River Damming Reduces Wetland Function in Regulating Flow

The global scale wetland loss or degeneration triggers the assessment of how their function provisions are likely to change under different management scenarios. However, how and to what extent river damming can modify the hydrological function of wetlands remain largely unknown. In this study, we apply a distributed hydrological modeling platform for a larger river basin in Northeast China with a paired modeling scenario: (1) modeling with no dam present (i.e., under natural conditions), and (2) modeling with dam present (i.e., under disturbed conditions). The overarching goal of the study is to quantify the effect of damming on wetland hydrological processes. The modeling study demonstrates that river damming can alter the wetland effect on daily flow by significantly reducing flow under low flow conditions but slightly increasing flow under high flow conditions. Damming can impact the wetland function in alleviating floods with a 7% decrease when compared to the natural conditions without a dam. Consequently, the supporting effect of wetlands on baseflow is weakened substantially by damming regulation. These results indicate that river damming can impair flow regulation functions of downstream wetlands, and therefore, new flow regulation and optimization strategies for achieving complementary hydrological functions of wetlands and reservoirs are important to maximize basin resilience to hydrological extremes under climate change.