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www.uni-hohenheim.de/sfb564Slide 1 <Uplands Symposium/ Land Use and Matter Flows> – Hanoi, 21-23 July 2010
SFB 564
Tracing nutrient fluxes with
turbidity sensorsA time saving alternative for better
understanding fluxes at landscape level
International Symposium "Sustainable Land Use and Rural Development
in Mountainous Regions of Southeast Asia"
21-23 July 2010 Hanoi, Vietnam
J. Slaets, P. Schmitter, A. Bürger, T. Hilger, G. Dercon ,
T.T.L. Ha, N. Lam, T.D.Vien, G. Cadisch
SFB 564 – The Uplands Program
„Sustainable Land Use and Rural Development in Mountainous Regions of Southeast Asia“
www.uni-hohenheim.de/sfb564Slide 2 <Uplands Symposium/ Land Use and Matter Flows> – Hanoi, 21-23 July 2010
SFB 564
1. Background
2. Methodology
3. Preliminary results in Chieng Khoi, Vietnam
4. Application in Mae Sa, Thailand
5. Planned work
Outline
www.uni-hohenheim.de/sfb564Slide 3 <Uplands Symposium/ Land Use and Matter Flows> – Hanoi, 21-23 July 2010
SFB 564 BackgroundSFB 564
1. Introduction – 2. Topic x – 3. Topic y – 4. Topic z – 5. Conclusions
Population pressure and intensified cultivation
on steep slopes severe erosion
Reallocation of nutrients also affects lowlands
Irrigation channel acts as nutrient conveyor
Picture Anna BuergerPicture Petra Schmitter
www.uni-hohenheim.de/sfb564Slide 4 <Uplands Symposium/ Land Use and Matter Flows> – Hanoi, 21-23 July 2010
SFB 564 Rationale of the studySFB 564
Need to understand nutrient fluxes at catchment level:
Automatic water samplers
interesting data but
expensive and
labour intensive
Turbidity sensors
continuous and
cost-effective
alternative?
Picture Petra Schmitter
www.uni-hohenheim.de/sfb564Slide 5 <Uplands Symposium/ Land Use and Matter Flows> – Hanoi, 21-23 July 2010
SFB 564
“The cloudiness or haziness of water,
caused by suspended solids”
How can we measure it?
Optical backscatter technology
Wiper avoids biofouling
What are the units?
Nephalometric Turbidity Units (NTU)
For our sensors 0 to 4000 NTU
What is turbidity?
1. Introduction – 2. Topic x – 3. Topic y – 4. Topic z – 5. Conclusions
IR beams
www.uni-hohenheim.de/sfb564Slide 6 <Uplands Symposium/ Land Use and Matter Flows> – Hanoi, 21-23 July 2010
SFB 564
• Turbidity has been used extensively as a measure for total suspended solids
• Good correlation between turbidity and particle size (Ziegler, 2007)
Proxy for sediment quantity
1. Introduction – 2. Topic x – 3. Topic y – 4. Topic z – 5. Conclusions
iTotal suspended solids (TSS) as a function of (a) turbidity (TNU) and (b) discharge (Q). The relationships are based
on 234 samples collected during all three periods during 2006 and 2007 (adapted from Ziegler, 2007).
