I love your poster, great maps and GIS related work. Spatial data is hard to manage. I was wondering how you came to your conclusions that swimmers near storm drains were at greater risk to contracting GI. Also super curious, as a beginner sufer myself, about how you found a correlation between surfers and higher chances of the disease when compared to swimmers?
Thanks for browsing through and your thoughtful questions!
QMRA allowed us to “simulate” the gastrointestinal illness (GI) prevalence from the available water quality data. So we came to the conclusion that there is an elevated GI risk near the storm drains after we performed QMRA simulation for 9 different sites (some near storm drains, some away from storm drains). There is an EPA limit of “acceptable GI cases”, but they are often exceeded in simulation, and if we have relatively high fraction of exceedances, that would mean the water is likely to be risky for recreational activities.
We gathered water ingestion data from other people’s published work, and we simulated how much water surfers and swimmers would take in while they are in the water (simulated randomly for 10,000 times). We found out that there are higher risk for surfers than for swimmers at the same site (thus same water quality). This is because surfers were found to ingest more water when out in the water.
Also a good guide for surfers that you probably already know:
– Don’t swim right 3 days after the rain! (Higher tide = good, but also higher GI risk)
Hi Nick Poon and Linda Tseng,
I love your poster, great maps and GIS related work. Spatial data is hard to manage. I was wondering how you came to your conclusions that swimmers near storm drains were at greater risk to contracting GI. Also super curious, as a beginner sufer myself, about how you found a correlation between surfers and higher chances of the disease when compared to swimmers?
Hi Jacob!
Thanks for browsing through and your thoughtful questions!
QMRA allowed us to “simulate” the gastrointestinal illness (GI) prevalence from the available water quality data. So we came to the conclusion that there is an elevated GI risk near the storm drains after we performed QMRA simulation for 9 different sites (some near storm drains, some away from storm drains). There is an EPA limit of “acceptable GI cases”, but they are often exceeded in simulation, and if we have relatively high fraction of exceedances, that would mean the water is likely to be risky for recreational activities.
We gathered water ingestion data from other people’s published work, and we simulated how much water surfers and swimmers would take in while they are in the water (simulated randomly for 10,000 times). We found out that there are higher risk for surfers than for swimmers at the same site (thus same water quality). This is because surfers were found to ingest more water when out in the water.
Also a good guide for surfers that you probably already know:
– Don’t swim right 3 days after the rain! (Higher tide = good, but also higher GI risk)