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archiving, and scientific analysis were provided by the DMN in Casablanca. The GOM provided the field operations center and facilities for Morocco's first weather radar in Khouribga, 180 kilometers southeast of Casablanca. Rawinsonde launch facilities were built at Beni Mellal and Tissa, about 230 and 260 kilometers southeast of Casablanca, respectively. Airborne seeding operations were conducted up to the spring of 1986 by four OV-10 aircraft based at Marrakech and thereafter by two King Air 100 aircraft based at Kenitra, 200 kilometers northeast of Casablanca. One of the King Airs was equipped with Morocco's first cloud physics data acquisition system in 1987. In addition, a radar-equipped Alpha Jet was available for high- altitude seeding missions throughout the duration of the project. It was normally based at Meknes. American assistance provided over $2 million in scientific equipment and supplies. These included the weather radar with its digital recording system, a cloud physics data acquisition system, aircraft navigation systems, a satellite direct-readout ground station and analysis system, 2 rawinsonde systems, 12 microcomputers and software for them, radio communications systems, teiecopier and facsimile data receivers, electronics workshop and test equipment, tools, and miscellaneous other hardware and expendable supplies. The balance of the $4 million was provided in technology transfer, which included long- and short-term training programs, both formal and informal, project design and management, and administrative assistance for procurement. Scientific basis. - The project was designed to use the latest available technology in winter orographic cloud seeding to increase the precipitation efficiency of cold clouds in the Central High Atlas Mountains in the vicinity of 320 N. and 70 W. The project used silver iodide (AgI) as the seeding agent. Silver iodide particles act as ice nuclei, converting supercooled cloud droplets to ice crystals, which can grow rapidly into snowflakes. The silver iodide was released from aircraft, ground-based seeding generators, or both during periods when seedable clouds existed that could affect the target area. The methods were similar to those successfully employed in operational and research projects in the Sierra Nevada of California, an area with climate and geography similar to those of MoroCco. Project design. - Due to the severity of the ongoing drought, the cloud seeding plan called for the treatment of all storms with seeding potential that were expected to affect the drainage area of about 7000 km2 feeding Bin El Ouidane reservoir. A target-control design was selected for the statistical evaluation. This design required the selection of a control area near the target. Cloud systems affecting the control area were not to be treated, but measurements would be made for eventual use in the evaluation of seeding effects. Streamflow was selected as the primary response variable for the statistical evaluation because lengthy records existed for the target and control areas. Streamflow is also the variable of primary importance to Moroccan water resources needs. Major Achievements 1. Implementation of field operations. - The field program was initiated in July 1984 with the construction of facilities and staffing of project headquarters and field sites. Headquarters were set up at the Casablanca Anfa Airport. Field sites, including the radar operations center and a rawinsonde station, were activated. Cloud seeding aircraft were modified for cloud seeding and placed on station at Marrakech. vi I I I I I I I I I I I I I I I I I I I