Was Crocodile stronger at Marineford? Or was he holding back in Alabasta?

 During the Alabasta arc, Crocodile displayed a level of power that was initially considered overwhelming by the Straw Hat Pirates. He possessed the Logia-type Devil Fruit called the Suna Suna no Mi (Sand-Sand Fruit), which granted him the ability to control and transform into sand. He had a reputation as a Shichibukai and controlled the desert kingdom of Alabasta from the shadows. His strength was showcased through his battles with Luffy and others. At Marineford, Crocodile was present as part of the war that took place at Marine Headquarters. While he did participate in the battle, he didn't display the same level of dominance as some other powerful characters present. This has led fans to speculate that he might not have been as strong as initially portrayed in Alabasta. It's important to note that power scaling and character abilities can be subject to interpretation and development by the author. Oda often keeps details deliberately open-ended to keep the story intriguing.

How were dams historically used?

 Dams have been used by humans for a variety of purposes throughout history. Some of the main ways in which dams have been used include:

Water storage: One of the most common uses of dams is to store water for irrigation, domestic use, and other purposes. Dams can be used to store water in reservoirs, which can be used to provide a reliable source of water for agriculture, industry, and other purposes.

Flood control: Dams can also be used to control and regulate the flow of water in rivers and streams, helping to prevent floods and protect communities from the destructive effects of rising water levels.

Hydroelectric power: Dams can be used to generate electricity by harnessing the energy of falling water. Water stored behind a dam is released through a turbine, which generates electricity as it spins.

Navigation: Dams can be used to improve navigation on rivers and streams by creating a series of locks that allow boats to move between different water levels.

Recreational use: Dams can also be used for recreational purposes, such as swimming, boating, and fishing.

Overall, dams have been used throughout history for a variety of purposes, including water storage, flood control, hydroelectric power, navigation, and recreational use.