Chapter 4: Hydrologic Cycle and Physiography of Groundwater Habitats

What is the aquatic habitats based on what?

landscape geomorphology and hydrology.

What is Hydrodynamics

the variations in movement and distribution of water.

•Aquatic habitats exists across multiple scales.

How can water return to the atmosphere

Evaporation or transpiration

•Precipitation is either intercepted by vegetation or falls directly on nonvegetated surfaces.•Water that is not evaporated infiltrates the soil.  If the precipitation is heavy enough it will result in sheet flow runoff.

•Water that infiltrates may be stored to saturation or may percolate down into groundwater or underground streams that flows into above ground streams.

What is the movement of water through soils and aquafers?

•Water that percolates into the soil becomes part of the groundwater.

•The vadose zone ranges from dry to wet depending on the amount of infiltration.

•The water table represents the area where the ground is saturated.

•Aquifers may be confined by bedrock or unconsolidated (not confined)

What are the examples of water that spend variable amount of time in aquifers

•Karst aquifers like those found in central Texas have short holding times of weeks or months.

•The Ogallala aquifer of the Midwest has a residence time of thousands to millions of years.

What is the soil types and composition affect rates of infiltration

Soil types

What is porosity?

the volume fraction of pores and fractures.

•As pores get smaller, retention increases.

•As pores get bigger, yield increases.

However there are exceptions to both.

If the sediments is saturated, what are the two components?

•Water that will drain away from the sediment (yield)

•Water that is held in the sediment (retention)

What are groundwater habits

•Aquifers can occur where the soils are homogeneous and flow is continuous or in soils that are heterogeneous and flow is interrupted.

•Aquifers may be confined by a two layers of impenetrable rock.

•Aquifers may be semiconfined by a single layer of impenetrable rock.

•Aquifers can occur in karst (limestone) regions which can form underground rivers and pools. Some areas become shallow enough to cave in forming sinkholes.

What occurs when groundwater impinges on the surface?

A transition zone called hyporheic zone