SCHWALL_2012. Basic research for river type specific evaluation of hydropeaking impacts. University of Natural Resources and Life Sciences Vienna

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Resources and Life Sciences Vienna Christian Doppler

Modelling and Engineering Christoph Hauer & Helmut

1 SCHWALL_2012 Basic research for river type specific evaluation of hydropeaking impacts University of atural Resources and Life Sciences Vienna Christian Doppler Laboratory for Advanced Methods in River Monitoring, Modelling and Engineering Christoph Hauer & Helmut Habersack 2012 Feb. 27th, SCHWALL_2012 I Hauer & Habersack 1

2 Outline 1. Problem definition 2. Aims 3. Methods 4. Results 5. Discussion 6. Summary and Conclusions SCHWALL_2012 I Hauer & Habersack

3 Problem definition International and national - a lack of knowledge concerning hydropeaking processes (e.g. estimation of thresholds Q base / Q peak = 1:3; 1:5; 1:10) dealing with various river types and local river morphology. Up to now only limited (mostly not validated) models and process analysis for an integrative evaluation (hydraulic / aquatic ecology) of hydropeaking impacts are given. High economic losses due to the aims of the European Waterframework Directive (WFD) are possible (e.g Mio. per year for a specific Austrian HP, if the threshold for discharge ratio 1:3 is implemented) (Stigler et al., 2005). Aims Aim of the research project Schwall 2012 was to test the main hypothesis that a river type specific classification of hydropeaking is necessary. SCHWALL_2012 I Hauer & Habersack

4 Study reaches SCHWALL_2012 I Hauer & Habersack 4

5 Study sites (local scale) Aerial Pictures and DTM models used for hydrodynamic-numerical modelling (one-dimensional / two-dimensional) (I) Ill_1, (II) Ill_2 und (III) Ill_3. SCHWALL_2012 I Hauer & Habersack 5

6 Study sites (local scale) Aerial Pictures and DTM models used for hydrodynamic-numerical modelling (one-dimensional / two-dimensional) (IV) Bregenzerach_1, (V) Bregenzerach_2 und (VI) Inn_1. SCHWALL_2012 I Hauer & Habersack 6

7 Study reaches (local scale) Aerial Pictures and DTM models used for hydrodynamic-numerical modelling (one-dimensional / two-dimensional)(vii) Inn_2, (VIII) Inn_3 und (IX) Inn_4. SCHWALL_2012 I Hauer & Habersack 7

8 Study sites (local scale) [m] Aerial Pictures and DTM models used for hydrodynamic-numerical modelling (one-dimensional / two-dimensional) (X) Inn_5, (XI) Drau_1 und (XII) Drau_ [m] SCHWALL_2012 I Hauer & Habersack 8

(one-dimensional / two-dimensional) (XIII) Ziller_1,

9 Study sites (local scale) Aerial Pictures and DTM models used for hydrodynamic-numerical modelling (one-dimensional / two-dimensional) (XIII) Ziller_1, (XIV) Ziller_2, (XV) Enns_1 und (XVI) Enns_2. SCHWALL_2012 I Hauer & Habersack 9

10 Methods Evaluation of hydropeaking impacts on various scales Point Punktebene scale XS Buhnenfeld XS Q peak Q Schwall Q base Hydropeaking analysis Q Basis Local scale lokale Ebene 0 25 [m] recorded data Reach Streckenebene scale 0 5 [km] synthetic data SCHWALL_2012 I Hauer & Habersack 10

11 Methods Reach scale 13 river reaches H-modelling unsteady 195 model runs peak flow retention ramping velocity in relation to various hydromorphological characteristics (e.g. bed slope, dewatering area, specific discharge, etc.) Discharge Abfluss discharge (m 3 s 3-1 s ) -1 ) (m 3 s -1 ) Discharge Abfluss discharge (m (m 3 s s ) -1 ) (a) (b) Q Basis t 1 Q 1 Δt t 2 Q 2 Zeit (h) rr 1 / Δt Time (h) ΔQ [h] Zeit time (h) (h) rr 2 / Δt Time (h) Q Schwall_3 Q Schwall_2 Q Schwall_1 MQ MQ T 1:3 1:5 1:10 KW_Silz KW_Imst SCHWALL_2012 I Hauer & Habersack 11

12 Methods Local scale Hydro-morphological analysis (planimetric view) 630 1:3 QL 1:5 1:10 WUA* / ΔA* d84/d16 point bar Investigated local scale investigated meso-unit Hydro-morphological analysis (cross sectional view) Point scale Durchgang Finer (%) (%) Korngröße Grain size (mm) (mm) surface-layer Freeze-Core Height (m.a.sl) Höhe (m.ü.a.) 625 *TH_QM **WUA_QM ΔB = m d90 = 0.12 m *TH_QL Δh = 1.18 m **WUA_QL Stationing Stationierung (m) (m) Legend WS QM WS QL Ground Bank Sta SCHWALL_2012 I Hauer & Habersack 12

4 total I = SI d SI v concluded = i= 1 SI 1 0.8 0.6 0.4 SI total SI i WUA = n i= 1 HSI i A i juvenile brown trout 0.2 0.2 0 0 0 0.

