 It is particularly vulnerable to floods because it is a naturally enclosed basin and because very few natural drainage basins remain, as many of the aquifer system streams and rivers have either dried up or encased and converted into sewers.The hydrological cycle used to be in equilibrium; elevated mixed forests interacted with infiltration, evapotranspiration, and with the system of rivers, seasonal streams and lakes that acted as watersheds, or drainage basins, for precipitation runoff.The monsoon season is characterized by high intensity storms of short duration, averaging 800 mm of annual precipitation (although this spreads differently by region