Isotope-derived young water fractions in streamflow across the tropical Andes mountains and Amazon floodplain
<p>The role of topography in determining water transit times and pathways through catchments is unclear, especially in mountainous environments – yet these environments play central roles in global water, sediment, and biogeochemical fluxes. Since the vast majority of intensively monitored cat...
| Main Authors: | , , , , |
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| Format: | Article |
| Language: | English |
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Copernicus Publications
2023-08-01
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| Series: | Hydrology and Earth System Sciences |
| Online Access: | https://hess.copernicus.org/articles/27/2883/2023/hess-27-2883-2023.pdf |
| _version_ | 1797756539962916864 |
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| author | E. I. Burt E. I. Burt D. H. Coayla Rimachi D. H. Coayla Rimachi A. J. Ccahuana Quispe A. Atwood A. J. West |
| author_facet | E. I. Burt E. I. Burt D. H. Coayla Rimachi D. H. Coayla Rimachi A. J. Ccahuana Quispe A. Atwood A. J. West |
| author_sort | E. I. Burt |
| collection | DOAJ |
| description | <p>The role of topography in determining water transit times and pathways
through catchments is unclear, especially in mountainous environments
– yet these environments play central roles in global water, sediment, and
biogeochemical fluxes. Since the vast majority of intensively monitored
catchments are at northern latitudes, the interplay between water transit,
topography, and other landscape and climatic characteristics is particularly
underexplored in tropical environments. To address this gap, here we present
the results of a multiyear hydrologic sampling campaign (twice-monthly and
storm sampling) to quantify water transit in seven small catchments
(<span class="inline-formula"><i><</i>1.3</span> km<span class="inline-formula"><sup>2</sup></span> area) across the transition from the Andes mountains
to the Amazon floodplain in southern Peru. We use the stable isotope
composition of water (<span class="inline-formula"><i>δ</i><sup>18</sup></span>O) to calculate the fraction of
streamflow comprised of recent precipitation (“young water fraction”) for
each of the seven small catchments. Flow-weighted young water fractions
(<span class="inline-formula"><i>F</i><sub>yw</sub></span>) are 5 %–26 % in the high-elevation mountains, 22 %–52 % in the mid-elevation mountains, and 7 % in the foreland floodplain. Across these
catchments, topography does not exert a clear control on water transit;
instead, stream <span class="inline-formula"><i>F</i><sub>yw</sub></span> is apparently controlled by a combination of
hydroclimate (precipitation regime) and bedrock permeability. Mid-elevation
sites are posited to have the highest <span class="inline-formula"><i>F</i><sub>yw</sub></span> due to more frequent and
intense rainfall; less permeable bedrock and poorly developed soils may also
facilitate high <span class="inline-formula"><i>F</i><sub>yw</sub></span> at these sites. Lowland soils have low <span class="inline-formula"><i>F</i><sub>yw</sub></span> due
to very low flow path gradients despite low permeability. The data presented
here highlight the complexity of factors that determine water transit in
tropical mountainous catchments, particularly highlighting the role of
intense orographic precipitation at mountain fronts in driving rapid
conveyance of water through catchments. These results have implications for
the response of Earth's montane “water towers” to climate change and for
water–rock reactions that control global biogeochemical cycles.</p> |
| first_indexed | 2024-03-12T18:01:57Z |
| format | Article |
| id | doaj.art-f1946aeb583d45a4a8a640ede765d63c |
| institution | Directory Open Access Journal |
| issn | 1027-5606 1607-7938 |
| language | English |
| last_indexed | 2024-03-12T18:01:57Z |
| publishDate | 2023-08-01 |
| publisher | Copernicus Publications |
| record_format | Article |
| series | Hydrology and Earth System Sciences |
