Abstract: In order to solve the problems of low exploration accuracy and difficulty in improving resolution in the
process of comprehensive engineering geological exploration in shallow water areas, we introduce transient
electromagnetic method as an alternative into shallow water engineering geological exploration. With the detailed
analysis of the previous transient electromagnetic results and based on Maxwell's equations, the formula for
high-precision transient electromagnetic response for multi-turn rectangular small frame current source in shallow
water is derived, and the induced voltage expression is obtained. The half space simulation models with shallow water
layer and underwater layer are designed, respectively. Forward modeling of the transient electromagnetic response in
the stratum with shallow water layer is conducted. The high precision transient electromagnetic optimization
inversion technique for the layered earth in shallow water is studied, and the practical engineering application verifies
the feasibility and effectiveness of the forward and inversion technique.

Key words: Transient electromagnetic method, Shallow water area, Engineering geological survey, Forward
modeling, Inversion