*Article* **Water Resource Management through Understanding of the Water Balance Components: A Case Study of a Sub-Alpine Shallow Lake**

**Marzia Ciampittiello \*, Claudia Dresti and Helmi Saidi**

Water Research Institute, National Research Council, Largo Tonolli 50, 28922 Verbania, Italy; Claudia.dresti@irsa.cnr.it (C.D.); helmi.saidi@irsa.cnr.it (H.S.)

**\*** Correspondence: marzia.ciampittiello@irsa.cnr.it

**Abstract:** Water availability is a crucial factor for the hydrological balance of sub-alpine shallow lakes and for their ecosystems. This is the first study on water balance and water management of Lake Candia, a small sub-alpine, shallow morainic lake. The aims of this paper are to better understand the link between surface water and groundwater. The analyses carried out included: (i) evaluation of water balance, (ii) identification of trends for each component of water balance, (iii) detection of the presence of a break point or change in the behavior of each component, and (iv) regression analyses of the terms of hydrological balance and their relative importance. The analyses revealed a high variability mainly regarding the groundwater component, and very good correlation between rainfall and volume variation, between rainfall and the water inflow, and between groundwater source and outflow. Volume variation is linked with rainfall, outflow, groundwater source, and surface water inflow. Despite the fact that the groundwater component does not seem to have a great importance relative to direct rainfall on the lake, it is necessary to study the component with careful resource management policies that point toward the protection of the water resource, sustainable uses, and protection of the Lake Candia ecosystem.

**Keywords:** water balance; regression analyses; hydro-meteorological trend
