The pot experiment was conducted to access the soil microorganisms biomass (physiological method – Substrate Induced Respiration) and emissions of N2O, CO2 and CH4 (photoacoustic infrared detection method), and grasses biomass (weight method). The obtained results of analysed gases were converted to CO2 equivalent. There was no effect of the microorganisms biomass on the N2O emissions. The increase in CO2 emissions was accompanied by an increase in the microorganisms biomass (r = 0.48) under the conditions of the I swath and acid soil reaction, as well as the II swath and neutral reaction ( r = 0.94). On the other hand, in the case of CH4 emission, such a relationship was noted both swaths under the conditions of neutral reaction ( r = 0.51), but a negative correlation ( r = –0.71) was noted for the acid reaction only at the II swath. The increase in the grasses biomass with the increase in the microorganisms biomass was recorded only at the II swath in neutral reaction ( r = 0.91). In a short period of time, with the neutral soil reaction with the increase in the soil microorganisms biomass, an increase in CO2 sequestration and biomass of cultivated grasses was noted. Information on the determination of the microorganisms groups responsible mainly for the transformation of carbon compounds and CO2 and CH4 emissions from the soils of grasslands would be valuable scientifically.
Rainfall forecast information is important for the planning and management of water resources and agricultural activities. Turksvygbult rainfall near the Magoebaskloof Dam (South Africa) has never been modelled and forecasted. Hence, the objective of this study was to forecast its monthly rainfall using the SARIMA model. GReTL and automatic XLSTAT software were used for forecasting. The trend of the long-term rainfall time series (TS) was tested by Mann–Kendall and its stationarity was proved by various unit root tests. The TS data from Oct 1976 to Sept 2015 were used for model training and the remaining data (Oct 2015 to Sept 2018) for validation. Then, all TS (Oct 1976 to Sept 2018) were used for out of sample forecasting. Several SARIMA models were identified using correlograms that were derived from seasonally differentiated TS. Model parameters were derived by the maximum likelihood method. Residual correlogram and Ljung–Box Q tests were used to check the forecast accuracy. Based on minimum Akaike information criteria (AI) value of 5642.69, SARIMA (2, 0, 3) (3, 1, 3) 12 model was developed using GReTL as the best of all models. SARIMA (1, 0, 1) (3, 1, 3) 12, with minimum AI value of 5647.79, was the second-best model among GReTl models. This second model was also the first best automatically selected model by XLSTAT. In conclusion, these two best models can be used by managers for rainfall forecasting and management of water resources and agriculture, and thereby it can contribute to economic growth in the study area. Hence, the developed SARIMA forecasting procedure can be used for forecasting of rainfall and other time series in different areas.
University of Johannesburg, Faculty of Engineering and the Built Environment, Department of Civil Engineering Sciences, PO Box 524, Auckland Park, 2006 Johannesburg, South Africa
Soil erosion has been severely affecting soil and water resources in semi-arid areas like the Mediterranean. In Morocco, this natural process is accelerated by anthropogenic activities, such as unsustainable soil management, overgrazing, and deforestation. With a drainage area of 395,600 ha, the Bouregreg River Watershed extends from the Middle Atlas Range (Jebel Mtourzgane) to the Sidi Mohamed Ben Abdellah (SMBA) dam reservoir south-east of Rabat. Its contrasted eco-geomorphological landscapes make it susceptible to unprecedented soil erosion due to climate change. Resulting changes in erosive dynamics led to huge amounts of solid loads transported to the catchment outlet and, thus, jeopardised the SMBA dam lifespan due to siltation. The research aims to quantify the average annual soil losses in this watershed using the Revised Universal Equation of Soil Losses (RUSLE) within a GIS environment. To highlight shifts in land use/land cover patterns and their effects on erosional severity, we have resorted to remote sensing through two Landsat 8 satellite images captured in 2004 and 2019. The C factor was combined with readily available local data regarding major erosion factors, e.g. rainfall aggressiveness ( R), soil erodibility ( K), topography ( LS), and conservation practices ( P). The helped to map the erosion hazard and determine erosion prone areas within the watershed where appropriate water and conservation measures are to be considered. Accordingly, from 2004 to 2019, average annual soil losses increased from 11.78 to 18.38 t∙ha –1∙y –1, as the watershed area affected by strong erosion (>30 t∙ha –1∙y –1) evolved from 13.57 to 39.39%.
Moulay Ismail University, Faculty of Sciences, Department of Geology, Laboratory of Geoengineering and Environment, Research Group “Water Sciences and Environment Engineering, Zitoune, Meknes BP11201, Morocco
Sidi Mohamed Ben Abdellah University, Faculty of Science and Technology, Functional Ecology and Environmental Engineering Laboratory, Fez, Morocco
Mohammed VI Polytechnic University, International Water Research Institute, Ben Guerir, Morocco
Realising the need for improving irrigation system management, the Bahr Sanhoor Canal (BSC) was selected as a case study, and the effect of covering a reach with a concrete box culvert where the irrigation canal passes through a crowded rural area on the efficiency of the canal system was examined. The field inspection of the canal system revealed multiple problems. Two alternatives for improving irrigation management were introduced. A local alternative was offered by applying a suitable numerical model to enhance the efficiency of the current status of the canal system, the water level upstream of the covered part reached 13.54 m, this solution will lower the water levels by approximately 2 m, which is below the bank levels at an affordable cost. Additionally, it will help to avoid the risk of inundating the adjacent residential area. A sustainable and environmental alternative was considered to offer a new path in which the covered reach passed outside the residential area. This alternative is permanent and sustainable. Although the proposed second path to the right of the residential area is the long-term recommendation and is sustainable, any path of flow to either the left or right of the BSC will be associated with initial high costs. The two proposed alternatives may help decision makers improve the performance of irrigation systems.
