Autoregressive models (AR) are extensively used to understand the behavior of streamflow. The literature abounds with examples of AR models from different families applied "everywhere" to fully understand how streamflow changes throughout the hydrologic year. One particularly well accepted model is the periodic autoregressive model, as in Hipel and McLeod (1984).
So far, from all I've ever read, all streamflow AR models will have a signficant first order lag. That is, when one calculates the PACF to find the order p of the model, p will assume a value of 1, at least.
Is there any known case registered in the literature of an AR streamflow model of order 0, i.e., AR(0) for streamflow? That is, is there a possible way that the "yesterday's flow" won't explain the "today's flow"?