Land Use Effects On Major Ion Biogeochemistry And Hydrologic Flowpaths In The Panama Canal Watershed
Birch, Andrew L 1 ; Bush, Sidney 2 ; Stallard, Robert 3 ; Barnard, Holly 4
1 INSTAAR, University of Colorado
2 INSTAAR, University of Colorado
3 INSTAAR, University of Colorado, United States Geologic Survey
4 INSTAAR, University of Colorado
Humid tropical regions experience disproportionately greater energy inputs in terms of water fluxes, more intense precipitation, more rapid weathering, and rapid introduction of large water and sediment volumes when compared to more temperate regions, along with increasing pressure from both climate and land use change (Wohl et al., 2012). Despite this, humid tropical regions of the world have a notable lack of data and experimental research in comparison; often decades behind in terms of our understanding of the hydrologic processes which govern their water resources. This poster presentation shares some initial results from a larger research project to better understand the influence of land use/ land cover on hydrologic flowpaths, streamflow generation, and biogeochemistry in the humid neo-tropics of Central America. Data was collected during a three month period during the 2016 wet season (May to July 2016) from a series of small headwater catchments in Central Panama, covering a variety of land covers; mature rainforest, young secondary rainforest, active pasture, and traditionally cut rainforest. Samples of soil moisture, groundwater, overland flow, and preferential flow were collected weekly from each catchment at multiple hillslope positions for major ions (Ca, Mg, Na, K, NH4, Cl, Br, NO3), stable water isotopes (18O, D), dissolved organic carbon, pH, and conductivity. Stream samples were collected daily, and aggregate precipitation was collected every ~3 days. Initial analysis of major cations and anions indicates differences in biogeochemistry across the catchments, which we hypothesize are the results of altered subsurface hydrologic structure, and ecological changes brought on by changes in land use. Future work will seek to better characterize biogeochemistry and flowpath alteration using additional water chemistry data, and hydrometric data for each catchment (currently being processed).
Wohl, E., Barros, A., Brunsell, N., Chappell, N.A., Coe, M, Giambelluca, T., Goldsmith, S., Harmon, R., Hendrickx, J.M.H., Juvik, J., McDonnell, J., and Ogden, F., 2012, Hydrology of the humid tropics: Nature Climate Change v. 2, p. 655-662.