Potential effects of development on flow characteristics of two streams in the Raritan River Basin, New Jersey

Parts of the Raritan River basin in central New Jersey have undergone increasing development over the last several decades. The increasing population relies on the region's ground water and surface water sources for its residential, commercial, and industrial water supply. Urbanization, regionalized wastewater‐treatment facilities, stream channel alterations, and interbasin transfers of water can all affect water availability. This pilot study was conducted to determine whether significant trends exist in the base‐flow and overland‐runoff characteristics of streams in two subbasins with different percentages of urban/built‐up land (Anderson et at., 1976). Changes in flow characteristics that could indicate future reductions in safe water yield of the Raritan River basin were examined. Flow and flow variability of the steams draining these two subbasins have increased over time. Many of the flow measures studied experienced pronounced trend shifts about 1960. The cause of these changes cannot be readily determined from the data, nor is it clear whether the increased flow variability lies outside the natural range of flow variability of the streams draining the subbasins.