Hydrologic functioning of the deep critical zone and contributions to streamflow in a high-elevation catchment: Testing of multiple conceptual models

Ravindra Dwivedi, Thomas Meixner, Jennifer McIntosh, P. A.Ty Ferré, Christopher J. Eastoe, Guo-Yue Niu, Rebecca L. Minor, Greg A Barron-Gafford, Jon Chorover

Research output: Contribution to journalArticle

1 Citation (Scopus)

Abstract

High-elevation mountain catchments are often subject to large climatic and topographic gradients. Therefore, high-density hydrogeochemical observations are needed to understand water sources to streamflow and the temporal and spatial behaviour of flow paths. These sources and flow paths vary seasonally, which dictates short-term storage and the flux of water in the critical zone (CZ) and affect long-term CZ evolution. This study utilizes multiyear observations of chemical compositions and water residence times from the Santa Catalina Mountains Critical Zone Observatory, Tucson, Arizona to develop and evaluate competing conceptual models of seasonal streamflow generation. These models were tested using endmember mixing analysis, baseflow recession analysis, and tritium model “ages” of various catchment water sources. A conceptual model involving four endmembers (precipitation, soil water, shallow, and deep groundwater) provided the best match to observations. On average, precipitation contributes 39–69% (55 ± 16%), soil water contributes 25–56% (41 ± 16%), shallow groundwater contributes 1–5% (3 ± 2%), and deep groundwater contributes ~0–3% (1 ± 1%) towards annual streamflow. The mixing space comprised two principal planes formed by (a) precipitation-soil water-deep groundwater (dry and summer monsoon season samples) and (b) precipitation-soil water-shallow groundwater (winter season samples). Groundwater contribution was most important during the wet winter season. During periods of high dynamic groundwater storage and increased hydrologic connectivity (i.e., spring snowmelt), stream water was more geochemically heterogeneous, that is, geochemical heterogeneity of stream water is storage-dependent. Endmember mixing analysis and 3H model age results indicate that only 1.4 ± 0.3% of the long-term annual precipitation becomes deep CZ groundwater flux that influences long-term deep CZ development through both intercatchment and intracatchment deep groundwater flows.

Original languageEnglish (US)
JournalHydrological Processes
DOIs
StateAccepted/In press - Jan 1 2019

Fingerprint

streamflow
catchment
groundwater
soil water
water
mountain
winter
tritium
baseflow
water storage
snowmelt
groundwater flow
connectivity
residence time
monsoon
observatory
chemical composition
summer
analysis

Keywords

  • conceptual models
  • critical zone
  • dynamic storage
  • endmember mixing analysis
  • tritium model ages

ASJC Scopus subject areas

  • Water Science and Technology

Cite this

@article{dd937fd0e1c8432eb19fff2a6bf27b85,
title = "Hydrologic functioning of the deep critical zone and contributions to streamflow in a high-elevation catchment: Testing of multiple conceptual models",
abstract = "High-elevation mountain catchments are often subject to large climatic and topographic gradients. Therefore, high-density hydrogeochemical observations are needed to understand water sources to streamflow and the temporal and spatial behaviour of flow paths. These sources and flow paths vary seasonally, which dictates short-term storage and the flux of water in the critical zone (CZ) and affect long-term CZ evolution. This study utilizes multiyear observations of chemical compositions and water residence times from the Santa Catalina Mountains Critical Zone Observatory, Tucson, Arizona to develop and evaluate competing conceptual models of seasonal streamflow generation. These models were tested using endmember mixing analysis, baseflow recession analysis, and tritium model “ages” of various catchment water sources. A conceptual model involving four endmembers (precipitation, soil water, shallow, and deep groundwater) provided the best match to observations. On average, precipitation contributes 39–69{\%} (55 ± 16{\%}), soil water contributes 25–56{\%} (41 ± 16{\%}), shallow groundwater contributes 1–5{\%} (3 ± 2{\%}), and deep groundwater contributes ~0–3{\%} (1 ± 1{\%}) towards annual streamflow. The mixing space comprised two principal planes formed by (a) precipitation-soil water-deep groundwater (dry and summer monsoon season samples) and (b) precipitation-soil water-shallow groundwater (winter season samples). Groundwater contribution was most important during the wet winter season. During periods of high dynamic groundwater storage and increased hydrologic connectivity (i.e., spring snowmelt), stream water was more geochemically heterogeneous, that is, geochemical heterogeneity of stream water is storage-dependent. Endmember mixing analysis and 3H model age results indicate that only 1.4 ± 0.3{\%} of the long-term annual precipitation becomes deep CZ groundwater flux that influences long-term deep CZ development through both intercatchment and intracatchment deep groundwater flows.",
keywords = "conceptual models, critical zone, dynamic storage, endmember mixing analysis, tritium model ages",
author = "Ravindra Dwivedi and Thomas Meixner and Jennifer McIntosh and Ferr{\'e}, {P. A.Ty} and Eastoe, {Christopher J.} and Guo-Yue Niu and Minor, {Rebecca L.} and Barron-Gafford, {Greg A} and Jon Chorover",
year = "2019",
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T1 - Hydrologic functioning of the deep critical zone and contributions to streamflow in a high-elevation catchment

