Experimental investigation of Microcystis aeruginosa cyanobacteria thickening to obtain a biomass for the energy production

The purpose of the presented research is to analyse possible methods of thickening of the Microcystis aeruginosa (Kützing) Kützing cyanobacteria using the obtained concentrate as a biomass for the production of energy carriers and biologically valuable substances. Method of cyanobacteria thickening under the action of electric current and in the electric field, as well as the method of coagulation–flocculation and gravity thickening, was experimentally investigated in labscale conditions. Electrical methods didn't show positive results for the Microcystis aeruginosa thickening, despite the reports of their potential efficiency in a number of previous studies. The high efficiency of the method of coagulation– flocculation and gravity thickening of Microcystis aeruginosa suspensions was obtained. The optimum concentrations of industrial polymeric coagulants and flocculants for the thickening of Microcystis aeruginosa suspensions were defined in the range of about 10 ppm for the coagulants and about 1 ppm for the flocculants. Negative effect of the previous cavitational treatment of the diluted suspensions of Microcystis aeruginosa on the effectiveness of the coagulation–flocculation and gravitational thickening was confirmed experimentally. Hydrodynamic cavitation should be recommended to use after the thickening as the next step of processing of concentrated suspensions of Microcystis aeruginosa to achieve maximum extraction of energy carriers and biologically valuable substances.

Hydrological modeling using the SWAT model based on two types of data from the watershed of Beni Haroun dam, Algeria

The dam of Beni Haroun is the largest in Algeria, and its transfer structures feed seven provinces (wilayas) in the eastern part of Algeria. Due to its importance in the region, it has now become urgent to study its watershed as well as all the parameters that can influence the water and solid intakes that come into the dam. The Soil and Water Assessment Tool (SWAT) model is used to quantify the water yields and identify the vulnerable spots using two scenarios. The first one uses worldwide data (GlobCover and HWSD), and the second one employs remote sensing and digital soil mapping in order to determine the most suitable data to obtain the best results. The SWAT model can be used to reproduce the hydrological cycle within the watershed. Concerning the first scenario, during the calibration period, R2 was found between 0.45 and 0.69, and the Nash–Sutcliffe efficiency (NSE) coefficient was within the interval from 0.63 to 0.80; in the validation period, R2 lied between 0.47 and 0.59, and the NSE coefficient ranged from 0.58 to 0.64. As for the second scenario, during the calibration period, R2 was between 0.60 and 0.66, and the NSE coefficient was between 0.55 and 0.75; however, during the validation period, R2 was in the interval from 0.56 to 0.70, and the NSE coefficient within the range 0.64–0.70. These findings indicate that the data obtained using remote sensing and digital soil mapping provide a better representation of the watershed and give a better hydrological modelling.

Identifying the pool-point bar location based on experimental investigation

Morphological relationships of meander evolution in terms of hydraulic and geometric characteristics are essential for river management. In present study, an experimental based study of meander evolution was employed to develop a prediction formula for identifying the pool-point bar location by using the dimensional analysis technique and multiple nonlinear regressions. Through the experimental work on a race of the non-uniform river sand, a set of experimental runs have been carried out through combining different hydraulic and geometric parameters to produce different empirical conditions that have a direct impact on the pool-point bar location. Based on the experimental observations and measurements, the variation in pool–point bar locations could be interpreted to that the hydraulic and morphologic properties through the meander evolution were varied during the time causes the variations in the patterns of the pool-point bar formations accordingly. The developed formula was verified by using another set of the experimental data and tested with three statistical indicators. The predicted results indicated that the proposed formula had high reliability for practical estimation of the pool-point bar location. This reliability was tested by the statistical indicators, where the less values have been resulted for bias and mean absolute error (MAE), 0.0004 and 0.0110 respectively, whereas the higher values 0.935 and 0.930 are achieved for the Nash–Sutcliffe efficiency (NSE) and the determination coefficient R2, respectively.

