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1 <br />3. PROGRAM DESIGN PHASE I <br />3.1. Background I <br />Previous cloud seeding projects have provided information clearly pointing to the need for conducting a <br />design phase for a program such as proposed for the Headwaters Region. However, design studies for <br />the Headwaters Region are somewhat facilitated by the availability of results of prior studies conducted in <br />the Park Range. Cloud physics and modeling studies were conducted as part of COSE (Rauber et al., <br />1986; Rauber and Grant, 1986; Rauber, 1987). Since the COSE studies, a high- altitude (10,520 feet) <br />laboratory known as the Storm Peak Laboratory (Borys and Wetzel, 1997), currently managed by the <br />, <br />Desert Research Institute of the University of Nevada at Reno, has been maintained for further study of <br />winter clouds and aerosols. Other Park Range data collection occurred during the mid -1960s as part of a <br />5 -year program of cloud seeding investigations (Rhea et al., 1969). Some experiments involved the <br />release of AgI and airflow tracer material to study the transport and dispersion of ground -based and <br />aircraft released cloud seeding agents. The results of studies by Rhea et al. should be used as additional <br />background information on cloud seeding in the Park Range. The previous studies will provide useful <br />information, but the proposed project is facing considerably more formidable tasks such as determining <br />the placement of more than 50 seeding devices, most likely at high elevations and in rugged terrain. <br />Placement must facilitate adequate residence time in -cloud for growth of seeding created ice particles for <br />deposition in the intended target area. <br />The Grand Mesa winter cloud seeding studies (see appendix A, chapter 7) provide additional background <br />information useful to pursuing field studies in the Headwaters Region. Aircraft and surface observations <br />of seeding trials provide convincing results that cloud seeding can cause precipitation increases (Super <br />and Boe, 1988). The early 1990s seeding experiments in the Wasatch Plateau of Utah (Super and <br />Holroyd, 1994) provide more results in conducting orographic cloud seeding. Aircraft and surface <br />observation collected before, during and after seeding trials also document precipitation increases and <br />clear evidence that clouds were seeded. , <br />Design studies are needed to develop an operational seeding plan that mitigates the following existing <br />conditions in the Headwaters Region and allow for incorporation of new technologies that improve cloud <br />seeding and reduce costs. <br />• The terrain differs widely within the Headwaters Region. Terrain differences and the presence of <br />large wilderness areas will present additional problems and challenges to planning and program <br />conduct. Design studies will enable determining the proper cloud treatment approaches, and <br />equipment types, numbers and siting for the terrain and weather conditions of the Headwaters <br />Region. <br />• Cloud treatment effects must be directed at the lee side of the Park Range and Sierra Madre <br />Mountains for additional runoff into the North Platte River. Typically, targeted areas for cloud are <br />located on the windward slope. Targeting the lee slope will require additional study and observations <br />on ice particle growth and residence times in favorable cloud environments under typical storm wind <br />conditions. Cloud modeling will help scope this issue. <br />• Design studies will allow the testing and incorporation of new technology for the Headwaters Region. , <br />In particular, automated seeding systems must be tested in the conditions of high elevations and <br />winter weather. Power is not available for most likely equipment locations. The cost of power plants <br />and their operation is considerable. It is hoped that solar energy systems and rechargeable batteries <br />8 <br />