| description abstract | Two relatively simple physical oceanographic processes are suggested as plausible explanations for the biblical description of the Israelites' Crossing of the Red Sea during their exodus from Egypt. The first involves strong wind that blows along the Gulf of Suez and pushes the water a considerable distance away from the regular shoreline. This process is examined with the aid of a simple conceptual model consisting of a shallow, narrow, and long channel (corresponding to the Gulf of Suez) connected to a large body of water (corresponding to the main body of the Red Sea). Uniform wind is allowed to blow over the entire gulf for a period of about a day and the resulting phenomena are examined by solving the appropriate governing equations. It is shown that, in a similar fashion to the familiar wind setup in a long and narrow lake, the water at the edge of the gulf slowly recedes away from its original prewind position. The receding distance of the shoreline and the associated sea level drop are computed by solving the nonlinear equation that governs the motion resulting from the wind. It is found that, even for moderate storms with wind speed of about 20 s?1 receding distance of more than 1 km and a sea level drop of more than 2.5 m are obtained. These relatively high values are a result of the unique geometry of the gulf (i.e., its rather small width-to-length and depth-to-length ratios) and the nonlinearity of the governing equation. Upon an abrupt relaxation of the wind, the water returns to its prewind position as a fast (nonlinear) gravity wave that floods the entire receding zone within minutes. It is suggested that the crossing occurred while the water receded and that the drowning of the Egyptians was a result of the rapidly returning wave. The second possible mechanism that is considered is a tsunami (i.e., a flood resulting from an earthquake under the sea)m that arrived at the Gulf of Suez from the main body of the Red Sea. In a similar fashion to the wind setup mechanism, a fast nonlinear gravity wave that could be responsible for the drowning is involved. Of the two possible mechanisms, the wind setdown appears to be a more plausible explanation, because it is more closely related to the biblical description in terms of the strong wind prior to the event, the receding water, and the crossing in the midst of the sea. | |
