This project analyzed hydrological conditions in the Kuril area of Dhaka, Bangladesh to help drainage engineers design better storm drains. Students measured precipitation, abstraction, direct runoff and discharge rates during a heavy rainfall event. They calculated the runoff depth, total rainfall, duration and unit hydrograph to understand flow patterns. The analysis found the area has high surface runoff due to impervious surfaces and a drainage outlet near Kuril Canal. The project provided practical experience in basic hydrological concepts to help design drainage structures.

1. NORTH SOUTH UNIVERSITY
GROUP PROJECT
HYGDROLOGY PROJECT

3. Introduction
Hydrology is the study area which relates to water. Precipitation, surface runoff, base flow, flow
rate, average flow, rainfall event, rainfall intensity, etc are explained in hydrology which are
important factors for managing every area’s water resource, sewer system, water usage.
Seasons, natural event, climate change, area type depending on development, population, etc
affect them. The world’s hydrologic system has been changed than before. Therefore
Bangladesh also faces the changes as days goes by. Previously Bangladesh was called temperate
country. But as it’s average temperature has increased and it is becoming warmer it is not
anymore temperate. This important change affects almost everything related to the weather of
Bangladesh. Now we see some major changes and rare event for this reason. Hydrological
research can inform environmental engineering policy and planning.
Background
Our local Ward Commissioner has heard that we are studying at NSU CEE Department and as
we have basic hydrology concepts has asked us to help solve the local drainage problem with the
City Corporation drainage engineers. We took some of our class-mates to meet the drainage
engineers. In the meeting, they ask for our help to determine from where the storm water is
coming and where it is draining out. They also want our help to estimate flow rates for different
rain events that will help them design better drains in your local area. So that is why we made 3
groups (each including 3 members ) and took different areas as our study area and then we
observed a rainfall event. Focusing on that event we took It’s discharge then calculated the direct
runoff.
Study Area Description
The focused area was Kuril, Dhaka. The boundary is within 0.5 km^2. It is residential area and
mostly impervious. The area is higher than It’s neighboring area. So infiltration rate is less than
surface runoff. It is near Bashundhara and Bishwa road. During rainfall event water is hardly
seen stored on the roads. Storm water drains out from different pipes which acts like channels to

4. a particular drainage tunnel. Drainage outlet is in Kuril canal. During rainfall events water rolls
down to the study area increasing flow rate. There are many difficulties in maintaining the
pressure of flow rate results in water log creating trouble. Outflow of the study area is just beside
it. This thing also helps us to understand the flow condition.

5. Kuril area
Focused area 0.5 km^2
Precipitation
Precipitation is any product of the condensation of atmospheric water vapor that falls under
gravity. In this project precipitation is seen for the catchment boundary. There are lots of trees in
study area and these trees hold water. There are many trees seen. So there will be a significant
precipitation value. While the rainfall event was occurring these trees were holding some water.
The usual precipitation rate of that boundary is 3-3.5 mm. Which affects other sectors of
hydrologic concepts. Precipitation is a major component of the water cycle, and is responsible
for depositing the fresh water on the plane.

6. Abstraction
Abstraction is something which holds water but it does not allow water to flow through. This
will lead to some loss of water from runoff. In our study area there are some abstractions. Those
abstractions are there because of breaking the road specially. Adding to that there is constructing
a new flyover, which lead to many new abstractions which were not there in the previous times
and some old abstraction are being filled up. This makes the abstraction value variable with time
and condition.
Methodology
The first thing was to select the area and fix the boundary. The area was taken 0.5 km^2. The
drainage channel are along the left side of the roads. A particular rainfall event on 20th march
2017 left the capital’s traffic in complete chaos as all the major roads along with numerous alleys
got submerged, causing immense sufferings to commuters. The traffic congestions lasted for
longer periods compared to other rainy days as many vehicles went out of order in the middle of
the waterlogged streets, obstructing traffic for hours together. The met office recorded it 40 mm
in 4 hrs.
So, the intensity would be, i= 10mm/hr.
Then the discharge values per time was collected. After that the values were plotted on graph.
With the help of straight line base flow method the Direct Runoff was calculated. The volume
was calculated then from the graph. To get the Ø index the difference between total rainfall and
total direct runoff will be divided by unit hour.
Calculation

7. Average flow
(cumecs) 0 0 8.8 26.3 34.3 28.3 21.2 15.2 10.1 7.7 6.1 2.8 0
Area of DRH = (4*60*60)*(0+0+8.8+26.3+34.3+28.3+21.2+15.2+10.1+7.7+6.1+2.8+0)
= (4*60*60)*160.8
= 2315520 cm
Runoff depth= Runoff volume/Catchment area = 2315520 / (0.5*10^6) = 4.631 cm
Total rainfall= 40 mm= 4cm
Duration= 4hrs
Ø index= (4.631-4)/4 = 0.1578 cm/h
Superposition Method :
Superposition approach for make unit hydrograph for 8 hrs.
0
2
4
6
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10
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-10 0 10 20 30 40 50
Hydrograph
y

8. In the desire to predict the future, research focused on modeling the behavior of technological
innovation and technologies itself. That is where the S-curve of technology emerged. However,
S-curves are used in literature to explain multiple events. Now, to get the unit hydrograph the
values of the rainfall event will be shifted by one unit depth. For 8 hours unit hydrograph we are
advised to take 2 hour unit hydrograph and then draw the S curve.
Unit Hydrograph
0
50
100
150
200
250
0 5 10 15 20 25 30
Direct Runoff
y

9. Conclusion
This work provides a contribution to understanding of the usual amount of rainfall events. This
project helps to understand about precipitation which impacts on other sectors. This experimental
project highlights the basics of delineating a catchment. Estimation of direct runoff hydrograph
for a particular storm event will be practically understood. Unit hydrographs of different
durations can be estimated easily from now and how his unit hydrograph changes over time is
also observed by this. As this project work consists of most of the hydrologic key principles then
designing a drainage structure will be much easier. Because these are the basic thing of
hydrology and the practical work will be very beneficial for further work.
0
5
10
15
20
25
30
35
40
-20 0 20 40 60 80
S Curve
y

10. References
http://www.accuweather.com/en/bd/dhaka/28143/daily-weather-forecast/28143
http://www.timeanddate.com/weather/bangladesh/dhaka/ext
https://en.wikipedia.org/wiki/Hydrograph
https://water watercycleprecipitation.html.usgs.gov/edu/
THE END