Hostname: page-component-745bb68f8f-g4j75 Total loading time: 0 Render date: 2025-01-26T06:25:32.395Z Has data issue: false hasContentIssue false
  • English
  • Français

Estimates of Past Climate at Paleolake Chad, North Africa, Based on a Hydrological and Energy-Balance Model

Published online by Cambridge University Press:  20 January 2017

John E. Kutzbach
John E. Kutzbach*
Affiliation:
IES-Center for Climatic Research and Department of Meteorology, University of Wisconsin -Madison, 1225 West Dayton Street, Madison, Wisconsin 53706
Get access Rights & Permissions [Opens in a new window]

Abstract

Modeling the combined hydrological and energy balances of Paleolake Chad and its drainage basin yields an estimate of at least 650 mm/yr for annual precipitation during portions of the early Holocene (10,000 to 5000 yr B.P.); the current rainfall in Chad Basin is 350 mm/yr. Two versions of the model are developed. The first version is one in which precipitation and lake area are linearly related. This version requires specification first of the area, net radiation, and Bowen ratio of the lake and second of the paleovegetation, net radiation, and Bowen ratio of the surrounding basin. In the second version of the model the ralationship between precipitation and lake area is nonlinear because the runoff ratio and Bowen ratio of the basin are made functions of precipitation. As the lake increases in area in response to increased precipitation, this version of the model allows for further increases in runoff (from the basin into the lake) as the vegetation changes from steppe to savanna and swamp. This nonlinear process may provide a partial explanation for the expansive paleolakes of the early Holocene. The results derived from both models are in good agreement with previously derived estimates of precipitation for North Africa during the early Holocene.

Type
Articles
Information
Quaternary Research , Volume 14 , Issue 2 , September 1980 , pp. 210 - 223
Copyright
University of Washington

