Water quality of wetlands - Sengkang Floating Wetland

My name is J, and I am an undergraduate studying Environmental Studies in NUS. I will be starting on my honors thesis with my professor Dr. L this coming semester, and it is based on water quality monitoring at constructed wetlands-Sengkang Floatingwetland and Lorong Halus wetland. I have been reading your blog, and it has a lot of wonderful information very useful to me. I am still in the midst of my research before I start fieldwork, and I would like to ask you a few questions.

1. What are the parameters that you have measured in these wetlands before, and is it possible for me to obtain the data of these parameters? Considering the fact that I will be conducting some tests, a comparison with previous records of your data would be very useful.

2. Also, have you done a dissolved carbon analysis of the waters in Singapore/pCO2 analysis?

Thank you very much Sir!

Regards,

J


Hi J,

Glad that you like my posts. And I am happy to see that you are doing some field work at Sengkang Floating Wetland and Lorong Halus Wetland. I feel that not enough is being done to monitor the water quality in our water bodies.

1) I have not done any monitoring at Lorong Halus.

As for Sengkang Floating Wetland, I have conducted a workshop for teachers (1, 2) there in collaboration with PUB. No data was officially documented as that was a training workshop rather than a scientific monitoring session. But I have dug up a photo of the white board when the participants presented their results. See if you can make sense of it.

Figure: Results of water quality monitoring workshop at Sengkang Floating Wetland (11 Nov 2011)

 

 

2) No, I have not a dissolved carbon/ pCO2 analysis. My choice of parameters in water bodies is determined more by the demands of a healthy ecology. (Naturally, if I am working with drinking water or wastewater, the demands and thus parameters will be different.) In my opinion, dissolved carbon/ pCO2 are indirect parameters when it comes to water ecology as they reflect the interactions of water and geology more.  There are already so many parameters to monitor. No need to complicate matters or use up more resources unnecessarily :-)

 

Good luck!

Request for additional information about Punggol and Serangoon Reservoirs

* Parts of the email have been removed for conciseness*

I read with interest about the blog posts which you have made about the newly opened Punggol Reservoir as well as the overall knowledge that you have about water quality monitoring. Given your enthusiasm and expertise in this field, we hope that you will be able to furnish us with some of the details that we require, such as:


- An overall idea of the environmental monitoring process

- The critical parameters which are monitored and their baselines [understand from Greenspan that, for water, this includes: Dissolved Oxygen (DO), Temperature, Turbidity, pH, Conductivity, Chlorophyll-a and Nitrate (NO3)]

- How often/when are samples collected for testing?

- Are there any typical steps taken if the baseline conditions are exceeded?


It would be beneficial if some of the information are specific to the Punggol/Serangoon Reservoirs.

T


Like all other reservoirs on mainland Singapore, Punggol and Serangoon Reservoirs (PSR) are under the purview of PUB. The water quality in these reservoirs is definitely monitored though little detail has been publicised - type of water quality parameters monitored, frequency of monitoring, results and implications of the water quality data.

You may want to try the following reference books to find out more about water quality monitoring

1. Water quality monitoring : a practical guide to the design and implementation of freshwater quality studies and monitoring programmes, edited by Jamie Bartram and Richard Ballance
   I find it useful as it covers the topic comprehensively though it may be slow reading at times. Published on behalf of United Nations Environment Programme, World Health Organization
2. Water quality assessments : a guide to the use of biota, sediments, and water in environmental monitoring (2nd ed), edited by Deborah Chapman
   This is a follow-up to the above title. Again, useful and comprehensive. Published on behalf of UNESCO, United Nations Educational, Scientific, and Cultural Organization, WHO, World Health Organization, UNEP, United Nations Environment Programme

You are indeed right. Dissolved oxygen (DO), temperature, turbidity etc. are relatively easy to measure and hence routinely monitored, probably around once a week (my estimate, feel free to dispute).

I am sure many other parameters are also measured. (Just look at the WHO drinking water guidelines - they have about 200 parameters.) For example, heavy metals, pesticides, oil, volatile organic compounds (VOCs) are good bets. Even the fancy ones like dioxins and radioactivity are possible candidates. Of course, the frequency of monitoring of these chemicals (and radioactivity) depends on the cost and effort of analysis (e.g. expensive lab instruments or tedious lab preparation steps are needed), the likelihood of these chemicals existing in our reservoirs and their impact on health and environment. I won't be surprised if some of the fancy parameters are measured only once a year.

