(8)
Where \(\overset{\overline{}}{Y_{i}}\) is the average elevation within the neighborhood of the i-th point on the bottom line of the runoff path, \(\overset{\overline{}}{Y_{\text{imin}}}\) is the minimum elevation of the i-th point on the bottom line of the runoff path, and m is the point on the bottom line of all runoff paths in the runoff plot.
2.3.3. Determination of runoff characteristics
Surface runoff coefficient was used to reflect the surface runoff characteristics of each runoff plot. When studying the coupling effects of the spatial distribution of cypress and topography on surface runoff coefficient, it was necessary to eliminate the interference of extreme rainfall events on surface runoff coefficient. Therefore, the rainfall intensity with the most frequent occurrence in this area was taken as the standard, and 10 groups of runoff and precipitation data with similar rainfall intensity were selected to calculate the surface runoff coefficient: