Determining discharge rating curve at Karai sub watershed

Abstract

Abstract The availability of discharge rating curve equation in a watershed is very important to predict river discharge in a watershed, while discharge shown the water availability in a watershed. This research aims to determine discharge rating curve equation at Karai Sub Watershed in rainy season. This research was conducted by recording water level using water level logger and measuring river discharge using current meter and then analyze the relation of the water level and river discharge data to make the equation of discharge rating curve. The equation of discharge rating curve determined by using several methods that are polynomial, linear, power function, logaritmic and exponential. The equation which obtained by that methods will be examined by the value of coefficient determination (R2) and root mean square error (RMSE). The result shown the best methods in obtaining the equation was polynomial method which performs the R2 = 0.849 and RMSE= 0.01 with the equation Q = -1.327h2 + 3.807h - 0.215.