Projecting the impacts of end of century climate extremes on the hydrology in California
- 1Energy Geosciences Division, Lawrence Berkeley National Laboratory 1 Cyclotron Road, M.S. 74R-316C, Berkeley, CA 94704, USA
- 2Climate and Ecosystem Sciences Division, Lawrence Berkeley National Laboratory 1 Cyclotron Road, M.S. 74R-316C, Berkeley, CA 94704, USA
- anow at: NASA Goddard Space Flight Center, Hydrological Sciences Laboratory, Greenbelt, MD, USA
- 1Energy Geosciences Division, Lawrence Berkeley National Laboratory 1 Cyclotron Road, M.S. 74R-316C, Berkeley, CA 94704, USA
- 2Climate and Ecosystem Sciences Division, Lawrence Berkeley National Laboratory 1 Cyclotron Road, M.S. 74R-316C, Berkeley, CA 94704, USA
- anow at: NASA Goddard Space Flight Center, Hydrological Sciences Laboratory, Greenbelt, MD, USA
Abstract. In California, it is essential to understand the evolution of water resources in response to a changing climate to sustain its economy and agriculture and build resilient communities. Although extreme conditions have characterized the historical hydroclimate of California, climate change will likely intensify hydroclimatic extremes by the End of Century (EoC). However, few studies have investigated the impacts of EoC extremes on watershed hydrology. We use cutting-edge global climate and integrated hydrologic models to simulate EoC extremes and their effects on the water-energy balance. We assess the impacts of projected driest, median, and wettest water years under a Representative Concentration Pathway (RCP) 8.5 on the hydrodynamics of the Cosumnes river basin. High temperatures (> 2.5 °C) and precipitation (> 38 %) will characterize the EoC extreme water years compared to their historical counterparts. Also, precipitation, mostly in the form of rain, is projected to fall earlier. This change reduces snowpack by more than 90 %, increases peak surface water and groundwater storages up to 75 % and 23 %, respectively, and makes these peak storages occur earlier in the year. Because EoC temperatures and soil moisture are high, both potential and actual evapotranspiration (ET) increase. The latter, along with the lack of snowmelt in the warm EoC, cause surface water and groundwater storages to significantly decrease in summer, with groundwater showing the highest rates of decrease. Besides, the changes in the precipitation phase lead the lower-order streams to dry out in EoC summer whereas the mainstream experiences an increase in storage.
Fadji Zaouna Maina et al.
Status: closed
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RC1: 'Comment on hess-2021-472', Anonymous Referee #1, 23 Oct 2021
The manuscript simulates End of Century (EOC) extremes and their effects on the water-energy balance in the Cosumnes river basin, using cutting-edge global climate and integrated hydrologic models (ParFlow-CLM). I really like the way the authors used to analyze the hydroclimatic changes by median WY, dry WY and wet WY (e.g., Figures 3-5). The manuscript is overall clearly written, and the results are well discussed.
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My first concern is the insufficient validation of the models’ simulations in the historical period. Besides temperature and precipitation outputs, other watershed-integrated fluxes, and storages (e.g., ET, soil moisture, TWS and streamflow) should also be validated as much as possible using the observations, remote sensing data and reanalysis, to ensure the models’ simulations reasonable. Only then will we believe the further analysis between future and historical periods is valid. In my opinion, the historical simulation of VR-CESM is not so good because the simulated dry, median, and wet water years are distinct from the PRISM (Figure A2).
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The authors may argue the historical simulations are acceptable, because a global climate and integrated hydrologic models are used (more complex and larger simulation domain). However, one can use a finer-resolution hydrological model (e.g., VIC, SWAT, and many others) driven by statistically or dynamically downscaled regional climate model outputs to obtain more reasonable (maybe more accurate from the perspective of validation) simulations in this river basin (7000 km2), and to do further analysis like the authors did in this study. Please explain why the global climate and integrated hydrologic models are more suitable for this case study?
- AC1: 'Reply on RC1', Fadji Zaouna Maina, 22 Dec 2021
-
RC2: 'Comment on hess-2021-472', Anonymous Referee #2, 09 Nov 2021
- AC2: 'Reply on RC2', Fadji Zaouna Maina, 22 Dec 2021
Status: closed
-
RC1: 'Comment on hess-2021-472', Anonymous Referee #1, 23 Oct 2021
The manuscript simulates End of Century (EOC) extremes and their effects on the water-energy balance in the Cosumnes river basin, using cutting-edge global climate and integrated hydrologic models (ParFlow-CLM). I really like the way the authors used to analyze the hydroclimatic changes by median WY, dry WY and wet WY (e.g., Figures 3-5). The manuscript is overall clearly written, and the results are well discussed.
Â
My first concern is the insufficient validation of the models’ simulations in the historical period. Besides temperature and precipitation outputs, other watershed-integrated fluxes, and storages (e.g., ET, soil moisture, TWS and streamflow) should also be validated as much as possible using the observations, remote sensing data and reanalysis, to ensure the models’ simulations reasonable. Only then will we believe the further analysis between future and historical periods is valid. In my opinion, the historical simulation of VR-CESM is not so good because the simulated dry, median, and wet water years are distinct from the PRISM (Figure A2).
Â
The authors may argue the historical simulations are acceptable, because a global climate and integrated hydrologic models are used (more complex and larger simulation domain). However, one can use a finer-resolution hydrological model (e.g., VIC, SWAT, and many others) driven by statistically or dynamically downscaled regional climate model outputs to obtain more reasonable (maybe more accurate from the perspective of validation) simulations in this river basin (7000 km2), and to do further analysis like the authors did in this study. Please explain why the global climate and integrated hydrologic models are more suitable for this case study?
- AC1: 'Reply on RC1', Fadji Zaouna Maina, 22 Dec 2021
-
RC2: 'Comment on hess-2021-472', Anonymous Referee #2, 09 Nov 2021
- AC2: 'Reply on RC2', Fadji Zaouna Maina, 22 Dec 2021
Fadji Zaouna Maina et al.
Fadji Zaouna Maina et al.
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