Limitations of Hydrological Forecasting

[adminchy13]

The Commission considered the draft WMO Statement on the Scientific Basis for and Limitations of Hydrological Forecasting. It recognized the need for and importance of such a statement but recommended developing the statement further by focusing on limitations for streamflow and water level forecasting. It decided that an expert group under the guidance of the new AWG would review the statement, outlining in a general but comprehensive manner limitations for streamflow and water level forecasting. The Commission recommended that the members of the Commission be invited to provide their comments on the draft through e-mail. The Commission also directed the AWG to finalize and approve the statement on its behalf as expediently as possible. The Commission underlined the importance of continuing to address issues related to limitations in hydrological forecasting in the context of the QMF.

Paragraph 6.9 extracted from the CHy-XIII report (WMO Publication No. 1033)

The draft document can be downloaded here below.

WMO STATEMENT ON THE SCIENTIFIC BASIS FOR, AND LIMITATIONS OF, RIVER DISCHARGE AND STAGE FORECASTING - Draft 15 January 2009

[muttiah]

I have made my comments in attached file. Hopefully, the file makes it through.

[Gabriel Arduino]

Thank you Mr Muttiah for your interesting contributions that are the beginning of the discussions. I would appreciate it if you could also answer the questions included in the Welcome address.
I would suggest all the contributors to read paragraph 6.9 with the CHy-XIII resolution on how to proceed with the “Limitations paper”.
I am looking forward to continue receiving your contributions.

[mvmuste]

A (new) statement on the "Scientific Basis for River Discharge and Stage Forecasting" cannot anymore overlook the hysteresis process occurring in rivers during unsteady flow conditions. The hysteresis (or loop rating curve) was not accounted for in the conventional stage-discharge rating curves due to the difficulties related to monitoring. However, current instrumentation is increasingly capable and available to more homogeneously sample flows in field conditions such that the hysteresis can be documented and new methodological procedures can be implemented both in monitoring and modeling. I suggest to include this process as a source of major uncertainty both for Measurement uncertainty (page 1) and Hydrological model choice and use (Page p. 3).

[Gabriel Arduino]

Thank you Mr Muste for your contribution. I imagine that you have in mind, as the limitation paper directs the reader, the stage forecasting based on the discharge forecasting and your contribution is welcomed. I would suggest that in relation to stage forecasting the use of models that forecast also the stage is also taken into account. In this case, the hysteresis is managed by the model itself. Obviously we should consider the hysteresis process when we calibrate and verify the model. It would be wrongly calibrated if the use of, as you wrote, a traditional stage-discharge rating curve is made.

A general comment: as the last two contributions are not responding to the questions included in the Welcome address, I strongly recommend following them. For easy of reference I am repeating them below:

“We would appreciate your answers to the following six items:

1. Should the “WMO Statement on the scientific basis for, and limitations of, river discharge and stage forecasting” be approved in the present form? Yes / No

2. Should it be modified? Yes/ No

3. Is the topic of River Discharge addressed in a comprehensive manner in the current draft? Yes / No

4. If the answer to question 2 is Yes and question 3 is No, please provide alternative text as appropriate.

(Note: Please be specific as it is very difficult to make changes on the basis of vague or philosophical criticisms. No one will be offended if you propose deleting a part of the text and replacing it with alternative text).

5. Is the topic of River Stage addressed in a comprehensive manner in the current draft? Yes / No

6. If the answer is No, please provide alternative text as appropriate.

(Please follow the same Note included under item 4.)"

[DiezigR]

I made some comments/suggestions in the attached file.

[Gabriel Arduino]

That you for your detailed comments that will be taken into account. However, it would be nice if you could answer the general questions included in the post immediately before yours. The main objective is to define by the CHy Advisory Working group if the limitation paper should be issued because is useful or not.

Best regards,
Gabriel Arduino