Observability of Surface Irrigation Advance

Abstract

The conditions of observability and field‐parameter identifiability for surface irrigation advance are examined by analytical' techniques and the linearized zero‐inertia model. The existence and uniqueness of the inverse irrigation problem are established by numerical tests based on a nonlinear estimation algorithm. The limitations are examined for determining the field parameters of intake and surface resistance from, field‐measured values of advance and depth for border‐strip irrigation. The linearized zero‐inertia model proves to be conditionally observable, and the resistance and two infiltration parameters cannot be identified from measurements of the rate of advance alone. All three parameters on the other hand can be identified from measurements of the surface‐water profile. The design of appropriate experiments that lead to observability of the problem is examined and the analytical and numerical limitations of the zero‐inertia model that hinder the inverse solution of surface irrigation advance are identified.