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Soils, rocks, and groundwater
Published in Rodrigo Salgado, The Engineering of Foundations, Slopes and Retaining Structures, 2022
In studying water flow in hydraulics, we define the hydraulic head as the amount of energy per unit weight of water. If we consider a water drop at an elevation z (measured with respect to a reference plane called the datum), some of the energy contained in this water drop will be potential energy, which is a result of the elevation z; some will be a pressure-related energy (related to the water pressure u); and some will be kinetic energy (related to the water flow velocity). Mathematically: E=mgz+uV+12mvt2
Hydrogeology
Published in Mohammad Albaji, Introduction to Water Engineering, Hydrology, and Irrigation, 2022
Hydraulic head, also called piezometric head, is a specific measurement of liquid pressure above a vertical datum that is composed of pressure head (ψ) and elevation head (z). The ψ term can take on negative (suction situation) or positive (saturated situation) values. A pressure transducer can measure this parameter. The z term can be measured relative to an arbitrary datum; therefore, hydraulic head can be any value. The change in hydraulic head per length of flow path, termed head gradient, cause water to move from location of high h to location of low h. Among the relevant terms, hydrograph and drawdown can be mentioned. Hydrograph is a record of hydraulic head during a period at a well, and drawdown is the changes of hydraulic head recorded through a pumping test of a well (Figure 5.4).
Hydraulics of Groundwater
Published in Mohammad Karamouz, Azadeh Ahmadi, Masih Akhbari, Groundwater Hydrology, 2020
Mohammad Karamouz, Azadeh Ahmadi, Masih Akhbari
Groundwater in its natural state moves due to hydraulic forces. Because hydraulic head represents the energy of water, groundwater flows from locations of higher head, usually upland areas, to locations of lower head, such as lowland areas, marshes, springs, and rivers. This is a principle to use water-level data obtained from wells, springs, and surface water features to determine the horizontal and vertical direction of groundwater movement and to estimate the rate of groundwater flow. In the subsurface, water occurs in four phases: water vapor from transpiration by plants and direct evaporation from the water table, condensed water absorbed by dry soil particles, water held around soil particles by molecular attraction, and water under the influence of gravity.
Evaluation of solids removal and optimisation of backwashing for an upflow stormwater filtration system utilising novel floating fibrous media
Published in Environmental Technology, 2021
Yuhoon Hwang, Younggyo Seo, Hyowon Kim, Kunwan Roh, Dogun Kim
Our filtration equipment consisted of an influent tank, an SS suspension tank, an inlet chamber, a pretreatment chamber, a media chamber, and an air compressor for air backwashing (Figure 1). Freshwater stored in the raw water tank flowed into the pretreatment chamber through the inlet chamber, where the high concentration SS suspension from the SS suspension tank was mixed with fresh water through a three-way valve using a peristaltic pump. The SS concentration of the twenty-seven (27) influent samples, i.e. nine (9) samples per each three (3) experiments at different filtration velocity, was 168.4 ± 4.4 mg/L, which showed the low variation of the concentration, supporting that homogeneous high SS suspension was supplied to the pretreatment chamber. In addition, no sedimentation of solids was observed in the SS suspension tank, where the suspension was agitated. The mixed influent flowing into the pretreatment chamber flowed upward into the media chamber. The length of the media chamber was 90 cm, and the media depth was 60 cm. All chambers were square, with 10 cm width. A piezometer was installed every 10 cm on the media chamber to enable hydraulic head measurement. The outlet chamber was supplemented to keep a constant difference between the hydraulic heads of the inlet and outlet.
Insight into sea water intrusion due to pumping: a case study of Ernakulam coast, India
Published in ISH Journal of Hydraulic Engineering, 2021
S. K. Pramada, K. P. Minnu, Thendiyath Roshni
Boundary condition applied to flow model is the constant head of 0 m and constant concentration of 35,000 mg/l for sea side. The recharge is also applied to the model to represent interaction with the surface water system. Recharge is assumed as 10% of average rainfall (Bhosale and Kumar 2001). The local and seasonal fluctuations in the natural groundwater recharge cause fluctuations of hydraulic head. Monthly recharge rates in mm/year are used in the model. The average recharge rate is 300 mm/year for the study.
Determination of nodal desirable pressure-heads of water distribution network
Published in Urban Water Journal, 2020
The topography of the WDN is highly undulating in nature. The water flows from higher hydraulic-head to lower hydraulic-head and not from high pressure-head to low pressure-head. Thus, it is essential to account the hydraulic-head during the computation. Finally, desirable pressure-head can be arrived from the desirable hydraulic-head by deducting the nodal elevation.