Barito River
Banjarmasin is located on Barito basin and divided by the Martapura River into two parts. Slope of the city is 0.13% and the land is generally flat and low lying. The geological foundation of the city is dominated by clay and sandstone, but also includes alluvial sediments from the river. Several smaller rivers exist which form a dendritic drainage pattern. All the smaller rivers are connected to either the Martapura River or Barito River. The city's river system is affected by tides. The city is located in a swampy region and is generally below sea water level, making it prone to being flooded by tidal waves.