The return of the water - IUCN

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The Natural Resources of the Waza Logone Floodplain The floodplain is seasonally inundated for prolonged periods and water depth can reach one to two metres. The open, flooded grasslands, or yaérés, consist of the perennial grasses Echinochloa pyramidalis, Vetiveria nigritana, Oryza longistaminata, and Hyparrhenia rufa (White, 1983). The herb Sesbania pachycarpa occurs on places where flooding is less deep or less prolonged, especially on slightly sandy soils and elevated parts of the floodplain (Wit, 1975). Trees are absent in these grasslands and fires common. Black, clay Karal soils surround the actual floodplain and are saturated with water in the rainy season (WCMC, 1983). Acacia seyal is the dominant species here. Below the trees, a layer of herbs and coarse grasses grows to 3 m in height, including Caperonia palustris, Echinochloa colona, Hibiscus asper, Hygrophila auriculata, Sorghum purpureo-sericeum, and Schoenfeldia gracilis (White, 1983). On the higher dunes and sandy alluvial deposits in the southwest of the Park, open to dense woodland occurs with Anogeissus leiocarpa as the dominant tree. Other woody species include those that are also found in the Sclerocarya birrea woodlands in the western part of the Park. Open, wooded grassland, characterised by the tree Lannea humilis is found at places where the soil is very saline. The presence of the tree Balanites aegyptiaca close to the floodplain grasslands gives this woodland a very characteristic appearance. Old village sites are marked by the presence of tree species that are typical for past human habitation. The differences with the surrounding natural vegetation are very marked in the Karal soils and the floodplain area, and include Tamarindus indica, Adansonia digitata, Acacia sieberiana, and various Ficus spp. (Wit, 1975). Vegetation dynamics The composition of the plant communities of the floodplain is mainly determined by the high soil water availability during the dry season, resulting from saturation by floodwater during the wet season. Perennial grasses, such as Vetiveria nigritana, Echinochloa pyramidalis, and Oryza longistaminata continue to grow well into the dry season (Scholte et al., 2000a; Van De Klundert and Oosterhuis, 1997). When perennial grasses are grazed, or when they are burnt, the grasses continue to produce leaves, providing food for the grazers. In those areas of the floodplain where flooding was absent due to the combined effects of the drought in the 1980s and building of Maga Photo 6.1 Spur-winged geese in a shallow, dried up depression in Waza National Park (Photo P. Loth). 43
The Return of the Water dam, the perennial grasses disappeared and were replaced by annual grasses (Scholte et al., 2000a; Van Der Jagt and Pot, 1996). These annuals have a shorter period of growth and rather than investing in vegetative parts, these plants heavily invest in seeds. Herbivores thus not only find less biomass to feed upon when annual grasses dominate grasslands (Scholte et al., 1995, 1996), but also the production period is much shorter. After seed setting annual grasses die, whereas perennial grasses continue to grow. There is evidence, however, that the replacement of perennial grasses by annuals is reversible. Where the floods returned, due to increased rainfall in combination with the pilot flood releases in 1994 and 1997, re-colonisation of perennial grasses was recorded (Scholte et al.,2000b). Birds The Waza National Park is renowned for its biodiversity. In total 379 bird species have been identified in the Park. About half of the population of the black crowned crane (Balearica p. pavonia), some six per cent of the total world population, resides in the Waza National Park. This population has been (Van der Giessen and Raspe, 1997; Zekveld and Elissen, 1997), and will continue to be monitored by Leiden University. Annual water bird counts have been carried out in the Waza Logone area since 1993. The largest bird populations are white-faced whistling duck (Dendrocygna viduata), knobbilled goose (Sarkidiornis melanotus), garganey (Anas querquedula) and spur-winged goose (Plectropterus gambensis) (see Table 6.2). Species 1993 1995 1996 1997 White-faced whistling duck 7,524 5,784 5,427 15,317 Spur-winged goose 2,128 845 2,928 5,249 Garganey 121 735 6,781 2,035 Knob-billed goose 230 623 681 1,184 Total 12,103 7,986 15,817 23,795 Table 6.2 Numbers of the four most common waterbird species in and around Waza National Park between 1993 (De Kort and Van Weerd, 1995) and 1995-1997 (Bobo Kadiri, 1997). Guinea fowl have been studied intensively in and around the Waza National Park. The idea was to develop a management plan to harvest birds from the populations that occur around the villages near the Park to provide the villagers with extra meat. Before a study was initiated, however, the people were asked whether they would eat meat from these birds. It appeared that there was no taboo on eating guinea fowl and local communities welcomed the idea. Based on field data, a population dynamic model was developed with biotic and abiotic parameters as an input. It appeared that rainfall was a very good predictor for the number of eggs produced. Hence, rainfall amounts can be used to set harvest quota of guinea fowl (Njiforti, 1997, 2001). Mammals There are at least 30 species of mammals in the park, including elephant (Loxodonta africana), giraffe (Giraffa camelopardalis), lion (Panthera leo), two species of hyena (Crocuta crocuta and Hyaena hyaena), kob (Kobus kob), korrigum (Damaliscus korrigum), roan antelope (Hippotragus equinus), gazelle (Gazella rufifrons), warthog (Phacochoerus aethiopicus), reedbuck (Redunca redunca) and Grimm’s duiker (Sylvicarpa grimmia) in addition to smaller or less abundant species (Flizot, 1962; Tchamba, 1996a; Anonymous, 1997). The latter two species have become extremely rare and might join the list of species that have become locally extinct over the last few decades: leopard (Panthera pardus), cheetah (Acinonyx jubatus), waterbuck (Kobus ellipsiprymnus), bushbuck (Tragelaphus scriptus) and red flanked duiker (Cephalophus rufilatus) (Anonymous, 1997; pers. obs. H. Bauer). 44
