Disentangling streamflow impacts of check dams from vegetation changes.

• We develop a check dam module that is coupled into SWAT-PML to disentangle check dam impacts from vegetation changes. • With the continuous construction of check dams, there is an increasing trend in the impact of dams on streamflow. • Check dams under maximum operation have largest decrease in streamflow, followed by vegetation. • Normal operation of check dams has marginal impacts on decrease in streamflow. Check dam is an important soil and water conservation engineering measure to prevent and control the soil erosion in the Loess Plateau. However, how check dams influence catchment streamflow process remains largely unclear. This study develops a check dam operation module within SWAT model, which is then coupled with Penmen-Monteith-Leuning (PML)-V2 evapotranspiration model. The coupled model is finally used to disentangle streamflow impacts of check dam from vegetation changes by considering four scenarios: vegetation greening and normal operation of check dam, vegetation greening and maximum operation of check dam, vegetation greening only, and no-impact. Our results indicated a progressive increase in water reduction, with the gradual construction of check dams over the years. The vegetation greening plays a major role in reducing catchment streamflow by 9.9 % to 19.8 % in three studied catchments. The check dam under normal operation shows marginal impacted on streamflow (the three studied catchments experienced streamflow reduction ranging from 2.9 % to 4.9 %), though the maximum check dam operation had the largest impact (the proportion of streamflow reduction ranges from 28.2 % to 54.2 %). This study can help understanding the impacts of different check dam constructions and operations on streamflow, which is helpful for planning sustainable water resources. [ABSTRACT FROM AUTHOR]