Risk profile for reservoir dredging
Type:
Presented during:
CEDA Dredging Days 2024
Authors:
S. Sarkar and M.K Sarkar
Abstract
A reservoir is a large natural or artificial lake created using a dam to store fresh water. Reservoirs form a vital part of the Earth's water supply system. With climate crisis, droughts and drying up of lakes and reservoirs as well as devastating floods caused by excessive rains are becoming frequent. UN Water has mentioned climate change as a water crisis. Sedimentation of the reservoirs not only diminishes the storage capacity but also compromises the purpose of the reservoir and safety of the dams. Appropriate sediment management strategies are necessary to tackle reservoir sedimentation problems and water crises resulting from climate change. Dredging, if planned carefully is an effective and sustainable solution for sediment management and restoration of reservoirs. The location and type of reservoir, volume of sediments present, challenges in transporting and launching equipment, selection of equipment and disposal of dredged material have to be considered. Most reservoirs have multiple users leading to competition and potential conflicts among user groups. Reservoirs are often associated with complex and sensitive ecosystems. The effects of reservoir dredging on ecosystems need to be assessed in 3-dimensional space and time. Removal and disposal of contaminated sediments in reservoirs present additional challenges. 'Risk Profile' for reservoir dredging is necessary to reduce risks on stakeholders with minimal damage to associated ecosystems and environment. Identification of stakeholders and decision makers for reservoir dredging facilitates in a stake-holder driven process. Reservoir dredging life cycle consists of pre-tendering, tendering, mobilisation including site set-up, execution and demobilisation including site restoration phases. Risk identification, categorisation and rating associated with these phases are necessary for risk management and risk response. Reservoir dredging risks need to be mapped with risk tolerance of various stakeholders for optimizing the risk appetite of the stakeholders. This paper presents the risk matrices for different phases of reservoir dredging operations, highlighting the critical risks for different types of reservoirs.
Keywords: Risk Profile, Reservoir Sedimentation, Reservoir Dredging, Water Crisis