(Hydro) Full Report

FACULTY OF CIVIL & ENVIRONMENTAL ENGINEERING

DEPARTMENT OF WATER & ENVIRONMENTAL ENGINEERING

WATER ENGINEERING LABORATORY

LABORATORY REPORTSubject Code BFC21103

Code & Experiment Title BASIC HYDROLOGY TEST

Course Code 2 BFF(EX MATRIK/STPM) GROUP B

Experiment Date 4/03/2013

Group

Section 6

Group Members 1.Siu Kok Boon (AF110237)

2.MohamadAdiLqmal Bin Yahya (AF 110085)

3.SyazwanaBtTajulAriffin(AF110194)

4.MohdHazeeqAdhahuddinsa Bin MohdSobri (AF110086)

5.

Lecturer / Instructor/ Tutor Name

MohdShalahuddin Bin Adnan

Submission Date 18/03/13

TOTAL / 100

PART A : BASIC HYDROLOGY

1.0 OBJECTIVE

To identify the relationship between rainfall and runoff.

2.0 INTRODUCTION

The hydrologic cycle is a constant movement of water above, on, and below the earth's

surface. It is a cycle that replenishes ground water supplies. It begins as water vaporizes

into the atmosphere from vegetation, soil, lakes, rivers, snowfields and oceans-a process

called evapotranspiration.

As the water vapor rises it condenses to form clouds that return water to the land through

precipitation: rain, snow, or hail. Precipitation falls on the earth and either percolates into

the soil or flows across the ground. Usually it does both. When precipitation percolates

into the soil it is called infiltration; when it flows across the ground it is called surface

runoff. The amount of precipitation that infiltrates, versus the amount that flows across

the surface, varies depending on factors such as the amount of water already in the soil,

soil composition, vegetation cover and degree of slope.

3.0 THEORY

Runoff is generated by rainstorms and its occurrence and quantity are dependent

on the characeristics of the rainfall event, i.e. intensity, duration and distribution.

The rainfall-runoff process is extremely complex, making it difficult to model

accurately. There are, in addition, other important factors which influence the

runoff generating process like natural surface detention, soil infiltration

characteristics and the drainage pattern formed by natural flow paths. The soil type,

vegetative cover and topography play as important roles. Rainfall and runoff are very

important hydrologic components because of their direct relations with water

resources quantity, flood, streamflow and design of dam and hydraulic structure.

4.0 EQUIPMENT

I. Basic hydrology instrument

II. Stopwatch

III. Raingauge

5.0 PROCEDURE

Case 1: Flat and sandy soil surface profile (without slope)

Case 2: Flat and sandy soil surface with 1:100 slope profile.

a) The rail at side of the catchment area must be adjust to get the slope is zero,

according the requirement for case 1.

b) The steel ruler has been used to flat the sand or used our hand. That can be

more easy method.

c) Set the time according the computer time.

d) Put the rain gauge inside the rail and close the plastic curtains.

e) The pump has been switched on and started the stop watch at the same time.

The time while start of rainfall has been recorded.

f) The discharge and the reading from the rain gauge have been recorded every

30 second (during the rainfall).

g) The pump has been switched off when the peak discharge achieved (after 3

discharge reading with same value obtained) to stop the rainfall. The time

while stop of rainfall has been recorded.

h) At the same time, record the discharge for each 30 second until 1020 second.

i) The procedure has been repeated for case 2 by adjusting the slope reading of

1.8cm since the length of basic hydrology tank measured 180cm.

1.5.0 RESULT AND CALCULATIONS

*All measurement should be recorded in unit of milimeter (mm) and second (s) for purpose of following calculations.

Case 1: Flat and sandy soils surface profile which is without slope

TABLE 6.1 Basic hydrological experiment results

Time, t(s)

Case 1

Water Level (mm)

Discharge (liter/min)

Discharge (m3/s)

Rain Gauge Reading (mm)

