Evaluation and optimization of raingauge network based on probability kriging (case study: Gorgan-Rud watershed)

Rainfall is a key factor for water resources management. Raingauge networks with accurate measurement and appropriate density are required for the estimation of the rainfall in ungauged sites in watersheds. This study aimed at assessing a method based on kriging and normal probability distribution function for evaluating raingauge network in GorganRud watershed (114000 km2). The concept is based on criterion that named percentage of the total area with acceptable accuracy (Ap). Spatial variability of annual rainfall is analyzed using dimensionless variogram then using a sequential algorithm 33 raingauges in the network is evaluated. Results showed the base network for annual rainfall comprises 21 gauges and 12 remaining gauges have little contribution to estimate areal rainfall in the watershed. After optimization the non-based raingauges reduced to 7 gauges and will be more effective to estimate areal rainfall in whole of watershed. Furthermore, Results showed that simplifying and using GIS software by developing a toolbox will make it easier for evaluating a raingauge network.