Model detention discharge, storage change, and attenuation quickly. Enter inflow, timing, and routing constants easily. Compare scenarios with tables, graphs, exports, and practical guidance.
| Scenario | Start Inflow (m³/s) | End Inflow (m³/s) | Initial Outflow (m³/s) | K (hr) | Time Step (hr) | Steps |
|---|---|---|---|---|---|---|
| Detention Basin A | 25 | 8 | 5 | 2.5 | 0.5 | 10 |
| Channel Reach B | 18 | 6 | 4 | 1.8 | 0.25 | 12 |
| Pond Outlet C | 32 | 11 | 7 | 3.2 | 0.5 | 14 |
This calculator applies a linear storage routing approach often used for preliminary detention, pond, and reach analysis. The continuity relationship is:
dS/dt = I - O
Storage is linked to outflow with:
S = K × O
Using a discrete time step, routed outflow is estimated by:
Ot+Δt = Iavg + (Ot - Iavg) × e-Δt/K
Where Iavg is the average inflow during the step, Δt is the time increment, and K is the storage coefficient. This method helps estimate attenuation, lagging response, and temporary storage behavior in construction drainage studies.
This tool is best for screening-level checks, detention comparisons, and quick routing sensitivity reviews. Final design should still be verified with project-specific hydrologic criteria, outlet control details, and approved local methods.
Outflow routing is useful when evaluating temporary detention ponds, sediment basins, stormwater staging, and drainage paths during site development. By comparing inflow and routed outflow, teams can see how storage delays discharge, reduces peak release, and changes the timing of downstream loading.
On construction projects, this helps during planning for erosion control, dewatering support, culvert checks, access-road drainage, and phased grading work. The graph and routing table make it easier to communicate expected performance to field teams, designers, and reviewers.
Because this page exports results, it can also support quick documentation for method comparisons and design notes. Use smaller time steps for smoother routed curves, and test multiple K values when site storage behavior is uncertain.
It estimates routed outflow, storage response, peak attenuation, and net flow over time using a linear storage routing method for preliminary construction drainage checks.
K represents the response time of the routed system. Larger values usually mean slower release, more lag, and greater temporary storage effects.
Yes. It works well for early detention basin comparisons, outlet response checks, and quick stormwater planning before detailed hydraulic modeling.
Outflow is delayed by storage. When inflow rises or falls, the system needs time to respond, so the released discharge curve becomes smoother and lagged.
Use consistent units throughout. This layout assumes flow in cubic meters per second and time in hours, but any consistent unit system can work.
Yes. The Plotly graph shows inflow and routed outflow against time, helping you compare attenuation and timing across routing steps.
Use a smaller time step when the inflow changes rapidly or when you want smoother routed results and better numerical stability in comparisons.
No. It is a preliminary planning tool. Final design should follow project criteria, approved hydrology methods, and jurisdictional review requirements.
Important Note: All the Calculators listed in this site are for educational purpose only and we do not guarentee the accuracy of results. Please do consult with other sources as well.