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PRECIPITATION-RUNOFF MODELING SYSTEM (PRMS)

PRECIPITATION-RUNOFF MODELING SYSTEM (PRMS). STORM-MODE COMPONENTS. BASIC HYDROLOGIC MODEL. Q = P - ET ± S. Components. Runoff Precip Met Vars Ground Water

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PRECIPITATION-RUNOFF MODELING SYSTEM (PRMS)

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  1. PRECIPITATION-RUNOFF MODELING SYSTEM(PRMS) STORM-MODE COMPONENTS

  2. BASIC HYDROLOGIC MODEL Q = P - ET ± S Components Runoff Precip Met Vars Ground Water Soil Moisture Reservoirs Basin Chars Snow & Ice Water use Soil Moisture

  3. PRMS

  4. HYDROLOGIC RESPONSE UNITS (HRUs)

  5. HRUs as FLOW PLANES & CHANNELS (Storm Mode)

  6. SOIL MOISTURE ACCRETION - DAILY MODE infil(hru) = net_precip(hru) - sroff(hru) - STORM MODE Point Infil (fr) fr = dI/dt = ksat * [1. + (ps / S fr)] Areal Infil (fin) qrp = ( .5 * net_precip2 / fr ) net_precip < fr qrp = net_precip - (.5 * fr) Otherwise fin = net_precip - qrp

  7. INFILTRATION SOIL PROFILE moisture content wp fc sat profile t0 + depth Profile t0 true relations

  8. Darcy’s Law Applied to Profile h i x depth p m0 mt Total head = h + x + p di/dt = K [(h + x + p) / x] I = x (mt -m0) h<<p [Green & Ampt] di/dt = K (1. + [p (mt - m0) / i]

  9. INFILTRATION - STORM MODE Point Infil (FR) FR = dI/dt = ksat * [1. + (ps / I)]

  10. Computation of PS

  11. AREAL INFILTRATION (FIN) RE = ( .5 * PTN2 / FR ) PTN < FR RE = PTN - (.5 * FR) Otherwise FIN = PTN - RE

  12. ¶h ¶q + = re ¶t ¶x SURFACE RUNOFF net precip h infil q x

  13. Finite Difference Scheme t2 time t t1 t0 Dx distance x Nodes with known values Solution node

  14. Overland Flow q = m ( Dt / Dx ) (qb / hb) For q >= 1 qd = qc + re Dx - (Dx/Dt) ( hc -ha) hd = ( qd / a ) 1/m

  15. Overland Flow q = m ( Dt / Dx ) (qb / hb) For q < 1 hd = hb + re Dx - (Dt/Dx) ( qa -qb) qd = a hdm

  16. CHANNEL FLOW ¶A ¶Q + = q ¶t ¶x

  17. Finite Difference Scheme t2 t t1 t0 Dx x Nodes with known values Solution node

  18. Available Channel Types Rectangular Input width Triangular Input width from left and right bank to center line at one foot depth

  19. RADAR DATA NEXRAD vs S-POL, Buffalo Creek, CO

  20. Buffalo Creek Watershed, CO

  21. PRMS

  22. PRMS

  23. ANIMAS RIVER, CO SUBSURFACE SURFACE GW PREDICTED MEASURED

  24. PRMS

  25. IN dS =IN- (ssrcoef_lin * S) ------(ssrcoef_sq * S2) Subsurface Reservoir dt SUBSURFACE FLOW Equation solved at dt time step using analytical solution

  26. PRMS

  27. Ground-water Reservoir GROUND-WATER FLOW soil_to_gw + ssr_to_gw gwres_flow= gwflow_coeff *------------------gwres_stor Equation solved at 15 minute dt and pro rated to shorter dt as needed

  28. ¶(ch) ¶(cq) = er + ef + ¶x ¶t SEDIMENT - OVERLAND FLOW net precip h infil q Sediment conc (c) x

  29. Interrill Detachment & Transport - er - (hc * hbar2) er = kr * net_precip(hru)2 * e

  30. Rill Detachment & Transport - ef ef = kf * ( tc - tr) tc = transport capacity tr = current transport rate en tc = mm * hbar

  31. SEDIMENT - CHANNEL FLOW sed_lat c cQ ¶ cA ¶ cQ + = sed_lat ¶t ¶x

  32. Reservoir Routing Linear Routing res_out = sfres_coef * sfres_stor Modified Puls Routing 2 * sto2 2 * sto1 + O2 = (I2 - I1) + - O1 Dt Dt

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