## 1 Introduction  
Urban areas are becoming increasingly vulnerable to the effects of climate change, particularly the intensification of extreme precipitation events. Combined with rapid urbanisation, these phenomena are increasing surface runoff and overwhelming drainage systems, thereby increasing the risk of urban flooding. According to a Global Natural Disaster Assessment Report, floods will be the most frequent natural disaster in 2022, causing 8049 deaths and direct economic losses estimated at around $131 billion--more than double the historical average [1].  
A few years ago, sustainable urban drainage systems (SUDS) emerged as a new approach to managing urban hydrology. SUDSs aim to restore the natural balance of catchments prior to urbanisation and promote the local management of urban runoff. SUDS installation is mandatory in many areas worldwide, and considerable effort has gone into defining design and construction standards for SUDSs, as well as evaluating their performance in terms of quantitative and qualitative impacts. SUDSs have been addressed in the literature from a variety of perspectives, ranging from the analysis of the effectiveness of individual SUDSs to the strategic provision of SUDSs at neighbourhood or city scale. This covers a wide range of scientific topics related to SUDSs. Recent literature reviews highlight the growing urgency and relevance of research on this topic [2; 3; 4; 5; 6]. Notable studies on the effectiveness of individual SUDSs include those on porous pavements [7; 8; 9; 10], green roofs [11; 12; 13; 14], combinations of green roofs and permeable pavements [15], and basins and swales [16; 17].  
Some studies have broadened their focus to include small urban areas. These studies have examined the implementation of SUDSs in urban contexts and assessed their impact on stormwater management and flood risk reduction in small urban areas [18; 19; 20; 21; 22], specific urban drainage systems [23; 24], and urban areas [25; 26; 27; 28; 29; 30; 31; 32]. Studies analysing the role of SUDSs at the catchment scale remain relatively scarce. [PERSON] et al. investigated flood risk reduction at the catchment scale, focusing on specific SUDS technologies. Although that study covered a broader scale than previous studies, the analysis remains limited in terms of providing a comprehensive assessment at catchment scale. [PERSON] et al. [32] and [PERSON] et al. [33] have attempted to address the relationship between SUDSs and groundwater flows by integrating groundwater interaction modules into their SUDS models. However, these studies still do not fully address catchment-scale dynamics, as their analyses are limited to individual components of the hydrological cycle. As infrastructure designed to manage hydrological processes, SUDSs affect hydrological cycles at the catchment scale, including surface and groundwater flows, as well as water quality. In addition to controlling runoff and removing pollutants at the neighbourhood or city scale, SUDS infrastructure has an effect at the catchment scale by altering natural water dynamics and balances. Upscaling to the catchment level can provide valuable insights into the impact of SUDSs on the natural balance of the catchment, which must be considered when designing and installing SUDSs. This study aimed to develop and test a methodology for assessing the impact of SUDS implementation under climate change scenarios at the catchment scale. To this end, we propose a series of steps, techniques, and approaches for evaluating these impacts in urban environments.  
To demonstrate the applicability and effectiveness of the proposed approach, we will apply it to the city of Bari, which is located in southern Italy.