Population growth provokes environment problems related to space. Interaction between human and environment is very complex. Human pressure causes forest conversion from forest to other land uses which is also expressed as conversions in land cover types. Those changes are mostly caused by economic and population growth reasons. People always maximize their land to get the best benefit by choosing the commodity that gives the best benefit. Population growth needs more space for their settlement, housing and farming so that people cut down the forest. The wood will be used to make their house. One of the effects of land cover is flood on the down stream. This research aims to analyze the pattern of land cover change during 1992 to 2003 and to analyze the effect of land cover change to the discharge and flood hazard on the down stream. Land cover change in Gesing subwatershed can be divided into three parts. Land cover in the upper part changed slightly. The down stream the changing is relative not significant. The most significant land cover change happened on the middle part of Gesing subwatershed. During 1992 to 2003 the forest area decreased from 2934.76 ha in 1992 to 2419.41 ha in 2003. In the same time, the barren land increased from 102.89 ha in 1992 to 455.24 ha in 2003. Plantation area also increased from 885.67 ha in 1992 to 1048.38 ha in 2003. Conversion from forest to plantation is the highest. Total conversion area from forest to plantation is 545.84 ha. The conversion from forest to plantation occurred because the people interested in clove that gives more benefit to them. Decreasing land cover influences a negative effect on hydrological processes. It affected to the discharge. The discharge in 1992 and 2003 were modeled using PCRaster. Based on the modeling, discharge during 1992 to 2003 increased 31.28m3/s. Discharge in 1992 is 79.97m3/s and discharge in 2003 is 111.24m3/s. Increasing discharge affects to the flood hazard on Piji Kibon. In this research, flood hazard was determined by flood height. The flood height in Piji Kibon was determined using kriging in ILWIS 3.3. Based on kriging, flood height increases during 1992 to 2003. Flood height in 1992 varies from 0-0.7m and flood height in 2003 varies from 0-0,98m. The flood extent also increased. The flood area in 2003 is wider than in 1992. The flood increasing flood height is not mainly caused by land cover change. It is also caused by the rainfall and may be caused by sedimentation on the river.