Wetlands as Nature Based Solutions for In Situ Water Purification: The Case of Urban Wetlands, Jimma, Ethiopia
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Date
2018-07
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Addis Ababa University
Abstract
Nature provides valuable solution to tackle different socio- environmental challenges. Wetlands
have a potential to purify water which is mainly influenced by its hydro-system, including
landform setting and the water regime, and different biogeochemical processes. In East Africa,
it’s estimated that approximately 80% of wastewater is discharged untreated or partially treated.
Although there are some studies dealing with the water purifying effect of wetlands, its
application for in-situ water purification is still in its infancy.
The main objective of this study is to determine the effect of natural riverine wetlands to reduce
nutrient and organic pollutant concentrations. And to assess the difference among the study
wetlands.
A cross sectional study on water samples collected from different locations before entering the
wetlands, within the wetlands and after passing through the wetlands, was conducted between
February 5 and February 25, 2017. Data collection check list and standard field protocol were
used to collect data from three urban wetlands (urban downstream wetland and two urban
upstream wetlands). After compiling, data analysis was done using R statistical software.
The results of this study showed a lower concentration of nutrients, and BOD in sites after joining
the wetlands compared to those before the confluence of the wetland. This implied the presence
of pollution attenuation by the wetlands. Among the three wetlands, the one located in the urban
downstream revealed a higher level pollution. The PCA model showed nutrient and pollution
gradient along its axis. Urban downstream wetland was positively correlated with nutrients as
shown in the PCA biplot.
In conclusion, the study revealed the potential of urban wetlands to reduce/ attenuate pollution
from the water which passes through them. However, discharging unlimited amount of nutrients
and other toxicants to wetlands may affect the functioning of wetlands
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Keywords
urban wetlands, Wetlands, situ water, Jimma, Ethiopia