*5.2.2 Disaster variables*

*Recent Advances in Flood Risk Management*

phenomenon is repeated at a high rainfall and exceeds the 5-year moving average. Damage includes the destruction of thousands of cars, the displacement of hundreds of families, the evacuation of homes in the affected areas and the nearby neighborhoods during the crisis, in order to avoid possible future rains, the destruction of farms, and the emergence of mental disorders of people who lived the disaster. Losses were estimated at \$ 3 billion, resulting in damages of \$ 5.1 billion [3]. In this context, it was necessary to address the environmental impact assessment of the floods, to determine the size of the disaster and its geographic distribution, and thus to identify the factors and dynamics of the flow of water and drifting load, so that the appropriate solutions can be conceived and the right decision can be taken. The study is subject to global climate changes and specifically with the expectation of increased rainfall and simultaneous rainfall frequency in the coming years in extreme quantities [15]. The concept of environmental impact assessment emerged at the beginning of the 1960s and included all studies on the direct or indirect impact of any intervention on the environment based on a vision that includes planning and forecasting. The environmental assessment study of a project examines the potential or resulting environmental impacts, identifies appropriate actions to address adverse impacts and minimizes them, and achieves positive returns to the environment in line with existing standards. The environmental assessment process requires identifying all elements that can be classified, its structure in terms of basic data organization, prediction of impacts and changes, and providing solutions and recommendations [16]. The evaluation process has two main aspects: the first aspect is the interactive planning of a purely technical and administrative nature, while the second is participatory planning involving a technical and administrative part. The technical aspect includes study, interpretation, and prediction of the project. The management aspect focuses on the sound decision-making process, with ongoing field monitoring of the environmental impact of the project. The impact study is based on three methods: identifying impacts, developing strategies, and evaluating variables. The effects are identified using several methods, including ad hoc methods,

checklist impacts, matrices, networks, overlays, and models.

• Analysis of results and preparation of standards.

• Procedures for investigation and preparation of diagnosis.

This typology can help to make decisions at four levels:

• Describe and present results systematically and formally.

• Decision modeling and operational methods.

• Sort them according to their own values.

• Choose the best procedures.

• Sort by relevance.

The environmental impact assessment process is based on several criteria which allow for the appropriate decision of environmental solutions at four levels:

• The subject matter of the decision and the activities involved in the original

*5.2.1 Multiple standards to support decision-making*

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problem.

The flow of floods in deserts and arid regions is a product of the interaction of a number of factors and physical and human variables that overlap and affect each other at different degrees. In this context, the cause of the disaster floods in the city of Jeddah is due to a range of variables, including those listed below.

The high density of the hydrographic network and the absence of widening of the sewage for the flow quantities with the intensity of the descent of the springs; the intensity and the high rates of precipitation in short periods, which were in the form of convective and frontal storms and the absence of channels and waterways suitable to absorb the flowing quantities, in addition to the urban expansion of the city on the valleys; and the lack of a strong infrastructure to contain the rapid population growth. Moreover, these variables include the rise of the water table due to the leakage of sewage, irrigation, and rainwater with the high level of seawater.
