Lecture 15: Slope Hydrology and Groundwater

Question 1

What are the four major routes of water flow to the stream channel?

Answer 1

(1) direct precipitation onto the channel,
(2) overland flow to the channel,
(3) interflow or throughflow through the soil zone to the channel,
4) groundwater flow to the channel (baseflow).

Question 2

During dry periods, most of the water in a stream channel is coming from the ______

Answer 2

ground water

Question 3

A ______ is a plot of stream discharge as a function of time. The response of a stream toa precipitation input is influenced by several basin and storm variables, including:

Answer 3

hydrograph

• Basin Size
• Basin Shape
• Basin Relief
• Vegetation Cover in Basin
• Surface Materials in Basin •Storm Intensity influencing the Basin
• Antecedent (Preceding) Soil Moisture Conditions

Question 4

What are the effects of urbanization on infiltration capacity?

Answer 4

There is an overall reduction due to the low infiltration capacities of surfaces such as pavement and rooftops.

Question 5

What are the effects of urbanization on vegetation?

Answer 5

There may be a net removal of vegetation (depending upon the urban area and the pre-urban land use) resulting in less evapotranspiration and interception of precipitation

Question 6

What are the effects of urbanization on drainage systems?

Answer 6

Urban areas have very efficient storm drainage systems to route overland flow from roadways, rooftops, parking lots etc to stream channels through a storm drainage system.

Question 7

______ is the position at which the groundwater (the water in the soil’s pores) is at atmospheric pressure

Answer 7

Unsaturated zone

Question 8

______ is the area in an aquifer, below the water table, in which relatively all pores and fractures are saturated with water.

Answer 8

saturation zone

Question 9

An ______ is an underground layer of water-bearing permeable rock, rock fractures or unconsolidated materials (gravel, sand, or silt).

Answer 9

aquifer

Question 10

The ______ is the upper surface of the zone of saturation. The zone of saturation is where the pores and fractures of the ground are saturated with water.

Answer 10

water table

Question 11

______ is any geological formation that absorbs and holds water but does not transmit it at a sufficient rate to supply springs, wells, etc.

Answer 11

Aquiclude

Question 12

What is withdrawal?

Answer 12

Excessive pumping of groundwater from an aquifer which can cause

Question 13

What are the two effects of withdrawal on a aquifer?

Answer 13

Drawdown (lowering of water level) and subsidence (sinking)

Question 14

______ of aquifers can occur from point sources such as underground storage tanks and landfills, or from the areal sources (non-point sources) such as agricultural fertilizers applied across a large area.

Answer 14

Contamination

Question 15

How can you protect the aquifer from leachate

Answer 15

Proper lining