An Analytical Solution Of Richards' Equation Providing The Physical Basis Of Scs Curve Number Method And Its Proportionality Relationship

Keywords

infiltration; proportionality hypothesis; Richards' equation; runoff; SCS curve number method; water table

Abstract

The empirical proportionality relationship, which indicates that the ratio of cumulative surface runoff and infiltration to their corresponding potentials are equal, is the basis of the extensively used Soil Conservation Service Curve Number (SCS-CN) method. The objective of this paper is to provide the physical basis of the SCS-CN method and its proportionality hypothesis from the infiltration excess runoff generation perspective. To achieve this purpose, an analytical solution of Richards' equation is derived for ponded infiltration in shallow water table environment under the following boundary conditions: (1) the soil is saturated at the land surface; and (2) there is a no-flux boundary which moves downward. The solution is established based on the assumptions of negligible gravitational effect, constant soil water diffusivity, and hydrostatic soil moisture profile between the no-flux boundary and water table. Based on the derived analytical solution, the proportionality hypothesis is a reasonable approximation for rainfall partitioning at the early stage of ponded infiltration in areas with a shallow water table for coarse textured soils.

Publication Date

8-1-2016

Publication Title

Water Resources Research

Volume

52

Issue

8

Number of Pages

6611-6620

Document Type

Article

Personal Identifier

scopus

DOI Link

https://doi.org/10.1002/2016WR018885

Socpus ID

84988001309 (Scopus)

Source API URL

https://api.elsevier.com/content/abstract/scopus_id/84988001309

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