INFLUENCE OF CLIMATE ON COMPLEXITY OF CONTINENTAL SCALE DRAINAGE DIVIDES

Variability of continental divide trace irregularity is affected by many factors, one of which is the climatic condition. Here we evaluate the effect of climate on the map view complexity of continental drainage divide segments on six continents. An estimate of degree of complexity of the continental divide traces is provided by fractal dimension, D value as calculated by the divider method. A high D value indicates more irregularity along the divide trace and low D value suggests smoothness along the divide trace. For the study four major climate zones have been considered: tropical (5 segments), temperate (6 segments), arid (4 segments) and polar (2 segments). The D values calculated for the tropical zone at fine scale (approximately 10-70 km) range from 1.04 (Sumatra segment) to 1.11 (Central Africa segment) and at coarse scale from 1.01 (Sumatra) to 1.08 (North of South America segment). Similarly, the D values calculated for temperate climate at fine scale range from 1.02 (Scandinavia segment) to 1.12 (Himalayas) and at coarse scale vary from 1.01 (Scandinavian) to 1.18 (Alps). For the arid zone, the estimated D values at fine scale range between 1.07 (North and South of Africa segment) to 1.10 (South Rockies) and at coarse scale from 1.04 (South Rockies) to 1.10 (South Rockies). The D values calculated for polar climate at fine scale range between 1.10 (Siberia segment) to 1.13 (North Rockies) and at coarse scale from 1.05 (North Rockies) to 1.12 (Siberia). Lowest mean D value is obtained for tropical zone at coarse scale; polar zone at fine scale shows unusually high mean D value. At fine scale there is an unusually narrow range of fractal dimension values found in arid and polar climate while a broad range of D values is found for tropical and temperate climate. The narrow range of D value may suggest that climate has the major control along complexity of the divide in areas experiencing polar and arid climate. At coarse scale the drainage divide shows a broad range of fractal dimension for temperate climate suggesting that there are other factors playing a primary role other than climate.