www.uni-hohenheim.de/sfb564Slide 7 <Uplands Symposium/ Land Use and Matter Flows> – Hanoi, 21-23 July 2010
SFB 564
• Turbidity has been used extensively as a measure
for total suspended solids
• Good correlation between turbidity and particle
size (Ziegler, 2007)
Hypothesis: Turbidity can be calibrated with total
nitrogen and total organic carbon in the river and
irrigation channel water of Chieng Khoi watershed
Proxy for sediment quality
1. Introduction – 2. Topic x – 3. Topic y – 4. Topic z – 5. Conclusions
www.uni-hohenheim.de/sfb564Slide 8 <Uplands Symposium/ Land Use and Matter Flows> – Hanoi, 21-23 July 2010
SFB 564
Method for turbidity
Calibration, applied in
Vietnam
Sensors suspended in
perforated pvc pipes
Calibrating turbidity sensorsSFB 564
1. Introduction – 2. Topic x – 3. Topic y – 4. Topic z – 5. Conclusions
www.uni-hohenheim.de/sfb564Slide 9 <Uplands Symposium/ Land Use and Matter Flows> – Hanoi, 21-23 July 2010
SFB 564
Method for turbidity
Calibration, applied in
Vietnam
Probe “floating” in water
column, depth below
surface similar for all flow
ranges
Calibrating turbidity sensorsSFB 564
1. Introduction – 2. Topic x – 3. Topic y – 4. Topic z – 5. Conclusions
www.uni-hohenheim.de/sfb564Slide 10 <Uplands Symposium/ Land Use and Matter Flows> – Hanoi, 21-23 July 2010
SFB 564
Chieng Khoi watershed
• Son La province,
Northwest Vietnam
• Climate:Rainy season April - Sept
Annual rainfall 1200 mm
Annual temperature 22 °C
• Soils:Alisols and Luvisols
Study site in Vietnam
1. Introduction – 2. Topic x – 3. Topic y – 4. Topic z – 5. Conclusions
www.uni-hohenheim.de/sfb564Slide 11 <Uplands Symposium/ Land Use and Matter Flows> – Hanoi, 21-23 July 2010
SFB 564
Chieng Khoi watershed
• From composite
swidden agriculture to
monocropping
• Rice paddies fed by
irrigation channel and
draining into river
Study site in Vietnam
1. Introduction – 2. Topic x – 3. Topic y – 4. Topic z – 5. Conclusions
Picture Petra Schmitter
www.uni-hohenheim.de/sfb564Slide 12 <Uplands Symposium/ Land Use and Matter Flows> – Hanoi, 21-23 July 2010
SFB 564
Method for turbidity
Calibration, applied in
Vietnam
Five sensors at strategic
locations in the catchment
SFB 564
1. Introduction – 2. Topic x – 3. Topic y – 4. Topic z – 5. Conclusions
Methodology
Outlet
Reservoir
= Sensor
www.uni-hohenheim.de/sfb564Slide 13 <Uplands Symposium/ Land Use and Matter Flows> – Hanoi, 21-23 July 2010
SFB 564
Taking water samples
Bottles held horizontally in
the direction of the flow
Storm-based sampling,
catching a range of rainfall
intensities and baseflow
MethodologySFB 564
1. Introduction – 2. Topic x – 3. Topic y – 4. Topic z – 5. Conclusions
1 2
3 4
www.uni-hohenheim.de/sfb564Slide 14 <Uplands Symposium/ Land Use and Matter Flows> – Hanoi, 21-23 July 2010
SFB 564
Analyzing water samples
• Total suspended solids (weighing)
• Total (organic) carbon, total nitrogen of both
particulate and dissolved fraction (combustion)
• Texture (Mid Infrared Spectroscopy)
MethodologySFB 564
1. Introduction – 2. Topic x – 3. Topic y – 4. Topic z – 5. Conclusions
www.uni-hohenheim.de/sfb564Slide 15 <Uplands Symposium/ Land Use and Matter Flows> – Hanoi, 21-23 July 2010
SFB 564
Turbidity data
Preliminary resultsSFB 564
1. Introduction – 2. Topic x – 3. Topic y – 4. Topic z – 5. Conclusions
www.uni-hohenheim.de/sfb564Slide 16 <Uplands Symposium/ Land Use and Matter Flows> – Hanoi, 21-23 July 2010
