SHORT TERM VARIATION OF RUNOFF-RAINFALL RATIOS IN NOVA SCOTIA IHD WATERSHEDS

Abstract

Runoff-rainfall ratios are estimated from streamflow hydrographs using precipitation and streamflow data for three IHD watersheds in Nova Scotia. The study watersheds are located in eastern, central and western Nova Scotia. Instrumentation for the measurement of precipitation, temperature and streamflow was installed in the watersheds as part of the International Hydro logical Decade program. Annual hydrographs were plotted and separated into their direct runoff and groundwater runoff components. Average annual direct runoff varied from 20 to 29.8 inches and groundwater runoff varied from 11.3 to 28.7 inches. Individual and largest storms were selected for each month from the meteorological records (Fraser Brook 3 years, April Brook 2 years, Sharpe Brook 1 year of period). Storm hydrographs were also plotted and separated into their two components of direct and groundwater runoff. Ratios of direct runoff to average weighted rainfall were determined for each watershed. Estimates revealed that these ratios varied from 0. 03 to 29% for the period of study. Annual runoff-rainfall ratio in the watersheds varied from 66 to 97%.