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

Brakenridge, G.R. Evidence for a cold, dry full-glacial climate in the American Southwest. Quaternary Research 9 1978 22 40 Google Scholar
Bryson, R.A. The lessons of climatic history. Environmental Conservation 2 1975 163 170 Google Scholar
Budyko, M.I. Climate and Life Vol. 18 1974 Academic Press New York International Geophysics Series Google Scholar
Butzer, K.W. Climatic changes in the arid zones of Africa during early to mid-Holocene times World Climate from 8000 to 0 B.C. 1967 Royal Meteorological Society London 72 83 Google Scholar
Butzer, K.W. Issac, G.L. Richardson, J.A. Washbourn-Kamau, C. Radiocarbon dating of East African lake levels. Science 175 1972 1069 1076 CrossRefGoogle ScholarPubMed
Churchill, D.M. Galloway, R.W. Singh, G. Closed lakes and the paleoclimatic record Pittock, A.B. Frakes, L.A. Jenssen, D. Peterson, J.A. Zillman, J.W. Climatic Change and Variability—A Southern Perspective 1978 Cambridge Univ. Press London 97 107 Google Scholar
Flohn, H. A scenario of possible future climates—natural and man-made “World Climate Conference,” extended summaries of papers presented at the conference Geneva, February 1979 1979 World Meteorological Organization Geneva Google Scholar
Griffiths, J.F. Climates of Africa, World Survey of Climatology Vol. 10 1972 Elsevier Amsterdam Google Scholar
Grove, A.T. Pullan, R.A. Some aspects of the Pleistocene paleogeography of the Chad Basin Howell, F.C. Bourliere, F. African Ecology and Human Evolution 1963 Adeline Chicago 230 245 No. 36 Google Scholar
Grove, A.T. Warren, A. Quaternary landforms and climate on the south side of the Sahara. The Geographical Journal 134 1968 194 208 Google Scholar
Lamb, H.H. Climate: Present, Past and Future Vol. 2 1977 Methuen London (Climatic History and the Future) Google Scholar
Lettau, H. Evapotranspiration climatonomy, I. A new approach to numerical prediction of monthly evapotranspiration, runoff, and soil moisture storage. Monthly Weather Review 97 1969 691 699 Google Scholar
Lettau, H.H. Explaining the world's driest climate Lettau, H.H. Lettau, K. Exploring the World's Driest Climate. IES Report 101 1978 Center for Climatic Research, Institute for Environmental Studies, University of Wisconsin-Madison 182 248 Google Scholar
Lettau, H.H. Lettau, K. Molion, L.C.B. Amazonias' hydrologic cycle and the role of atmospheric recycling in assessing deforestation effects. Monthly Weather Review 107 1979 227 238 Google Scholar
Löf, G.O.G. Duffie, J.A. Smith, C.D. World distribution of solar radiation. Report 21 1966 Solar Energy Laboratory, College of Engineering, University of Wisconsin Engineering Experiment Station, University of Wisconsin-Madison Google Scholar
Maley, J. Analyses polliniques et paléoclimatologie des douze derniers millénaires du Bassin du Tchad (Afrique Centrale). Recherches Francaises sur le Quaternaire, INQUA 1977, Supplément au Bulletin AFEQ 1977 50 1977 187 197 Google Scholar
Maley, J. Palaeoclimates of central Sahara during the Holocene. Nature (London) 269 1977 573 577 Google Scholar
Newell, R.E. Kidson, J.W. Vincent, D.G. Boer, G.J. The General Circulation of the Tropical Atmosphere Vol. 2 1974 MIT Press Cambridge, Mass Google Scholar
Peterson, G.M. Webb, T. III Kutzbach, J.E. van der Hammen, T. Wijmstra, T.A. Street, F.A. The continental record of environmental conditions at 18,000 yr B.P.: An initial evaluation. Quaternary Research 12 1979 47 82 CrossRefGoogle Scholar
Priestley, C.H.B. Taylor, R.J. On the assessment of surface heat flux and evaporation using large-scale parameters. Monthly Weather Review 100 1972 81 92 Google Scholar
Reeves, C.C. Jr. Introduction to Paleolimnology 1968 Elsevier Amsterdam Google Scholar
Rockwood, A.A. Cox, S.K. Satellite inferred surface albedo over Northwestern Africa. Journal of Atmospheric Science 35 1978 513 522 Google Scholar
Rognon, P. Williams, M.A.J. Late Quaternary climatic changes in Australia and North Africa: A preliminary interpretation. Palaeogeography, Palaeoclimatology, Palaeoecology 21 1977 285 327 Google Scholar
Sellers, W.D. Physical Climatology 1965 Univ. of Chicago Press Chicago Google Scholar
Servant, M. Servant, S. Les formations lacustres et les diatomées de Quaternaire récent du fond de la cuvette Tchadienne. Revue de Géographie Physique et de Géologie Dynamique 7 2 1970 63 76 Google Scholar
Servant-Vildary, S. Paleolimnolodie des lacs du Bassin Tchadien au Quaternaire récent. Palaeoecology of Africa 11 1979 65 78 Google Scholar
Singh, G. Joshi, R.D. Singh, A.B. Stratigraphic and radiocarbon evidence for the age and development of three salt lake deposits in Rajasthan, India. Quaternary Research 2 1972 496 505 Google Scholar
Street, F.A. Late Quaternary precipitation estimates for the Ziway-Shala Basin, S. Ethiopia. Palaeoecology of Africa 11 1979 135 143 Google Scholar
Street, F.A. Grove, A.T. Environmental and climatic implications of late Quaternary lake-level fluctuations in Africa. Nature (London) 261 1976 335 390 CrossRefGoogle Scholar
Street, F.A. Grove, A.T. Global maps of lake-level fluctuations since 30,000 yr B.P.. Quaternary Research 12 1979 83 118 Google Scholar
Wickens, G.E. Changes in the climate and vegetation of the Sudan since 20,000 B.P.. Boissiera 24 1975 43 65 Google Scholar