THE DISCHARGE OF RIVER WATER

Discharge estimates were produced for each of the three rivers in the study by development of stage - discharge relationships at monitoring sites located as near to the basin outlets as was possible.  Discharge estimates were calculated at two sites on the North Stann Creek since this river has the greatest agricultural development. The estimation of discharge at each site involved:

  1. Continuous monitoring of water levels (stage) at a fifteen minute frequency throughout the whole duration of the study. This was achieved using pressure sensors and Campbell Loggers 

  2. Measurement of actual river discharge at a range of stages. This was achieved using a Braystoke (propeller-type) current meter 

  3. Development of a stage discharge relationship for each of the sites. To increase the data set used to derive these relationships, data collected by the Hydrological Unit (Government of Belize) were verified and included. Channel surveys were also made at each of the sites.  These were used to estimate discharge where measurements were not available, and to correct zero flow conditions.

Campbell logger
Braystoke current meter

The Rating Relationships developed for each of the four sites are shown in the graph below. In each case the rating equation and associated r2 (correlation coefficient) values are shown.

It should be noted that these relationships were developed to be applied to the range of stage values occurring during this study and should be used with caution if extending beyond the shown relationships.

The channel cross-section on the Sittee River was felt to be too irregular for a single rating equation and consequently different rating relationships were developed for lower and higher stage measurements.

A - North Stann Creek (Middlesex)  B - North Stann Creek  (Melinda)

C - Sittee River D - South Stann Creek