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Objective In this study， the effect of seasonal lake level changes on the sedimentary characteristics， growth process， and sedimentary architecture of the finger bar in shallow delta fronts is clarified. Methods Based on the modern mud and sand and hydrological data of finger bar in the Ganjiang Delta， sedimentary numerical simulation software Delft3D， which is commonly used in China and elsewhere， is used to conduct numerical simulation of the sedimentation of the finger bar under seasonal lake level changes and constant lake level conditions， comparing the differences in sedimentary architectures. Results The study shows that under seasonal lake level changes， the finger bar exhibit the following sedimentary architecture and growth evolution characteristics： （1） There are few finger bar， small curvature （average ~1.42）， long length （average ~9.2 km）， thick in the middle， and thin at the edge， with a thickness difference of 15.4 m. There is no evident confluence between the finger bar， presenting a plane combination style dominated by bird-foot shape. （2） The finger bar develop deep distributary channels， the natural levees are wide and thick， and the thickness of the single-stage accretionary body in the mouth bar is large. （3） The finger bar exhibit stable growth. During lake level drop， the finger bar undergo progradation， the distributary channels are mainly eroded-extended， and mouth bar deposits are formed at the front edge of the distributary channels. The distributary channels are also affected by the mouth bars and undergo diversion and breach， forming multiple terminal distributary channels， and the natural levees are almost undeveloped； during lake level rise， the finger bar undergo retrogradation， the erosion of the distributary channels is weak， the distributary channels are abandoned and optimized， and the natural levees on both sides of the distributary channels accumulate and continue to thicken. For constant lake level， the finger bar show the following sedimentary architecture and growth evolution characteristics： （1） There are many finger bar， with large curvature （average ~1.53）， short length （average ~7.2 km）， large overall thickness （maximum and minimum thickness differ by only 4.8 m）， and no evident topographic difference； multiple finger bar are constantly bifurcated and merged locally， forming a complex the finger bar network， and the plane combination style of the finger bar is mainly interlaced. （2） Deep distributary channels are developed in the finger bar， the single-stage accretion body of the estuary bar is thick， but the most important difference is that there is no natural levee deposition. （3） The growth process of the finger bar is relatively simple， with multiple the finger bar growing simultaneously， intertwining with each other， and finally forming an interlaced plane combination style. Conclusions Therefore， seasonal lake level change is an important formation condition for the finger bar at the front of shallow deltas， promoting the development of natural levees， improving the stability of distributary channels and the finger bar， and playing an important role in controlling the sedimentary architecture and growth process of the finger bar.
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| 科 Family | 属数 Number of genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) | 属 Genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) |
|---|---|---|---|---|---|---|
| 鹅膏菌科Amanitaceae | 2 | 11 | 5.26 | 鹅膏菌属 Amanita | 10 | 4.78 |
| 小菇科 Mycenaceae | 2 | 12 | 5.74 | 丝盖伞属 Inocybe | 5 | 2.39 |
| 多孔菌科 Polyporaceae | 8 | 14 | 6.70 | 蜡蘑属 Laccaria | 5 | 2.39 |
| 红菇科 Russulaceae | 3 | 23 | 11.00 | 小皮伞属 Marasmius | 6 | 2.87 |
| 小菇属 Mycena | 11 | 5.26 | ||||
| 光柄菇属 Pluteus | 5 | 2.39 | ||||
| 红菇属 Russula | 17 | 8.13 | ||||
| 栓菌属 Trametes | 5 | 2.39 |
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