13 Methods Local scale HEM Habitat Evaluation Model (IWHW, 2012) Mesohabitat modelling Mesohabitat-classes.based on depth-averaged flow velocity, water depth and bottom shear stress Microhabitat modelling SI SI total I = SI d SI v concluded = i= 1 SI SI total SI i WUA = n i= 1 HSI i A i juvenile brown trout Water Wassertiefe depth (m) (m) Flow tiefengemittelte-v velocity (ms -1 ) selected benthic organisms (e.g. Allogamus auricollis) SCHWALL_2012 I Hauer & Habersack 13

14 Results Reach scale Peak flow retention (scenario 0.5 hours peak flow duration) 0-20 ΔA / bed slope (m 2 ) 0.E+00 1.E+07 2.E+07 3.E+07 4.E+07 5.E+07 6.E+07 7.E+07 8.E+07 9.E+07 ΔQ (m 3 s -1 ) R 2 = 0.83 Q base /Q peak 1_3 1_5 1_ n = (1:3 = black squares, 1:5 = grey circles, 1:10 = white triangles) Influence of various reach lengths is given SCHWALL_2012 I Hauer & Habersack 14

15 Results Reach scale Peak flow retention (scenarios 0.5, 1.0, and 2.0 hours peak flow duration) Slope (-) Q base /Q peak ΔQ (m 3 s -1 km -1 ) n = 39 1_3 (0.5) 1_5 (0.5) 1_10 (0.5) 1_3 (1.0) 1_5 (1.0) 1_10 (1.0) 1_3 (2.0) 1_5 (2.0) 1_10 (2.0) ΔQ/km determined for t 2 hours and reach scale bed slope SCHWALL_2012 I Hauer & Habersack 15

16 Results Reach scale River type / morphological specific differences V-peak ΔV V-Schwall Sunk/Schwall flow (ms -1 ) -1 ) ΔA km -1 (m 2 ) v_1_3 v_1_5 v_1_10 da_1_3 da_1_5 da_1_10 ΔV peak/base flow (ms -1 ) Inn_1_1 Inn_1_1 Inn_1_2 Inn_1_2 Inn_2_1 Inn_2_1 Inn_2_3 Inn_2_3 Inn_2_4 Inn_2_4 Inn_3_1 Inn_3_2 Inn_3_3 Ill_1 Ill_1 Ill_2 Ill_2 BA_1 BA_1 BA_2 BA_2 Drau Drau V-peak for a ramping rate 1:10 for the Bregenzerach < 1:3 in most of the Inn-reaches ΔV peak/base for 1:3 and 1:10 - similar magnitudes within a river system possible SCHWALL_2012 I Hauer & Habersack 16

17 Results Local scale Fine sediment concentration / Freeze Core < 0.5 mm Fines <0.5 mm (%) Feinanteil < 0.5 mm (%) n = 210 Enns Drau Ill Inn Ziller Bregenzerach umber of samples: 41 Freeze-Cores, 210 sub-samples Different size classes analysed: < mm, < 0.5 mm, < 2 mm o correlation between discharge ratio (e.g. 1:3) and fine sediment concentration Feinanteil Fines <0.5 < 0.5 mm mm (%) (%) Freezecoretiefe (cm) Freeze core depth (cm) 0 10 cm n = cm n = Q peak /Q base Verhältins Sunk/Schwall Feinanteil Fines <0.5 < 0.5 mm mm (%) (%) no reference sites sampled! Q peak /Q base Verhältins Sunk/Schwall SCHWALL_2012 I Hauer & Habersack 17

18 Results Local scale Fine sediment concentration / Freeze Core Analysis of discrete river reach samples, e.g. Ill_River / Frastanz Feinanteil Fines < < mm (%) Ill_2_1 Ill_2_2 Ill_2_3 dewatering area Freeze Freezecoretiefe depth (cm) SCHWALL_2012 I Hauer & Habersack

19 Results Local scale Surface layer sampling / gravel bars d 90 percentage finer (%) d I_1 I_5 Importance of d 90 (d 84 ) for the stranding of aquatic organisms (a) grain size (mm) Connex to sediment regime and sediment continuum important - coarsening of bed surface material - incision processes (b) (c) SCHWALL_2012 I Hauer & Habersack 19

20 Results Local scale macroinvertebrates / morphological structures Inn_ 2 groin field Inn_ 3 gravel bar (a) (b) According to abundance (Ind./m 2 ) and biomass (g/m 2 ) more than 22- and/or 51-times higher numbers were recorded at the gravel bar site SCHWALL_2012 I Hauer & Habersack 20