| spelling | doaj.art-f1946aeb583d45a4a8a640ede765d63c2023-08-02T09:43:10ZengCopernicus PublicationsHydrology and Earth System Sciences1027-56061607-79382023-08-01272883289810.5194/hess-27-2883-2023Isotope-derived young water fractions in streamflow across the tropical Andes mountains and Amazon floodplainE. I. Burt0E. I. Burt1D. H. Coayla Rimachi2D. H. Coayla Rimachi3A. J. Ccahuana Quispe4A. Atwood5A. J. West6Department of Earth Sciences, University of Southern California, Los Angeles, California 90089, USAnow at: Schmid College of Science and Technology, Chapman University, Orange, California 92866, USAEscuela profesional de Ingenieria Forestal y Medio Ambiente, Universidad Nacional San Antonio Abad del Cusco (UNSAAC), Cusco, PeruEscuela de posgrado de Ingenieria Ambiental, Universidad Científica del Sur, Lima, PeruFacultad de Ciencias Biologicas Universidad Nacional San Antonio Abad del Cusco (UNSAAC), Cusco, PeruDepartment of Earth Sciences, University of Southern California, Los Angeles, California 90089, USADepartment of Earth Sciences, University of Southern California, Los Angeles, California 90089, USA<p>The role of topography in determining water transit times and pathways through catchments is unclear, especially in mountainous environments – yet these environments play central roles in global water, sediment, and biogeochemical fluxes. Since the vast majority of intensively monitored catchments are at northern latitudes, the interplay between water transit, topography, and other landscape and climatic characteristics is particularly underexplored in tropical environments. To address this gap, here we present the results of a multiyear hydrologic sampling campaign (twice-monthly and storm sampling) to quantify water transit in seven small catchments (<span class="inline-formula"><i><</i>1.3</span> km<span class="inline-formula"><sup>2</sup></span> area) across the transition from the Andes mountains to the Amazon floodplain in southern Peru. We use the stable isotope composition of water (<span class="inline-formula"><i>δ</i><sup>18</sup></span>O) to calculate the fraction of streamflow comprised of recent precipitation (“young water fraction”) for each of the seven small catchments. Flow-weighted young water fractions (<span class="inline-formula"><i>F</i><sub>yw</sub></span>) are 5 %–26 % in the high-elevation mountains, 22 %–52 % in the mid-elevation mountains, and 7 % in the foreland floodplain. Across these catchments, topography does not exert a clear control on water transit; instead, stream <span class="inline-formula"><i>F</i><sub>yw</sub></span> is apparently controlled by a combination of hydroclimate (precipitation regime) and bedrock permeability. Mid-elevation sites are posited to have the highest <span class="inline-formula"><i>F</i><sub>yw</sub></span> due to more frequent and intense rainfall; less permeable bedrock and poorly developed soils may also facilitate high <span class="inline-formula"><i>F</i><sub>yw</sub></span> at these sites. Lowland soils have low <span class="inline-formula"><i>F</i><sub>yw</sub></span> due to very low flow path gradients despite low permeability. The data presented here highlight the complexity of factors that determine water transit in tropical mountainous catchments, particularly highlighting the role of intense orographic precipitation at mountain fronts in driving rapid conveyance of water through catchments. These results have implications for the response of Earth's montane “water towers” to climate change and for water–rock reactions that control global biogeochemical cycles.</p>https://hess.copernicus.org/articles/27/2883/2023/hess-27-2883-2023.pdf |
| spellingShingle | E. I. Burt E. I. Burt D. H. Coayla Rimachi D. H. Coayla Rimachi A. J. Ccahuana Quispe A. Atwood A. J. West Isotope-derived young water fractions in streamflow across the tropical Andes mountains and Amazon floodplain Hydrology and Earth System Sciences |
| title | Isotope-derived young water fractions in streamflow across the tropical Andes mountains and Amazon floodplain |
| title_full | Isotope-derived young water fractions in streamflow across the tropical Andes mountains and Amazon floodplain |
| title_fullStr | Isotope-derived young water fractions in streamflow across the tropical Andes mountains and Amazon floodplain |
| title_full_unstemmed | Isotope-derived young water fractions in streamflow across the tropical Andes mountains and Amazon floodplain |
| title_short | Isotope-derived young water fractions in streamflow across the tropical Andes mountains and Amazon floodplain |
| title_sort | isotope derived young water fractions in streamflow across the tropical andes mountains and amazon floodplain |
| url | https://hess.copernicus.org/articles/27/2883/2023/hess-27-2883-2023.pdf |
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