Flooding is a natural event that causes extensive environmental damage. Due to consecutive floods in the past, the impacts of these catastrophes on soil properties have already been witnessed and there are significant economic losses. It brings changes to soil quality in addition to different socioeconomic losses. A huge amount of debris is deposits on the agricultural plains and contaminates the plain. Because the importance of agricultural plains as a source of food security increases in terms of the development of any country. Flood occurrence results in several physical, chemical, and biological changes in these agricultural soils such as changes in pH, redox potential, cation exchange capacity (CEC), decreased oxygen level, and potential poisonous elements. The potentially toxic elements are contaminants for soil and can leach into underground water and are transported to humans by plant-based food. Biochar can lessen the effects of soil alterations brought on by flooding. The change can be restored by biochar. In this chapter, flood-related physical, chemical, and biological changes are discussed, along with the use of biochar to mitigate soil alterations.