SFB 564
filling
Preliminary resultsSFB 564
1. Introduction – 2. Topic x – 3. Topic y – 4. Topic z – 5. Conclusions
Irrigation channel versus river
www.uni-hohenheim.de/sfb564Slide 17 <Uplands Symposium/ Land Use and Matter Flows> – Hanoi, 21-23 July 2010
SFB 564
Calibration: Example based on dataset of 2008 (4 events)
Preliminary resultsSFB 564
1. Introduction – 2. Topic x – 3. Topic y – 4. Topic z – 5. Conclusions
(Data: Petra
Schmitter)
www.uni-hohenheim.de/sfb564Slide 18 <Uplands Symposium/ Land Use and Matter Flows> – Hanoi, 21-23 July 2010
SFB 564 OutlookSFB 564
1. Introduction – 2. Topic x – 3. Topic y – 4. Topic z – 5. Conclusions
• Turbidity could be a powerful tool in monitoring
nutrient flows on a landscape scale
• Potentially useful in understanding C and N fluxes in
Chieng Khoi catchment, Vietnam
• Different application of turbidity: in site with very
different types of land use, example of Mae Sa,
Thailand
www.uni-hohenheim.de/sfb564Slide 19 <Uplands Symposium/ Land Use and Matter Flows> – Hanoi, 21-23 July 2010
SFB 564
Applying turbidity technology in Mae Sa
Contrast with Vietnam: very different land use
Estimate contributions of different land uses to sediment in
river by monitoring subwatersheds with characterised
land use
Goal: compare the C and N flows at different levels of
land use intensification
Estimating contributions of land use typesSFB 564
1. Introduction – 2. Topic x – 3. Topic y – 4. Topic z – 5. Conclusions
www.uni-hohenheim.de/sfb564Slide 20 <Uplands Symposium/ Land Use and Matter Flows> – Hanoi, 21-23 July 2010
SFB 564
Mae Sa watershed
• Chiang Mai province, Northwest
Thailand
• Climate: Rainy season May – Oct
Annual rainfall 1200 mm
Annual temperature 20 °C
• Soils:Acrisols and
Cambisols
Estimating contributions of land use types
www.uni-hohenheim.de/sfb564Slide 21 <Uplands Symposium/ Land Use and Matter Flows> – Hanoi, 21-23 July 2010
SFB 564
• 70 percent mixed
deciduous and
evergreen forest
Estimating contributions of land use types
• Rest is agricultural production,
dominated by:
vegetables
litchi and flower production
bell pepper cultivated in greenhouses
Land use in Mae Sa
Picture Walaya Sanchan
Picture Walaya Sanchan
www.uni-hohenheim.de/sfb564Slide 22 <Uplands Symposium/ Land Use and Matter Flows> – Hanoi, 21-23 July 2010
SFB 564
• Map mae sa with locations
Location of
installed
turbidity
sensors in
Mae Sa
Outlet
Headwater
Estimating contributions of land use types
Sensor
www.uni-hohenheim.de/sfb564Slide 23 <Uplands Symposium/ Land Use and Matter Flows> – Hanoi, 21-23 July 2010
SFB 564SFB 564
1. Introduction – 2. Topic x – 3. Topic y – 4. Topic z – 5. Conclusions
Planned work
• Establish calibration between turbidity and nutrient
content for Mae Sa and Chieng Khoi
• Use this calibration to monitor nutrient flows in and
out the catchments
• Compare these nutrient flows in the two
catchments with different level of land use
intensification
www.uni-hohenheim.de/sfb564Slide 24 <Uplands Symposium/ Land Use and Matter Flows> – Hanoi, 21-23 July 2010
Thank you for your attention!
Questions?
www.uni-hohenheim.de/sfb564Slide 26 <Uplands Symposium/ Land Use and Matter Flows> – Hanoi, 21-23 July 2010
SFB 564SFB 564
1. Introduction – 2. Topic x – 3. Topic y – 4. Topic z – 5. Conclusions
Considerations
• Turbidity and organic matter: is a calibration
possible?
• Saturation: sensors go up to 4000 NTU