A Comparison of Precipitation Downscaling Procedures to Guide Studies of Climate Change Impacts on Flooding and Water Resources

Location: Southwest United States
Sponsors: Department of the Interior, Bureau of Reclamation
PI/Co-PIs: Dr. Eylon Shamir (HRC)
Collaborators: Bureau of Reclamation

This was a collaborative project with Dr. Eve Halper from the Bureau of Reclamation (Reclamation), Phoenix Area Office. The project was funded by the Reclamation Science and Technology Grant Program under a cooperative agreement between HRC and the Reclamation Lower Colorado Region (Agreement # R16AC00024).

In recent years, Reclamation and other agencies have been engaged in climate impact assessments of increasingly smaller river basins and local rural communities. The existing methods and datasets that were developed for larger watersheds may not be adequate for arid ephemeral river basins that are often the prevailing landscape of these rural communities. In these relatively small and arid basins, the rainfall characteristics are highly variable and streamflow is tightly associated with the nuances of the rainfall temporal and spatial patterns.

The objective of this research, which is conducted in two arid watersheds in Arizona (the Upper Santa Cruz River watershed and the Bill Williams River watershed) are to:

  • Evaluate the suitability of various global climate models downscaling methods to produce future projections of precipitation;
  • Develop a test to decide on the preferred procedure for a given type of study;
  • Quantify the impact of each method on the Reclamation planning activities.

The study and results are presented in the following documents:

Project Final Report

Shamir Eylon and Eve Halper, Estimating climatic change impacts on water resources in arid environments: the role of downscaling methodology, Research and Development Office, Science and Technology Program, Final Report ST-2019-9039-01. March 2019. Executive Summary  Full Report

Research Bulletin:

Estimating climatic change impacts on water resources: the role of downscaling methodology.  Bulletin

Open access manuscript: Journal of Hydrology X

Shamir E, E. Halper, T. Modrick, K. P. Georgakakos, H-I. Chang, T.M. Lahmers, C. Castro, Statistical and dynamical downscaling impact on projected hydrologic assessment in arid environment: A case study from Bill Williams River basin and Alamo Lake, Arizona, Journal of Hydrology X, Volume 2,2019,100019,ISSN 2589-9155,    Manuscript

The manuscript can also be downloaded at the following: http://www.sciencedirect.com/science/article/pii/S2589915519300033 

Slide Presentation

A Reclamation Science and Technology webinar, presented in 25 March 2019


A poster presented at the American Meteorological Society, 8-11 January 2019

HRC Technical Notes

HRC prepared a report that describes the development of the hourly precipitation Weather Generator (WG) for the Upper Santa Cruz River Basin, near the international Mexico-U.S border. This WG was developed as a tool to assess the impact on the water resources of various natural and man-made changes in the basin.  In addition, it was used to explore various water resources management and planning schemes that best address water resources challenges. (Shamir, E., 2017: Modification and calibration of the rainfall weather generator for the Upper Santa-Cruz River basin, Arizona HRC Technical Note No. 94.  Hydrologic Research Center, San Diego, CA, 1 August 2017.)

HRC prepared a report that describes the technical details of the hydrologic modeling framework for the Bill Williams River Watershed and Alamo Lake, Arizona.  The primary objective of the modelling framework, which consists of a precipitation weather generator, a hydrologic model and a lake model for Alamo Lake, is to assess the hydrologic impact of projected climatic changes.  (Shamir, E., T. Modrick-Hansen and KP. Georgakakos 2017. Development of hydrologic Modeling Framework for the Bill Williams River Watershed. HRC Technical Note No. 97.  Hydrologic Research Center, San Diego, CA, 1 December 2017. )