Quantifying the effect of overland flow on Escherichia coli pulses during floods: use of a tracer-based approach in an erosion-prone tropical catchment

Bacterial pathogens in surface waters threaten human health. The health risk is especially high in developing countries where sanitation systems are often lacking or deficient. Considering twelve flash-flood events sampled from 2011 to 2015 at the Houay Pano catchment, and using Escherichia coli as a fecal indicator bacteria, our objective was to quantify the contributions of both surface runoff and sub-surface flow to the in-stream concentration of E. coli during flood events. We found that in-stream E. coli concentration is high regardless of the contributions of both surface runoff and sub-surface flow to the flood event. However, we measured the highest concentration of E. coli during the flood events that are predominantly driven by surface runoff. This indicates that surface runoff, and causatively soil surface erosion, are the primary drivers of in-stream E. coli contamination. This was further confirmed by the three models applied to each flood event (linear model, partial least square model, and mixing model). The three models showed that the percentage of surface runoff in stream flow was the best predictor of the flood event mean E. coli concentration. The mixing model yielded a Nash-Sutcliffe efficiency of 0.65 and showed that on average, 89% of the in-stream concentration of E. coli resulted from surface runoff, while the overall contribution of surface runoff to the stream flow was 41%.

The paper was published in the Journal of Hydrology. 50 days’ free access is available here.

More news

Articles

Decay Rate of Escherichia coli in a Mountainous Tropical Headwater Wetland

Fecal indicator bacteria like Escherichia coli (E. coli) are widely used to assess water contamination, but their behavior in tropical ecosystems is poorly documented. The main objectives of this study led by Paty Nakhle, PhD student at GET in collaboration with iEES Paris, were to: (i) evaluate decay rates (k) of the total, particle-attached and […]

30.07.2021

Articles

The M-TROPICS CZO releases long-term meteorological, hydrological, sedimentary geochemical, and land use datasets in Cameroon, Lao PDR, and India

The CZO M-TROPICS (Multiscale TROPIcal CatchmentS) investigates the response of tropical catchments to global change based on long-term collection of meteorological, hydrological, sedimentary, geochemical, and land use data in partnership with academic and governmental institutions in various tropical countries. M-TROPICS includes in particular the experimental watersheds of Nyong in Cameroon (1994-), Houay Pano in Lao […]

25.05.2021

Articles

Experimental and modelling evidence of splash effects on manure borne Escherichia coli washoff

In tropical montane South-East Asia, recent changes in land use have induced increased runoff, soil erosion and instream suspended sediment loads. Land use change is also contributing to increased microbial pathogen dissemination and contamination of stream waters. Escherichia coli (E. coli) is frequently used as an indicator of faecal contamination. Field rain simulations were conducted […]

01.03.2021

Search