Based on Thoma supposition and basic equations of surge tank, a few formulas were proposed for the stable sectional area of tailrace surge tank on complicated tailrace system.

• 摘要在托马假定前提下，从调压室基本方程入手，推导复杂尾水系统的尾水调压室稳定断面计算公式，并通过工程实例进行验证。