Dear Preeti Koirala,

Maybe this link be useful:

https://swmm5.org/2017/11/06/epa-swmm-5-water-quality/

The key concept is to recognize how the different land uses affect hydraulic and hydrologic variables. For example, sub-catchment elements allow modifying the percentage of impervious area, which is very high for developed terrain and very low for natural environments. The selection of the Manning's coefficient for overland flow and of the equation for the infiltration are also important decisions that should be related to land use. Similarly, natural channels present in undeveloped zones tend to meander (smaller slopes), and have higher resistance to flow. These aspects should be reflected in the choice of parameters for the link elements.

If modeling wastewater, different land uses present different volumes and patterns, which need to be defined at the junctions and with the time pattern/series tools. If modeling continuously (and not only event-wise) groundwater variables can be defined in aquifer elements, and these can similarly be tied to land use. Finally, water quality simulations have their own inputs that relate to contaminant build-up and wash-off that need to be consistent with use type. The land use editor is but one of the tools under the water quality engine that allows you to communicate this heterogeneity to your model but, as usual, you should first consider the hydraulic behavior before entering quality considerations.

Land use types defined in SWMM are mainly used for setting parameters related to pollutant accumulation and erosion process.