Water Quality.

Rivers provide invaluable resources - water for drinking or domestic use, agriculture, habitat for plants and animals, transportation, energy, and recreation.
River water is undoubtedly one of the most important resources on our planet.

Chao Phraya Water quality

Periodic testing by the Pollution Control Department (PCD) and the Ministry of Public Health (MOPH) indicates that there is evidence of heavy pollution in the lower basin of the Chao Phraya River.

The Chao Phraya River exhibited serious organic and bacterial pollution that was a threat to many aquatic species. Similarly, water quality was heavily degraded due to discharges from industrial, domestic and rural inflows. Nitrates and phosphates used in agriculture and washing detergents are also serious contaminants leading to excessive algal or plant growth, which can in turn lead to eutrophication and serious water degradation.


Water quality deteriorates quickly when large volumes of effluent and organic matter enter the river system

The Chao Phraya River and the Thai Way

Rivers and water symbolism are inextricably bound up with Thai village and cultural life. Water is the incubator for the staple foods of rice and fish. It is the principal element in rites of passage and in Thailand 's two most important festivals, Songkran and Loy Kratong. Its soft sensuality pervades the flowing lines of Sukhothai Buddha images, and the sinuous lines and planes that proliferate in wat (monastery) architecture and mural paintings.

The river provides an allegory of the Thai mode of negotiating life's obstacles: it does not confront them, it flows around them. Thais do not lives as independent entities, they blend their lives together, melding through consensus and compromise to preserve a liquid continuity whose surface, while often masking turmoil and contradiction, serves to lubricate social interaction.

- Steve Van Beek, 'The Chao Phya: River in Transition'

Introduction to testing water quality

We can begin to recognise trends and patterns in Chao Phraya water quality by taking physical, chemical, and biological measurements of the river.

In an attempt to devise a system to evaluate water quality for easy comparison between different sites, the National Sanitation Foundation (NSF) created and designed a standard index, called the Water Quality Index (WQI).

The WQI is one of the most widely used of all existing water quality indices. It was developed in 1970 and can be used to measure water quality changes in a particular river over time, compare water quality from different sections of the same river, and even compare water quality of different rivers. The results can be used to determine if a particular stretch of the river is in a good healthy state or not.

To determine the WQI, nine tests are performed. These include measuring dissolved oxygen, faecal coliform bacteria, pH, biochemical oxygen demand, temperature change, phosphates, nitrates, turbidity, and total dissolved solids.


A water sample for WQI analysis is collected (source: riverkeeper.org).

After completing the nine tests, the results are recorded and converted to a unit-less number called the Q-value. Each parameter has its own weighting curve chart for making this conversion. This is the only way that the data from different parameters can be compared.

The data is then processed further by multiplying the Q-values by its weighting factor. The weighting factors allow us to account for the varying levels of significance of the different tests. Finally, these values are added together to obtain the WQI which scores the cleanliness of the water on a scale from 0-100.

Data collection on the barge

On the barge program we regularly collect water samples and perform WQI tests on those samples. Some of this data is presented here, showing some of the monthly average values from the Chao Phraya WQI, from November 2008 to January 2010.

Our data collection is done mainly with students during barge trips throughout the year spanning Thailand’s three seasons: cool season from October to February; hot season from March to May; and rainy season from June to September. At this time we do not have any data for those months missing from these graphs. Error bars show the standard error of the mean.


Fig.1. Chao Phraya average monthly Water Quality Index (WQI) values (Jan 2010-Nov 2008)


Fig.2. Biological parameters of Chao Phraya River water quality - average monthly Q value for Fecal Coliform (FC) and Biological Oxygen Demand (BOD) (Jan 2010-Nov 2008).


Fig.3. Chemical parameters of Chao Phraya River water quality – average monthly Q value for Dissolved Oxygen (DO) and pH (Jan 2010-Nov 2008).


Fig. 4. Chemical parameters of Chao Phraya River water quality – average monthly Q value for Phosphate and Nitrate (Jan 2010-Nov 2008).

What does the data tell us?

The best water quality on average is found in the river during the month of January, and the lowest quality during August. This could be attributed to the level of faecal coliforms, and BOD levels indicating bacteria in the water during August from fig.2. Dissolved oxygen levels are also very low in August which is to be expected since the levels of bacteria in the water were also very high, and require oxygen to respire. Phosphate and nitrate levels tend not to fluctuate significantly during the time scale.

The data gathering continues...


Another group of students enter the barge for another data of data collection and water related discussions on the Chao Phraya upstream of Bangkok.