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This paper summarizes the initial results (first 4 yr) of a whole‐catchment manipulation to evaluate the impact of a loss of hydrologic connectivity of a boreal lake with its watershed on lake thermal and evaporative regimes. We diverted the upstream flow to a fourth order lake resulting in a marked reduction (81%) in watershed area, and compared the response to a comparable control lake in a headwater position. The manipulation reduced runoff into the experimental lake from 2400 mm to 90 mm, greatly increased theoretical residence time (from 2.3 yr to 18.3 yr), and reduced average dissolved organic carbon concentration from 5.8 ± 0.3 mg L−1 to 5.5 ± 0.3 mg L−1. Average Secchi depth was increased by 0.6 m, resulting in a 0.25 m deeper epilimnion and cooler surface water temperatures (8% of the time) than those predicted by pre‐manipulation relationships. There was some evidence that the response of evaporation to episodic events was altered, but this was not extensive enough to alter annual evaporation or median evaporation rates. Our findings show that the impacts of hydrologic connectivity on lake chemistry can cascade to alter the energy budgets of boreal lakes. These results can inform how differences in hydrological connectivity across the landscape due to lake‐watershed topology and climate will impact boreal lakes. Of note is that very clear lakes in the boreal region are highly sensitive to impacts from a change in clarity. Information on their spatial distribution will be necessary to assess impacts of hydrological connectivity on the boreal lake complex. [ABSTRACT FROM AUTHOR]

Actual evapotranspiration ( ET ) over the Tibetan Plateau (TP) is an important component of the water cycle, and greatly influences the water budgets of the TP lake basins. Quantitative estimation of ET within lake basins is fundamental to physically understanding ET changes, and thus will improve the understanding of the hydrological processes and energy balance throughout the lake basins. In this study, the spatiotemporal dynamic changes of ET within the Lake Selin Co (the TP's largest lake) and its surrounding small lakes and land area during 2003-2012 are examined at the basin scale. This was carried out using the well-established Water and Energy Budget-based Distributed Hydrological Model (WEB-DHM) for the land area, the Penman method for the water area when unfrozen, and a simple sublimation estimation approach for the water area when frozen. The relationships between ET changes and controlling factors are also discussed. Results indicate that the simulated land ET from the WEB-DHM reasonably agrees with the estimated ET values from the nonlinear complementary relationship model using appropriately calibrated parameter values at a point scale. Land ET displayed a non-significant increase of 7.03 mm year, and largely depends on precipitation. For the water area, the combined effects of reduced wind speed and net radiation offset the effect of rising temperature and vapor pressure deficit, and contributed to a non-significant decrease in evaporation of 4.17 mm year. Sensitivity analysis shows that vapor pressure deficit and wind speed are the most sensitive variables to the changes of evaporation from the water area. [ABSTRACT FROM AUTHOR]