Rain falling on the Watershed will turn into a stream in the river, this is because the rainwater is not entirely infiltrated into the soil, the unabsorbed water is called surface runoff. Factors affecting runoff are meteorological elements and drainage elements. This study aims to calculate the surface runoff coefficient using land cover maps 2017 and 2050, slope and soil type as parameters. Cook method divides the watershed characteristics into 4 sections as parameters to calculate the runoff coefficient of topography, soil type, vegetation cover and surface deposit. Each parameter is weighted based on its characteristics to calculate the coefficient of surface runoff symbolized by the letter C. The analysis results show that in the year 2017 obtained the value of C = 0.4734 and for the year 2050 C = 0.4785. There's a difference of 0.0051 coefficient of runoff value between land use map and land cover in 2017 and 2050. The results of this study will be used to calculate the flood discharge design in the object of research in Makassar City.

Precipitation is the descent of water from the atmosphere to the surface of the earth which is usually rain, snow, fog, dew and hail, the amount of water falling on the surface of the earth can be measured by rain gauges, the distribution of rain in the space can be known by measuring rain in some locations and areas reviewed. In a variety of human activities, rainfall becomes one of the data needs, especially in the study of water availability for consumption, irrigation building planning and mapping of flooded areas. This study aims to analyze local rainfall data on research objects by utilizing global weather data, the observation period for 15 years i.e., from 2000-2014. This research using Thiessen polygon method based on Geographic Information System (GIS) application, rainfall data sourced from global wheater, accessed on August 28, 2017. The results showed that the distribution of rainfall in the research object is represented by 2 rainfall stations, namely station p_521194 and station p_521197. The highest maximum daily rainfall occurred in 2002 of 149.80 mm while the lowest occurred in 2008 amounted to 68.76 mm. Rainfall data will be used to analyze flood discharge in Makassar city.

Flooding is a threat to coastal cities such as Makassar City. To Avoid the threat of flooding, it is necessary to determine the ground level of the building. This study aims to develop a spatial model for determining the ground level of buildings for Makassar City based on climate change data and environmental geography. Prediction of sea level rise using MAGICC/SCENGEN application, GIS-based satellite image analysis, rainfall analysis using Thiessen polygon method, surface runoff coefficient value determined by Cook method, and design flood discharge analysis with HSU Nakayasu method. The spatial model of the ground level of Makassar City building for 2030 is a function of sea tides, sea level rise due to climate change, alluvial floods and inflow floods that can occur simultaneously. The model produces a spatial map with attributes of geographic coordinates (x,y,z).

Migration from rural area to urban area increases urban population. It increases and needs for settlements, leading to conversion of agricultural lands into settlement areas. Inconsistent land use compared with spatial planning causes change in land use. Spatial land use expansion can be monitored and predicted by modeling. NetLogo application is a software integrated with Agent-Based Modeling (ABM), which can be used to predict change of land use with various complex parameters. The present study used population growth as a parameter to predict change of land use of Makassar in 2050 based on 2017 land use classification map as the start of the prediction. The analysis result showed that the biggest change of land use happens to Settlement class which is 594.74 hectares and the smallest is Water Body class which is 8.76 hectares.