Hydrology
Contents
Hydrology#
The hydrologic processes in the Storm Water Management Model (SWMM) encompass a range of components designed to simulate the complex interactions of water within an urban drainage system. SWMM incorporates precipitation input to model rainfall-runoff processes, allowing users to input data such as rainfall intensity, duration, and temporal distribution. The software employs various hydrologic methods, including the Soil Conservation Service (SCS) Curve Number method, Green-Ampt infiltration model, and Horton infiltration model, to simulate the movement of water through different land surfaces.
Additionally, SWMM accounts for snowmelt by integrating temperature-based methods to estimate snow accumulation and melting rates. The model also considers groundwater interactions, enabling users to evaluate the impact of saturated and unsaturated subsurface flow on overall drainage. By comprehensively addressing these hydrologic processes, SWMM provides a robust platform for assessing the performance of stormwater management systems and designing effective urban water infrastructure.
SWMM as a hydrologic model#
The two major components to employ SWMM as a hydrologic (runoff generation) model are:
Sub-catchments
Raingages
The subcatchment elements are a special type of node that has properties of area, slope, width, and connectivity to an ordinary, storage,or outfall node. The element also has an infiltration model (runoff generation) associated with it.
The raingage objects serve as input devices that record precipitation data for hydrological modeling. Typically a time-series of rainfall (hyetograph) is supplied for simulating and analyzing rainfall-runoff patterns within the drainage network. The subcatchment(s) (above) receive inputs from one or more raingages; convert the excess into runoff, route that excess to the subcatchment outlet, which then feeds into hydraulic elements to produce an integrated hydrology and hydraulic simulator.
A couple of examples that focus on the hydrology follow:
Examples#
Simple