hmp Flashcards
maximum rate of pumpage that can be allowed while ensuring that water-level declines are kept with acceptable limits.
Groundwater yield
maximum pumping rate that can be supplied by a well without lowering the water level in the well below the pump intake
well yield
maximum rate of withdrawal that can be sustained by the complete hydrogeologic system in a groundwater basin without causing unacceptable declines in hydraulic head in the system or causing unacceptable changes to any other component of the hydrologic cycle in the basin
basin yield
maximum rate of withdrawal that can be sustained by an aquifer without causing an unacceptable decline in the hydraulic head in the aquifer
Aquifer yield
Inflow – Outflow =
change in volume
What can observe about groundwater systems?
problems with lab methods
Conducting a pump test (theoretically)
Infrastructure
- At least one pumping well…
o K and transmissivity properties can be determined from single well tests
- At least one observation well
o To determine storage properties
- Multiple observation wells
o Better estimates of storage and transmissivity
o Boundaries
o Anisotropy
- From the test – record the pump rate and know the location of the pumping well, and observation wells.
What properties affect drawdown in an unconfined aquifer?
- Storativity
- Horizontal conductivity
- Vertical conductivity
- Specific yield
Neuman solution – Three phases of unconfined drawdown
- Phase 1: Drawdown is controlled by the Ss of the saturated part of the aquifer
- Phase 2: Drawdown is controlled by the vertical conductivity of the aquifer
- Phase 3: Drawdown is controlled by the specific yield of the aquifer
- This is called the concept of delayed yield
Three Phases System: Solid, Liquid and Gas
- Zone of aeration
- Or zone of unsaturation
- Or vadose zone
is the depression or the rise of a liquid in a small capillary passage tube having small cross sectional area such as openings in the porous materials
Capillarity
is the subsurface layer in which groundwater seeps up from a water table by capillary action to fill pores. Pores at the base of the capillary fringe are filled with water due too tension saturation
Capillary Fringe
results from 2 force: mutual attraction (Cohesion) between water molecules and the molecular attraction (Adhesion) between water and different soil materials
- Capillarity
can provide a mean of direct evaporation of ground water if the water table is close enough to the surface that the capillary fringe reaches the ground surface
- capillary fringe
measuring instrument used to determine water potential (soil moisture tension) in the vadose zone
- Device typically consists of glass or plastic tube with porous ceramic cup and filled with water
- Tensiometer
- Soil moisture at a location varies with changes in the amount of ___and _____
precipitation and evapotranspiration
when soil-moisture content of a layer reaches to the points at which the force of gravity acting on the water = the surface tension, gravity drainage cease.
- Field capacity
the remaining moisture is too tightly bound the soil particles
wilting point
primary method through which water enters an aquifer
- usually topographic high places
- deeper water table
groundwater recharge zone
an area which groundwater is discharged to the land surface, surface water, or atmosphere
- topographic lows
- shallow water table
- spring, seep, lake. or streams
- vegetation: wet soil
- arid: thicker veg cover or salt deposit
groundwater discharge zone
importance of recharge and discharge and time
important to characterize the bedding
pila nadaw edad anang tubig or unsa daw to deep well sa davao huhu
40 years
_____ wetlands, water moves from the wetland into the groundwater
recharging
____ wetlands, water moves from groundwater into the wetland
discharging
a line in a 2 dimensional groundwater flow field such that the total hydraulic head is the same everywhere on the surface
equipotential line
connects points or equal head and thus represents the height of the water table/ or potentiometeric surface of a confined aquifer, above a datum plane
equipotential line
idealized paths followed by particles of water as they move through the aquifer
- indicates recharge and discharge
flow lines
played a role in the settlement pattern of many lands
spring