Estimation of CN Parameter for Small Agricultural Watersheds Using Asymptotic Functions

Water

Tomasz Kowalik²  Andrzej Walega¹ 

[1] Department of Sanitary Engineering and Water Management, University of Agriculture in Krakow, St. Mickiewicza 24-28, Krakow 30-058, Poland;Department of Land Reclamation and Environmental Development, University of Agriculture in Krakow, St. Mickiewicza 24-28, Krakow 30-050, Poland; E-Mail:

关键词: agricultural watershed;    rainfall-runoff model;    CN parameter;    asymptotic equation;    SCS method;   

DOI  :  10.3390/w7030939

来源: mdpi

【 摘 要 】

This paper investigates a possibility of using asymptotic functions to determine the value of curve number (CN) parameter as a function of rainfall in small agricultural watersheds. It also compares the actually calculated CN with its values provided in the Soil Conservation Service (SCS) National Engineering Handbook Section 4: Hydrology (NEH-4) and Technical Release 20 (TR-20). The analysis showed that empirical CN values presented in the National Engineering Handbook tables differed from the actually observed values. Calculations revealed a strong correlation between the observed CN and precipitation (P). In three of the analyzed watersheds, a typical pattern of the observed CN stabilization during abundant precipitation was perceived. It was found that Model 2, based on a kinetics equation, most effectively described the P-CN relationship. In most cases, the observed CN in the investigated watersheds was similar to the empirical CN, corresponding to average moisture conditions set out by NEH-4. Model 2 also provided the greatest stability of CN at 90% sampled event rainfall.

【 授权许可】

CC BY   
© 2015 by the authors; licensee MDPI, Basel, Switzerland.