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The runoff curve number (also called a curve number or simply CN) is an empirical parameter used in hydrology for predicting direct runoff or infiltration from rainfall excess. [1] The curve number method was developed by the USDA Natural Resources Conservation Service , which was formerly called the Soil Conservation Service or SCS — the ...
This approach is adopted from the NRCS (SCS) curve number method for estimating runoff. It assumes that the total infiltration capacity of a soil can be found from the soil's tabulated curve number. During a rain event this capacity is depleted as a function of cumulative rainfall and remaining capacity.
A number of methods can be used to calculate time of concentration, including the Kirpich (1940) [2] and NRCS (1997) [3] methods. Time of concentration is useful in predicting flow rates that would result from hypothetical storms, which are based on statistically derived return periods through IDF curves .
Runoff routing is a procedure to calculate a surface runoff hydrograph from rainfall. Losses are removed from rainfall to determine the rainfall excess which is then converted to a hydrograph and routed through conceptual storages that represent the storage discharge behaviour of overland and channel flow. [23] [24]
A runoff models or rainfall-runoff model describes how rainfall is converted into runoff in a drainage basin (catchment area or watershed). More precisely, it produces a surface runoff hydrograph in response to a rainfall event, represented by and input as a hyetograph. Rainfall-runoff models need to be calibrated before they can be used.
A stream hydrograph is commonly determining the influence of different hydrologic processes on discharge from the subject catchment. Because the timing, magnitude, and duration of groundwater return flow differs so greatly from that of direct runoff, separating and understanding the influence of these distinct processes is key to analyzing and simulating the likely hydrologic effects of ...
A model for nitrogen sources was developed and analysed in comparison with a statistical method. A model for suspended sediment transport in tropical and semi-arid regions was developed and tested. It was shown that riverine total nitrogen could be well simulated in the Nordic climate and riverine suspended sediment load could be estimated ...
The degree and nature of correlation may be quantified, by using a method such as the Pearson correlation coefficient, autocorrelation, or the T-test. [19] The degree of randomness or uncertainty in the model may also be estimated using stochastics, [20] or residual analysis. [21]