30 2 0.0 0 31.8

60 6 0.3 5.00 x 10-6 32.0

90 15 2.5 4.17 x 10-5 35.0

120 18 3.8 6.33 x 10-5 38.0

150 31 5.5 9.17 x 10-5 41.0

180 24 7.9 1.32 x 10-4 44.0

210 25 8.2 1.37 x 10-3 47.0

240 26 9.4 1.57 x 10-4 50.0

270 26 9.4 1.57 x 10-4 53.0

300 27 10.2 1.70 x 10-4 56.0

330 27 10.2 1.70 x 10-4 59.0

360 27 10.2 1.70 x 10-4 62.0

390 29 7.9 1.32 x 10-4 0

420 21 5.5 9.17 x 10-5 0

450 19 4.2 7.00 x 10-5 0

480 18 3.8 6.33 x 10-5 0

510 17 3.1 5.17 x 10-5 0

540 16 2.7 4.50 x 10-5 0

570 15 2.5 4.17 x 10-5 0

600 15 2.5 4.17 x 10-5 0

630 15 2.5 4.17 x 10-5 0

660 13 2.6 2.67 x 10-5 0

690 13 2.6 2.67 x 10-5 0

720 12 1.4 2.33 x 10-5 0

750 12 1.4 2.33 x 10-5 0

780 11 0.9 1.50 x 10-5 0

810 11 0.9 1.50 x 10-5 0

840 10 0.8 1.33 x 10-5 0

870 10 0.8 1.33 x 10-5 0

900 9 0.7 1.17 x 10-5 0

930 8 0.5 8.33 x 10-6 0

960 8 0.5 8.33 x 10-6 0

990 8 0.5 8.33 x 10-6 0

1020 8 0.5 8.33 x 10-6 0

Table 1: Result for Basic Hydrology test Case 1

Case 2: Flat and sandy soils surface with 1:18000 slope profile

Time, t

(s)

Case 2

Water Level

(mm)

Discharge

(liter/min)

Discharge

(m3/s)

Rain Gauge

Reading (mm)

30 4 0.1 1.67 x10-6 0.4

60 5 0.2 3.33 x 10-6 2.8

90 11 4.0 6.67 x 10-5 5.6

120 17 3.1 5.17 x 10-5 8.4

150 22 5.5 9.17 x 10-5 11.0

180 24 7.9 1.32 x 10-4 13.8

210 25 8.2 1.37 x 10-4 16.4

240 26 9.4 1.57 x 10-4 19.2

270 27 10.2 1.70 x 10-4 22.0

300 27 10.2 1.70 x 10-4 25.0

330 27 10.2 1.70 x 10-4 27.8

360 24 7.9 1.32 x 10-4 0

390 21 5.5 9.17 x 10-5 0

420 19 4.2 7.00 x 10-5 0

450 18 3.8 6.33 x 10-5 0

480 18 3.8 6.33 x 10-5 0

510 16 2.7 4.17 x 10-5 0

540 15 2.5 4.17 x 10-5 0

570 15 2.5 4.17 x 10-5 0

600 15 2.5 4.17 x 10-5 0

630 15 2.5 4.17 x 10-5 0

660 15 2.5 4.17 x 10-5 0

Table 2: Result for Basic Hydrology test Case 2

Time, t

(s)

Case 2

Water Level

(mm)

Discharge

(liter/min)

Discharge

(m3/s)

Rain Gauge

Reading (mm)

690 14 2.0 3.33 x 10-5 0

720 13 1.6 2.67 x 10-5 0

750 12 1.4 2.33 x 10-5 0

780 11 0.9 1.50 x 10-5 0

810 11 0.9 1.50 x 10-5 0

840 10 0.8 1.33 x 10-5 0

870 10 0.8 1.33 x 10-5 0

900 10 0.8 1.33 x 10-5 0

930 9 0.7 1.17 x 10-5 0

960 9 0.7 1.17 x 10-5 0

990 9 0.7 1.17 x 10-5 0

1020 8 0.5 8.33 x 10-6 0

1.5.2 CALCULATIONS

*Due to numerous of calculation steps involved for the calculations of flow

rate/discharge (m3/s), hence only few example will be shown here.

For case 1

At time, t = 30s

Discharge1−1=0.0 litremin

0.3=0.001m3

60 s=0 m3/ s

At time, t= 60s


=0.3 0.001 m3

60 s=5.00 x10−6 m3/ s

At time, t= 90s


=2.5 0.001 m3

60 s=4.17 x10−5 m3 /s

For case 2

At time, t = 30s


=0.1 0.001m3

60 s=1.67 x10−6m3/s

At time, t= 60s


=0.2 0.001m3

60 s=3.33 x10−6 m3/s

At time, t= 90s


=4.0 0.001m3

60 s=6.67 x10−5 m3/ s

1.6.0 QUESTIONS

Q1: Graph of discharge (m3/s) versus time (second) graphs for both cases, case 1

& case 2, had been plotted on the following pages.

Q2: From the graph plotted, determine:

a. Time concentration

* Time concentration, tcis the time when the discharge is at its maximum.

