Use of Cokriging and Map Correlation to Study Hydrological Response Patterns and Select Reference Stream Gauges for Ungauged Catchments

Abstract

Insufficient unregulated streamflow observation is a practical challenge and limits the effective utilization and management of water resources. In this paper, the recently introduced univariate map-correlation method to select reference stream gauges and estimate daily streamflows at ungauged catchments was evaluated. The concept was further developed into a multivariate map-correlation using ordinary cokriging. The characteristics of the hydrological response correlations among 27 unregulated catchments were used as the primary sources of information for the analyses. In addition, the lack of information about the hydrological response correlations between catchments was supplemented by extracting correlation information from topographic and climatic covariables. The study was applied to investigate regional hydrological response patterns and select reference stream gauges for ungauged catchments. The analyses revealed that distinct regional hydrological response patterns exist in the case study area. Furthermore, the presence of the hydrological response patterns influenced the location of the best-correlated reference stream gauges to the ungauged catchments in the study area. The analyses results also showed that geographic proximity could not entirely explain the catchment hydrological response correlations, and the nearest stream gauge was not necessarily the best-correlated stream gauge. The multivariate map-correlation approach applied in this study added a physical understanding to the hydrological response correlations between the ungauged catchments and reference stream gauges.