Drought sensitivity characteristics and relationships between drought indices over Upper Blue Nile basin

Drought is an extreme event that causes great economic and environmental damage. The main objective of this study is to evaluate sensitivity, characterization and propagation of drought in the Upper Blue Nile. Drought indices: standardized precipitation index (SPI) and the recently developed standardized reconnaissance drought index (RDIst) are applied for five weather stations from 1980 to 2015 to evaluate RDIst applicability in the Upper Blue Nile. From our analysis both SPI and RDIst applied for 3-, 6-, 12 month of time scales follow the same trend, but in some time steps the RDIst varies with smaller amplitude than SPI. The severity and longer duration of drought compared with others periods of meteorological drought is found in the years 1984, 2002, 2009, 2015 including five weather stations and entire Upper Blue Nile. For drought relationships the correlation analysis is made across the time scales to evaluate the relationship between meteorological drought (SPI), soil moisture drought (SMI), and hydrological drought (SRI). We found that the correlation between three indices (SPI, SMI and SRI) at different time scales the 24-month time scale is dominant and are given by 0.82, 0.63 and 0.56.

Effect of water scarcity on households’ livelihoods in Iwoye-Ketu Area of Ogun State, Nigeria

Water is an essential commodity which affects life and livelihoods in the universe. This study examined perceived effect of water scarcity on livelihoods in Iwoye-Ketu, Ogun State. Random sampling was used to select 80 rural households and water samples for the study. Data collected were analysed using descriptive, inferential and laboratory analyses. Findings showed that the mean age of respondents was 38 years with an average household size of four persons. The major sources of water were boreholes (97.5%) and rainwater (90.0%), the average trekking time to the water source was 24 minutes and the households requires an average of 162 litres of water per day. Water analysis’ result showed that the water has pH (6.87), total dissolved solids (0.175 mg∙dm−3), temperature (29.9°C) and turbidity (0.6 FTU). The major causes of water scarcity include insufficient rainfall (97.5%), increased sunlight intensity (97.5%), pollution of water sources (95.0%) and increased population (93.8%). About 60% of them perceived water scarcity to have a negative effect on their livelihoods. Correlation analysis shows that there is a significant relationship between usage of water (r = 0.370, p < 0.01) and perceived effect of water scarcity. It was concluded that water available for household use is not sufficient, although it is safe but contain some elements which are not of World Health Organization standard for good potable water. It is recommended that the community should build a hub for water collection and distribution close to the village centre and the government should provide water infrastructures to increase the supply of potable water.

Geospatial and socioeconomic traits encumbering tractorisation of farmland among crop farmers in Ogun State, Nigeria

The objective of this study was to ascertain the socioeconomic and geospatial traits responsible for little or no usage of tractors for land clearing and cultivation by rural farmers in Ogun State, Nigeria. Data were obtained on the study objectives with use of interview guide, in-depth discussion and field observation a randomly selected 247 arable crop farmers. The obtained data were subjected to frequency count and binominal analysis of variance. Results showed factors such as farmers’ inability to afford tractor acquisition and/or hire tractors services (prop = 1.00, p < 0.05) as the major economic traits encumbering tractor usage for land preparation. The social traits included inadequate available of tractors to serve the farmers (prop = 0.76, p < 0.05), and farmers’ apprehension of possible destruction of soil structure and/or farm land (prop = 0.64, p < 0.05) as a result of tractor usage for land preparation. The geospatial traits were stump/tree distribution (prop = 0.97, p < 0.05) and land fragmentation (prop = 0.92, p < 0.05). It was thus concluded that both socioeconomic and farm geospatial traits interactively encumbered farm tractorisation in the study area. It was recommended that farmers should be supported technically and financially by stakeholders in agro-development so as to enable them to afford tractor usage for land cultivation.

