## 1 Introduction  
Geothermal energy has established itself as a renewable and sustainable energy source with great potential in response to the growing demand for energy and the need to reduce greenhouse gas emissions [1]. A report by the Massachusetts Institute of Technology (MIT) concluded that geothermal energy has the potential to provide a highly efficient and sustainable energy source with the capacity to generate a significant amount of electricity worldwide [2]. This renewable energy source aligns with the United Nations' (UN) Sustainable Development Goals (SDGs), specifically SDG7, which \"_aims to ensure access to affordable, reliable, sustainable and clean energy_\" [3]. It is also aligned with the European Union's (EU)energy objectives, aiming for climate neutrality by 2050 [4]. To achieve this goal, the EU has developed several directives and regulations to encourage the development and implementation of renewable energies, including geothermal energy [5]. In addition to these UN and EU initiatives, there are numerous countries across the globe that have promoted the use of geothermal energy. For instance, the U.S. Department of Energy is strongly supporting the development and deployment of low-enthalpy geothermal systems [6]. Shallow geothermal systems (SGS), also known as low-enthalpy geothermal systems [7] have been highlighted as a promising alternative for heating and cooling buildings, as well as for other industrial and agricultural applications [8]. Moreover, geothermal power generation can make up for the elevated energy demands of numerous industrial procedures reducing their costs [9]. Heating and cooling buildings using geothermal heat pumps is the most energy- and environmentally efficient system, and the most cost-effective from an economic standpoint [10]. It has been demonstrated that the cost of heating one square meter of space utilizing geothermal systems is less expensive than traditional energy sources [11]. The heat exchangers are located in transitional thermal domains, which are influenced by the atmospheric temperature in shallow horizontal geothermal systems [12]. Despite this scenario, they offer better performance than when functioning under atmospheric conditions throughout the year [13], given the fact that the further down they are placed into the ground, the more stable the temperatures are throughout the year [14]. This is a key factor in this type of system and it is important in order to minimize the influence of the ambient temperature on Geothermal Heat Exchangers (GHEs) [15]. Various authors have explored the implications and importance of the water-energy nexus within the need for further implementation of SGS [16]. Both water and energy are critical resources that future societies have to address [17], particularly given the influence of climate change and unpredictable scenarios. Previous investigations have paved the way for the study of the role of geothermal systems and their potential combination with Sustainable Drainage Systems (SuDS) with a special interest in the exploration of SGS [18]. SuDS are a set of drainage techniques, which, in many cases, are included under the nature-based solution (NBS) framework where they are designed with nature at their core. SuDS aim to address stormwater management at local and micro-scales in specific locations with particular weather and site constraints [19; 20]. SuDS are guided by the urban design philosophy known as water-sensitive urban design (WSUD), which encompasses a wide range of techniques from SuDS to environmental techniques such as those described in low-impact development (LID) [21]. These techniques aim to restore the natural hydrological cycle while managing the quantity and quality of stormwater [22]. Simultaneously, they create new spaces that promote amenities and biodiversity in cities [23]. Permeable Pavement Systems (PPSs) [24], perhaps one of the most widespread SuDS techniques [25], were the main SuDS technique studied in previous investigations in the literature.