The SWMM 5.0.001 to 5.1.013 main components are: rain gages, watersheds, LID controls or BMP features such as Wet and Dry Ponds, nodes, links, pollutants, landuses, time patterns, curves, time series, controls, transects, aquifers, unit hydrographs, snowmelt and shapes (Table 3). Other related objects are the types of Nodes and the Link Shapes. The purpose of the objects is to simulate the major components of the hydrologic cycle, the hydraulic components of the drainage, sewer or stormwater network and the buildup/washoff functions that allow the simulation of water quality constituents. A watershed simulation starts with a precipitation time history. SWMM 5 has many types of open and closed pipes and channels: dummy, circular, filled circular, rectangular closed, rectangular open, trapezoidal, triangular, parabolic, power function, rectangular triangle, rectangle round, modified baskethandle, horizontal ellipse, vertical ellipse, arch, eggshaped, horseshoe, gothic, catenary, semielliptical, baskethandle, semicircular, irregular, custom and force main.