Streamflow variability response to climate change and cascade dams development in a coastal China watershed

• The effects of climate change and human activities were distinguished.
• Human activities had a greater impact on the availability of water resources.
• The development of dams changed the pattern of low and high flow regimes.
• Little variation in the flood pattern was detected associated with dams operation.

Coastal watersheds and their changes in streamflow have become a particular concern in hydrology and water resource management. The ecohydrologic analysis and environmental flow component were coupled in this study to assess the streamflow variability response to climate change and human activities in the Jiulong River Watershed (JRW). Results showed that human activities were the main contributing factors to decreasing streamflow in the JRW. Available water resources decreased by 4.34% and 3.17% in the North River and West River, respectively. In addition to climate change, watershed characteristics partly influenced the streamflow quantity and regime in the North River and West River. The cascade dam construction along the mainstream of the JRW, which made the water bodies from free-flowing rivers to cascade lakes, altered the patterns of streamflow regime in terms of low and high flow events, as well as the flood pattern. The monthly low flow increased in almost all seasons; the high flow pulses homogenized; and little variation in the flood pattern was detected within the JRW. We present a case study in a southeast coastal watershed to illustrate a combined approach that could facilitate to evaluate the streamflow variability in terms of streamflow quantity and regime response to climate change and cascade dams development in two adjacent rivers within the JRW, which could hopefully provide water managers on the strategies to fight the effect of environmental changes on watershed ecosystem.