EVELOPMENT OF RISK ASSESSMENT AND MANAGEMENT MODEL FOR CONSTRUCTION OF DAMS

Abstract

Risk assessment and management study for dams is a very complex problem, because dams constitute the biggest construction projects and have long term effects. A large number of issues ranging from social to environmental, hydrologic to structural, construction to failure are involved. These issues carry significant risks which can affect the project in positive and negative manner. The best approach to tackle such problems is to formulate an effective risk management study wherein risks are identified before hand, evaluated, mitigated and a risk management strategy formed for every likely risk. If the risks are not given due consideration then the end results maybe catastrophic. The objective of this study is to better understand the risk assessment techniques for dam and give its practical demonstration. Another objective is to investigate in depth the environmental, social and water related risks due to Dam Construction Project. All these issues are subject of much debate. Hence results obtained in this study will help to see these issues in proper perspective. The general methodology adopted is to identify broad categories for risk management study. The techniques used for risk identific ation includes filling of questionnaire by the key project participant, previous experience, interviews with key project participants, and b rain storming with project team, then with in each category risk variables list is drawn and each identified risk is analyzed and evaluated in detail. Risk mitigation and aversion options are discussed, Risks are given a rating ii and their management strategy formulated. The study also discusses both positive and negative risks to help in forming a balanced opinion. It is concluded that the Dam Project poses various social and environmental risks. These risks though small in magnitude have the potential to affect the project or delay its completion. In this study a wide range of these risks have been evaluated and it is found that these risks are manageable. This can be achieved by due compensations and taking proper mitigation measures. Based upon this study a risk assessment and management model has been developed which can help in the management of risk that can occur in these types of projects. The most important risk is of assured water availability or chances of filling the dam. The study has discussed historic inflows, reservoir operations and sedimentation losses to arrive at a rational understanding of situation. The Bhasha versus no Bhasha scenario upstream Tarbela is discussed which establishes that Tarbela Dam will gain another lifeline by timely construction of Bhasha Dam. In addition, precious water wasted in floods can be utilized for storage. Various supply and demand scenarios have been evaluated to arrive at a rational estimate of reservoir filling. The results of this study are encouraging and may be helpful for the planners working on the project. The study also lays down the principles for risk assessment and management which can be used in further studies.