Temporal and Spatial Distribution of Underwater Light Field for a Waterfront Tide-Influenced Water Body

The underwater light model for Neijiang was established.Two typical tidal cycles in flood season and dry season were selected to demonstrate the underwater light field characters in Neijiang.The results were as follows: The underwater light condition in flood season was distinctly better than that in dry season. The light intensity at 0.3m depth decreased by 89.1%,83.5% than that at the water surface in flood and dry season respectively. Light intensity in the east region of Neijiang in flood season was in average increased by 59.2% than that in the west region, and in dry season the light intensity in the north and south bottomland of Neijiang was about 2.63 times than that in the mainstream. The impact of tide on underwater light distribution in flood season was not evident, but in dry season, as a result of the greater tidal gap suspended sediment began to settle down during the ebb-tide, and the underwater light intensity increased by 47.2% than that during the spring tide in average.