Abstract
Abstract The annual runoff coefficient required a single hydrograph and hourly rainfall in a year. The relationship between the river regime coefficients and runoff coefficients will produce correlations in linear equations. The calculation results obtained the relationship of the River Regime Coefficient (KRS) with Runoff Coefficient in the Sidutan Watershed is proportional with the equation y = -2E-05x2 + 0.0048x -0.0539 with the coefficient of determination R2 = 0.6796. KRS values obtained in 2011-2016 were respectively 67.69; 43.99; 188.92; 53.78; 45.01 which is included in the low to to high classification range. This indicates the watershed is in bad condition. Runoff coefficient (C) each 0.188; 0.101; 0.229; 0.163; 0.148 shows good classification, so that the watershed is in good condition. In the Reak River Basin, the relationship between KRS and C is proportional with the equation y = 0.0003x2 -0.011x + 0.1618 with a coefficient of determination R2 = 0.7855. KRS values obtained in 2011-2016 are respectively 27.46; 29.80; 31.06; 16.96; 14,11 which are included in the very low to low classification range. This indicates the watershed is in good condition. Classification of good C values respectively 0.071; 0.106; 0.110; 0.074; 0.058, indicating that the watershed is in good condition.