PaleoRiada database, through the conceptual, logical, and physical models, systematically integrated the paleoflood records of Spain and made accessible to users through forms such as web GIS. It also served the local water management. I believe such a database is not only necessary for analyzing the relationship between climate and flood disasters, but also very important for modern flood risk management of water systems.

I have some minor questions or suggestions:

1. In BIT data, have you included the river/channel forms of paleoflood? For examples, did these paleoflood occur in narrow valley, wide channel or river beach?
2. The evidence of each paleoflood (sediments, channel erosion, vegetation damage, etc) should be mentioned in tables or text or the database, to help the later researchers.
3. I suggest that you mention the limitation somewhere, as some evidence of early paleoflood probably were destroyed by later more strong flood, this will influence the frequency analyses.

Review of the manuscript essd-2024-549

I reviewed the ms. PaleoRiada: A new integrated spatial database of palaeofloods in Spain by Sandoval-Rincón et al.

This is a very important applicative paper which deals with an extensive paleoflood data storage – the PaleoRiada, which includes numerous palaeoflood records (299 records, 157 of which have discharge values) all over Spain which spans from 97,000 yr BP until 2014, and organize them in a friendly, open-format, accessible, applicable and reusable platform. This platform offers extremely important hydrological data for incorporation into flood risk assessments and management, land-use management, providing new data of the most extreme floods that already occurred in the past and thus enhancing flood frequency analysis. Paleoflood data in general is available, but their use in flood risk analysis and other potential research issues is limited due to the low data accessibility.

The paleo-data includes different types of floods, in different basin sizes and various climates mainly Mediterranean and Atlantic. It includes many different studies which obviously have different outcomes, used different methods and therefore have different limitations and biases. The paleo-data is derived from many types of records with various degrees of preservation. Specific peak discharges range from 0.02 to 320 m³/km²·s due to the wide range of types of floods and basins.

In relation to other and previous platforms and models, the PaleoRiada follows a similar conceptual models and includes equivalent fields and categories. PaleoRiada allows for collaborative updates of new data. These present the potential of incorporation PaleoRiada data into global databases.

Major comments 

Lines 183-185 – Similar to the comment about long records and past climate, the issue of past land-use versus present land-use, which may cause large differences for the same basin, should be mentioned. A sentence/section related to this, is clearly needed.

Table 4 – (a) What is the A_max? Is it the area of the entire basin or the area up to the measuring/study site?  (b) Although the table uses specific peak discharges Q/A the enormous range – 3-4 orders of magnitude, needs some clarification. It is hard to compare a small arroyo to the Duero, for example. I suggest to add a column of the basin area to each basin. 

Lines 238-240 – Although paleoflood records in rivers are considered conservative because of the gap between the related sediments deposition and the water elevation, for long records levels of the channel bed or base levels may have changed. These may cause over/under estimation of discharges and is a limitation which causes uncertainty. I believe it has to be clarified

* Paleoflood records are usually partial records depending on the preservation of the evidence. Usually these records include the largest floods in term of discharge but misses the small and more frequent floods. This has to be taken into consideration in any analysis for any purpose when using these data  

* In addition to risk assessment and climate change a very important implication of paleofloods is estimations of transmission losses along channels. This important hydrological parameter connects surface flows and groundwater recharge which is a major component of water resources mainly during climate changes. For this issue see: Greenbaum et al. (2002); Dahan et al. (2008);  Morin et al. (2009); Benito et al. (2010; 2011).    

Minor comments and corrections

Line 39 – change “go”  to ”be”.;

Line 39 – “…records and have been….”

Line 41 – “…occurred in remote areas…”

Line 229 – Terminology – is one flood defined a record?

Table 6 – A good example for extensive paleoflood data exists in Israel with 11 records in arid regions which go back up to 7600 years BP and basin size range from 60 to 3600 km², all of them include discharges. For these records see: Greenbaum et al. (2000; 2001; 2006; 2020); Zituni et al. (2021).

Line 296 – Paleo records are important, not only for ungauged basins, but also basins with short records of few years or tens of years and even 100 years such as the Colorado River (Greenbaum et al., 2014).

Figure 6 – Pls. add for each picture at the caption the relevant river and also in sections 6.2.1 – 6.2.3 pls. refer to Fig. 6a, 6b and 6c, accordingly.

Line 346 – not only according to the type of flood but also the size of the basin.