**1. Introduction**

According to the European Environment Agency (EAA) [1], the total reported economic losses in Europe caused by weather and climate-related extremes over the period 1980–2017 amounted to approximately EUR 453 billion; the losses in Spain amounted to EUR 37 billion. In the words of the Spanish Insurance Compensation Consortium (CCS, for its acronym in Spanish), it is estimated that around 50% of the damage was covered by insurance in Spain. For example, the total losses from the Lorca earthquake in 2011 were estimated at EUR 1 billion, EUR 0.5 billion of which was insured and thus compensated [2]. Nowadays, economic losses from flood events at the urban level are increasingly relevant, in line with socioeconomic changes such as population growth and the expansion of infrastructure density in cities around the world [3]. Floods are the most damaging natural hazard in Europe, with around two-thirds of the total damage costs. Moreover, rising temperatures are expected to intensify the hydrological cycle, thus leading to more frequent and intense floods in many regions, together with a corresponding increase in economic losses. Nevertheless, it has to be noted that increases in costs from flooding in recent decades can be partly attributed to more people living in flood-prone areas [4].

The types of damage caused by floods are numerous and can be classified as tangible and intangible; these, in turn, can be categorized as direct or indirect [5]. Traditionally, economic flood damage assessment (i.e., direct damage) concerning flood impacts has been studied in more depth. Particularly in urban areas, the focus has been on damage caused to flooded properties. Thus, a variety of methodologies, which still need more development, have led to important advancements.

Gilbert F. White (1945) [6] was a pioneer in considering the damage to properties. Among other aspects, White [6] defined in greater detail the types of losses in urban areas when a flood occurs, such as those related to properties and shops. His study addressed losses that can occur in residential areas, such as to the foundations and structure of dwellings and other buildings, garages, and vehicles. Also, the loss of property rental income (i.e., indirect damage) was considered. A relevant statement in White's [6] work was that water depth and velocity variables established the degree of severity of damage to the foundation and structure of dwellings. Water depth was stated to be the most limiting factor for such losses. Although White [6] did not distinguish directly between direct and indirect damage, both categories were addressed in his study.

In Spain, the Directorate General for Civil Defense and Emergencies, and the Spanish Insurance Compensation Consortium (Consorcio de Compensación de Seguros, CCS) have reported that flooding has caused the death of 312 people over the last 20 years, and economic damage amounting to EUR 800 million per annum [7]. In this context, European Directive 2007/60/CE on the assessment and management of flood risks [8] was published, and enacted by the Royal Decree 903/2010 on flood risk evaluation and management [9] in the Spanish legislation. It requires the Member States to develop, adopt, and implement flood risk management plans. These plans encompass a number of measures that involve land management and urban planning, civil protection, insurance, early warning, and improving the condition of rivers and coastal areas. One of the measures included in these plans was the development of guidelines to reduce the vulnerability of properties exposed to floods [7]. The main aim of these guidelines was to improve knowledge of flood consequences and foster citizens' commitment to risk reduction, focusing on the vulnerability of people and assets and enhancing the resilience of high risk properties.

Although measures to increase buildings' resilience have been proposed, these plans are focused on riverine floods, which indeed involve important risks that must be dealt with, but only for those urban areas located in flood-prone areas. However, sewer flooding should not be underestimated since all cities are prone to this type of flooding once a drainage system exceeds its design capacity, regardless of the distance to rivers. This type of flood is also expected to become more frequent due to the effects of climate change [10], increasing risk, damage, and disruptions to citizens.

In the framework of the RESCCUE project, tailored depth-damage curves for Barcelona have been developed. These curves encompass 14 different types of properties that are usually found in highly urbanized areas. There is no standardization at a national level regarding the employment of depth-damage curves for flood damage assessment. Therefore, this study attempts to bridge the gap in the inability to compare flood damage reduction studies from different Spanish regions. Ultimately, it expects to provide a tool to carry out homogeneously nationwide flood damage assessments. To do so, regional adjustment indices have been derived for transferring the Barcelona curves to other Spanish municipalities. Moreover, temporal adjustment indices have been performed to modify the depth-damage curves for the damage estimation of future flood events.

This paper offers in Section 2 a review of a variety of flood damage models and depth-damage curves that can be found within the literature, grouped according to their geographical application: a) worldwide or b) Spain-specific. Section 3 presents the particular context of pluvial floods in Barcelona, the role of the Spanish public insurance company (CCS), and the methodology applied in this study. The data used, its analysis and the processes to create semi-empirical depth-damage curves tailored to Barcelona are described. The procedure to transfer them in space and time is presented in this section. In Section 4, the relative depth-damage curves are presented together with their monetization for Barcelona city. Moreover, depth-damage curves for the most damaged municipalities in Spain due to flooding (pluvial and fluvial) for the 2020 reference year are presented. Finally, Section 5 recaps the main messages of this study, and the usefulness and adequacy of the proposed depth-damage curves for Spanish cities are argued.
