The characteristics of inland waters are altered by anthropogenic and natural factors. Increased human population and consumption patterns have created global demand for agriculture, leading to an increased mobilisation in catchments of sediment and nutrients that affect the characteristics of rivers. Often, this has adversely affected ecosystem services and biodiversity. Land use change affects the climate and the quantity and quality of water, notably for lakes, which are sentinels and integrators for catchment and climate forcing. An improved understanding of hydrological non-stationarity and land use and climate change (LUCC) impacts would benefit local and regional environmental managers, enabling them to understand the past and to be prepared for possible future changes in flow and water quality. In this context, the primary aim of this research is to assess the spatiotemporal responses of a lake catchment to changes in land use and climate change and variability. A detailed study was conducted on a mesotrophic lake in the temperate North Island of New Zealand. The specific objectives of the research are to: a) quantify the effect of land use and land cover change (LUC) implemented to meet nutrient load targets for a freshwater lake in New Zealand, b) estimate catchment streamflow and nutrient delivery into the lake and c) predict future changes in water quality given likely scenarios of changes in land use, climate, and management practice. Prediction of the extent of LUC required to meet water quality targets is challenging as flow and water quality observations are usually discrete, often sporadic, and the monitoring frequency can be variable. This study provides an example of addressing this challenge, using a combination of the process-based Soil and Water Assessment Tool (SWAT) model and a statistical model to provide an additional line of evidence to demonstrate the effect of afforestation on flow and water quality. [...]