Decision-making models using the Analytical Hierarchy Process in the urgency of land consolidation works

Poland is characterized by a number of factors which adversely affect the agricultural economy, so this paper will aim to present the possibilities of using multi-criteria decision-making methods of Analytical Hierarchy Process (AHP) in the analysis of the spatial structure of rural areas. AHP is a widely used tool for making complex decisions based on a large number of criteria, such as, for example, land consolidation works on fragmented agricultural land. The first step is to formulate the decision-making process, then the assessment criteria and the solution variants guided by expert knowledge are determined.A ranking, according to which the order of land consolidation and land exchange works in the studied area should be determined, will be defined by using decision-making models of the AHP method. The basis for calculations will be the weights received for the factors/parameters defined for the five thematic groups. Calculations for individual villages will be made, and then the obtained results will allow creating a ranking for the studied commune, allowing for the effective (in terms of economic and socio-economic) spending of funds for this purpose. The presented method can be successfully used to conduct analogous analyses for any area.

Characterization of the climatic drought indices application to the Mellah catchment, North-East of Algeria

Drought is one of the important phenomena resulting from variability and climate change. It has negative effects on all economic, agricultural and social sectors. The objective of this study is to rapidly detect climate dryness situations on an annual scale at the Mellah catchment (Northeast Algeria) for periods ranging from 31 years through the calculation of: the standardized precipitation index (SPI), the standardized Streamflow index (SSFI), the standardized temperature index (STI). Calculations made it possible to locate periods of drought more precisely by their intensity, duration and frequency, and detect years of breaks using the tests of Pettitt, rang, Lee and Heghinian, Hubert and Buishand. The use of the statistical tests for the rainfall series analyzed show all breaks, the majority of which are in 1996/1997 and 2001/2002. For the temperatures the breaks are situated in 1980/1981.

Spatiotemporal evolution of land surface temperature of Lake Oubeira catchment, northeastern Algeria

The difficulties of access and detailed measurements of land surface temperature (LST) and water surface temperature (WST) especially in wetlands made the use of remote sensing data as one of the sources and techniques to estimate many climate elements including surface temperature and surface emissivity (ɛ). This study aims to estimate the surface temperature of the wetland of Lake Oubeira located in northeastern Algeria and their spatiotemporal evolution in both land and water. Landsat OLI-TIRS images in two dates (April and September 2016) obtained from the USGS have been used in this work, and forms the basis of a series of operations to obtain the final LST: development of the normalized difference vegetation index (NDVI), conversion of the digital number (DN) of the thermal infrared band (TIR) into spectral radiance as well as the calculation of the effective luminosity temperature of the sensor from the spectral radiation and surface emissivity (ɛ).The results show that the LST varies in space and time (from 16 to 31°C in April and from 24 to 41°C in September). This implies that the absorption of the equilibrium temperature at land cover depends on the optical properties of the surface, which are essentially determined by its water content, colour and morphology. At the same time, the water surface is the lowest land cover temperature, which also has a spatial variation (from 19 to 25°C in April and from 26 to 34.5°C in September) induced by atmospheric temperature, wind direction and speed and the depth of the lake.

Limiting horizontal water filtration using drainage-screened modules

In the context of climate change, it is important to minimize the changes that are introduced in the territory adjacent to the object of human economic activity. In some cases, this can be done with the help of drainage-screened modules – an anti-filtration screen that redistributes the zone of influence of the drain placed near it. As a result, the drain regulates to a greater extent the zone of human economic activity (drainage system, tailing dump, populated area, etc.) and to a lesser extent lowers the level of groundwater in the adjacent territory. The use of drainage-screened modules in tailing farms, for the organized storage of mineral waste of enterprises makes it possible to increase the filtration stability of dike, ensuring the uniform operation of the tailing dams, as well as reliable removal of intercepted groundwater. This is achieved because in the tailing farm the dikes are intensified by drainage-screened modules. Water, filtered through the body of the dike and under it, is intercepted by a drain. A part of the filtration flow, which is not intercepted by the drain, is stopped by the anti-filtration screen.