1. Development of a Hydrologic Model and Estimation of its Parameters Francisco Olivera, Ph.D., P.E. Department of Civil Engineering Texas A&M University

2. Hydrologic Parameters Watershed Abstractions and routing method Parameters Stream Routing method Parameters

3. Watershed Abstractions Precipitation (mm/hr) Excess precipitation (mm/hr) Excess precipitation = f(Precipitation, Terrain properties) Terrain properties

4. Watershed Abstractions SCS curve number method P e :cumulative excess precipitation (in) P :cumulative precipitation (in) CN :parameter of infiltration (curve number)

5. Watershed Abstractions Initial plus constant loss rate P e :cumulative excess precipitation (mm) P :cumulative precipitation (mm) I loss : initial loss (mm) C loss : constant loss rate (mm/hr) t - t 0 : time since the beginning of the storm (hrs)

6. Watershed Routing Excess precipitation (mm/hr) Flow (m 3 /s) Watershed Flow = f(Excess precipitation, Watershed geomorphology)

7. Watershed Routing Excess precipitation (mm/hr) Flow (m 3 /s) Time Excess precipitation Flow tptp SCS unit hydrograph t p :watershed lag-time (min)

8. Watershed Lag-Time (SCS) t p :lag-time (min) L W :length of longest flow-path (ft) S :slope of the longest flow-path (%) CN :average Curve Number  t: analysis time step

9. Watershed Lag-Time (L/V) t p :watershed lag-time (min) L w :length of longest flow-path (ft) V w :longest flow-path average velocity (m/s)  t: analysis time step

10. Watershed Routing Excess precipitation (mm/hr) Flow (m 3 /s) Time Precipitation Excess precipitation Flow Flow = f(Precipitation, Terrain properties, Watershed geomorphology) Precipitation (mm/hr)

11. Hydrologic Parameters Watershed Abstractions and routing method Parameters Stream Routing method Parameters

12. Watershed Parameters Area Abtractions: SCS curve number method (average curve number) Linear loss rate (initial and constant loss rate) Routing SCS curvilinear unit hydrograph (length and slope of longest flow path, average curve number, average velocity in longest flow path)

13. Elevation Grid

14. Flow Length Downstream

15. Flow Length Upstream

16. Longest Flow-Path

17. Flow Length Downstream to the Watershed Outlet

19. Flow Length Upstream to the Watershed Divide

21. Watershed Longest Flow-Path

23. Slope of Watershed Longest Flow Path

24. Watershed Parameters

25. Hydrologic Parameters Watershed Abstractions and routing method Parameters Stream Routing method Parameters

26. Routing Method

27. Flow time (L s /V s ) Ls/Vs <  t Muskingum Routing Ls/Vs >  t Pure Lag Routing L s :length of the stream V s :flow velocity in the stream  t:analysis time step

28. Pure-Lag Method Flow is delayed a fixed amount of time t lag. t lag : flow time in the reach I: inflow to the reach Q: outflow from the reach

29. Pure Lag Parameters t lag :flow time in the reach (min) L s :reach length (m) V s :reach average velocity (m/s)

30. Muskingum Method Flow is delayed a fixed amount of time K, and redistributed around its centroid. S: storage in the reach K: flow time in the reach (  t < K <  t/2X ) X: storage parameter I: inflow to the reach Q: outflow from the reach  t: analysis time step

31. Muskingum Parameters K :flow time in the reach (hr) [Muskingum K] X :storage parameter [Muskingum X] L s :reach length (m) V s :reach average velocity (m/s) n :number of sub-reaches  t: analysis time step

32. Hydrologic Parameters Watershed Abstractions and routing method Parameters Stream Routing method Parameters

33. Stream Parameters Length Routing Pure lag method (average flow velocity) Muskingum method (average flow velocity and storage coefficient)

34. Stream Parameters

35. Hydrologic Model

36. HEC-HMS Schematic in ArcView

37. HEC-HMS Basin File (1)

38. HEC-HMS Basin File (2)

39. HEC-HMS Basin File (3)

40. Basin File System Schematic

41. Basin File Watershed Parameters

43. Basin File Stream Parameters

44. Precipitation File

45. Control File

46. Hydrograph Time Table

47. Hydrograph Summary

48. Hydrograph Plot