB, while 0.2 M HCl was the best for MG and MB.
Keywords: Adsorption; Baobab; Biosorbent; Isotherm; Kinetic model; Composite

Unpredictability by local farmers, insufficiency and seasonality of rainfall have severely affected productivity of rain-fed agriculture in Cheleleka watershed. Thus, irrigated agriculture has a paramount role in lifesaving and insuring food security. Mismanagement of irrigation water influences agricultural productivity and efficiency of water uses. This study aimed to assess performance and potential of traditional surface irrigation schemes and to survey conflicts resulting from irrigation water use and management. Three major rivers in Cheleleka watershed (Wesha, Worka and Wodesa) where traditional irrigation has been widely practiced were selected purposively. The irrigable areas of each river were identified and categorized into upper, middle and lower parts based on its related location in the watershed. The soil samples, infiltration rate, long time meteorology, conveyance efficiency, irrigable areas and discharge at diversion points were analyzed. In addition, 49 households in irrigable areas of the three rivers were interviewed and three focus group discussions were held. About 0.16 and 0.14 m3/s of discharge were recorded in irrigation areas of the middle Wodesa and upper Worka rivers, respectively. The conveyance efficiency of the traditional surface irrigation canals at middle Wodesa and upper Wesha and Worka was less than 50%. The general potentials of surface irrigation water across the three perennial rivers were greater than 23 million cubic meters per year. The moisture stored in root zone or readily available water in existing farmers’ practices was found far beyond the carrying capacity of the soils, especially in middle Wodesa and upper Wesha and Worka areas. Performances of the traditional surface irrigation schemes are very low and had aggravated irrigation water losses and contributed to crop water scarcity and conflicts. The results also showed that farmers in the upper parts of the area and close to the diversion points excessively irrigate the cropland, whereas those far away and in lower watersheds of each river receive irrigation water insufficiently and irregularly. Even though there was irrigation management system/committee, the set principle was not respected.
Keywords: Irrigation potential; Performance; Water use efficiency; Conflicts