Hydrology of the Cache River

1. Hydrology of the Cache River

3. Outline of talk • Basic hydrology of the Cache River and associated wetlands • Alterations to the watershed and how they are affecting hydrology • Restoration goals to improve hydrology • Current research being done in association with restoration projects

4. “The stream and its valley” • Hydrology is largely determined by the landscape in which the river flows through (H.B.N Hynes 1975) • In order to understand the hydrology of the Cache River we need to consider the landscape (and subsequent alterations) that the river is located in

5. Hydrologic Cycle

6. Hydrologic Cycle

7. 5th order stream (midway between a small creek and the Mississippi River)

8. Gradient (slope) is more pronounced in the upper part of the river leading to faster flowing water

9. The lower half of the river has a naturally low gradient (drops 1.2 feet per mile) leading to slow water velocity

12. -Recognized as wetlands of international importance -Provide local recreation and educational opportunities -Provide valuable ecosystem functions for the Cache River watershed

13. Ecosystem functions that wetlands provide Entrapment of sediment and nutrients Flood mitigation Source of nutrients and energy to main-stem of the river

15. Connectivity important in ecosystem function by promoting nutrient (N and P) matter, energy, and organismal flow between river channel and wetlands

16. The Natural Flow Regime • Defined by Poff et. al 1997 as the characteristic pattern of a river's flow quantity, timing, and variability over a number of years • 5 critical components that regulate ecosystem processes • 1.timing • 2.duration • 3.magnitude • 4.frequency • 5.rate of change

17. Natural Flow Regime and Floodplain Connectivity • The natural flow regime (Poff et al. 1997) allows for the flood pulse and subsequent lateral connectivity with wetlands (Junk et a.l1989)

19. Post Creek Cutoff

20. Drainage • ~70% of the land use in the Cache watershed is used for agricultural practices • Main problem in the Midwestern U.S. is getting water off of the crop fields • To address this issue “drainage ditches” have been constructed

21. Picture of drainage

22. Map of drainage in US

24. Modified from Dimessie et al. 2008

25. Upper Cache -Altered flow regime -Increased slope -Bank incision -Wetland encroachment • Lower Cache • Altered flow regime • Sedimentation • Poor water quality • Decreased dissolved oxygen Modified from Dimessie et al. 2008

26. Upper Cache River • Altered hydrology due to an increased slope (associated with the Post Creek Cutoff) • Causing bank incision and threatening to drain important wetlands • Restoration activities include lateral gully plugs and rock weirs

29. Rock Weir Gully Plug

30. Upper Cache • While the rock weirs/gully plugs were originally designed to address the issue of channel incision and wetland encroachment, research has shown that they have a positive impact on both the Cache River and the surrounding landscape

31. Rock Weirs Gully Plugs • Increase density and nesting success of Prothonotary warblers in adjacent wetlands • Benefit in-stream invertebrate community by increasing total biomass and biomass of larger bodied sensitive species • Increase insect emergence and subsequent avian response • May increase in-stream invertebrate diversity

32. Lower Cache • Altered flow regimedue to the loss of headwater inputs • Causing reduced flows, especially in the summer months, leading to sedimentation and poor water quality • Hydrologic reconnection (to the upper Cache) in order to restore the flow regime continues to be a major restoration goal

35. Consequences of low flow • Possible shifts in invertebrate community • Decreased dissolved oxygen concentration • Sedimentation • Formation of a duckweed cover over the stream

37. Lower Cache • Currently research is being done to predict how increasing the flow will effect the

38. Lower Cache 95% Confidence Intervals DO = 7.95Q0.12 n = 33, R2 = 0.27

39. Invertebrate Community Production ν > 0 P = 1.1HD + 14.3 ν ≈ 0 P = 0.3HD + 4.2

40. Conclusion • Significant alterations to the watershed have led to disconnection between 2 major sections of the river • The 2 sections differ strongly in terms of their hydrology • Watershed managers have and continue to set restoration goals for both sections • Currently, research is being done to evaluate and guide the restoration projects

41. Papers • Demissie et al. 2008. Hydrologic and hydraulic modeling and analyses for the Cache River for the purposes of evaluating current conditions and alternative restoration measures. Illinois State Water Survey Contract Report 2008-01 • IDNR 1997: Cache River Area Assessment vol1:section1 (Hydrology section) • Poff et al. 1997: The natural flow regime • Bunn and Arthington 2002: Basic principles and ecological consequences of altered flow regimes for aquatic biodiversity • Junk et al. 1989: TheFlood pulse concept in river-floodplain systems

42. Contact me for questions • Eric Scholl • Email: EScholl86@gmail.com