Page 1 and 2:
IUCN - The World Conservation Union
Page 3 and 4:
The designation of geographical ent
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Table of Contents Foreword vii Cont
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Foreword This book tells the story
Page 10 and 11: Contributors Dr. Mike Acreman, Head
Page 12 and 13: from the Atlas de la Province de l
Page 14 and 15: List of Tables 1.1 Major floodplain
Page 16: List of Plates 1.1 Different views
Page 20 and 21: 1 1.1 Floodplains Introduction By P
Page 22 and 23: Introduction Rainfall in the Sahel
Page 24 and 25: species of ungulates, such as korri
Page 26 and 27: From its inception, the Waza Logone
Page 28: Part II The Receding Water
Page 31 and 32: The Return of the Water tonnes to 4
Page 33 and 34: The Return of the Water that the re
Page 36 and 37: 3 Consequences of the Dam and the D
Page 38 and 39: eduction in flooding (Drijver and M
Page 40: 3.3 Socio-economic consequences Con
Page 44 and 45: 4 The Wider Context By Sun Yan Evan
Page 46 and 47: Africa. A third migration route to
Page 48 and 49: The Wider Context The geographical
Page 50 and 51: 5 Hydrology of the Waza Logone Area
Page 52 and 53: variable, the extent, depth, durati
Page 54: Hydrology of the Waza Logone Area C
Page 57 and 58: The Return of the Water brought to
Page 59: The Return of the Water 1997). The
Page 63 and 64: The Return of the Water 1948; Ngog
Page 65 and 66: The Return of the Water into the bu
Page 68: Part IV Living with the Seasons
Page 71 and 72: The Return of the Water While the f
Page 73 and 74: The Return of the Water Most of the
Page 75 and 76: The Return of the Water which the f
Page 77 and 78: The Return of the Water from € 0.
Page 79 and 80: The Return of the Water The Musgum
Page 81 and 82: The Return of the Water check their
Page 83 and 84: Plate 1.2 Kob antelopes at the Mahe
Page 85 and 86: Plate 7.2 Seasonal movements of pas
Page 87 and 88: Plate 7.4 Fishing cannals in the Lo
Page 89 and 90: Plate 7.7 Big fish are only caught
Page 91 and 92: The Return of the Water staple food
Page 94 and 95: 8 Conflicts and Conflict Management
Page 96 and 97: Conflicts and Conflict Management i
Page 98 and 99: Conflicts and Conflict Management i
Page 100: Part V The Intervention
Page 103 and 104: The Return of the Water for the Exi
Page 105 and 106: The Return of the Water both techni
Page 107 and 108: The Return of the Water (IUCN 2000a
Page 109 and 110: The Return of the Water 9.5 The Waz
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The Return of the Water of the part
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10 The Waza Logone Project in Actio
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The Waza Logone Project in Action F
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The Waza Logone Project in Action F
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The Waza Logone Project in Action f
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follow to obtain permits, and also,
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started by painting in red trees or
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The Waza Logone Project in Action
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The project maintained relations wi
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11 11.1 Introduction Economic Justi
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Although it is impossible to effect
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Economic Justification of Additiona
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Figure 11.5 Composition of incremen
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12 Tools and Practices for Floodpla
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of the 1994 and 1997 pilot flood re
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Tools and Practices for Floodplain
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A major output from the study was a
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Step 10. Monitor, evaluate and adap
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5. Assess the impacts of options.
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Introduction 137
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Introduction From this premise the
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Introduction One of the most promis
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Introduction reorganisation of the
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Introduction Improving the effectiv
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Map 6.1 Satellite images showing se
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Map 6.3 Positions of two elephants
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Introduction Beauvilain, A. 1981.
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Introduction Gash, J.H.C., C.A. Nob
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Introduction Moritz, M., P. Scholte
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Introduction communities’ and ind
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