WMOD00413

• Title: Validation of Precipitation Management by Seeding Winter Orographic Clouds in the Colorado River Basin
• Date: 9/1/1993
• Weather Modification - Doc Type: Report

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The proposed name for this program is the CREST (Colorado River Enhanced Snowpack Test).
The first year of the proposed program will be devoted to initiation of environmental
compliance activities for the two experimental areas, and to equipment and contract
procurement. No cloud seeding will take place until environmental compliance is accomplished.

The first program phase involving seeding will concentrate on comprehensive "direct detection"
cloud seeding experiments that will monitor the important links in the chain of physical events
following seeding. For AgI (silver iodide) seeding, important linkS include:

. The reliable production of the seeding agent by remote-controlled AgI generators.
. T&D (transport and dispersion) of the seeding agent into SLW (supercooled liquid water)
orographic cloud.
. Nucleation of appropriate concentrations of ice crystals by the AgI.
. Growth of seeded ice crystals into snowflakes and snow pellets (graupel).
. Fallout ofthe largest ice particles onto the surlace while crossing the mountain barrier.

This direct detection experimental phase will require three winters. The field efforts will be
conducted simultaneously at both experimental areas.

Analysis and numerical modeling studies during and after the direct detection field programs
will lead to design of a randomized statistical experiment for each area. The statistical
experiments will be conducted during the "statistical/physical" phase, which willla.st 4 yr. A
strong physical component will be continued throughout the statistical experiments. The
continued physical experiments will test the proper design and conduct of the statistical
experiments, and will provide the means to test the physical plausibility of the statistical
results.

The comprehensive physical and statistical analyses are expected to show that winter cloud
seeding is a viable technology capable of helping meet future water needs of the West and many
foreign countries where climate and terrain are suitable. Replicating the experiments at two
different locations will substantially enhance the credibility ofthe results.

Investigations to facilitate the transferability of cloud seeding technology throughout the Basin
will be conducted during both the direct detection and statistical/physical phases. Observations
of certain important cloud characteristics will be made, and numerical model simulations
calculated, for 6 other representative mountain regions in the Colorado River Basin.

1.4 Reclamation Authority to Develop Cloud Seeding Technology

The Department of the Interior, specifically the Secretary, is responsible for water supplies in
the Colorado River Basin. These responsibilities include:

. Regulating and operating the river.
. Contracting for water.
. Declaring water surplus or shortage.
. Accounting for all the water of the Basin.
. Supplying water to Mexico.
. Preparing and developing augmentation plans to meet water requirements.
. Controlling salinity (water quality implementation).

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