in the series of questions, a lot of discussion is mentioned about drainage. Here is a simple way to find out how to see what kind of drainage you have.
*Drainage is important to plant growth and success in the garden.
First dig a hole perhaps a foot deep and wide. Then fill it with water and see how long it takes to drain. If it disappears in a half hour or less, you have good drainage. if the water is still there the next day, you likely have poor drainage. Sandy soils tend to be well drained, and clay or adobe tend to be slower draining.
Season of the year is also a factor. If you do this test in winter when rains have saturated the soil, moisture will seep into the soil at a much slower rate. An additional factor about winter rainy season is that a water table(the underground level of subterranean moisture levels) can come up and drown plants. This is common around bodies of water such as lakes, rivers, streams. It can also depend on the substrata of the rock layers well below the soil surface. Simply put, the water level comes up very high beneathe the ground surface and this condition will drown plant roots which need oxygen to live. Some plants are very sensitive to this condition and will die outright(cherries, peaches/nectarines, apricots, rhododendrons, azaleas, camellias and their relatives(Ericacea family in general)
If you have poorly draining soil, don’t give up hope. You can plant, just plant everything on a high mound or berm so roots will have a place to grow above the typical soil grade. Many plants can grow like this and do quite well in an otherwise poorly draining site.
Or you can just plant riparian type species and bog species, of which there are many choices. Willows, poplars, cottonwoods, birches, elderberries(Sambucus species, cvs.)
Japanese iris, other water loving iris, etc. there are many choices!