Some of the most attractive hydro power plants are severely affected by silt erosion at certain times of the year, particularly during monsoons. Erosion of hydro-turbine components through sediment-laden river water is one of the most challenging problems in the Himalayan region. Detailed analysis of sediments, erosion of runner blades, guide vanes and labyrinth of a 304-MW hydro power plant has been reported. The efficiency of a desilting chamber in removal of particles of size greater than the threshold particle size (0.15 mm) has been verified for a hydro power plant in Uttarakhand, India. Finally, weight loss of turbine and subsequent reduction in the turbine's efficiency due to silt erosion were also investigated.

Experiments on initiation of motion and rate of bed load transport of different fractions in case of nonuniform sediments are reported. Analysis of these data as well as those from earlier studies by other investigators has shown some limitations of the available relationships for critical tractive stress (CTS) of sediment mixtures. Further analysis of the data has resulted in a new relationship for CTS in terms of the size of the particular fraction in question (d_i ), the geometric mean size (d_g ) and the geometric standard deviation (σ _g ) of the mixture. An empirical relationship has been obtained for the critical tractive stress of the size d _σ defined as d_g σ_g.