These tributaries also lengthen their longitudinal courses through headward erosion and branches of tributaries are developed in due course of time. Major tributary streams of the master stream develop on either side of the trunk stream (fig. The master consequent gradually but slowly lengthens its longitudinal course through headward erosion. First of all the master or trunk consequent stream develops on gently sloping topographic surface. The evolution of dendritic pattern is guided by the lithological characteristics mainly the permeability of underlying rocks, the amount and regime of rainfall and resultant surface runoff and the time factor. This pattern develops in a variety of structural and lithological environments such as in the mountainous and hilly areas (e.g., dendritic pattern is one of the dominant patterns in the Himalayas), on extensive plateau surfaces (e.g., Deccan plateau), on peneplain surfaces (e.g., the Peninsular peneplains of India, mostly in the basins of the Mahanadi, the Godavari, the Krishna, the Cauvery, the Domodar etc.), in the alleviated plains (e.g., Great Plains of North India), in the desert plains (e.g., Rajasthan desert), in the glaciated lowland regions (e.g., North European plains and northern lowlands of North America) etc. Though dendritic pattern is independent of structural and lithological controls but almost uniform lithology (presence of same type of rocks in extensive area) presents most ideal condition for the development of dendritic drainage pattern. The dendritic pattern is associated with the areas of homogeneous lithologies, horizontal or very gently dipping strata, flat and rolling extensive topographic surface having extremely low reliefs. The pattern is called dendritic on the ground that the network of tributaries of various orders and magnitudes of the trunk or master stream resembles the branches and roots and rootlets of a tree. Trellised drainage patterns are generally formed in the regions of cuesta topography where hard beds become escarpments and soft beds are eroded to become valleys or lowlands.ĭendritic or tree-shaped drainage pattern is the most common and widespread pattern to be found on the earth’s surface. If the streams are closely spaced the resultant pattern becomes trellised while rectangular pattern is formed when the streams are widely spaced. In fact, the trellised and rectangular patterns are differentiated on the basis of spacing between the streams. This pattern also resembles the rectangular pattern. Thus the resultant network of numerous longitudinal streams and transverse or lateral consequents is called trellised pattern. These tributary streams are called as lateral consequent streams. Several streams develop on both the flanks of the ridges and join the longitudinal synclinal streams at right angle. Several master consequent longitudinal streams valleys occupying the furrows between parallel ridges are parallel to each other. Such patterns are developed in the area of simple folds characterised by parallel anticlinal ridges alternated by parallel synclinal valleys. Trellised drainage patterns are formed by the network of tributaries and master consequent streams which follow the regional slope and are well adjusted to the geological structures. The drainage patterns are divided into the following ten types: 1.
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