Areal Precipitation for Regions in Trinidad Using a Triangulated Grid and the Depth-Area Duration Curves.

The areal precipitation of regions in Trinidad was determined using a domain discretized into

a mesh of a finite number of triangular elements. The rainfall at the nodes or rain gauge

stations and its x and y co-ordinates were used to determine elemental point rainfall values

via a linear interpolation of these three inputted data sets. Subsequently, the total volume of

rainfall over each element and the mean areal precipitation of each element of the grid were

determined. A decadal (2006-2015) average of monthly rainfall values were used to determine

the areal precipitation of the grid for each month. It was determined that the largest rain

fall month was November with an estimated value of 302 mm and the month of March had

the lowest areal precipitation of approximately 78 mm. Elemental analysis yields the result

that smaller irregularly shaped triangular elements which were located in the mountainous

regions of the domain, have the most differences in their monthly areal precipitation when

compared to the remaining grid elements. The grid was optimised via the configuration and

re-distribution of the nodes. It was determined that for the adjusted grid, there was more

similarity in terms of rainfall patterns for all the months in both the dry and rainy seasons as

well as high and low elevation elements when compared to the initial grid. The Depth- Area

Duration (DAD) Curves were generated for each month and for both seasons. These curves

showed how the average precipitation depth changes with each month for the area span of

the grid. This study is important in hydrological modeling and anaysis as areal precipitation

is needed from point rainfall data. Even though there exist a 75 (1911 - 1985) year Isohyetal

Map for Trinidad, this method provides a gridded network which allows the DAD Curve to

be generated with ease.