Case 1:

Discharge max 1 = 1.70 x 10-4m3/s

Time concentration (1) = 220s ≤ tc≤ 360s

Case 2:

Discharge max 2 = 1.70 x 10-4m3/s

Time concentration (1) = 270s ≤ tc≤ 330s

b. Rainfall duration

* Rainfall duration is the duration from the beginning until the pump is

switched off.

Case 1:

Rainfall Duration (1) = 360s = 6.0 min

Case 2:

Rainfall Duration (2) = 330s = 5.5 min

c. Peak discharge

* Peak discharge is the discharge when the curve of the graph is at its

highest.

Case 1:

Peak Discharge (1)

t =330s; Discharge(1) =1.70 x 10-4m3/s

Case 2:

Peak Discharge (2)

t =300s; Discharge(2) =1.70 x 10-4m3/s

d. Runoff volume

* Runoff volume is the area below the curve (top-half). To find the area of

the top-half of the curve, we count the number of boxes in each area and

times it by(0.0000125 m3/s x 50 seconds).

Case 1:

Runoff Volume (1) = 26 x 0.0000125 m3/s x 50s

= 0.01652 m 3

Case 2:

Runoff Volume (2) = 23 x 0.0000125 m3/s x 50s

= 0.01438 m 3

e. Rainfall intensity

* Rainfall intensity is the ratio of the last rain gauge reading and the time.

Case 1:

Rainfall intensity (1) = 62.0 mm−31.8 mm

360 seconds

= 0.0839 mm/s

Case 2:

Rainfall intensity (2) = 27.8 mm−0.4 mm

330 seconds

= 0.0830 mm/s

Storage volume

* Storage volume is the area below the curve (bottom-half). To find the area

of the bottom-half of the curve, we count the number of boxes in each area

and times it by (0.0000125 m3/s x 50 s).

Case 1:

Storage volume(1) = 73 x 0.0000125 m3/s x 50 s

= 0.04563 m 3

Case 2:

Storage volume (2) = 74 x 0.0000125 m3/s x 50s

= 0.04625 m 3

Q3. Provide a table for all the results obtained from question no. 2 and

make comparisons with case 1 and case 2.

Case 1 Case 2

Time concentration 220s ≤ tc≤ 360s 270s ≤ tc≤ 330s

Rainfall duration 360 sec or 6.0 min 330 sec or 5.50 min

Peak discharge t = 330 seconds,

discharge =1.70 x 10-4m3/s

t = 300 seconds,

discharge =1.70 x 10-

4m3/s

Runoff volume 0.01652 m3 0.01438 m3

Rainfall intensity 0.00839 mm/s 0.00830 mm/s

Storage volume 0.04563 m3 0.04625 m3

From the tabulated table above, it is clearly proven that the comparison

between both diff cases are so obviously, all the calculated values on case 1 is

greatly than the values on case 2, such as Time Concentration, Rainfall

Duration, Peak Discharge, Runoff Volume and Rainfall Intensity, only

exceptional occurred for the storage volume.

1.7.0 DISCUSSION

1.7.1 Based on the experimental result, we had learn that the urbanization process

increase surface runoff, by creating more impervious surface, such as pavement

and buildings, that do not allow water filtrate down through the soil to the aquifer.

It is instead forced directly into stream or stormwater runoff drains, where erosion

and siltation can be major problems, even when flooding is not. Increased runoff

reduce groundwater recharge, thus lowering the water table and making droughts

worse, especially for farmers and others who depend on waters.

1.7.2 From the result of this experiment, after our group discussions, we had found

some factor which might be influence the results. Firstly the slope and catchment

size are capable to affect whole testing results, which is the time concentration,

rainfall duration, peak discharge, runoff volume, rainfall intensity and storage

volume. Based on the plotted graph, the result of time concentration for case 1 is

relatively higher than case 2. This shown that time need for a drop of water to

reach the outlet of catchment from the most remote location in the catchment is

longer on case 2. Hence, the water is exposed for longer duration to bring

infiltration and evaporation process before it reaches to measuring point. It proven

that the sizes of catchment are directly affected the consuming time for the rain to

runoff efficiently or not.

1.7.3 Peak discharge for case 1 and case 2 have the same amount which is 0.0017m3/s.

The storage volume calculated by find the area of the bottom-half of the curve and

the result will multiply 0.000125m3/s x 50s. From the calculation the storage

volume in case 1 is higher than case 2.

