Wetland & Fish Ecology - Enviro Dynamics Namibia

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84 Figure 4-5 Makalani Palms, Hyphaene petersiana, alongside Cuvelai oshana. K.S. Roberts Draft Environmental Impact Assessment: Oshakati Flood Mitigation Project Specialist Study: Wetland Ecology and Fish Ecology Imputs July 2012
85 Although only one study on the ethnobotany of the Cuvelai is available (Rodin, 1985), it is well known that wild fruits as well as wetland vegetation is extensively used and collected to sell. This includes reeds and sedges as building material, to make fishing gear and baskets and in the case of the corms of some Cyperaceae species as food. The iishana also support large semi-aquatic grasslands in the wet season that provide good grazing in the dry times. The 2001 Forestry Act specifically makes it illegal to remove or damage any plant that grows within 100m of a watercourse; the iishana of the Cuvelai are very wide, braided watercourses. Any vegetation removal, or indeed disturbance of bottom or marginal soils and covering substrate e.g. by lining of the channel next to the dike or the Okatana River in Oshakati will have a negative effect not only on the vegetation itself but also on fish life in the following ways: Removal of protective cover for fish Increased predation by birds and predatory fish Reduction in surface area for aquatic invertebrates and epiphytic algae and bacteria by emergent vegetation removal Increased water velocity in the absence of submerged or marginal vegetation that would otherwise attenuate flow. 4.9.1 IMPACT RELATED TO DIKE AND IT’S CHANNEL: The dike will confine the larger floods to a 300m wide channel alongside it, preventing the natural spreading out of this water across a large area of floodplain and so reduce the surface area of flooded vegetation available for fish considerably, directly and by preventing flooding of areas behind the dike inside Oshakati town. With a projected expected fish biomass of 30kg per ha, 3000 kg fish production and growth is lost for every km 2 of oshana surface area that cannot be compensated for in any way. All along the proposed dike route, several large trees, particularly important fruit trees were noted: In fact each is visible in the large scale aerial photographs used. Care should be taken to avoid any unnecessary removal of these trees. By sensitive alignment of the dike to follow the natural contours of the iishana along which it passes, the removal of many of these trees which are all on slightly higher ground, can be prevented and where this is not possible saplings should be replanted on the bank opposite the dike to replace any trees lost. Important vegetation zones can be protected by creating or leaving some higher lying islands within the deepened channel allowing the flow to naturally braid around it or even by creating long islands as well as some quieter water areas. The focus should be to keep the channel natural. 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
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25 Discussion with Mr L. Hango, Hyd
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27 A full record of the discussion
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29 Oreochromis macrochir Greenhead
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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 and 88: 75 4.7.2 IMPACT OF DEEPENING AND LI
Page 91 and 92: 79 4.8 IMPACTS OF FLOODGATE OPERATI
Page 95: 83 4.9 IMPACTS OF REMOVAL OF VEGETA
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
Page 139 and 140: 127 Do not foresee any impacts of w
Page 141 and 142: 129 B) FISH SURVEY RESULTS - ACTUAL
Page 143 and 144: 131 Site 4 Dike 3 Tuesday 25 June T
Page 145 and 146: 133 Site 7 Thursday 28 June - Deep
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Wetland & Fish Ecology - Enviro Dynamics Namibia

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