Why would the isohyetal method typically provide the most accurate average areal rainfall for a watershed with complex topography, compared to other standard methods?

The isohyetal method typically provides the most accurate average areal rainfall for a watershed with complex topography because it uniquely accounts for the highly non-uniform spatial distribution of precipitation that such terrain creates. Average areal rainfall represents the total volume of rainfall over a watershed's entire surface area, divided by that area, yielding a single representative rainfall depth. This value is critical for hydrological analyses like flood forecasting or water resource management. Complex topography refers to landscapes characterized by significant variations in elevation, such as mountains, valleys, and steep slopes, which profoundly influence atmospheric conditions and precipitation patterns. For example, moist air rising over mountains expe....