T2 - Testing of multiple conceptual models

AU - Dwivedi, Ravindra

AU - Meixner, Thomas

AU - McIntosh, Jennifer

AU - Ferré, P. A.Ty

AU - Eastoe, Christopher J.

AU - Niu, Guo-Yue

AU - Minor, Rebecca L.

AU - Barron-Gafford, Greg A

AU - Chorover, Jon

PY - 2019/1/1

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N2 - High-elevation mountain catchments are often subject to large climatic and topographic gradients. Therefore, high-density hydrogeochemical observations are needed to understand water sources to streamflow and the temporal and spatial behaviour of flow paths. These sources and flow paths vary seasonally, which dictates short-term storage and the flux of water in the critical zone (CZ) and affect long-term CZ evolution. This study utilizes multiyear observations of chemical compositions and water residence times from the Santa Catalina Mountains Critical Zone Observatory, Tucson, Arizona to develop and evaluate competing conceptual models of seasonal streamflow generation. These models were tested using endmember mixing analysis, baseflow recession analysis, and tritium model “ages” of various catchment water sources. A conceptual model involving four endmembers (precipitation, soil water, shallow, and deep groundwater) provided the best match to observations. On average, precipitation contributes 39–69% (55 ± 16%), soil water contributes 25–56% (41 ± 16%), shallow groundwater contributes 1–5% (3 ± 2%), and deep groundwater contributes ~0–3% (1 ± 1%) towards annual streamflow. The mixing space comprised two principal planes formed by (a) precipitation-soil water-deep groundwater (dry and summer monsoon season samples) and (b) precipitation-soil water-shallow groundwater (winter season samples). Groundwater contribution was most important during the wet winter season. During periods of high dynamic groundwater storage and increased hydrologic connectivity (i.e., spring snowmelt), stream water was more geochemically heterogeneous, that is, geochemical heterogeneity of stream water is storage-dependent. Endmember mixing analysis and 3H model age results indicate that only 1.4 ± 0.3% of the long-term annual precipitation becomes deep CZ groundwater flux that influences long-term deep CZ development through both intercatchment and intracatchment deep groundwater flows.

AB - High-elevation mountain catchments are often subject to large climatic and topographic gradients. Therefore, high-density hydrogeochemical observations are needed to understand water sources to streamflow and the temporal and spatial behaviour of flow paths. These sources and flow paths vary seasonally, which dictates short-term storage and the flux of water in the critical zone (CZ) and affect long-term CZ evolution. This study utilizes multiyear observations of chemical compositions and water residence times from the Santa Catalina Mountains Critical Zone Observatory, Tucson, Arizona to develop and evaluate competing conceptual models of seasonal streamflow generation. These models were tested using endmember mixing analysis, baseflow recession analysis, and tritium model “ages” of various catchment water sources. A conceptual model involving four endmembers (precipitation, soil water, shallow, and deep groundwater) provided the best match to observations. On average, precipitation contributes 39–69% (55 ± 16%), soil water contributes 25–56% (41 ± 16%), shallow groundwater contributes 1–5% (3 ± 2%), and deep groundwater contributes ~0–3% (1 ± 1%) towards annual streamflow. The mixing space comprised two principal planes formed by (a) precipitation-soil water-deep groundwater (dry and summer monsoon season samples) and (b) precipitation-soil water-shallow groundwater (winter season samples). Groundwater contribution was most important during the wet winter season. During periods of high dynamic groundwater storage and increased hydrologic connectivity (i.e., spring snowmelt), stream water was more geochemically heterogeneous, that is, geochemical heterogeneity of stream water is storage-dependent. Endmember mixing analysis and 3H model age results indicate that only 1.4 ± 0.3% of the long-term annual precipitation becomes deep CZ groundwater flux that influences long-term deep CZ development through both intercatchment and intracatchment deep groundwater flows.

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