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The between lands mod
The between lands mod





Small watersheds are, within a given drainage system, represented by upland areas where rainfall and runoff depths are usually greater and an extensive, well-developed channel system is lacking. On the average, small watersheds are more nonlinear than large watersheds. The effect of averaging is to linearise the watershed behavior.

the between lands mod

In other words, spatial variability of watershed characteristics increases with size.Īs the watershed size increases, storage increases and averaging of hydrologic processes increases as a result. Small watersheds are usually least heterogeneous and large watersheds are most heterogeneous. Two watersheds of the same size may behave very differently if they do not have similar land and channel phases. Each phase has its own storage characteristics.ġ) They have well-developed channel networks and channel phase, and, thus, channel storage is dominant.Ģ) They are less sensitive to high-intensity rainfalls of short duration.ġ) They have dominant land phase and overland flow, have relatively less conspicuous channel phase.Ģ) They are highly sensitive to high-intensity, short-duration rainfalls.

the between lands mod

Runoff generation on these watersheds can be considered in two phases: i) land phase and ii) channel phase. This classification is vague, but the implication is in terms of spatial heterogeneity and dampening (averaging) of hydrological processes. Three types of watershed are distinguished according to size: Two hydrologically meaningful criteria are size and land use.ġ5.2 Classification of Watersheds by Size Watersheds can be classified based on size, mean slope, length, land use, etc. Watershed, catchment and basin are most commonly used terms by hydrologists.

the between lands mod

Other terms synonymous with drainage basin are watershed, catchment, basin, river basin, runoff area, and stream basin. The physical boundary of the drainage basin is called the drainage divide.The watershed area includes all the points that lie above the elevation of the outlet and within the drainage divide that separates adjacent watersheds. Thus, a basin is defined with respect to the outlet. One can move the drainage outlet up the drainage system or down the drainage system to any location of interest (makes possible the sub-basin studies).īy definition, any point on the main drainage system can be selected as the basin outlet. This definition permits the selection of any drainage outlet desired. Fig.15.1.Drainage basin with its sub-basins.







The between lands mod