Which method involves using contour lines to determine precipitation distribution?

The method that involves using contour lines to determine precipitation distribution is the Isohyetal method. This approach utilizes isohyets, which are lines on a map that connect points receiving equal amounts of precipitation. By drawing these lines, hydrologists can visualize variations in rainfall over a specific area, allowing for a more accurate estimate of precipitation distribution than simpler methods, such as the arithmetic mean, which calculates the average without accounting for spatial variation.

The Isohyetal method is particularly useful in regions where precipitation is unevenly distributed due to factors like topography, climate, and weather patterns. It helps in flood modeling, water resource management, and designing drainage systems by providing a clearer picture of how much rain falls at different locations.

In contrast, the arithmetic mean method simply averages precipitation data from various gauges, not considering spatial distribution. The SCS method is typically used for hydrologic modeling of rainfall-runoff relationships but does not focus on mapping precipitation distribution directly. Hydrograph separation refers to the breakdown of total streamflow into components, such as base flow and surface runoff, and also does not pertain to the contour-based analysis of precipitation.