rainfall runoff

Question 1

a graph that shows how the flow of water in a river changes over time

Answer 1

hydrograph

Question 2

it is the normal flow of the water at the river

Answer 2

base flow

Question 3

the period when the river or stream flow increases due to rainfall

Answer 3

rising limb

Question 4

highest point on the hydrograph when the rate of discharge is greatest

Answer 4

peak discharge

Question 5

the time between the peak precipitation and the peak discharge

Answer 5

lag time

Question 6

when the discharge decreases and the river level falls

Answer 6

falling limb

Question 7

purpose of hydrograph

Answer 7

-provide information about the contributions of precipitation, soil water, and groundwater to stream runoff, as well as hydrological processes and recharge properties of groundwater during rainfall event

Question 8

refers to the process of dividing a streamflow hydrograph into its different components

Answer 8

hydrograph separation

Question 9

this method of baseflow separation is suitable only for individual storm events

Answer 9

straight line method

Question 10

a method that assumes that base flow declines at a constant rate during and after the storm event and uses fixed time intervals after peak flow to distinguish between base flow and direct runoff

Answer 10

fix base method

Question 11

a technique used to separate base flow from direct runoff in a streamflow hydrograph that focuses on analyzing the recession limb of the hydrograph after the peak flow. This method assumes that the decline in flow over time is primarily due to base flow, as direct runoff diminishes quickly after the peak

Answer 11

recession curve method

Question 12

type of hydrographic methods that require hydrologist to perform the method, usually labor intensive and results are subjected to individual hydrologist interpretation

Answer 12

manual method

Question 13

type of hydrographic methods that utilizes computers in order to eliminate result subjectivity and reduce time required for streamflow record analysis

Answer 13

automated method

Question 14

represents the direct runoff resulting from 1 cm of effective rainfall over a drainage area

Answer 14

unit hydrograph

Question 15

assumptions in unit hydrograph

Answer 15

-effective rainfall is uniformly distributed over the entire drainage basin
-the effective rainfall occurs uniformly within its specified duration
-the effective rainfalls of equal duration will produce hydrographs of direct runoff having same or constant time base
-the ordinates of the direct runoff hydrographs having same time base are directly proportional to the total amount of direct runoff given by each hydrograph
-the hydrograph of direct runoff resulting from a given pattern of effective rainfall remain invariable irrespective of its time of occurence

Question 16

limitations of unit hydrograph

Answer 16

-not suitable for large complex basins
-cannot be used in snow-areas
-land use changes or basin alterations reduce its accuracy

Question 17

advantages of unit hydrograph

Answer 17

-requires minimal data
-useful for quick runoff estimation
-can be applied in flood forecasting and hydraulic design

Question 18

is a widely used method for estimation the peak runoff (Q) from a watershed or drainage area during a storm event

Answer 18

rational formula

Question 19

in the rational formula(Q=CIA) what does “I: stands for?

Answer 19

rainfall intensity

Question 20

in rational formula constraints, the drainage area should not be larger that _____ acres for the equation to be accurate

Answer 20

200

Question 21

is a widely used hydrological tool for estimating direct runoff from rainfall. It is based on the concept that a portion of rainfall infiltrates the soil, while remaining portion becomes runoff.

Answer 21

Soil Conservation Service Curve Number Method

Question 22

A numerical value representing the runoff potential of a specific watershed based on soil type, land cover, and antecedent moisture condition.

Answer 22

Curve number

Question 23

In SCS method, total amount of rainfall in a given time period is denoted to as “__”

Answer 23

P

Question 24

In SCS method, “S” is the?

Answer 24

Potential Maximum Retention

Question 25

The maximum amount of water that can be retained in the soil before runoff occurs

Answer 25

Potential Maximum Retention

Question 26

In SCS method, The amount of water retained in the soil before runoff begins is denoted as “___”.

Answer 26

la