In Vietnam, drought has been occurring persistently and in very complicated patterns, with a great impact on the water, energy, and food security nexus and regional development sustainability. The uncertainty surrounding annual water resources in combination with the low reliability of interbasin water transfer (IBWT) operations is the key driver of water deficits in several affected regions. This study aims to assess the impacts of four big IBWT projects in the Central Highlands of Vietnam, based on a proposed matrix of five evaluation criteria to quantify related impacts and to draw out lessons learned for future development of IBWT. The proposed criteria matrix was formulated on the basis of intensive reviews of IBWT assessments worldwide and relevant Vietnamese laws in force. The impacts were analysed and quantified mainly based on assessment of their operational database and water balance simulations for donor and recipient river basins in current and future states. The results show that the studied IBWT projects did not fully satisfy the proposed criteria set, all project did not meet the criteria of benefit sharing and information transparency; noticeably the Don Duong project fulfilled only one from five. Four lessons were determined for proper planning in river basins, flexibility in system design for unknown future, inadequate environmental impact assessment and delay in enactment of policies for IBWT project management. The results provide sound knowledge to revise the existing projects in the Central Highlands and procedures for impact assessment and approval of new IBWT systems.
Institute of Water Resources Planning, Division for Water Resources Planning for South Central and Central Highland Region, 162A Tran Quang Khai, Hoan Kiem, 100000, Hanoi, Vietnam
One of the main causes of damage to weirs regulating the flow of water in canals is local erosion of the bottom and banks. This is mainly due to the excessive kinetic energy of the stream flow and the uneven volumetric distribution of the water flow rate at the end of the strengthening. Due to this, 35–40% of hydraulic structures fail prematurely. The aim of the research was to determine the parameters of the spatial hydraulic jump arising behind the hydrotechnical structure and the rapid expansion of the cross-section. The research showed that the hydraulic jump with a curved cylinder in the plan is a spatial form and not only dissipates the energy of the stream, but also acts as a diffuser. With the stream expansion angle values in the range of 7–10°, a highly turbulent flow remains, which still has high kinetic energy at a distance from the end of the structure. At an angle of 25–27°, the flow is smooth, the velocity distribution is uniform across the width of the channel. In some cases, the forced expansion of the cross-section at the outflow of the weir favours the energy dissipation and uniform flow velocity distribution.
The purpose of the research is to summarise quantitative characteristics and to analyse the spatial distribution of artificial water bodies as anthropogenic fragmentation elements of medium and small rivers within the Dnipropetrovsk Region, Ukraine. The paper uses current data pertaining to existing reservoirs and mineralisation of water in rivers. Comparison included quantitative characteristics, water surface area, and the volume water in ponds and reservoirs. It has been established that although the total ratio was 97% for ponds to 3% for reservoirs, whereas their water surface area 48%, and the volume of water stored only 23% of the total resources. The paper shows the inexpediency and low efficiency of using ponds as water reservoirs feeding small rivers. Increasing the number of ponds in the river basin has a negative impact on the quality of water resources, in particular, by increasing water mineralisation – total dissolved solids ( TDS). Depending on the river, the following indicator of river basin fragmentation has been determined: 6–20 reservoirs per 100 km2 of the river catchment area, and on average 18–36 ponds and reservoirs are built for every 100 km of the river in relation to the length of the hydrographic network. It has shown the regularity of growing water mineralisation due to the fragmentation of rivers by a large number of artificial reservoirs. A strong correlation between regulation and fragmentation of river basins has been established (coefficient of determination R 2 ranges from 0.72 to 0.91). It proves the possibility to estimate the degree of change (increase) of water mineralisation based on the water flow coefficient K w and the river fragmentation coefficient K sfr in the Dnipropetrovsk Region. The paper offers ways of further research for planning and implementation of a water management strategy concerning ecologically safe levels of water use in small and medium-sized river basins.
