Combined hydrologic sampling criteria for rainfall and streamflow

David G. Tarboton, Utah State University
Rafael L. Bras
Carlos E. Puente


This paper considers the joint sampling of the rainfall and streamflow processes. The sampling frequencies in time and space are obtained as a function of basin and rainfall characteristics. The effectiveness of different sampling strategies is measured by the variance of the error of estimated or predicted streamflow. This is related to the rainfall and basin rainfall-discharge properties through parameterizations of these processes. Rainfall is modelled as a stochastic process with covariance structure separable in time and space. Streamflow is parameterized in terms of the fluvial geomorphology of the basin. Linear systems theory is used to link precipitation to flow and to compute the variance of basin discharge. The variance of the error in prediction of streamflow is computed in terms of the following: (1) basin and rainfall model parameters; and (2) measurement strategy consisting of numbers of rain gages plus rainfall and flow measurement intervals. This error variance is used to assess the effectiveness of a measurement strategy. The results should be of use in the formulation of hydrologic sampling strategies.