Hydrology

Question 1

Synder method

Answer 1

Convert observed storm unit hydrograph for a similar catchment

Question 2

Synder method steps

Answer 2

1. Measure storm length, time of peak flow, and peak flow
2. Calculate Cp and Ct for UH
3. Decide time for new storm then calculate parameters

Question 3

Limitations of synthetic unit hydrograph

Answer 3

• Empirical method: equations derived from prior analysis of data not physics of flowing water
• Event centric: rainfall/runoff considered in isolation from other catchment conditions

Question 4

Control volumes of water storage examples

Answer 4

Snowpack, lakes, groundwater

Question 5

Nash reservoir

Answer 5

Linear reservoirs output becomes input to another reservoir in series

Question 6

Evapotranspiration

Answer 6

Combination of evaporation and plant transpiration

Question 7

Evaporation

Answer 7

Liquid water to water vapour

Question 8

Plant transpiration

Answer 8

Vaporisation of liquid water contained in plants

Question 9

Potential ET

Answer 9

Accounts for evaporation from water bodies or bare soil (Penman)

Question 10

Reference ET

Answer 10

Accounts for two vegetation types (Penman-Monteith)

Question 11

Infiltration

Answer 11

Subsurface flow of water from ground surface into soil

Question 12

What causes infiltration?

Answer 12

Weight of water and capillary suction fuel infiltration, initially rapid then slow

Question 13

What does a high clay percentage mean for infiltration?

Answer 13

High suction head and lower conductivity

Question 14

Green & Ampt method objective

Answer 14

Given a rainfall hyetograph, calculate infiltration and runoff

Question 15

Green & Ampt steps

Answer 15

1. Calculate soil parameters
2. Calculate rate of infiltration
3. If rain, i, less than f all infiltrates, greater than f, only a fraction infiltrates
4. Calculate infiltration update

Question 16

Phi-index

Answer 16

Infiltration rate calculated from the difference between observed rainfall and streamflow

Question 17

Horton

Answer 17

Infiltration is assumed to be an exponentially decaying curve, take measurements to determine parameters

Question 18

Overland flow

Answer 18

During storm events, rain travels over the ground, first in sheets, then in small rills, eventually concentrating in larger gullies and channels

Question 19

Time of concentration

Answer 19

Travel time of longest catchment distance

Question 20

Kinematic wave equation

Answer 20

Describes transport of water: overland as runoff, in a channel, or a stream
Solved using finite differences approximation

Question 21

Muskingum parameter K

Answer 21

Time for flood wave to travel the x distance

Question 22

Muskingum parameter X

Answer 22

Parameter that controls the amount of diffusion

Question 23

Recurrence relation for muskinum method

Answer 23

2KX < t < K

Question 24

Muskingum Cunge method

Answer 24

Approximates wave diffusion using channel properties by discretizing the kinematic wave equation on the x-t plane

Question 25

Numerical stability for Muskingum Cunge method

Answer 25

0 < X < 0.5

Question 26

Selection of parameter X for Muskingum-Cunge method

Answer 26

Calculated as a function of physical properties: length, discharge, width, celerity and channel bottom slope

Question 27

Storage-Indication Method

Answer 27

Method for determining outflow and storage for a linear reservoir

Question 28

Storage-Indication method steps:

Answer 28

1. Determine storage and outflow as a function of height
2. Complete storage-indication calculate
3. Interpolate between table values using rainfall intensity
4. Present updated outflow and storage