1. The role of cloud forests as water storages in South America
Christof Schneider
Water Security and Climate Change Conference
Session 10 “Nature Based Solutions for WRM”
18-21 September 2017
Cologne, Germany

2. Hydrology of tropical montane cloud forests (TMCF)
Cloud water interception
<5% to >75% of water input (Bruijnzeel et al. 2011)
6% to 60% of water input (Villegas et al. 2008)
Low evapotranspiration (runoff coefficient > 0.8; Strauch et al. 2016)
High water retention capacities of soils

3. Value for water resources management
High quality water
Millions of people depend on water from TMCF
Increased stream flows
Improved water regulation
(cloud affected forests: Mulligan, 2010)

4. Threats to TMCF
Climate change
Land-use change

5. Investment in Watershed Services (IWS)

6. ClimateWIse project

7. WaterGAP3 modelling framework
(Cover of cloud affected forests: Mulligan 2010)

8. First analysis: How large is the impact of cloud water on low flows?
Change in Q90 low flows due to cloud water interception
Sensitivity analysis
5%, 15%, 30% and 45% cloud water input
27 large cities / 118 surface water withdrawal points (CWM, McDonald et al )

9. Impact on river flows
Definition benefit: >5% increase
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10. Impact at water withdrawal points

11. Impact on larger cities

12. Conclusions
Sensitivity analysis: TMCF are important water storages in South America
45,000 to 305,000 km river reaches benefit
3-43% of surface water withdrawal points benefit
TOP5-cities: Sao Paulo, Florianopolis, Quito, Medellin and Cali
Further model developments are required
Calculate cloud water interception
Need to consider seasonal variations and local characteristics
Approach will allow to evaluate:
How important are cloud forests as water storages in South America?
How will cloud water storages change in the future?
What are the impacts on human water supply today and in the future?
Better estimation of future water stress in South America
Support IWS and nature-based solutions

13. Outlook
What is the benefit of combining grey and green based solutions?
Water security
Hydropower generation
Flood control
Carbon sequestration
Protection against landslides and soil erosion
Biodiversity conservation
How can our findings be used in other parts of the world?
41% in the Americas (including Hawaii)
43% in Asia (including northern Australia and Oceania)
16% in Africa
What are the fields of future research?
Quantify ecosystem services
Ecological thresholds for biodiversity loss

14. Thank you for your attention!
contact:
funded by: (German Research Foundation) - FL 396/4-1

15. Next steps Calculate cloud water interception with WaterGAP3
Seasonal variations
Local characteristics: climate, vegetation characteristics, topography
f(air flux, liquid water content, area exposed, interception efficiency)
Improve estimation of TMCF distribution (current and future)
Simulate future impacts
Climate change
Land use change
Socio-economic changes
Identify hotspots of risk for future water stress

16. Literature research Magnitude of cloud water input
7-15% of water input, Kosnipata basin, Peruvian Andes (Clark et al. 2014)
7.4 to 19% of the water input Sierras de las Minas, Guatemala (Holder 2006)
11-30% of water input Kona Hawaii (Brauman et al. 2010, 2012)
30–45% of water input (Dawson, 1998; Holder, 2003; Ritter et al., 2008)
34% of water input, along California coast (Dawson 1998)
37-46% of the water input, leeward Maui (Scholl et al. 2007)
15-30% increase in rainfall (Bruijnzeel and Hamilton 2000)
25-40% increase of water input Canary Islands (Ritter et al. 2008)
<5% to >75% of water input (Bruijnzeel et al. 2011)
Significant impact at local scale
Variations (season, distance to ocean, vegetation structure)