The parameters monitored in our reservoirs probably exceed those given in WHO drinking water guidelines. And PUB is probably going into biological monitoring using macroinvertebrates (bugs). Check out my previous post, Water trends in the next decade, for more information on this topic.

Figure: Serangoon Reservoir with a dam in the distance. The dam serves to separate fresh water in the reservoir from salt water in the sea.

Figure: Punggol Reservoir with Sengkang Floating Wetland in the foreground




For water quality monitoring  (WQM) in our reservoirs, setting up limits for the water quality parameters can be a bit tricky. Do we apply drinking water guidelines to reservoir water? Probably not.

Or do we apply guidelines for aquatic life? Countries such as USA, Canada etc. already have such guidelines. Do we use their guidelines? Again, probably not as the environmental conditions are quite different between Singapore and say, USA. Even if we develop our own guidelines, I am certain every reservoir will be different from one another e.g. geology. How do we factor these differences into our guidelines? Hence, I always believe that baselines for each reservoir will have to be established based on long term WQM. Any deviation from those baselines may then be further investigated. As far as I know, PUB's guidelines (if any) for reservoir water quality have never been publicised.

Water quality monitoring (WQM) workshop for Sengkang Floating Wetland

I have a rare opportunity to conduct a WQM workshop at Sengkang Floating Wetland which lies smack in the Punggol Reservoir. All thanks to PUB for arranging the venue and coordinating the overall workshop!

At the same time, this workshop was funded by the Water Education Fund from FairPrice which also sponsored my book - Your first guide to water quality monitoring in Singapore. Not surprisingly, all the participants were given a copy of the book to help them implement their own WQM programme.

 Figure (courtesy of PUB): Classroom lesson at Anchorvale CC before heading out to the field

Figure: Getting water samples on the floating wetland was made easy with the help of contract workers who happened to be there maintaining the wetland

Figure: In the middle of the floating wetland 

Figure: Participants getting their hands wet and dirty along Punggol Reservoir

Water quality monitoring (WQM) workshop for Sengkang Floating Wetland

Below is a copy of the invitation sent out to MOE teachers.



Dear Educators,


We would like to invite you and your teachers to attend PUB’s Water Quality Monitoring Workshop:

Admission is free and course materials and equipments will be provided. Teachers will also receive a complimentary copy of the book,“ Your First Guide To Water Quality Monitoring in Singapore”, written by Mr Kwok Chen Ko in collaboration with PUB and the NTUC Water Education Fund.

This course is suitable for

 Science teachers, Green Club teachers and teachers interested in environmental or field work

 Teachers who are interested in conducting Water Quality Monitoring with students.

 Any teachers with a passion for the environment!


Trainer
Mr Kwok Chen Ko, Environmental Science lecturer from Singapore Polytechnic.

Course objectives

To introduce importance of water quality in the environment and how water quality monitoring can be carried out. At the end of the course, teachers will be able to:

(a) Appreciate the importance of water quality to the health of the environment.

(b) Explain how several fundamental water quality parameters interact with aquatic life.

(c) Perform field sampling of water.

(d) Perform water analyses in the field and classroom.


Topics covered

1. The types of freshwater systems in Singapore

2. What is water quality?

3. Important water quality parameters

4. The art of water sampling

5. The science of water analysis

6. How to conduct sampling, analysis and collection of water in the field.


Programme outline
The workshop consists of a classroom lecture followed by field work at the nearby Sengkang Floating Wetland.


Time Activity

1:00 PM – 1:30 PM Registration of participants

1:30 PM – 2:30 PM Lecture session:

-Introduction to Water Quality Monitoring in Singapore

- Water quality monitoring parameters

2:30 PM – 4:30 PM Practical session:

-Practical water quality testing exercise at Sengkang Floating Wetland

4:30 PM – 5:30 PM Debriefing session


Admission is limited to the first 20 participants only, so do register by 4 November 2011.