1.7.4 Runoff volume was obtained from direct flow in which the direct flow was

obtained by the total volume subtracted by best value (get from the graph). From

the calculation, runoff volume in case 1 was higher compared to case to due to

case 1 have lower slope and size. Rainfall intensity obtained by maximum rain

gauge divided by rainfall duration. From the calculation, the rainfall intensity in

case 1 is 0.075 and case 2 is 0.074 which shows that case 1 is higher than case 2

due to slope different.

1.7.5 Several errors has occurred such as residual error caused by human observation

which will contribute parallax error. This situation happened when taking the

reading of water level which located relatively at lower position. To avoid the

mistake, eyesight of observer has to perpendicular to the scale of the instrument.

The second error occurred is gross error, gross error occurred due to carelessness

such as misreading the measurement.

9.0 CONCLUSION

The objective of this experiment had been achieve, identification the relationship between

rainfall and runoff. Results indicated that each of the parameters representing the

properties of the hydraulic conductivity distribution on each Case 1 and 2 exerts an

important influence on the statistical properties of runoff events.

PART B: INFILTRATION TEST

1.0 OBJECTIVE

To identify the characteristics of the infiltration rate of water into soils in the field.

2.0 INTRODUCTION

Numerous infiltration basins and rain gardens have been installed in the Coon

CreekWatershed District (CCWD) in the last decade. The CCWD is concerned that some

ofthese areas are not performing according to approved permit requirements. The

purposeof this memo is to summarize infiltration tests conducted at three basins and

recommendcorrective action and future design considerations.

3.0 THEORY

The volume of water used during each measured time interval is converted into

an incremental infiltration velocity for both the inner ring and annular space using

the following equations; VIR = ∆VIR / (AIR .∆t) where, VIR is the inner ring incremental

infiltration velocity(cm/hr), ∆VIR is the volume of water used during time interval to

maintain constant head in the inner ring (mL), AIR is the internal area of inner ring (cm2)

and ∆t is the time interval (hour). For the annular space between rings, calculate as

follows; VA = ∆VA / (AA .∆t) where, VA is the annular space incremental

infiltration velocity (cm/hr), ∆VA is the volume of water used during time interval to

maintain constant head in the annular space between the rings (mL), AA is the area of

annular space (cm2) and ∆t is the time interval (hour). The infiltration rate calculated

with the inner ring should be the value used for results if the rates for the inner

ring and annular space differ.The difference in rates is due to divergent flow.

4.0 EQUIPMENT

Two stainless steels rings measure 12” and 24” diameter x 20” high and some other

equipments.

5.0 PROCEDURE

1. Hammer the outer ring at least 2/5 height ring into the soil. The timber was used

toprotect the ring from damage during hammering. Keep the side of the ring

vertical.

2. The inner ring was hammered into the soil or construct an earth bund around the

2/5 height ring to the same height as the ring and place the hessian inside the

infiltrometer to protect the soil surface when pouring in the water. Make sure the

ring in the centre outer ring.

3. Start the test by pouring water into the outer ring until the depth is 10cm. Wait the

water down until the depth is 5cm. Then add the outer or large ring with water

until the depthis 10cm again. At the same time, add water to the space between

the two rings or the ring and the bund to the same depth. Do this quickly.

4. The water in the bund or within the two rings was to prevent a lateral spread of

water from the infiltrometer.

5. Recorded the clock time when the test begins and note the water level on the

measuring rod.

6. After 1-2 minutes, recorded the drop in water level in the inner ring on the

measuring rod and added water to bring the level back to approximately the

original level at the start of the test. Recorded the water level. Maintained the

water level outside the ring similar to that inside.

7. The test was continued until the drop in water level was the same over the same

time interval. The readings were taken frequently (e.g. every 1-2 minutes) at the

beginning of the test until 35 minutes.

6.0 RESULT

Time, t(s)

Inner(mm)

Infiltration Capacity(mm/s)

Infiltration Rate(mm/s)

0 100 0 060 98 2 0.033120 98 2 0.017180 98 2 0.011240 98 2 0.008300 98 2 0.007360 98 2 0.006420 98 2 0.005480 98 2 0.004540 98 2 0.004

Table 3: Infiltration rate experiment results

7.0 DATA ANALYSIS

* Due to numerous of calculation steps involved for the calculations of discharge (m3/s),

thus only few example will be shown here.

