geoe111lecture 2-2011: relief & drainage

GEOE111: PHYSICAL,ECONOMIC AND POPULATION BACKGROUND OF AFRICA AND THE RSA GEOGRAPHY Lecture 2: Relief and Drainage: Dr.TM Ruhiiga, North West University, Mmabatho 2735, South Africa:

GEOE111: PHYSICAL,ECONOMIC AND POPULATION BACKGROUND OF AFRICA AND THE RSA GEOGRAPHY Lecture 2: Relief and Drainage: Dr.TM Ruhiiga , North West University, Mmabatho 2735, South Africa Relief regions Distribution of relief regions Processes and landforms Drainage basins and relative extent Stream dynamics and surface geology Seasonal variability in volume & impact

Relief Regions:

Relief Regions Defined…extensive territory showing similar characteristics of surface terrain, configuration and altitude Highlands, plateau, plains, rift valley system, basin, floodplain Variability in distribution, age, size, origin and underlying geology Concept of “old surfaces” and “young Surfaces”

Distribution:

Distribution Use an Atlas or internet downloads on google Use a blank outline map of Africa: Fig 1 Refer to Africa, Relief Identify the major relief regions and trace them on to your blank map with a pencil by dotted lines demarcating extent Insert a Legend to Figure 1 once all regions are entered

Process & Landforms:

Process & Landforms Plate tectonics..a series of forces-shearing, compression, tear, faulting responsible for continental drift, the evolution of island chains, deep sea troughs, earthquakes, large-scale volcanic eruptions, regional land forms and the current shape & distribution of continents. Time..a continuing process through millions of geological time: we talk of evolution

Process & Landforms:

Process & Landforms Faulting.. Subsidence.. Volcanism.. Uplift.. Folding.. Deposition.. Sedimentation.. Metamorphism

Synthesis:

Synthesis The continental mass of Africa is a product of millions of years of geological changes associated with continental drift The relief regions of Africa have over millions of years been subjected to internal and external changes leading a diversity of landforms The drainage systems today have been over the years adjusting to changes in landforms The result is a close link between landforms, drainage and weather processes producing diverse features

Rift Valley System:

Rift Valley System Rift valley system of Eastern Africa…use a relief map of Africa and trace the outline of the system…Fig 3. Fill in the boundaries of all countries that share the system Identify the distribution of volcanic mountains in Africa In what way are these linked to the rift valley system? The rift valley system is one of the most impressive landforms in Africa but it imposes certain limitations: List at least two such limitations.

Drainage :

Drainage Use internet or an Atlas map of Africa showing major drainage networks Identify the major river systems in terms of source, course, extent and countries through which they flow, destination Use a blank outline map of Africa..Fig 2 Trace the main river systems on to Fig 2 Using dotted lines, trace on to your Fig 2, a rough estimate of the drainage basin of each river Provide a title and Legend for your map

Seasonal Variability:

Seasonal Variability Elements… Volume of flow shifts with change in rainfall over catchment area Volume of flow shifts with changing evaporation rates over distance from origin to destination Volume of flow shifts depending on inputs from various tributaries & distributaries Variations in geology along course & landscapes crossed

Stream Dynamics:

Stream Dynamics Flow.. Energy provided by gravity generated by slope/gradient River flow..force, speed, resistance, depth, suspended matter, floor creep, duration, volume, erosive capacity, transportation capacity, attrition, seasonality, rainfall regime Increasing gradient lead to greater stream velocity, greater erosive capacity, greater transportation, increased transport and little deposition Forms..water falls, rapids, lagoons, islands, wetlands, lakes, floodplains, beach, pavements, debri