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Open access

Donny Harisuseno, Dian Noorvy Khaeruddin and Riyanto Haribowo

Abstract

Time of concentration, Tc, is defined as time elapsed from the beginning of rainfall infiltrated into soil layer until it reaches a constant infiltration rate (fc) which is indicated an equilibrium subsurface flow rate. In hydrological view, time of concentration plays a significant role in elaboration of transformation of rainfall into runoff in a watershed. The aims of this research are to define influence of soil density and soil water content in determining time of concentration using infiltration concept based on water balance theory, and to find out the effect of land slope this time. Watershed laboratory experiment using rainfall simulator was employed to examine time of concentration associated with infiltration process under different slope, soil density and soil water content based on water balance concept. The steady rainfall intensity was simulated using sprinklers which produced 2 dm3∙min−1. Rainfall, runoff and infiltration analysis were carried out at laboratory experiment on soil media with varied of soil density (d) and soil water content (w), where variation of land slopes (s) were designed in three land slopes 2, 3 and 4%. The results show that relationship between soil density and land slope to time of concentration showed a quadratic positive relationship where the higher the soil density address to the longer time of concentration. Moreover, time of concentration had an inverse relationship with soil water content and land slope that means time of concentration decreased when the soil water content increased.

Open access

Anna M. Baryła

Abstract

Green roofs play a significant role in sustainable drainage systems. They form absorbent surfaces for rainwater, which they retain with the aid of profile and plants. Such roofs therefore take an active part in improving the climatic conditions of a city and, more broadly, the water balance of urbanized areas. One of the factors influencing the hydrological efficiency of green roofs is the drainage layer. In the article, column studies were carried out under field conditions involving the comparison of the retention abilities of two aggregates serving as the drainage layer of green roofs, i.e. Leca® and quartzite grit. The average retention of the substrate was 48%; for a 5 cm drainage layer of Leca® retention was 57%, for a 10 cm layer of Leca average retention was 61%. For a 5 cm layer of quartzite grit average retention was 50%, for 10 cm layer of quartzite grit 53%. The highest retention was obtained for the column with the substrate and 10-centimeter layer of Leca®. At the same time, it was shown that Leca® is a better retention material than quartzite grit. The initial state of substrate moisture content from a green roof appears to be a significant factor in reducing rainfall runoff from a green roof; the obtained values of initial moisture content made for a higher correlation than the antecedent dry weather period.

Open access

Michael Chukwuma Obeta

Abstract

Water scarcity is a major and growing problem in Nigerian rural areas, leading to the emergence of private for-profit water services providers (PPWSPs). This paper characterizes the landscape of PPWSPs in Nigerian rural communities using information collected from field observations, in-depth interviews, questionnaire surveys, and from published water resources literature. The data collected were analysed through the use of descriptive statistical tools. The results revealed the characteristics, categories, contributions and concerns of water users regarding water supplies by PPWSPs. Responses show that PPWSPs are helping to engender development, guarantee end-users with access to sufficient and reliable supplies and reduce water shortages in the study communities. Sixty four percent of sampled households depend on PPWSPs for their water requirements. Many PPWSPs operate outside the purview of government regulations and have differentiated service modes and prizes to gain wider acceptability. Despite the progress made by PPWSPs, however, the strategy can neither guarantee universal access nor the supply of safe drinking water. Significant barriers to the operations of PPWSPs, how to close the policy-gaps that constrain services delivery by PPWSPs and improve performances through setting of standards and regulatory reforms are discussed.

Open access

Agatha Piranti, Gentur Waluyo and Diana R.U.S. Rahayu

Abstract

The water of Lake Rawa Pening is used as a source of drinking water. Indonesian Government Regulation Number 82 of 2001 on Management of Water Quality and Water Pollution Control stated that the water quality of Lake Rawa Pening should meet the quality standard of first grade and be categorized as no polluted water. The purpose of this research was to assess the water quality based on Indonesian regulation and to assess water quality based on international regulations. The quality of water was assessed using a survey method in 7 sites of the Lake Rawa Pening 3 times for 3 months. Parameters measured were all the water quality parameters required in accordance with Government Regulation No. 82 of 2001. The results indicated that there were 13 values that exceeded the water quality standard of first grade. These exceeded parameters were total suspended solids (TSS), biological oxygen demand (BOD), chemical oxygen demand (COD), orthophosphate (PO4), NO3, As, Se, Cd, Mn, Cu, Pb, H2S, faecal coliform, and total coliform. Water quality status of Lake Rawa Pening was categorized as heavily polluted. The water quality of Lake Rawa Pening should be improved by reducing the pollutants entering the lake by restriction of human activities causing lake pollution.