Dnipro State Agrarian and Economic University, Faculty of Water Management Engineering and Ecology, Serhiia Yefremova St, 25, Dnipro, Dnipropetrovs’ka oblast, 49600, Ukraine
Institute for Nature Management Problems and Ecology, Dnipro, Ukraine
Water scarcity is a phenomenon that is occurring more and more frequently in larger areas of Europe. As a result of drought, there are significant drops in yields. As demand for food continues to rise, it is becoming necessary to bring about a substantial increase in crop production. The best solution to water scarcity appears to be irrigation for crops that are particularly sensitive to drought. Today, many technical solutions are used to supply and distribute water to crops. The optimal solution is drip irrigation, which makes it possible to deliver water directly to the plant root system to save melting freshwater resources. In the article special attention was paid to methods of supplying electricity to power irrigation pumps. The analysis was made for areas with a significant distance between the agricultural land and the urbanised area (which has water and electricity). The authors have selected the parameters of an off-grid photovoltaic mini-hydropower plant with energy storage (with a power of 1.36 kW). An analysis was made of the profitability of such an investment and a comparison with other types of power supply. Based on the performed calculations, a prototype power supply system equipped with photovoltaic panels was made to show the real performance of the proposed system. The tests carried out showed that the irrigation pump will be powered most of the time with a voltage whose parameters will be very close to the nominal ones.
Atmospheric precipitation is the major input to the soil water balance. Its amount, intensity, and temporal distribution have an indubitable influence on soil moisture. The aim of the study (conducted in the years 2010–2013) was to evaluate soil water balance in an apple orchard as determined by daily rainfall. The amount and intensity of rainfall and daily evapotranspiration were measured using an automatic weather station. Changes in soil water content was carried out using capacitance probes placed at a depth of 20, 40 and 60 cm. The most common were single events of rainfall of up to 0.2 mm, while 1.3–3.6 mm rains delivered the greatest amount of water. A significant correlation was found between the amount of daily rainfall and changes in water content of individual soil layers. The 15–45 cm and 15–65 cm layers accumulated the greatest amount of high rainfall. The study showed a significant influence of the initial soil moisture on changes in the water content of the analysed layers of the soil profile. The lower its initial moisture content was, the more rainwater it was able to accumulate.
Quality assessment of shallow groundwater table is very important because it is the water that recharges deeper aquifers and constantly feeds the water levels of our surface streams and wetlands. Continuous monitoring of large number of quality parameters is essential for effective maintenance of water quality through appropriate control measures. However, it is very difficult and laborious task for regular monitoring of all the parameters even if adequate manpower and laboratory facilities are available. Therefore, this study presents the statistical analysis of physico- chemical parameters (pH, EC,TDS, Na, K, Ca, Mg, HCO3, Cl, CO3, SO4, TH, B, F) using correlation and Principal Component Analysis. The statistical analysis of the groundwater quality variables indicated that most of the variables are highly correlated. The strong correlation is an opportunity to develop a regression equation and monitor using few parameters. This provides an easy and rapid method of continuous groundwater quality monitoring. Moreover, groundwater of the area showed significant compositional variation. The compositional variability has implications for the source and origin of groundwater quality in the study area.
University of Johannesburg, Faculty of Engineering and the Built Environment, Department of Civil Engineering Sciences, PO Box 524, Auckland Park, 2006 Johannesburg, South Africa
Previous researchers have been widely studied the equation for calculating the energy dissipation in USBR Type IV, applied in the stilling basin structure as an energy dissipator. However, inefficient energy dissipating basins are commonly found in the field due to the large discharge and high water head, potentially damaging the bottom of the energy dissipating basin and its downstream river. Therefore, an energy dissipator plan fulfilling the safe specifications for the flow behaviour that occurred is required. This study aimed to determine the variation of the energy dissipators and evaluate their effect on the hydraulic jump and energy dissipation. For this purpose, a physical model was undertaken on the USBR Type IV spillway system. The novelty of this experiment showed that combination and modification dissipation features, such as floor elevation, end threshold and riprap lengthening, could effectively dissipate the impact of energy downstream. The final series exhibited a significantly higher Lj/y1 ratio, a favourable condition due to the compaction of the hydraulic jump. There was also a significant increase in the downstream tailwater depth (y2) during the jump formation. Therefore, the final series energy dissipator was better in the stilling basin design for hydraulic jump stability and compaction. The increase in energy dissipation for the final series type was the highest (98.4%) in Q2 and the lowest (84.8%) in Q10 compared to the original series. Therefore, this type can better reduce the cavitation risk damaging to the structure and downstream of the river.
The article presents an assessment of the effects of anthropogenic activities on the quality of water in four streams flowing through a camp based on a combined assessment of environmental impacts and the water quality index. The quantitative and qualitative assessment of environmental impact was made after identifying the anthropogenic activities carried out in the camp. The water quality index ( WQI) was calculated after monitoring seventeen physicochemical and microbiological variables and the Montoya index was applied. The samples were collected during 48 sampling campaigns, organised over the period of six months in eight stations. Two stations were located in each stream, one before and one after it passed through the camp. The results indicated that streams 1, 3, and 4 show a slight deterioration in water quality, affected by anthropogenic activities carried out in the said camp; meanwhile, stream 2 shows an increasing deterioration in water quality. The water quality of the streams before passing through the camp was determined to be between “uncontaminated” and “acceptable”, while after passing through the camp it was classified between “acceptable” and “slightly contaminated”. The results indicated a non-significant difference between the downstream and upstream WQI values for streams 1, 3, and 4; while stream 2 did show a significant difference in the WQI between upstream and downstream; indicating that anthropogenic activities alter the quality of the water.
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