WMOD00312 ‎(2)‎

• Title: Cloud Seeding Feasibility for the Shasta-Trinity Watershed
• Date: 12/1/1993
• Weather Modification - Doc Type: Report

CONTENTS

Page

Glossary .................................................................. iii

Executive Summary ........................................................ viii

1. Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 1

1.1 Background. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

1.2 Weather modification as a nonstructural water augmentation option .......... 1
1.3 Study objectives . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
2. Fundamentals of seeding winter clouds over mountains. . . . . . . . . . . . . . . . . . . . . . . . . . 2
2.1 Winter orographic clouds ........................................... 2
2.2 Seeding of winter orographic clouds ................................... 2
3. Summary of the SCPP results relevant to the Shasta-Trinity Watershed ............. 4

3.1 Introduction . . . . . . . . . . . . . . . . . . . . , . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

3.2 SL W studies . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

3.3 Exploratory seeding trials .........,................................ 9
3.3.1 Aerial seeding .............................................. 9
3.3.2 Ground seeding experiments. . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 13
3.4 General conclusions ............................ . . . . . . . . . . . . . . . . . .. 15
4. Analysis of precipitation data for the Shasta-Trinity Watersheds . . . . . . . . . . . . . . . . .. 17
4.1 Precipitation analyses ............,............................... 17
4.1.1 Shasta Watershed .......................................... 17
4.1.2 Trinity Watershed .........,............................... 18
4.1.3 Analysis of daily precipitation ................................ 18
4.1.4 Hourly precipitation analysis .................................. 26
4.1.4.1 Suspension criteria applied to hours of precipitation .......... 30
4.1.4.2 SHA hourly precipitation ................................. 31
4.1.4.3 COF hourly precipitation ...................................... 31
4.1.5 Discussion of potential seeding hours ................................... 35
4.1.5.1 Comparison of precipitation in the Shasta-Trinity
and American River Basiln .................................. 36
4.1.5.2 Analysis of icing data and precipitation in the
Shasta-Trinity Watershed. . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 38
4.1.5.3 Estimate of potential seeding hours ...................... 40
5. Operational seeding program design . . . . . .. . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46
5.1 Program objective and general overview . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . 46
5.2 Target area selection ............................................. 47
5.3 Operations base selection .......................................... 49

5.4 Management. .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . 49
5.5 Funding and program authorization ................................. 49
5.6 Environmental compliance and monitoring ............................. 50
5.7 General design and analysis considerations .............................. 51
5.8 Experimental units ............................................... 52
5.9 Randomized seeding program components ............................... 52
5.9.1 Seeding operations ........................................... 52
5.9.2 Precipitation gauge network ................................. 54

5.9.3 Radar ..................................................... 54
5.9.4 Surface remote weather observing station ......................... 54
5.9.5 Rawinsonde observations ...................................... 55
5.10 Physical observations program ...................................... 55

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