0 0 0 0 0 0 0 0 :0 :0 :0 :0 :0 :0 :0 :0 :0 :0 :0 0 3 6 9 2 5 8 1 0 3 6 0 0Time Zeit 0 1 1(h) 1 2 0 0 Uhrzeit SZ_16_SO-50+2 Basisabfluss +2 Turbinen + 75%

21 Discussion 16 e.g. Ill River (Summer) Discharge Abfluss (m 3 s -1-1 ) ) (a) River regulation as habitat limiting factor ³/s) 100 (m s 80 flu b 60 A :0 :0 :0 :0 :0 :0 :0 :0 :0 :0 : Time Zeit 0 1 1(h) Uhrzeit SZ_16_SO-50+2 Basisabfluss +2 Turbinen + 75% Mesohabitatfläche [m area 2 ] (m²) (b) :00 3:00 78 % 6:00 Str. 2 SZ_16_SO :00 12:00 81 % 15:00 18:00 Zeit [hh:mm] Time (h) 21:00 0:00 3:00 6:00 shallow water backwater pool run fast run riffle Mesohabitat-classes Q L Q M SCHWALL_2012 I Hauer & Habersack 21

22 Discussion River type specific differences based on local morphology Discharge (m 3 s -1 ) Abfluss (m 3 s -1 ) ΔWetted Δbenetzte width Breite (m) QZVÖ, 2010: discharge ratio Q base /Q peak must be lower than 1:3 pb_inn_3 1 pb_b_ach_2 2 pb_drau_1 3 agb_inn_2 4 agb_b_ach_1 5 mcb_inn_5 6 mcb_inn_4 7 gwd_ziller_2 8 gwod_inn_1 9 regulated pb = point bar, agb = alternating gravel bar, mcb = mid channel bar, gwd = groin field with fluvial deposits, gwod = groin field without fluvial deposits, black dots = Q M for the different investigated sites Inn_2: (alternating gravel bars) Q base / Q peak 1:5 = changes in wetted width 5.1 m for extreme low flow conditions in winter (Q base = 20 m 3 s -1 ) Q base / Q peak 1:2 = changes in wetted width 47.2 m formeansummerflow(q = 80 m 3 s -1 ) SCHWALL_2012 I Hauer & Habersack 22

23 Discussion River type specific differences based on local morphology QZVÖ, 2010: decrease of wetted area between Q peak and Q base must not be lower than -20 %. WUA_peak flow (m²) QZVÖ, 2010 pb = point bar, agb = alternating gravel bar, mcb = mid channel bar, gwd = groin field with fluvial deposits, gwod = groin field without fluvial deposits In contrast to regulated river reaches those sites with heterogenous river morphology (e.g. point bars) feature more suitable habitats (more habitats at Q base /Q peak = 1:5 possible). criterion Q base /Q peak = 1:3 (QZVÖ, 2010) should be adapted. the fulfill of the legal critera 20% is only possible in heavily regulated reaches; for this specific sites the habitats of juvenile fish feature a significant spatial reduction along the shore line (e.g. 88 % between Q L and Q M ). criterion - 20 % of wetted area (QZVÖ, 2010) should be adapted. SCHWALL_2012 I Hauer & Habersack 23

24 Summary and Conclusions Proof of the main hypothesis that river type specific evaluation of hydropeaking in alpine rivers is necessary concerning future management and mitgation measures. Criteria of GP und QZVÖ, 2010: (partially) only limited description and evaluation of the abiotic situation within hydropeaking rivers. Scaling approach is important to describe the relevant (unsteady) processes within a river catchment influenced by hydropeaking. Multi-pressures on river morphology (e.g. river regulation) are mostly given in alpine rivers, which are partially (seasonal aspects) superior stressors to the impacts of hydropeaking (e.g. Ill River). River type specific and/or local scale evaluation is recommended SCHWALL_2012 I Hauer & Habersack 24

25 Thank you for your attention! University of atural Resources and Life Sciences, Vienna Department of Water, Atmosphere and Environment Institute of Water Management, Hydrology and Hydraulic Engineering Christian Doppler Laboratory for Advanced Methods in River Monitoring, Modelling and Engineering Dr. Christoph Hauer, Univ. Prof. Dr. Helmut Habersack Muthgasse 107, A-1190 Wien Tel.: , Fax: christoph.hauer@boku.ac.at, Feb th, SCHWALL_2012 I Hauer & Habersack 25

Hydropeaking From Process understanding to mitigation measure design

Hydropeaking From Process understanding to mitigation measure design Christoph Hauer University of Natural Resources and Life Sciences, Vienna Special Issue Hydropeaking (Science of the Total Environment)