HYDROLOGY & SURFACE SUPPLIES

Question 1

is located by defining the direction of downhill flow at right angles to the contour lines

Answer 1

The catchment boundary

Question 2

Catchment areas can be determined quickly from ___. These include computer programs that will define a catchment boundary from any gridded data set. An example of which is ___

Answer 2

GIS systems and by the use of digital terrain models; HEC-HMS

Question 3

long streamflow records

Answer 3

Surface water sources

Question 4

long records of changing aquifer water levels

Answer 4

Groundwater sources

Question 5

is the flow of water in streams and other channels

Answer 5

STREAMFLOW

Question 6

is a primary source of water supply for:
○ human consumption
○ agriculture
○ industry
○ ecosystems

Answer 6

STREAMFLOW

Question 7

are crucial to the assessment of the potential yield of a source and in estimating water availability

Answer 7

flow records

Question 8

simplest way to measure stage level

Answer 8

PERMANENT STAFF GAUGE

Question 9

simple and inexpensive but must be read frequently to define the shape of the streamflow hydrograph

Answer 9

PERMANENT STAFF GAUGE

Question 10

is preferred to be constructed to accurately collect data and record charts

Answer 10

stilling well

Question 11

Precipitation is measured with a ___

Answer 11

rain gauge

Question 12

provide a spot sample of rain falling over a catchment area. A minimum density of 1 gauge per 25 km2 is preferred.

Answer 12

rain gauge

Question 13

○ most accurate method
○ a good understanding of the rainfall of a region is need to ensure its reliability

Answer 13

ISOHYETAL MAPS

Question 14

○ most popular method
○ an area around each gauge is obtained by drawing a bisecting perpendicular to the lines joining gauges. The portion of each resulting polygon lying with in the catchment boundary is measured and the rainfall upon each is assumed to equal the gauge reading.

Answer 14

THIESSEN POLYGONS

Question 15

○ The approach is not particularly good for mountainous areas because no account is taken of the effects of altitude on rainfall when deriving the Thiessen coefficients for individual polygons.

Answer 15

THIESSEN POLYGONS

Question 16

key part of the hydrological cycle in that, globally, about 75% of total annual precipitation is returned to the atmosphere by the processes of evaporation and transpiration.

Answer 16

Evaporation

Question 17

The ___ varies with the colour and reflective properties of the surface (the albedo) and with climatic factors. ___ is the main factor for which air temperature is often used as a proxy measurement.

Answer 17

rate of evaporation; Energy from solar radiation

Question 18

is the water used by plants. A small part of this water is
retained in the plant tissue but most passes through the roots to the stem or trunk and is – into the atmosphere through the leaves.

Answer 18

Transpiration

Question 19

The amounts of water used by both processes (Evaporation &
Transpiration) are usually combined and referred to as
“___”.

Answer 19

Evapotranspiration

Question 20

One of the most commonly used instruments for measuring evaporation directly

Answer 20

USA Class A Evaporation Pan

Question 21

It is constructed of galvanized iron or monel metal, 1.21 m in diameter and 255 mm deep, and is set on a standard wooden framework 100 mm above ground level.

Answer 21

USA Class A Evaporation Pan

Question 22

is the amount of water the catchwater
can provide with specified frequency or reliability over a given
period.

Answer 22

yield of the catchwater

Question 23

often originate at an intake on another stream, or
capture flows from streams they cross along their route. Intake
capacity and compensation flow requirements may therefore be
other limiting factors.

Answer 23

Catchwaters

Question 24

is the flow that must be discharged below an
impounding reservoir to maintain the water rights of riparian
owners and other abstractors downstream.

Answer 24

Compensation water

Question 25

is the natural variation of climatic parameters (i.e.
temperature, precipitation, etc.)

Answer 25

Climate variability

Question 26

is when there is a clear trend in the long-term average of
one or more climatic parameters over a long period.

Answer 26

Climate change