NMT ERTH 441 - Groundwater Flow (7 pages)

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Groundwater Flow

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Groundwater Flow

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Pages:
7
School:
New Mexico Institute of Mining and Technology
Course:
Erth 441 - Aquifer Mechanics
Aquifer Mechanics Documents
• 18 pages

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Groundwater Flow Groundwater Balance Change in storage compressibility porosity Recharge Pumping GW Discharge ETGW Underflow Today What causes groundwater flow Mechanical Energy Fluid Potential Energy per unit mass Hydraulic Head h po Reference fluid parcel d v po p z What is the ultimate cause of fluid movement h Energy gradients especially gradients of mechanical energy z Energy per unit weight Composed of Pressure head Elevation head of a fluid parcel p Reference fluid parcel po v d We quantify the mechanical energy of a fluid using the fluid potential Pumping What makes groundwater flow Answer p p p Datum the total mechanical energy per unit mass of fluid Components of Fluid Potential po Pumping Water flows from areas of higher total energy to areas of lower total energy h z z Datum z 0 d depth below water surface z height above datum a point of given total mechanical energy h total height of water above the datum p pressure on parcel omni directional v velocity of parcel one direction The reference fluid parcel is at rest at the datum so it has a fluid potential of zero 1 What forms of energy does water have What is the formula for gravitational potential energy mass m Why is this water flowing z Gravity accel of gravity g Gravitational PE m g z Why does the water rise Pressure Elastic Energy po p po Piston p EE Free surface Seal Seal m p po EE elastic energy pressure water density Piston pushing on water in a sealed tube density increases 2 Elastic Energy p dp po EE m Why is the water spraying up into the air Water is nearly incompressible if a fluid is only slightly compressible p p0 1 1 p dp dp p0 So for water in shallow systems we can say that EE m p m dp p po p 0 What is kinetic energy equal to What drives flow is the sum of these types of energy called the fluid potential The fluid potential is defined as the total mechanical energy per unit mass of water 3 Review What kinds of mechanical energy can a fluid parcel have Pumping Potential Energy

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