Introduction
An
urban area must have robust water drainage system. The rainwater seeps into the
soil but the excess rainwater goes into the drainage system. With proper
techniques and maintenance of the drainage system, the risk of flood can be
reduced. Otherwise after mild to heavy rainfall, the excess rainwater flows towards
low level areas and causes safety risks. A perfect water drainage system for
any urban area includes small drainage systems in residential and commercial
units for effective water drainage of that urban area as a whole. Water
drainage techniques and processes are discussed here with an example of a house
in England where the drainage system was efficiently applied. In addition to such kinds of small drainage
systems, utilization of the green spaces of an urban area as drainage areas increases
the efficiency of water drainage. Maintaining proper water drainage of an urban
area is discussed with an example of using vegetated areas in China.
Water Drainage System for a Residential
Unit
A
water drainage system was designed and maintained for a house that was reported
by Scholz (2004). The residential unit was in Sandy Lane (Bradford, West
Yorkshire England) and the rain water drainage system was built using the
technique of pond system. The drainage system included a vegetated attenuation
pond and a vegetated infiltration basin. These both were small ponds to store
and maintain the runoff rain water. There was aquatic vegetation in the
infiltration basin to improve its infiltration properties. There was a separate
sedimentation tank in which the rainwater was to be drained. The sedimentation
tank and attenuation pond together could carry up to 1.9m3 of the
runoff water and the additional infiltration basin had a capacity of 1.8m3.
That was a reasonable amount that this system could manage before letting the
runoff water escape. The depth of infiltration basin was 40cm. Two rain gauges
were fitted between attenuation pond and infiltration basin. Infiltration rates
were found out to determine the infiltration properties of the runoff water
that is going into the infiltration basin. Sampling and evaluation of the runoff
water was done weekly. The runoff water was evaluated for temperature, BOD5,
total and suspended solids, water conductivity, turbidity, dissolved oxygen, pH,
many nutrients analysis, and total concentration of elements. After sometime of
this setup, there was algal growth in the infiltration basin which was removed manually
from time to time as required. This algal growth was reduced using barley
straw, zooplankton and tadpoles to improve the workability and life of this
design.
The
benefits of this water drainage system included tackling of the excess
rainwater runoff as well as recycling of the collected water. The attenuation
pond had the water quality that could be used for irrigation and other
recycling purposes.
Application of Ecohydrology Technique for Water Drainage
When
the vegetation areas of a city are used properly as a part of water drainage
system, the rainwater can be controlled to a large extent. Ecohydrology is the system of finding the
solution of problems such as rainwater drainage by utilizing the potentials
that are embedded within the ecosystem itself. Analysis of these potentials and
balancing them with societal objectives can result in cost-effective and capable
water drainage system. In Beijing, China an ecohydrology technique was evaluated
by Li (2012) to tackle the water
drainage and water logging. A vegetated area that was concaved down was used
for rain water infiltration. The concaved down area was at lower elevation than
its surroundings. The concave surface was totally permeable as it was
constructed using porous bricks and porous concrete. That permeable layer was allowing
rainwater infiltration. The design was perfect to absorb rain water that was
running off towards it. Furthermore, along with addressing water drainage the
system was enabling evotranspiration and balancing the water cycle. The
benefits of using this system is that it is aesthetic, creative, cost-effective,
it can be applied to small area, and it offers optimum solution to water
drainage problem.
Conclusion
Due to heavy rainfall and inadequate water drainage
systems urban areas are at risk of casualties, overall economic fall and
traffic jams. Management of rainwater drainage is important for sustainable and
risk free urban areas. When there are good urban designs that are addressing
the problem of water drainage then the quality of life automatically becomes
better. Importance of water drainage is discussed with two examples. One
example is of water drainage system of a house. The rain water that was
collected through that technique could be recycled such as in car wash. The
other example explains the usage of green spaces of a city as a water drainage
system which also provided environmental benefits like evotranspiration. These
both systems if used in combination to one another can give long lasting and
cost-effective results in solving water drainage related issues.
References
Li, C. (2012). Ecohydrology and good urban design for urban storm
water-logging in Beijing, China. Ecohydrology
and hydrobiology, 12(4), 287-300.
Scholz, M.
(2004). Case study: design, operation, maintenance and water quality management
of sustainable storm water ponds for roof runoff. Bioresource Technology, 95, 269–279.
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