Inflow intrusions at multiple scales in a large temperate lake

Abstract

Lake Como receives inflows of vastly varying scales. The majority of the lake's water comes from the alpine inflows to the north, and much smaller inflows supply large amounts of pollutants in the south. We combined various data sets with a three-dimensional hydrodynamic model to investigate the processes affecting the fate of these inflows with potential applications for management responses to both pollution and climate change effects. During the stratified period inflow waters from the northern alpine sources intrude in the metalimnion, undergo a deflection due to the Earth's rotation, and subsequently affect local flushing in a semi-closed embayment receiving the shallower intrusions of the small polluted inflows.

Study of tributary inflows in Lake Iseo with a rotating physical model

“…Nydegger (1979) briefly argued about the importance of Coriolis force in the deflection of the tributary waters of 3 medium-size Swiss lakes, but he did not provide any quantitative indi-N o n -c o m m e r c i a l u s e o n l y cation to assess the validity of the physical model he used. The effects of Coriolis force were also documented by Hamblin and Carmack (1978) in Kamloops Lake, by Morillo et al (2008) in Coeur d'Alene Lake and mentioned by Laborde et al (2010) in Lake Como, whose width is comparable to that of Lake Iseo and where the river is deflected towards its right-hand shoreline irrespective of wind conditions.…”

Contribution of extreme meteorological forcing to vertical mixing in a small, shallow subtropical lake

“…The impact of typhoon-induced inflow was large although the inflow effect is usually minor in physical processes in large lakes (Michalsky and Lemmin, 1995). For understanding localized mixing for stratified water bodies, numerous spot measurements are necessary to reveal more precise characteristics of inflow-induced vertical mixing in specific areas with density plume phenomena (Laborde et al, 2010;Hogg et al, 2013). The overall suggestion is that the inflow had an important effect on vertical mixing although wind shear stress was also influential.…”

“…Vertical mixing is normally caused by wind-driven circulation (Kullenberg, 1976), cooling-related convection (Read et al, 2012), and inflow from heavy rainfall inputs (Laborde et al, 2010). In general, temperate lakes experience destratification because of cooling and the strong wind-induced mixing that occurs during winter in a seasonal cycle of mixing (Sundaram and Rehm, 1973).…”

Contributions of local knowledge to the physical limnology of Lake Como, Italy

“…Spectra of isotherms displacements also evidence a higher vertical mode internal wave with a phase keyed to the diurnal wind patterns. The lake's main inflows drain water from alpine catchments in the north and generally intrude as interflows during the stratified period, and interplay with wind patterns and the Earth's rotation to foster southward currents in the lake's metalimnion that tend to be stronger on the western side of the basin (10).…”