Why is it important to crack - dry
during pond Preparations.

The drying of the pond bottom is the most practical cheap and effective method of eliminating undesirable species in the pond prior to the culture period. Drying oxidizes harmful chemical substances especially sulphides and facilitates mineralization of organic matter. The pond is dried until the soil cracks or when it is firm enough to hold one's weight without sinking more than 5 cm on walking over the surface.

Hope that answers your question.

answer: tributaries flow into rivers.

wetland is a biome that develops when the water gets accumulated in a land exhibiting a huge depression. these form either seasonally or permanently. the water in the wetland comes from rivers, lakes, ocean, flood, rain or other sources. the wetlands includes mangroves, marshes and peatland.

tributaries flow into the rivers develops a wetland because such water will get deposited in the depression and will restrict the original flow of tributary water. hence, water with low drainage current combines with the river water.