Open access

Libor Ansorge and Adam Beran

Abstract

Evaporation and evapotranspiration is crucial part of hydrological and water resource management studies e.g. water footprinting. Proper methods for estimating evaporation/potential evapotranspiration using limited climatic data are critical if the availability of climatic data is extremely limited. In a large scale studies are very often used generalized (modelled or gridded) input data. For a large scale water footprint studies is also important to find methods as simple as possible with quantifiable error. In our study, nine simple temperature-based empirical equations were compared with a long term time series of real evaporation data from a 20 m2 tank at Hlasivo station. In the first step, we used real temperature measured at Hlasivo station for validation of equations. In the second step, the gridded temperature data (interpolated datasets) derived from the meteorological stations were used. For both datasets, the differences between observed and predicted values were categorized into three groups of accuracy and the statistical indices of each equation were calculated. Very good results were achieved with the Hamon equation from 1961 and the Oudin equation for both datasets with index of agreement (d) higher than 0.9, cross-correlation coefficient (R 2) around 0.7 and root mean square error (RMSE) around 0.5 mm∙(24 h)−1 The Kharrufa equation, which was developed for semi-arid or arid areas, also provides results with sufficient accuracy. Comparison of the results with similar studies showed a lower accuracy of very simple equations against more complex equations, which have RMSE lower than 0.25 mm∙(24 h)−1. But for some kind of studies, quantifiable errors with sufficient accuracy can be more important than the absolute accuracy.

Open access

Stanislav S. Dushkin, Serhii Martynov and Stanislav S. Dushkin

Abstract

In this paper we studied the intensification of the water clarification process on contact clarifiers with quartz sand filtering bed, which was modified with a solution of aluminum sulphate coagulant. The modification of the quartz sand filtering bed was carried out by applying to the surface of grains of quartz sand solution of coagulant aluminum sulphate with different doses. Investigation of the electrokinetic potential of the filtering material (quartz sand) was carried out by the percolation potential method.

The influence of electrical properties (size and sign of the charge) of the filtering bed itself and suspended solids in the water on the filtration process was studied. The filter material – quartz sand used in contact clarifiers has a negative electric charge. When the electric charge of the particles decreases, that is, as the ζ-potential decreases, the repulsive forces decrease and it the adhesion of particles becomes possible. This is the process of coagulation of the colloid. The forces of mutual gravity between the colloidal particles begin to predominate over the electric repulsive forces at the ζ-potential of the system less than 0.03 V.

Modification of quarts filtering bed with a solution of coagulant aluminum sulphate recommended for the purification of surface water allows: to intensify the process of water clarification, to reduce the consumption of reagents by 25–30%, with the obtaining purified water of the required quality, to reduce the production areas necessary for reagent management of treatment facilities, and to reduce the cost of water treatment by 20–25%.

Open access

Agnieszka Kowalczyk, Sylwester Smoroń and Marek Kopacz

Abstract

Research was conducted in selected points of the Szreniawa River basin (area 712 km2) located in the Miechowska Upland and the Proszowice Plateau. In the years 2016–2017 water samples from the Szreniawa River were taken monthly and the concentration of suspended solids was determined by filtration. The concentration of biogenic components NO3-N, NH4-N and PO4-P was determined by a colorimetric method, using an automatic flow analyser. The average concentration of suspended solids ranged from 192 to 390 mg·dm−3 (with minimum values of 5–20 mg·dm−3 and maximum 837–3937 mg·dm−3) at individual points. There was an upward trend between the content of suspended solids and the concentration of biogenic components. An extremely high concentration of suspended solids happened during storm-like precipitation at the end of June 2017 and amounted to 3937.2 mg·dm−3. The concentration of biogenic components was also highest in this period and amounted to 2.50 mg·dm−3 of NO3-N, 0.49 mg·dm−3 of NH4-N and 1.18 mg·dm−3 of PO4-P. At low precipitation the concentration of suspended solids was also low (5.0 mg·dm−3). A similar pattern was observed for the concentration of biogenic components which was 0.39 mg·dm−3 of NO3-N, 0.17 mg·dm−3 of PO4-P and 0.08 mg·dm−3 of NH4-N.

