Effect of land use and hydrological processes on Escherichia coli concentrations in streams of tropical, humid headwater catchments.
Lack of access to clean water and adequate sanitation continues to be a major brake on development. Here we present the results of a 12-month investigation into the dynamics of Escherichia coli, a commonly used indicator of faecal contamination in water supplies, in three small, rural catchments in Laos, Thailand and Vietnam. We show that land use and hydrology are major controlling factors of E. coli concentrations in streamwater and that the relative importance of these two factors varies between the dry and wet seasons. In all three catchments, the highest concentrations were observed during the wet season when storm events and overland flow were highest. However, smaller peaks of E. coli concentration were also observed during the dry season. These latter correspond to periods of intense farming activities and small, episodic rain events. Furthermore, vegetation type, through land use and soil surface crusting, combined with mammalian presence play an important role in determining E. coli loads in the streams. Finally, sampling during stormflow revealed the importance of having appropriate sampling protocols if information on maximum contamination levels is required as grab sampling at a fixed time step may miss important peaks in E. coli numbers.
iEES-Paris (IRD, Sorbonne Universités, UPMC Univ Paris 06, CNRS, INRA, UPEC, Université Paris Diderot), CC237, 4 place Jussieu, 75005, Paris, France.
Emma J
EJ
Rochelle-Newall
Géosciences Environnement Toulouse (GET), UMR 5563 (CNRS-UPS-IRD), 14 avenue Edouard Belin, 31400 Toulouse, France.
Olivier
O
Ribolzi
IRD-iEES-Paris, Department of Agricultural Land Management (DALaM), P.O. Box 4199, Ban Nongviengkham, Xaythany District, Vientiane, Lao PDR.
Marion
M
Viguier
IRD-iEES-Paris, Department of Agricultural Land Management (DALaM), P.O. Box 4199, Ban Nongviengkham, Xaythany District, Vientiane, Lao PDR.
Chanthamousone
C
Thammahacksa
IRD-iEES-Paris, Department of Agricultural Land Management (DALaM), P.O. Box 4199, Ban Nongviengkham, Xaythany District, Vientiane, Lao PDR.
Norbert
N
Silvera
IRD-iEES-Paris, Department of Agricultural Land Management (DALaM), P.O. Box 4199, Ban Nongviengkham, Xaythany District, Vientiane, Lao PDR.
Keooudone
K
Latsachack
Soils and Fertilizers Research Institute (SFRI), Duc Thang Ward, Bac Tu Liem District, Hanoi, Vietnam.
Rinh Pham
RP
Dinh
National Park, Wildlife and Plant Conservation Department (NPD), 61 Phaholyotin Road, Ladyao, Chatuchak, Bangkok 10900, Thailand.
Piyapong
P
Naporn
Soils and Fertilizers Research Institute (SFRI), Duc Thang Ward, Bac Tu Liem District, Hanoi, Vietnam.
Hai Tran
HT
Sy
IRD-iEES-Paris, Department of Agricultural Land Management (DALaM), P.O. Box 4199, Ban Nongviengkham, Xaythany District, Vientiane, Lao PDR.
Bounsamay
B
Soulileuth
National Park, Wildlife and Plant Conservation Department (NPD), 61 Phaholyotin Road, Ladyao, Chatuchak, Bangkok 10900, Thailand.
Nikom
N
Hmaimum
National University of Laos (NUoL), Faculty of Agriculture, Nabong Campus, Ban Paksap Mai, Xaythany District, Vientiane, Lao PDR.
Pem
P
Sisouvanh
iEES-Paris (IRD, Sorbonne Universités, UPMC Univ Paris 06, CNRS, INRA, UPEC, Université Paris Diderot), Centre IRD France-Nord, 32 avenue Henri Varagnat, 93143 Bondy Cedex, France.
Henri
H
Robain
iEES-Paris (IRD, Sorbonne Universités, UPMC Univ Paris 06, CNRS, INRA, UPEC, Université Paris Diderot), Centre IRD France-Nord, 32 avenue Henri Varagnat, 93143 Bondy Cedex, France.
Jean-Louis
JL
Janeau
iEES-Paris (IRD, Sorbonne Universités, UPMC Univ Paris 06, CNRS, INRA, UPEC, Université Paris Diderot), Centre IRD France-Nord, 32 avenue Henri Varagnat, 93143 Bondy Cedex, France.
Christian
C
Valentin
Géosciences Environnement Toulouse (GET), UMR 5563 (CNRS-UPS-IRD), 14 avenue Edouard Belin, 31400 Toulouse, France.
Laurie
L
Boithias
IRD-iEES-Paris, Department of Agricultural Land Management (DALaM), P.O. Box 4199, Ban Nongviengkham, Xaythany District, Vientiane, Lao PDR.
Alain
A
Pierret
D000383:Agriculture; D000818:Animals; D058491:Bacterial Load; D003906:Developing Countries; D004784:Environmental Monitoring; D004926:Escherichia coli / Q000302:isolation & purification*; D005243:Feces / Q000382:microbiology; D006801:Humans; D006813:Humidity; D062070:Hydrology; D007812:Laos; D011891:Rain; D045483:Rivers / Q000382:microbiology*; D012621:Seasons; D013785:Thailand; D014329:Tropical Climate; D014744:Vietnam; D014871:Water Microbiology; D014881:Water Supply