Principal Techniques for Precipitation Rate Estimation in the Watersheds of Tarhuna

The recording of water resource data is a very important step for extracting their information and
characteristics. It is particularly important in countries with a shortage of this vital resource. In Tarhuna
region, rain is the main source of water used in agriculture and grazing. In any region, rainfall estimate
is based on measuring the amount of precipitation by rain meters at meteorological stations. Then,
calculate the average precipitation in that area or basin. In this context, the precipitation data included
missed data from some stations, which led to a failure in the calculation accuracy of the average
precipitation. For this reason, there is an urgent need to process lost data and achieve more accurate and reliable results. GIS and other related programs were used in processing of the average weighted rainfall
calculation in the large catchment basins of Tarhuna region through the application of Thiessen
polygons, and Isohyetal lines on the data that obtained from rainfall recording stations in Tarhuna and
adjacent areas in order to determine and know the distribution of rainfall values on the spatial parts of
each basin. The results of the study showed that the calculation by applying Thiessen polygons have not
yielded high-reliability results due to, firstly, to the lack of a sufficient number of measurement stations
in the region, and secondly, to their irregular spatial distribution, by comparison, the result of the
Isohyetal lines method has provided more reliable data on the estimation of spatial distribution and
location of precipitation rates in the catchment basins of Tarhuna region.