🌧️ Rules for NRCS Unit Hydrographs in InfoSWMM 📈

Subject: 🌧️ Rules for NRCS Unit Hydrographs in InfoSWMM 📈

When applying NRCS (Natural Resources Conservation Service) Unit Hydrographs for hydrological modeling in InfoSWMM adhere to the following rules or guidelines to ensure accurate hydrological simulations:

1. Curve Number (CN) Source 🗂️: Obtain the Curve Number (CN) from the NRCS_CN column in the Subcatchment Table, representing runoff potential based on soil type, land use, and treatment practices.

2. Time of Concentration (TC) ⏱️: The Time of Concentration, critical for hydrograph development, is sourced from the TC column within the Subcatchment Table.

3. Infiltration Model Selection 💧: Select the Infiltration Model according to the CN Infiltration Model Column in the Subcatchment Database Table to ensure consistency in infiltration calculations.

4. CN Consistency Across Tables 🔄: The CN value in the Soil Database Table must match the CN in the Subcatchment Database Table for uniform hydrological parameters.

5. Depression Storage and Initial Abstraction 🕳️➡️💧: If Depression Storage is zero in the Subcatchment Database Table, Initial Abstraction (IA) in inches will be internally calculated using the formula $��=0.2\times (1000\mathrm{/}��-10)$.

6. Initial Abstraction Calculation ✏️: Clearly state that Initial Abstraction in US units is $��=0.2\times (1000\mathrm{/}��-10)$, indicating the use of American measurement standards.

By following these emoji-highlighted guidelines 📝, hydrological modeling using NRCS Unit Hydrographs within InfoSWMM will be precise and reliable, leading to better water management outcomes. 💦🏙️