Scientific Insights: Is Bagmati really improving??

Bagmati Clean-up Campaign is on progress since May, 2013 uniting civilians , government authorities and activists to come together to save degrading Bagmati river and its tributaries. The weekly campaign has extracted significant volume wastes from river and has pressurized authorities to come together to solve crosscutting issues on sewerage treatment and river improvement. The campaign is more than three years old and river restoration activities are on progress since then. From this background, many of us feel a question,  "Is Bagmati river water quality improving along with Bagmati Clean Up Campaign??" 

Extracting wastes from Bagmati river(credit: nepalmountainnews)

Campaigners on 192nd week in Bhatkekopool
( credit:Lok Bdr Tandan)

cleaning at Rudramati (Credit: Nirmla KC)

Considering Water quality data from High Powered Committee for Integrated Development of Bagmati river on Dissolved Oxygen, Biological Oxygen Demand(BOD), and Chemical Oxygen Demand, I have tried to analyze BOD in Gokarna and Minbhawan over three years. The samples were collected in same month( Mangsir) in all three years and were analysed following same method. The BOD parameter is widely used to monitor level of organic pollutants in water bodies. Scientifically, it is the amount of oxygen required by aerobic microorganisms to break down organic material in water and a BOD value higher than 2 to 5 mg/l in given water sample is considered polluted river.
 Gokarna

Bagmati Clean Up Campaign and BOD(mg/l)  in  2071, 2072 and 2073 in Gokarna

As shown by decreasing values of BOD over three consecutive years at Gokarna and negative slope of trendline in above graph,  it can be inferred that the organic load in water is decreasing indicating improvement. This certainly allows us to believe Bagmati Clean Up has positive impact in river water quality and this river section can be as pristine as it was before along with continuation of the campaign.
Gokarna section arrives when the river gets out of Shivapuri National Park and gets into human settlement. The river in this stretch receives natural and non natural pollutants. Despite of natural sources of organic material like decaying aquatic organisms and plants, this river stretch being associated with all rituals and life and death culture of Hindu civilization, offering prayers to almighty, cleaning of temples by roadside and cremation cultures input pollutant make this river section.

Peoples connection and Rituals in river bank at Gokarna( credits: picture links in reference below)

Minbhawan

Bagmati Clean Up Campaign and water quality changes in Minbhawan

The BOD values in Minbhawan over three consecutive years 2071, 2072 and 2073 shows decreasing trendline indicating reduction in organic load in water (which is major cause of Bagmati Pollution). The pollutant load was highest(175mg/l) in 2071, and has decreased by 50% (80mg/l) in 2073. The decrease percent is pretty convincing about positive impact of Bagmati Clean Up campaign on water quality.
However, we cannot infer the river as "cleaned" from above analysis because BOD values should be within 5mg/l  to be clean and we have more than 10 times of BOD which is indicator of grave pollution. 
Minbhawan river section lies in core Kathmandu city area and is without life and is merely an open sewage. 

 Minbhawan river section in background (Sujata Karki sampling water at Minbhawan for laboratory analysis)

From this comparision of BOD over 2071, 2072 and 2073, we can infer that organic pollutant load is decreasing in the river water. This should be attributed to ongoing Bagmati Cleaning Campaign and this certainly provides scientific insight and a hope that Bagmati river improvement is on way and it will be achieved.

Jay Bagmati!!

 Picture Sources:

http://www.mountainsoftravelphotos.com/Nepal%20-%20Kathmandu/Best/
http://www.gettyimages.no/detail/photo/temple-guardian-performing-puja-by-the-high-res-stock-photography/148631186
http://www.nepalmountainnews.com/cms/archives/92147