RUSLAN WIROSOEDARMO, FAJRI ANUGROHO, NOFA RATNA SARI ANDKIKI GUSTINASARI
Abstract
The main factor of watershed quality degradation is an unsuitable land use change due to the increased population growth that trigger the need for land resources. Gunting sub-watershed is one of the existing sub-watershed in Jombang Regency, East Java. The land use for forest (X1), garden (X2), settlement (X3), irrigation paddy (X4), rainfed paddy(X5), shrub (X6) and field (X7) areas in the sub-watershed area of Gunting in the comparison years of 2009 and 2014 had been changed. The land use for forest, settlement and shrub areas were increase by 0.208%, 2.278% and 0.158%, respectively. However, the land use for garden, irrigation rice field, rainfed rice field areas were decreased by 1.511%, 0.544%, 0.201%, 0.389%, respectively. The flood discharge in m3/s (Y) was influenced by seven land uses with the linear trend of Y = 196.959 + 0.067 X1 + 0.028 X2 + 0.058 X3 + 0.033 X4 + 0.080 X5 + 0.051 X6 + 0,056 X7. Flood discharge was 167.515 m3/s in 2009 increased to 226.402 m3/s in 2014. The land use for settlement had high impact on flood discharge as shown in a strong correlation coefficient.