Ecohydrology and Water Resources of Monteverde, Costa Rica: Implications of a Changing Climate

Transcription

1 University of Massachusetts Amherst Amherst Water Resources Research Center Conferences Water Resources Research Center Ecohydrology and Water Resources of Monteverde, Costa Rica: Implications of a Changing Climate Andrew J. Guswa Amy L. Rhodes Follow this and additional works at: Guswa, Andrew J. and Rhodes, Amy L., "Ecohydrology and Water Resources of Monteverde, Costa Rica: Implications of a Changing Climate " (2007). Water Resources Research Center Conferences. 27. Retrieved from This is brought to you for free and open access by the Water Resources Research Center at ScholarWorks@UMass Amherst. It has been accepted for inclusion in Water Resources Research Center Conferences by an authorized administrator of ScholarWorks@UMass Amherst. For more information, please contact scholarworks@library.umass.edu.

2 Ecohydrology and Water Resources of Monteverde, Costa Rica: Implications of a Changing Climate Andrew J. Guswa Picker Engineering Program Amy L. Rhodes Department of Geology Smith College

3 Collaborators Evelyn Kim 02 Sarah Katchpole 02 Annalee Wells 02 Irma Torres-Leon 05 Silvia Newell 04 Aruna Sarma 04 Ilona Johnson 06 Mai Kobayashi 06 Liz Koenig 05 June Yeung 07 Merilie Reynolds 08 Linda Sorto 07 June, Mai, Merilie, and Ilona during the summer-2005 campaign The Monteverde Institute Alan Pounds, Monteverde, Costa Rica Martha Scholl, USGS, Reston, VA Achim Hager, Univ. of Gottingen Simon Poulson, UNR, Isotope Lab Ann Pufall, Aqueous Geochemistry Lab Jon Caris, Spatial Analysis Lab

4 Costa Rica Monteverde lies on the Pacific side of the continental divide at N, W at an elevation of 1500 m.

5 Monteverde: Regional Topography Lac Arenal Volcan Arenal Monteverde

6 Views on next slides Monteverde

7 Monteverde Landscape Looking NE from the road to Monteverde June Monteverde Rio San Luis Rio Guacimal RG100

8 Monteverde Landscape Looking NE from the road to Monteverde April Monteverde Rio San Luis Rio Guacimal RG100

9 Why study Monteverde? Cloud Forest Unusual environment in which forests are continually bathed in clouds and fog. Biodiversity Home to many endemic species, including epiphytes, amphibians, and birds. Pounds et al. report anuran crashes, including Golden Toad and Harlequin Frog. Water Resources and Ecotourism Monteverde Cloud Forest Preserve brings approx. 60,000 visitors per year (200,000 to the area). Potential vulnerability Global climate change (Still et al., 1999) and lowland deforestation (Lawton et al., 2001) have the potential to reduce cloud formation.

10 Cloud Forest Cloud Forest Steve Tilley

11 Elizabeth Koenig 05 Biodiversity

12 Biodiversity

13 Why study Monteverde? Cloud Forest Unusual environment in which forests are continually bathed in clouds and fog. Biodiversity Home to many endemic species, including epiphytes, amphibians, and birds. Pounds et al. report anuran crashes, including Golden Toad and Harlequin Frog. Water Resources and Ecotourism Monteverde Cloud Forest Preserve brings approx. 60,000 visitors per year (200,000 to the area). Potential vulnerability Global climate change (Still et al., 1999) and lowland deforestation (Lawton et al., 2001) have the potential to reduce cloud formation.

14 Water Supply 1 l/s will support about people

15 Supply is out of phase with demand Precipitation [mm] Jan Mar May Jul Sep Nov Preserve Visitors Annual Average = 2700 mm Amherst, MA = 1100 mm

16 Meteorology, 2006 ET and Radiation [mm/day] Daily Precipitation [mm] Measurements made at the Monteverde Institute, Monteverde, Costa Rica. Data are available at mm/hr 0 Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Temperature [ o C]

17 Watersheds of Interest

18 Chemistry Summary Adapted from Rhodes, et al., in press.

19 QC 200 Streamflow,, Watershed area = 1.7 km l/s 5 mm/day Daily Precipitation [mm] 50 Q = 37 l/s 1000 Discharge [l/s] Jan 0 Feb Mar Apr May Jun Jul Aug 0 How important is the dry-season precipitation?

20 Stable Isotopes of Water 2 H 1 H 16 O 1 H 1 H 18 O δ 18 O = ( ) ( ) O O O sample O ( ) 18 O 16 O VSMOW VSMOW 1000 Delta values for terrestrial liquid waters are usually negative, and more negative values indicate lower concentrations of the heavier isotopes. Isotope concentrations are affected by evaporation and condensation. The shift is a function of temperature and relative humidity. When vapor condenses in a cloud, the heaviest isotopes condense and rain-out first. Thus, rainfall becomes progressively lighter as it continues. Transpiration does not cause a fractionation because roots do not discriminate among isotopes.

21 Stable Isotopes in Precipitation June 2003 April 2005 Adapted from Rhodes et al., 2006

22 Adapted from Rhodes et al., 2006 Isotopic composition exhibits seasonal variation.

23 Can we trace the precipitation signal to the streams? Adapted from Guswa et al., in press δ 18 O = -2.2 δ 2 H = -3 δ 18 O = -8.3 δ 2 H = -54

24 Spatial variation in δ18 O ( )( Dry-Season Rain: δ 18 O = -2.2 Wet-Season Rain: δ 18 O = -8.3 Adapted from Guswa et al., in press

25 Monteverde Continental Divide Adapted from Guswa et al., in press

26 Monteverde: Regional Topography Lac Arenal Volcan Arenal Monteverde Rio Guacimal Rio San Luis

27 Temporal Variation

28 Temporal Variation Adapted from Guswa et al., in press

29 Conclusions The water resources of Monteverde, Costa Rica depend on supply from streams and springs with very little storage. The greatest contributions of orographic precipitation to streamflow are in catchments near the Brillante Gap. In catchments affected by orographic precipitation, the temporal variation in stream isotopes generally follows the variation in precipitation but regresses to the annual average during the dry season.

30 Implications Streamflows for watersheds near the Brillante Gap depend on trade-wind delivered orographic water. Water resources in these catchments will be susceptible to changes in this precipitation input, which could be affected by global climate change. Streamflows in the dry season depend on water stored from the rainy season. Water resources will be affected by land-use changes that impact infiltration capacity.

31 Questions? Andrew J. Guswa Steve Tilley

32 References Guswa, Andrew J., A. L. Rhodes, and S. E. Newell, in press. Importance of orographic precipitation to the water resources of Monteverde, Costa Rica, Advances in Water Resources. Rhodes, Amy L., A. J. Guswa, and S. E. Newell, Seasonal variation in the stable isotopic composition of precipitation in the tropical montane forests of Monteverde, Costa Rica, Water Resources Research, 42, W11402, doi: /2005wr Rhodes, Amy L., A. J. Guswa, S. Dallas, E. M. Kim, S. Katchpole, A. Pufall, in press. Water quality in a tropical montane cloud forest, Monteverde, Costa Rica. In: Bruijnzeel, L.A., Juvik, J., Scatena, F.N., Hamilton, L.S., and Bubb, P. (eds), Forests in the Mist: Science for Conservation and Management of Tropical Montane Cloud Forests, University of Hawaii Press.