1 / 20

libHydro

libHydro. LibHydro. LibHydro in Excel LibHydro in ArcMap. LibHydro in Excel. Functions list that is called by Excel VBA. Moisture Content. 0. L i. L(t). f t. Φ. θ r. θ e. Δθ. θ i. LossGreenAmpt.

winka
Download Presentation

libHydro

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. libHydro

  2. LibHydro • LibHydro in Excel • LibHydro in ArcMap

  3. LibHydro in Excel Functions list that is called by Excel VBA

  4. Moisture Content 0 Li L(t) ft Φ θr θe Δθ θi LossGreenAmpt The Green and Ampt model computes the precipitation loss on the pervious area in a time interval as: ft: Infiltration Rate (L / T) K: Hydraulic Conductivity (L/T) Ft: Cumulative loss at time t (L) Sf: Wetting Front Suction Head (L) ΔΘ:Moisture Deficit (-) Φ: Porosity (-) Θi: Initial Moisture Content (-) Li: START INITIAL LOSS L(0): START INFILTRATION L(END): FINAL INFILTRATION

  5. Basic Concept for LossInitialConstant Et = Et (Impervious) + Et (pervious) Et (Impervious) = Pt Et (pervious) = Et : Excess at time t Pt : Precipitation at time t Ia: Initial Loss fc: Constant Loss Rate 0 if ΣPt < Ia Pt – fc if ΣPt > Ia and Pt > fc 0 if ΣPt > Ia and Pt < fc LossInitialConstant

  6. LossSCSCurveNumber Pe = Accumulated precipitation excess at time t (mm) P = Accumulated rainfall depth at time t (mm) Ia = Initial abstraction (initial loss) (mm) S = Potential maximum retention (mm) (For SI Unit) CN = Curve number (30 < CN < 100)

  7. Precipitation (mm) Loss Rates (Green Ampt, Initial Constant or SCS Curve Number Excess (mm) Unitgraph Size # of unitgraph ordinates Unitgraph (Snyder, SCS or Clark) Unit Runoff (m3/s per mm of excess) Unitgraph Convolution Runoff (m3/s) Unit hydrograph

  8. Unitgraph Clark Parameters Time of Concentration: The time of flow from the farthest point on the watershed to the outlet Storage Time: Storage constant R with the linear reservoir model St = R*Ot • Process of the Unitgraph Clark • 1. Estimate the contribution area with • 2. time-area relationship • 3. Calculate the average inflow It to the storage at time t • 4. Calculate the unitgraph ordinates with the following equations

  9. Snyder’s Unit Hydrograph • Input Variables • tp : Snyder Lag (hr) • Cp: Snyder Cp • A: Basin Area (km2) • tR: Time interval Output Variable: unitgraph ordinates (m3/s per mm of excess) tpR=tp-(tr-tR)/4 (when tpR≠5.5tR) Standard UH (when tpR=5.5tR) tr tR tpR tp qP=2.75*Cp/tp Discharge per unit area qpR qPR=qP*tp/tpR qp Discharge per unit area W75 W50 tb Time Time

  10. Tr Excess Rainfall Tr/2 tp Direct Runoff qp Tp tb SCS Dimensionless Hydrograph qp: Peak runoff (m3/s) C:2.08 for SI A: Basin Area (km2) Tp: Time of rise Tr: Excess Duration (hour) Tp: lag time (hour) Tc: Time of concentration (hour)

  11. Discharge recession threshold Total flow Time BaseflowHEC1 • total flow > recession threshold at falling limb • or total flow is at rising limb Qb: base flow Q0: initial base flow K: recession constant T: time Qt: total flow Qr: flow where recession starts tr: time when recession starts (B) total flow < recession threshold at falling limb Baseflow

  12. Muskingum Routing Prism Storage Wedge Storage St: Storage at time t It: Inflow at time t Ot: Outflow at time t K: Muskingum K X: Muskingum X

  13. Feasible region Muskingum Routing Feasible region for Muskingum model parameter 2 1 0 0.5 1.0 X

  14. EarthDistance in ArcMap

  15. LibHydro in ArcMap

  16. Model Builder Input Box for LossInitialConstant

  17. Loss Initial Constant

  18. Model Builder Input Box for Snyder Unitgraph

  19. Snyder Unitgraph

  20. Model Builder Process

More Related