This publication provides introductory technical guidance for civil engineers, mechanical engineers, electrical engineers and other professional engineers, construction managers and power utility operators in sizing of hydroelectric power plants and integrating them into regional electric power systems. Here is what is discussed: 1. INTRODUCTION, 2. PROCEDURE FOR SIZING POWERPLANTS, 3. POWER SYSTEM REQUIREMENTS AND MARKETABILITY, CONSIDERATIONS, 4. PHYSICAL CONSTRAINTS, 5. ENVIRONMENTAL AND NON-POWER OPERATING CONSTRAINTS, 6. SELECTION OF ALTERNATIVE POWER INSTALLATIONS, 7. DEPENDABLE CAPACITY, 8. INTERMITTENT CAPACITY, 9. FLEXIBILITY, 10. MEASURES FOR FIRMING UP PEAKING CAPACITY, 11. HOURLY OPERATION STUDIES