31 Jan 2023
 | 31 Jan 2023
Status: a revised version of this preprint is currently under review for the journal HESS.

Monetizing the role of water in sustaining watershed ecosystem services using a fully integrated subsurface–surface water model

Tariq Aziz, Steven K. Frey, David R. Lapen, Susan Preston, Hazen A. J. Russell, Omar Khader, Andre R. Erler, and Edward A. Sudicky

Abstract. Water is essential for all ecosystem services, yet a comprehensive assessment of total (overall) water contributions to ecosystem services production has never been attempted. Quantification of the many ecosystem services impacted by water demands integrated hydrological simulations that implicitly characterize subsurface and surface water exchange. In this study, we use a fully integrated hydrological model—HydroGeoSphere (HGS)—to capture changes in subsurface water, surface water, and evapotranspiration (green water) combined with the economic valuation approach to assess ecosystem services over an 18-year period (2000–2017) in a mixed-use but predominantly agricultural watershed in eastern Ontario, Canada. Using the green water volumes and ecosystem services values as inputs, we calculate the marginal productivity of water, which is $0.45 per m3 (in 2022 Canadian dollars). The valuation results show that maximum green water is used during the dry years, with a value of $1.16 billion during a severe drought that struck in 2012. The average product of water for ecosystem services declines during the dry years. Because subsurface water is a major contributor to the green water supply, it plays a critical role in sustaining ecosystem services during drought conditions. For instance, during the 2012 drought, the subsurface water contribution to green water was estimated at $743 million, making up 72 % of the total value of green water used in that year. Conversely, the surface water contributions in green water provision over the modeling period are comparatively miniscule. This study informs watershed management on the sustainable use of subsurface water during droughts and provides an improved methodology for watershed-based integrated management of ecosystem services.

Tariq Aziz et al.

Status: final response (author comments only)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on hess-2023-25', Anonymous Referee #1, 07 Mar 2023
    • AC1: 'Reply on RC1', Tariq Aziz, 18 Apr 2023
  • RC2: 'Comment on hess-2023-25', Anonymous Referee #2, 19 Mar 2023
    • AC2: 'Reply on RC2', Tariq Aziz, 18 Apr 2023

Tariq Aziz et al.

Tariq Aziz et al.


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Short summary
The study determines the value of water towards ecosystem services production in an agricultural watershed in Ontario, Canada. It uses a computer model and an economic valuation approach to determine how subsurface and surface water affect ecosystem services supply. The results show that subsurface water plays a critical role in maintaining ecosystem services. The study informs on the sustainable use of subsurface water and introduces a new method for managing watershed ecosystem services.