Estimation of hydraulic parameters for Karoon river by cokriging and residual kriging

The determination of hydraulic properties of open-channels and rivers is very important in water resources management and engineering. Geostatistical estimation methods in comparison with direct measurements and/or using mathematical models can be more cost and time effective. The objective of this study is to evaluate the possibility of applying cokriging and residual kriging methods to estimate some hydraulic parameters of rivers or open-channels. The results indicate that cokriging can be used to estimate flow cross-sectional area, flow velocity and hydraulic radius, while residual kriging can be used to estimate flow cross-sectional area, flow velocity and water surface level elevation. It is concluded that water surface width is preferable to water depth as an auxiliary variable in the cokriging method. The relative error of estimation for geostatistical estimators was about 0.87 to 22%. Thus, these methods can be considered appropriate and the user’s expected accuracy is important in choosing the geostatistical estimators for estimation of hydraulic parameters in open-channels or rivers. In general, cokriging and residual kriging can be used to estimate open-channel hydraulic parameters by using 25% (29 data) of measured data instead of 115 measured cross-sections along the channel or river with minimal cost and the least amount of time.