Temporal variation scale of the catchment water storage capacity of 91 MOPEX catchments

Abstract

Study region: MOPEX catchments across the continental United States. Study focus: Understanding the patterns of temporal variation of the Catchment Water Storage Capacity (CWSC) under changing environments supports superior hydrological predictions. Extensive literature usually assumed the variation scale of CWSC was equal to the time scale of the adopted hydrological model. However, this assumption may be doubted as these two scales may be inconsistent. This study focused on the combined impacts of different variation scales and different function forms of the CWSC on the hydrological prediction under climate change. The time-varying patterns of the GR4J model parameter were deduced to reveal the potential variation in the real CWSC. And the CWSC parameter was assumed as a different formula of physically-based covariates that reflected the main features of catchments. New hydrological insights for the study region: 61.5 % (56 in 91) of studied catchments had the variation scales from 1 day to 1 month while the remaining 38.5 % of catchments possessed the variation scale of 2–24 months; (2) improved model performances have been identified in all catchments when including the regression functions in the parameter θ1. The CWSC of 51.6 % of catchments (47/91), 15.4 % of catchments (14/91), and 33.0 % of catchments (30/91) had periodic variation, linear trend, both periodic variation, and linear trend, respectively; (3) larger catchments usually have longer variation scale for the CWSC, which implies that these larger catchments had more complicated runoff yield and concentration process, and were less susceptible to climate changes.

Keywords

• Catchment water storage capacity
• GR4J model
• Variation scale
• MOPEX catchments
• Climate change
• Time-varying parameter