At time, t = 0s

infiltrationcapacity=100−100=0mm/s

infiltrationrate=0mm/ s

At time, t= 60s

infiltrationcapacity=100−98=2mm

infiltrationrate=2 mm60 s

=0.033mm /s

At time, t= 120sinfiltrationcapacity=100−98=2 mm


=0.017 mm/s

At time, t= 180s



=0.011mm/s

At time, t= 240s



=0.008mm /s

At time, t= 300s



=0.007 mm/s

1. Two graphs are obtained in this infiltration rate test. Graph of infiltration capacity

versus time and infiltration rate versus time are shown in previous page with its

description.

2. As we know that in dry soil, water infiltrates rapidly due to the great amount of

empty pores. This is called as initial infiltration rate. When more water replaces

the air in the pores of soil, the water from soil surface infiltrates more slowly and

eventually reaches a steady rate. This is called as basic infiltration rate.

3. Three graphs of infiltration rate versus time for three different characteristics of

soils are sketched and studied.

a) Dry soil

From the above sketched graph, we understand that the infiltration rate for

dry soil is high, and it eventually reduces as time passes. This is because dry

soils are porous and there are much empty spaces for water to occupy. And

it will comes to a steady state where infiltration rate no longer decreases or

increases, this is where the pores are all occupied by water or we can called

it saturated.

b) Wet soil

Infiltration rate

Time

Infiltration rate

Time

For wet soil, the value of the initial infiltration rate may slightly smaller than

that of dry soil. The infiltration rate drops tremendously in a very short time

period. This is due to the pores of the soil have already fully filled by the

water. The very first contact with water already covers up all the left over

empty pores. Therefore, the steady state of infiltration rate for wet soil is

faster than that of dry soil.

c) Saturated Soil

As for the saturated soil graph, we can know that the infiltration rate drops

to the minima as the test begins. This is due to the pores of soils have

already filled up with water and there is no more empty pores to fill. We

can study the difference between wet soil and saturated soil where the

steady state of infiltration rate is different. Saturated soil has the lower

steady state of infiltration rate compared to wet soil. This is because there

is no water can infiltrates in saturated soil, while there is still a small

amount of water can infiltrates into the wet soil.

4. The result that we obtained can consider as a wet soil or saturated soil due to the

heavy rain a day before the experiment done. The chosen soil mainly containing

clay that tends to have high potential for runoff and a very slow rate of infiltration

when thoroughly wetted.

Infiltration rate

Time

5. Some errors occur throughout the test that may affect the accuracy of the actual

result which includes:

i. The inner and the outer stainless steel cases may not have the same depth of

hammered down into the ground.

ii. Parallax error that is inevitable when readings are recorded.

iii. The stainless steel cases do not have a permanent or accurate scale that can

affect the actual reading when we are setting the level of the water.

iv. The chosen ground is not complete clear and flat.

6. In order to achieve an accurate result, some precaution is required to practice.

i. Take several reading for each time of interval at different places around the

case and thus get the average.

ii. A flat surface and clear from rubbish as well as grasses is choosing for the test

to avoid inaccuracy of infiltration rate test.

iii. Make sure the ground is dry for 24 hours before the experiment for dry soil is

begins.

iv. Water should pours into the outer case first after hammered down into the soil

for 10-15 millimeters deep.

v. Make sure a correct scale is draw onto the cases with sharp lines that ease the

observant to read.

vi. Make sure the inner and outer stainless steel cases have the same height and

hammer down into the ground using a plain wood to place above it.

9.0 CONCLUSION

In conclusion, we understand the type of soils and its condition can influence the

infiltration rate. Besides, we also understand the concept of infiltration of water into soils

and the factors which influence the infliltration rates. Soil investigation report that

includes the type of soil, soil porosity as well as infiltration rate of the soil is very crucial

before a construction begins because we could know the quality and the hardness of the

soil.

10.0 APPENDIX

10.1 EXPERIMENT PART A

Rain gauge which have been set time firstly before placed in machine

Measuring cylinder to measure the discharge of rain in sandy soil

A tank which rain water runoff head for its symbolic to a river or any watershed area.

10.2 EXPERIMENT PART B

The small ring same level as big ring and it located on the centre of big ring and the surface in the ring is clean.

Mark 10cm and 5cm from surface level on outer ring and 10cm on inner ring.

Set a ruler/measuring device and record infiltration rate on fixed time interval.

11.0 REFERENCE

11.1 Lab sheet of Basic Hydrology and Infiltration Rate Test.

11.2 Nota Pengajaran Hidrologi.

11.3 Internet.

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