Methodology for geohazard assessment for hydropower projects

Abstract

The paper presents a comprehensive methodology for a multihazard assessment, including an associated multihazard monitoring programme. An existing method in system theory is extended for multiple systems and used to demonstrate the importance of considering geohazard interrelations in the safety monitoring of reservoirs and dams. The method is applied to systems of geohazards and monitoring parameters. In both systems, there is a reservoir retained by one or more dams. Geohazards in hydropower project perspectives as well as monitoring opportunities are classified. The results are presented in a colour-coded matrix visually mapping ranked interrelations for the two systems. The methodology proposed provides a clear view on the prospective that individual geohazards may trigger other geohazards as well as on the geohazard-triggering potential of the reservoir itself. The warning potential of the possible monitoring parameters is also mapped and interrelated to the individual geohazards. The results demonstrate the importance of a comprehensive multidisciplinary monitoring programme for reliable operation and risk management of hydropower projects.

Appendix

The submatrices of the two-system interrelation matrix are presented as tables in this appendix. In the main text, Fig. 3b describes connection of the appended tables to Fig. 4. In Tables A-1 through A-4, the following three stages of interrelation, triggering, or alarm potential are identified: “Strong”, “Medium”, and “Weak”. These stages are presented in the tables along with a short description where relevant as well as appropriate reference to the literature. The different stages and options used are defined in Table A-0.

Table A-0 Legend for Tables A-1 through A-4

Table A-1 is divided into four parts for readability. Figure 3c in the main text explains this division. The interrelation matrix presented in Tables A-1.1 through A-1.4 defines geohazard interrelation and interactions. Possible interrelations as well as cascading effects from triggering are accounted for. Additionally, possible impact of individual geohazards on safety and sustainability of the reservoir is considered. In the case of impaired safety, potential damages or failures of dams and appurtenant structures are accounted for. The damage/failure possibility comprises loss of life and/or damage to or failure of a reservoir/dam or the surrounding environment.

In Table A-2, the effects of geohazards on monitoring parameters are accounted for. These effects can also be from cascading effects. If a monitoring parameter is directly linked to a particular geohazard, this is indicated with a brownish colour of the relevant cell and the abbreviation IS. However, the brownish cell colour without the IS abbreviation indicates indirect monitoring explaining that the geohazard in the same row as the cell does not induce changes in the monitoring parameter in the same column as the cell, although the monitoring parameter might provide alarm for this particular geohazard.

The alarm potential of each monitoring parameter with respect to individual geohazard is presented in Table A-3. Additionally, the value of the monitoring parameter for back calculation and evaluation of the respective geohazards is accounted for.

Finally, the interrelation of monitoring parameters is described in Table A-4. Cascading effects are not considered in this table.

Table A-1.1 Geohazard interrelation part 1

Table A-1.2 Geohazard interrelation part 2

Table A-1.3 Geohazard interrelation, part 3

1. ^aGoodman and Powell (2003)
2. ^bDegu et al. (2011), Zhao et al. (2012), Hossain (2010), and Hossain et al. (2010)
3. ^cZou et al. (2013)

Table A-1.4 Geohazard interrelation, part 4

Table A-2 Geohazard and reservoir effects on monitoring parameters

1. ^aRajendran et al. (2013), Telesca et al. (2012), Ferreira et al. (2008), Gahalaut et al. (2007), Peinke et al. (2006), Do Nascimento et al. (2004), Lunn et al. (2004), Gupta (2001)
2. ^bItaba (2008), Chadha et al. (2008), Singh et al. (2008). Alarm potential (Reddy and Nagabhushanam 2011; Yuce et al. 2010; Zhang et al. 2013a)
3. ^cGupta (2013), Pandey and Chadha (2003), Mekkawi (2004), Gupta (2002)
4. ^dDef is abbreviation for deformation

Table A-3 Alarm potential of monitoring parameters and usability for back-calculations

1. ^aSparks (2003), Bonaccorso et al. (2013), Langer et al. (2011), Špičák et al. (2004)
2. ^bGoodman and Powell (2003)

Table A-4 Monitoring parameter interrelation