For registration please contact:

Ms Farah’ Ain Niza
Email: Farahain_Niza_Md_Tamren@pub.gov.sg
Tel no : 6731 3274

Singapore latest water attraction - Sengkang Floating Wetland

I finally had the chance to visit this latest water attraction in Singapore. It is not in Sentosa but right in the middle of Punggol Reservoir surrounded by Sengkang, Anchorvale and Punggol housing estates. Publicised since at least 2007, the Sengkang Floating Wetland was finally launched in Nov 2010 by PUB (Public Utilities Board). See PUB press release 07 Nov 2010: Wet and Wild

Figure: PUB poster on "Sengkang Floating Island" (circa 2007)

Figure: A map showing the floating wetland (in green) in the middle of Punggol Reservoir with Anchorvale Community Club in the east and Sengkang Riverside Park in the west

What I found highly useful are the numerous signboards describing the wetland, how it works, the importance of the watershed (covering Punggol, Anchorvale and Sengkang) and the various water plants grown on the wetland itself.

Figure: This is probably the best take-home message from the signboards. It actually shows the delineation of the watersheds (light blue)for all 17 reservoirs (dark blue) in Singapore. Of particular interest are the white areas which represent non-watershed areas i.e. rainwater falling in these areas do not go into any reservoir. A good guess would be about 70% of Singapore's land area is used to collect rainwater. Another interesting point is Changi Airport area is NOT a watershed though the airport itself harvest rainwater for its own water demands. See previous post - How to reduce flooding in Singapore? Harvest more rainwater!

Now, a floating wetland is a kind of constructed wetland but unlike the traditional constructed wetland, it floats on the surface of a water body rather than acts as a container for the water body. Flotation is achieved using a mat of polymeric material which acts as a substrate for water plants to grow and at the same allows the roots to penetrate into the water column. PUB already has several of these floating wetlands (in a smaller scale) in other reservoirs - Lower Seletar, Pandan.
(Update: Sengkang Wetland is based on BioHaven floating islands which have been used in other countries.)

Figure: A mini floating wetland at Pandan Reservoir

Figure: A conventional constructed wetland in Mississippi (http://coastal.msstate.edu/cwres.html)

Constructed (and floating) wetlands are usually designed to clean up the water, improving water quality. The roots and the underside of the polymeric mat tend to accumulate a layer of biofilm containing bacteria, fungi and algae which help in the decomposition of organic matter, nitrogen (e.g. ammonia) and phosphorus compounds. The water plants themselves also can absorb nitrogen and phosphorus, as well as certain heavy metals. Their roots extend into the water column not just for aesthetics but they can also filter and trap sediments. Such a use of plants to clean up the environment is known as phytoremediation. For a more complete discussion, check out this post - Before you write off a plant as a weed, read this

Besides the benefits of cleaning up water and providing a refuge for wildlife, a floating wetland has several advantages over a conventional constructed wetland. It is easily fabricated elsewhere and several units can be joined together to make a large wetland in actual deployment. It can be conveniently placed in existing water bodies without excavation and retrofitting of the existing landscape. If you find lake X has poor water quality, just push a few floating units into the lake. And when they have accomplished their tasks or if problems crop up, they can be conveniently removed as if they were never there in the first place.

However, a key design of constructed is the depth and width of the water body. For the plants (and associated biofilm) to work their magic, the water has to pass through the zone of influence of the roots. A lone floating wetland in the middle of a wide and deep river is not likely to have enough juice to clean up the river. I am not sure how deep the Punggol Reservoir is but if it is like most reservoirs, probably a few metres deep. I doubt the roots can reach to such depths. Also, when I look at the map of the Sengkang Floating
Wetland (see above), it appears exactly like a lonesome patch of greenery surrounded by a swath of blue. Can it really improve the water quality? If yes, how much? (As a side note, I may be conducting water quality monitoring workshops here so perhaps, the water quality data can provide a better picture.)

Anyway, water cleaning efficiency aside, Sengkang Floating Wetland is an excellent showcase of Singapore's focus on active, beautiful and clean water.

Figure: A boardwalk connects the floating wetland to the 2 banks and allows visitors to get up close and personal.

Figure: Viewing the floating wetland and boardwalk from Anchorvale CC. Notice Sengkang flats in the distance