Open access

Amina Malek, Mohamed Kahoul and Hamza Bouguerra

Abstract

Drinking water is a possible source of humans’ illness when it contains chemicals and microorganisms especially from anthropogenic activities. The water supply from groundwater remains very important in Algeria. To assess the quality of groundwater in the region of Sedrata, analyses were carried out on 26 wells belonging to two neighbouring areas: one urban and the other rural. A study of physicochemical parameters has focused on the measurement of in situ temperature, electrical conductivity, pH and turbidity. Then the following parameters were analysed: hardness, and the elements: Ca2+, Mg2+, SO4 2−, PO4 3−, Cl, NO2 , NO3 , NH4 + as well as metal trace elements Fe2+, Mn2+, Al3+. The samples taken for the bacteriological study were filtered and introduced into growth medium for the research and enumeration of total germs, faecal coliforms, faecal streptococci and sulphite reducing Clostridium. As a result, the contamination of the studied waters is almost general. Some of the most important obtained values are ranging from 4.8 to 76 mg∙dm−3 for nitrates, the recorded values for mesophilic germs vary from 1 to 1100 CFUs∙cm−3. Agricultural activity and livestock products on the one hand and the use of fertilizers on the other hand are the main sources of physicochemical and bacteriological pollution. Contaminated wells should be treated as soon as possible to limit contamination before spreading in the deep aquifers. In the future, it will be necessary not only to assess the health risks related to the level of contamination of these waters, but also to proceed with their treatment before supplying them to consumers.

Open access

Megersa Olumana Dinka

Abstract

Wonji Shoa Sugar Estate (WSSE), located in the flood plain of the Awash River (Ethiopia), has been under long-term (>60 years) irrigation, industrial activities and agro-chemical usage. In this study, the hydrochemical properties of groundwater bodies available at WSSE have been characterized for quality compositions. Water samples were collected from groundwater monitoring piezometers distributed in the sugarcane plantation and then analysed for physico-chemical quality parameters (pH, EC, major cations and anions) following standard procedures. Other chemical indices (e.g., total dissolved solids (TDS), total hardness (TH), magnesium absorption ratio (MAR), base exchange (r 1), meteoric genesis (r 2)) were derived from the measured water quality parameters. The compositional variability and groundwater classification has been presented using the Box and Piper plots. The potential sources of minerals were suggested for each of the considered water sources based on their quality characteristics. Both trilinear Piper plot and meteoric genesis index revealed that groundwater of the area is shallow meteoric water percolation type with a changing of hydrochemical facies and mixing trend. Groundwater of the area, is group 1 (Ca-Mg-HCO3) type, with no dominant cations and HCO3 are the dominant anions. Overall, the study result elucidates that the chemical composition of GW of the area showed spatial variability depending upon the variations in hydrochemical inputs from natural processes and/or anthropogenic activities within the region. The local anthropogenic processes could be discharges from sugar factory, domestic sewage and agricultural activities.

Open access

Abdelhalim Yahiaoui

Abstract

Extreme streamflow drought is the direct problem of serious on damaging and on social impacts, so the frequency analysis of hydrological drought is an important work can be done to studying the drought phenomenon in catchments. So the hydrometric data for a river conducts to the establishment of the flow duration curve (FDC) as an important index of streamflow drought regime, from this characteristic, a threshold level can be defined for both perennial or intermittent streams. Well, two partial duration series can be derived for each year; the deficit volume and drought duration series. In the catchment of Wadi Mekerra in the North-West of Algeria, the minimum value estimated from the Pareto’s annual maximum instantaneous flood population (0.60 m3∙s−1) is considered as the threshold level index where, the largest deficit volume and the largest drought duration occurring in a given year are taken into consideration. Hence, the frequency analysis of the streamflow drought regime of the catchment is analysed with Weibull distribution for both deficit volume and drought duration combined with the probability of occurrence which is determined under some criterion in order to forecasting the streamflow drought in the catchment.