COMPARISON OF STREAMFLOWS IN THE SOUTH COASTAL BASIN SE MASSACHUSETTS

SE Massachusetts is largely underlain by glaciofluvial surficial deposits of various hydrological characteristics, ecological environments, different potential for water resources, and influenced by different land use practices. In South Coastal River Basin are two medium sized drainage catchments with continuous streamflow monitored by the USGS since 1966. The Indian Head River (IHR) and Jones River (JR) monitoring stations are located roughly 13 miles apart, their respective regions share the same average annual temperatures (IHR 15.2 deg.C, JR 14.9 deg.C), very similar precipitation profiles (IHR 46.9”, JR 49.5”) but differ substantially in land use distribution: forested land (IHR 26.7%, JR 63.5%), developed land (IHR 50.7%, JR 19.8%), and impervious surface (IHR 17.8%, JR 5.3%). Annual streamflow data averaged over a 30 year period between 1986 and 2016 normalized to their respective drainage areas are for IHR 2.17 and for JR 2.38 cfs per sqmi respectively. Despite these similarities, further comparison of averages of 30 year monthly streamflows however display unique differences. During the winter months, the discharges in both watersheds are nearly equal reflecting similar overall hydrological characteristics of both watersheds. However between March to September, the JR drainage has much higher average monthly streamflow gradually increasing from March to August before sharply decreasing in September and returning back to the similar levels as the IHR drainage in October. This annual pattern consequently reflects the defining differences in land use between the drainage basins, i.e. higher percentage of urban cover in IHR in contrast to higher percentage of forested land in JR areas. This is most apparent during the summer months when there is a substantially higher evapotranspiration compared to streamflow (IHR relative to JR). Understanding the differences of the hydrological responses between IHR and JR watersheds can provide the framework to help assess the impact of land use in other watersheds such as the Third Herring Brook catchment, also part of this study.