Studies of dam disaster in India and equations for breach parameter

Abstract

It has been found that the less care is shown while constructing the water retention structures as compared to the amount of care shown in designing for it. This is more often in earthen embankments, where soil properties need to be controlled within the designed limits. The life and stability of embankments are entirely based on the extent to which the design assumptions are achieved in the field. History shows many failures were due to the lack of quality control during construction. In India every year many water storage structures fail, but very few were reported. Till date, only 37 dam failures in India are reported but not appropriately analyzed. This paper is focused on compiling the Indian dam failure list with relevant data which can be used for developing breach parameters equation. The data are collected from Government reports, articles news reports and magazines. This paper is also focused on developing new empirical equations for breach parameters and peak outflow from the dam failure which suits Indian condition. In developing the regression equation for breach depth, average breach width, peak discharge and failure time, different combinations of control variables is highlighted such as the dam height, reservoir capacity, average dam width, dam type, failure mode and dam erodibility. In this study, we incorporate the dam average thickness as another control variable for finding out the breach parameters and found suitable for breach depth calculation. New equations are proposed to compute the peak outflow rate. Further, these equations are compared with other developed regression equations for breach parameters and peak outflows.

Appendix

See Table 11.

Table 11 Breach parameter equations by different authors

1.1 Variables

• B_avg = Average breach width (m)

• B_t = Breach top width (m)

• g = Acceleration due to gravity (9.8 m/s²)

• h_b = Breach height (m)

• h_d = Dam height (m)

• h_r = Dam reference height = 15 m

• h_w = Height of water above breach bottom (m)

• Q_p = Peak outflow (m³/s)

• t_f = Failure time (h)

• t_r = Time reference = 1 h

• V_w = Volume of water above breach bottom (m³)

• V_er = Volume of embankment material eroded

• C_b = Constant in Von Thun and Gillette breach width relation

• V = Storage capacity of reservoir (m³)

• W = A verage dam thickness

• DC = Dam with core wall

• FD = Concrete-faced dam

• HD = Homogeneous dam

• ZD = Zoned dam

• O = Overtopping

• S/P = Seepage erosion/piping

• HE = High erodibility

• ME = Medium erodibility

• LE = Low erodibility

• d_ovtop = Overtopping depth

$V_{w}$ × 106	< 1.23	1.23–6.17	6.17–12.3	> 12.3
$C_{b}$	6.1	18.3	42.7	54.9