Abstract
The current condition of the Cisangkuy sub-watershed has undergone many changes in land use
from non-developed areas to built-up areas such as settlements, housing, etc. This resulted in not much rain
falling in the upper reaches which could seep into the ground but rather more surface runoff, thereby increasing
flood discharge in the Cisangkuy River (CR). This study aims to analyze the effect of land use change on
existing flood discharge and recommend the most effective control alternatives to flood discharge. the analytical
method used is one of the Synthetic Unit Hydrograph (SUH) which is often used in the calculation of flood
discharge in Indonesia is the Nakayasu (1940) SUH. The results showed that there was a change in the value of
runoff coefficient from 2009 amounting to 0.33 to 0.39 in 2018 due to changes in land use. Flood debit is
getting bigger every year. After calculating the return value of flood period 1000 years in 2009 is 472.70 m3
/sec,
in 2012 is 489.16 m3
/ sec, in 2015 of 516.89 m3
/sec., and in 2018 becomes 545,27 m3
/ sec. After modeling the
existing condition of the CR, there are several points that flooding occurred. These problem needs flood control
by normalizing the cross section of the CR, so that it can reduce the elevation of flood water levels and floods
can be overcome

Key words: Cisangkuy sub-watershed, Flood control, Land use, Nakayasu Hydrograph