SMALL DAMS PETITS BARRAGES

More documents

Recommendations

Info

specific exceptional flood around the world and the following table lists order of magnitude (but not maximum) 10 000 year flood flows for different climates and catchment area. Table 3.2 – Order-of-magnitude ten thousand year flood discharge in m 3 /s (Bulletin 109, 1997) Catchment Area (km 2 ) 2 km 2 10 km 2 50 km 2 Climates with moderate rainfall (Northern Europe, Russia, Canada, North-West USA) Intermediate climates (Mediterranean, Central America, South America) 10 30 100 30 100 300 Climates with extreme rainfall (South and East Asia) 100 300 1000 Worldwide Maximum of registered values 200 700 2000 In some cases, the overtopping causes a general sliding of the downstream part of the dam embankment then a rather large initial breach. But in most cases, the initial breach resulting from the toe erosion is relatively narrow, as in case of piping, and may or not widen according to cross section and materials characteristics. For a same dam and same initial plan of breach, breach flow is higher for overtopping than for piping, due to higher water level and arriving flow. Over 3% of dam failures occurred due to the failure of a dam further upstream. This risk should not be overlooked in the coming years for both existing and new dams. Nor should partial obstruction of the spillways by vegetation or floating debris be forgotten. During extreme flood occurred in Czech Republic in 2002, there were 23 small dams failed after dam overtopping. About 50 others small dams had been strongly damaged at this time. At Figures 3.1 (A) and (B) are presented some photos of small dams breached by overtopping during this time at the Czech Republic. (A) (B) Fig. 3.1 – A small dam during the overtopping (A) and after the failure(B). (Czech Republic). 34
Fig. 3.2 – Massive dam break overtopping, during extremely high floods in the Czech Republic. (A) (B) Fig. 3.3 – (A) Paraguaçu embankment dam failure by overtopping, after severe flooding in Brazil. (B) Downstream erosion damages at an embankment road access, in January, 2007. At Figures 3.4 and 3.5 are presented the failures of small dams Nix Lake and Bear Foot Lake, in Texas, USA, by overtopping, as presented by Purkeypile and Samuelson, at the ASDSO Annual Conference, in Sept/ 2007 [1]. 35
Page 1 and 2: SMALL DAMS Design, Surveillance and
Page 3 and 4: FOREWORD The ICOLD - International
Page 5 and 6: ACKNOWLEDGEMENT The Ad Hoc Committe
Page 7 and 8: FOREWORD ACKNOWLEDGEMENT SUMMARY TA
Page 9 and 10: 5.5.5 Compaction in confined areas
Page 11 and 12: 7.2.1 Introduction 7.2.2 Spillway c
Page 13 and 14: 1. SMALL DAMS DEFINITION AND CLASSI
Page 15 and 16: 2 Fig. 1.2 - Relationship H . V wit
Page 17 and 18: 1.3 REFERENCES [1] French Committe
Page 19 and 20: 2.3 ZONED EARTHFILL DAMS In arid pa
Page 21 and 22: sloping core guarantees water impou
Page 23 and 24: Fig. 2.11 - Hlinky Concrete Gravity
Page 25 and 26: Fig. 2.13 - Photograph of Neusberg
Page 27 and 28: The gabion dam as the gabion retain
Page 29 and 30: Some inflatable dams are operated b
Page 31 and 32: 3.1 INTRODUCTION 3. SAFETY OF SMALL
Page 33: Condition Effect on safety 13. Dama
Page 37 and 38: and suffusion or internal instabili
Page 39 and 40: downstream part of the embankment m
Page 41 and 42: small dam impounding a lot of water
Page 43 and 44: Whenever the Supervising Authority
Page 45 and 46: emergency management organizations
Page 47 and 48: c) The decommissioning plan should
Page 49 and 50: 5.1 INTRODUCTION 5. FEATURES OF THE
Page 51 and 52: 5.2 DESIGN FLOODS Inadequate flood
Page 53 and 54: downstream slope will show seepage
Page 55 and 56: Fig. 5.2 - Design Freeboard 5.4.3 F
Page 57 and 58: 2 U f Fe S 1400 D Where Uf is the d
Page 59 and 60: Maximum compaction is obtained at c
Page 61 and 62: characteristic must be determined.
Page 63 and 64: 5.6.1 Foundation Watertightness The
Page 65 and 66: � A continuous vertical chimney d
Page 67 and 68: Thickness of pervious layer Thick D
Page 69 and 70: t 5.7.1.4 Practical Considerations
Page 71 and 72: It is generally accepted that cohes
Page 73 and 74: � Simple Bishop (1955) � Spence
Page 75 and 76: � The elements for surface draina
Page 77 and 78: The supporting layer for the rip-ra
Page 79 and 80: For very small reservoirs (fetch of
Page 81 and 82: The junction of the downstream slop
Page 83 and 84: Fig. 5.14 - Hongshiyan homogenous d
Page 85 and 86:
material has been left in place or
Page 87 and 88:
The homogeneous dam is recommended
Page 89 and 90:
[3] OL and OH soils are not recomme
Page 91 and 92:
part (core) lies in the zone (Fig.
Page 93 and 94:
6. GUIDELINES ON SURVEILLANCE OF SM
Page 95 and 96:
cases the owner may retain the serv
Page 97 and 98:
Surface displacement on an embankme
Page 99 and 100:
Fig. 6.1 - Leakage measurement usin
Page 101 and 102:
Water Level Sounder - Details of th
Page 103 and 104:
pressure) Left abutment 2 5 Weir ga
Page 105 and 106:
Fig. 6.9 - Recommended standpipe pi
Page 107 and 108:
the others weir gauges need to be i
Page 109 and 110:
� Earthquakes sensible at the dam
Page 111 and 112:
APPENDIX INSPECTION CHECKLIST FOR S
Page 113 and 114:
Exposed reinforcement � The condu
Page 115 and 116:
These spillways can be lined or unl
Page 117 and 118:
flowing water. Flowing water with h
Page 119 and 120:
Fig. 7.3 - Installation of the arti
Page 121 and 122:
Fig. 7.7 - Dam overtopping protecti
Page 123 and 124:
complete construction was in 2001,
Page 125 and 126:
In some cases, the downstream face
Page 127 and 128:
Tube-a-manchettes injection system
Page 129 and 130:
7.3.5 Slope Protection Measures 7.3
Page 131 and 132:
Pipe Rehabilitation SLIPLINING MODI
Page 133 and 134:
Conditions Pros Cons Comments types
Page 135 and 136:
Embankment dams that have properly
Page 137 and 138:
and minimize erosion. Design of sui
Page 139 and 140:
[20] SMEC- “Draft Guidelines for
Page 141 and 142:
present visual information. It must
Page 143 and 144:
Fig. 8.1 - Three small dams in casc
Page 145 and 146:
Social Disruption low (rural area)
Page 147 and 148:
Fig. 8.4 - Flood water level after
Page 149:
8.9 REFERENCES [1] BURREC (1994) -
show all

SMALL DAMS PETITS BARRAGES

Create successful ePaper yourself

Delete template?

Save as template?