What is the appropriate term for a map that depicts the variations in rainfall?

An isohyetal map is specifically designed to represent variations in rainfall by using lines, known as isohyets, that connect points of equal precipitation. This type of mapping is crucial for understanding meteorological patterns and making decisions in fields such as agriculture, water resource management, and civil engineering.

The isohyetal map provides clear visual representations of rainfall distribution over a particular area, allowing observers to easily identify regions that receive more or less rainfall. This is particularly useful for assessing drought conditions or planning irrigation systems.

While other options may relate to geographic data, they do not focus specifically on rainfall variations. A cartographic map can refer to many types of maps without specializing in any particular data such as rainfall. An assessment map typically evaluates land use or property values rather than precipitation. A hydrological map, on the other hand, relates more broadly to the water cycle and water resources rather than exclusively depicting rainfall. Thus, the isohyetal map is the most accurate term for a map that captures variations in rainfall.