Wetland & Fish Ecology - Enviro Dynamics Namibia

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76 ISSUE POTENTIAL IMPACT UNMANAGED MANAGED IMPACT POTENTIAL IMPACT UNMANAGED EXT DUR INT SIGN MANAGED IMPACT MITIGATION SIGN A. Removal of material from oshana for dike building and channel construction Turbidity and salinity increase during and after construction Reduced aquatic vegetation for first few seasons until recolonised R ST/MT MOD MT -M/ H M Con+ SF1-2 M Con+ SF1-2 Difficult to manage , accept some turbidity change during + after construction of dike and channel Will have impact during construction but allow plant regrowth along margins Very difficult during construction but will recover if exposed areas are covered with sand or stabiliser Use hollow bricks or rough surfaces to allow regrowth + recolonisation L Fish migration, feeding, breeding impacted Fishing success lowered, community disadvantaged below and next to dike ST ST M SF1-2 M Ong Accept local impact on fish populations and migrations during construction, within a few seasons return to normal fishing in iishana No real mitigation possible Expect some impact during construction but will recover if exposed areas are covered with sand or sediment is allowed to naturally build up. Fish survival in Omadhiya pans low – pans fill with MT/LT H Con+ Omadhiya water quality and fish community will Draft Environmental Impact Assessment: Oshakati Flood Mitigation Project Specialist Study: Wetland Ecology and Fish Ecology Imputs July 2012
77 ISSUE POTENTIAL IMPACT UNMANAGED MANAGED IMPACT POTENTIAL IMPACT UNMANAGED EXT DUR INT SIGN MANAGED IMPACT MITIGATION SIGN sediments and SF1-2 be temporarily affected water deteriorates sooner B. Unpurified street runoff from Oshakati is allowed to collect in storm-water drains and to flow via Okatana River into iishana downstream Water quality and health of oshana system and Omadhiya wetland deteriorates N LT MOD -M M Ong Water quality in iishana downstream of Oshakati is normal and safe. Needs cooperation of Oshakati Municipality to prevent contamination, adhere to MAWF effluent permit requirements + initiate monthly biomonitoring. Create natural wetland at bottom end of Okatana river to filter runoff. Reposition + upgrade sewerage treatment Enforce water quality/effluent regulations on outflow from industry. Monthly biomonitor ing of water quality + health to test Okatana River outflow L POTENIAL IMPACT UNMANAGED MANAGED IMPACT POTENTIAL IMPACT UNMANAGED EXT DUR INT SIGN MANAGED IMPACT MITIGATION SIGN ISSUE CONTINUED 3.6 Fish life in oshana system and Omadhiya N LT MOD -M M Ong Normal fish life in iishana Runoff has to be purified before release into oshana system, either by creating a natural L Draft Environmental Impact Assessment: Oshakati Flood Mitigation Project Specialist Study: Wetland Ecology and Fish Ecology Imputs July 2012
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PROPOSED FLOOD MITIGATION MEASURES
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ii EXECUTIVE SUMMARY The Cuvelai Ri
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iv Decreased surface area of iishan
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vi CONTENTS EXECUTIVE SUMMARY .....
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viii 4.9 IMPACTS OF REMOVAL OF VEGE
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x Figure 4-7 Raised floor of bridge
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1 1 INTRODUCTION 1.1 BACKGROUND: Th
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3 were also still present although
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5 2 LEGAL AND REGULATORY REQUIREMEN
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7 3.1.1 CUVELAI WETLAND SYSTEM: The
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9 Figure 3-1 below is a map of the
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11 In the 1950s and 1960s, a progra
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13 Recommendations to the Departmen
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15 invertebrate fauna by Nakanwe, (
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17 possibly via the Calueque-Oshaka
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19 harvesting fish along the Ondang
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21 from survivors from the last flo
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23 As this underlines the importanc
Page 37 and 38: 25 Discussion with Mr L. Hango, Hyd
Page 39 and 40: 27 A full record of the discussion
Page 41 and 42: 29 Oreochromis macrochir Greenhead
Page 43 and 44: 31 26 June 2012 Site 5 DIKE 10 Oshi
Page 45 and 46: 33 Oshanas at end of canal, Dec 198
Page 47 and 48: 35 Fish species Common names Iishan
Page 49 and 50: 37 Fish species Common names Iishan
Page 51 and 52: 39 The following sizes of fish were
Page 53 and 54: 41 4 IMPACT ASSESMENT (OF THE DIKE
Page 55 and 56: 43 Channing and Griffin (1993) and
Page 57 and 58: 45 A) Impact related to dike and it
Page 59 and 60: 47 ISSUE POTENTIAL IMPACT UNMANAGED
Page 61 and 62: 49 blooms as has happened in Gorean
Page 63 and 64: 51 A) Impact related to dike and it
Page 67 and 68: 55 4.4 IMPACTS OF ALTERED FLOWS (VE
Page 69 and 70: 57 Figure 4-3 Inakulo Yomadhiya Gra
Page 71 and 72: 59 High fishing pressure can be exp
Page 77 and 78: 65 During low floods, especially af
Page 81 and 82: 69 Okatana channel of marginal vege
Page 83 and 84: 71 4.6 IMPACTS ON FROGS (PARTICULAR
Page 87: 75 4.7.2 IMPACT OF DEEPENING AND LI
Page 91 and 92: 79 4.8 IMPACTS OF FLOODGATE OPERATI
Page 95 and 96: 83 4.9 IMPACTS OF REMOVAL OF VEGETA
Page 97 and 98: 85 Although only one study on the e
Page 101 and 102: 89 4.10 IMPACTS OF DEEPENING THE CH
Page 105 and 106: 93 4.11 HEALTH IMPACTS/SPREAD OF BI
Page 107 and 108: 95 POTENTIAL IMPACT UNMANAGED MANAG
Page 109 and 110: 97 4.12 COMMENT ON POTENTIAL FOR FI
Page 111 and 112: 99 This includes following the natu
Page 113 and 114: 101 5 CONCLUSIONS AND RECOMMENDATIO
Page 115 and 116: 103 6 REFERENCES Berry, H.H. (1972)
Page 117 and 118: 105 Geiss, W. (1971). A preliminary
Page 119 and 120: 107 Van der Waal, B.C.W. (2000a). F
Page 121 and 122: 109 Mr Shakelia responded that the
Page 123 and 124: 111 his earlier studies to see whic
Page 125 and 126: 113 Amaranthaceae Nymphaeceae Vahli
Page 127 and 128: 115 Poaceae Poaceae Poaceae Poaceae
Page 129 and 130: 117 Cypercaeae Cypercaeae Cypercaea
Page 131 and 132: 119 Class: Branchiopoda Order: Anos
Page 133 and 134: 121 Sars 1909 Macrothrix spinosa 18
Page 135 and 136: 123 7 1 0 Osprey Pandion haliactus
Page 137 and 138: 125 APPENDIX 3: Field Notes FIELD N
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127 Do not foresee any impacts of w
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129 B) FISH SURVEY RESULTS - ACTUAL
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131 Site 4 Dike 3 Tuesday 25 June T
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133 Site 7 Thursday 28 June - Deep
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Wetland & Fish Ecology - Enviro Dynamics Namibia

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