Structure

Changes in the shape of the bottom of lakes, rivers, or impoundments, especially those that influence fish behavior. Examples include flooded roadbeds, washes, arroyos, humps, ledges and drop-offs.

The patterns of the distribution of matter in the universe, as probed by the cosmic microwave background radiation or observations of galaxies.

Arrangement of components in a forest. Vertical structural layers include overstory trees, understory trees, snags, shrubs, and herbs. Horizontal structural layers include number and species of trees, spacing of trees, and number and species of shrubs and herbs. Forest structure affects ecological processes and biodiversity.

Any apparatus constructed to divert or impound water, such as a berm, head gate, pipe, or well.

See "data structure".