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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.

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.

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.

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.

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.

Abstract

Monitoring studies of ichthyofauna, in particular non-indigenous species, are an important element of research on aquatic ecosystems. This information is essential for modelling population growth and predicting rates of expansion, quantifying ecological impacts and assessing the efficacy of removal and control strategies. Actually, the most compelling fish invasion in Polish freshwaters is arguably the accidental introduction of the topmouth gudgeon (Pseudorasbora parva). Age and lengths structure, condition factor and growth rate of the invasive populations of the topmouth gudgeon from small Polish rivers was examined. The samples were collected from the rivers: Molnica (n = 41), Myśla (n = 21) and Wardynka (n = 101) soon after the invasion was recorded (2017). Estimated ages of topmouth gudgeon ranged from 1+ to 3+ for the Myśla River, from 1+ do 4+ for the Molnica River, and from 1+ to 5+ for the Wardynka River. The fish from the Molnica River was characterised by the lowest total and standard length (TL, SL), weight, and highest condition. The results of back-calculations and the parameters of von Bertalanffy’s growth equation revealed distinct disproportions in the standard length (mm) in individual age groups (Molnica River: Lt = 54.94 [1 – e−0.68885 (1 − 0.003404)], Myśla River: Lt = 55.39 [1 – e−0.74921 (1 – 0.030962)], Wardynka River: Lt = 66.33 [1 – e−0.69348 (1 – 0.369505)]). The introduction of the topmouth gudgeon occurred in the upper and medium sectors of small rivers, but in subsequent years the species migrated to new sites further downstream and this may have affected the native ichthyofauna.

Abstract

Hydrological modelling and processes using modern hydrological models like SCS Curve Number, HCS, HSPF (Hydrologic Simulation Package-Fortran) and kinematic wave models are widely used nowadays in various researches. But using these modelling in drawing the attention of urban planners for challenges and multiple interactions in heterogeneous urban catchments and water systems is still a shortcoming in water sensitive, planning principle. The art of urban planning and technical implementation using behavioural changes in water responses to urban catchments is the need of present urban planning. The complexities of effects and behavioural changes in the water system or urban catchments and incomplete knowledge of these interactions result in failures of sustainable urban developments. Urban planning needs water sensitive methodology to synchronize soil, water and land cover operational with the population over it. The paper reviews the water sensitive urban planning considering the role of soil in urban planning for water and lands correlations, with the purpose of identifying current limitations and opportunities for future urban planning.

Data availability and simplified methods are still a strong limitation for urban planners. Therefore, urban hydrology is often simplified either as a study of surface runoff over impervious surfaces or hydraulics of piped systems. Hence the paper provides approach and universal solution to forecast the behaviour of urban catchment for urbanization in terms of natural land-water cycles and its application in planning existing or new urban catchments. The methodology consists of observing Urban watershed catchment areas with different soil groups and built-up induction over them. A detailed study of water levels in hydrological wells and runoff pattern for the period of 40 years have provided a linear correlation of soil, roughness, land cover, infiltration, ground water and built upon the basis of soil behaviours. These correlations conclude to make regression equations as the blueprint for future urban planning norms to be followed by the planners, engineers, and hydrologists for planning.

Abstract

The paper presents the results of the analysis concerning the verification of the actual hydraulic load and the load of organic pollutants compared to the conditions designed for 4 household wastewater treatment plants. The researches were carried out in the annual period from May 2015 to April 2016. Based on the conducted analysis, it was found that objects act as underloaded hydraulically and the actual inflow of sewage to the analysed objects during the research period ranged from 7.3% to 32.7% in relation to the inflow assumed in the project. Furthermore, in the case of loading the treatment plant with the load of pollutants expressed as PE, it was fund that the actual PE values were lower than assumed in the project. Therefore, it is important that the sizes of the series of household sewage treatment plants were selected depending on the individual conditions of household, i.e. the number of inhabitants or the amount of consumed water.

Abstract

The treatment of pool water, whether for recreational or sporting purposes, by phytoremediation is widely applied. This work evaluates two artificial vertical flow wetlands, one on a real scale and the other on a laboratory scale, which have been planted with Typha domingensis, for the treatment of pool water in the climatic conditions of the city of Santiago de Cuba. When the hydraulic load applied to the real scale wetland was less than 0.25 m3∙m–2∙d–1, the levels of organic and microbiological contamination in the pool were below the maximum limits allowed by Cuban standards. At a laboratory scale, the presence of vegetation favoured the elimination of nitrogen compounds (nitrates and ammonium) and organic materials (BOD and COD). This behaviour is explained by the presence of processes of assimilation of organic compounds, or by the action of microorganisms associated with the rhizome of plants, which establish a symbiotic mechanism favourable to phytodepuration. The minimum concentration of ammonium obtained in outflow from the laboratory-scale reactor without vegetation reached a value of 2.15 mg∙m–3, which is within the limits allowed by the sanitary regulations.

Abstract

With a flow estimated at 1200 m3∙s−1 and a height of 8 m downstream, the flood that occurred on October 10, 2008 spread along the M’zab River over a length of more than 180 km. Material and human damage is visible, but its effects on the quality of the waters of the alluvial layer remain unknown: this is the purpose of this paper. Samples of groundwater were taken during the period 2005–2012 in 4 oases of the valley. Physicochemical analyses were performed using molecular and flame spectroscopic methods and also volumetric methods on water samples. The results obtained were interpreted using histograms and hydrochemical diagrams, such as the Avignon software (L.H.A) (version 4, 2008). Low effect of flood on the water quality of the alluvial aquifer was manifested by concentrations of magnesium sulphate and calcium chloride. On the other hand, there is an accumulation of salts infiltrated by sewage except for the zone of Bouchen. The diagrams show that there is an improvement in water quality in this area.