Assessment of Stormwater Drainage System in Assosa Town
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Date
2019-01-13
Authors
Abdu, Biru
Journal Title
Journal ISSN
Volume Title
Publisher
Addis Ababa University
Abstract
Urbanization is one of the key factors that contribute to urban flooding, which has caused major
destruction to the environment, public and private buildings and disrupts public life. In
particular, the increase in population and building density influence the change in hydrological
characteristics in urban areas. Conversion of pervious areas into impervious areas increases the
stormwater runoff quantity dramatically.
One way of minimizing urban flooding is to convey stormwater to receiving waters through
stormwater drainage systems, which has been practiced in some parts of Assosa town. In Assosa
town, drainage problem become an issue during rainy season. This study deals with evaluate the
existing stormwater drainage system of Assosa town considering hydraulic and hydrologic
parameters in stormwater model. Despite there are many places in the city facing storm drainage
problem; Stadium-Mazoria, Stadium-Hibret Bank, Sarbetoch-Anuar, Police commissionEthiopia
Hotel
and
Gebriel-Muluwongel
church
are
areas
selected
for
this
study.
This
stormwater
drainage
problem
has
necessitated
use
of
simulation
studies
for
understanding
complexities
related
to
the
urban
flood
management;
so,
the
simulation
has
done
by
Stormwater
Management
Model
(SWMM).
Daily
rainfall
data
is
obtained
from
nearby
Assosa
meteorology
station.
The
selected
extreme
daily
event
was
disaggregated
into
hourly
events using reduction
formula. Thereafter, the EPA SWMM is used to simulate the response of catchment to rainfall
events in which runoff, water depth profile, and outflow hydrograph are obtained. Runoff is also
obtained from rational formula for comparison purpose, and for obtaining design intensity a
frequency analysis is carried out. LID measures (vegetative swales) also performed to evaluate
how LID measures (vegetative swales) influenced urban runoff reduction.
The result of this study shows that the problem in the study area caused by insufficient drainage
operation, minimum drainage pipe size, improper maintenance and clogging of drainage line by
waste material. In addition the results showed that the LID measures are effective in controlling
the surface runoff.
Description
Keywords
Stormwater drainage, mitigation measure, Assosa, SWMM, runoff reduction, Assosa