Hydros

Hydros provides a database on evolution of river flows. This database is produced using a climate and hydrological modeling chain developed by Hydroclimat. These data meet a variety of needs in engineering, climate change impact studies, and water resource management.

Hydros relies on three complementary hydrological modelling approaches to represent changes in river flows:

1.Process-based hydrological models

2.Data-driven hydrological models

3.Hybrid hydrological models

Hydros delivers reliable and consistent simulations of flows and resource availability across a wide range of climatic and geographical contexts. Hydros provides simulations from daily to annual time scales, from 1951 to 2100. It thus provides a consistent, high-resolution basis for water management, hydrological risk assessment, and climate change adaptation planning.

Hydrological database specifications

Specification	Description
Experiment	CMIP6
Climate scenarios	4 Shared Socioeconomic Pathways : SSP1-2.6 (Low-carbon, +1.8°C) SSP2-4.5 (Intermediate, +2.7°C) SSP3-7.0 (High-emission, +3.9°C) SSP5-8.5 (Very high-emission, +4.4°C) Global Warming Levels (GWLs) +1.5 °C (global) / +2 °C (France – TRACC) +2 °C (global) / +2.7 °C (France – TRACC) +3 °C (global) / +4 °C (France – TRACC)
Climate models	18 bias-corrected GCMs
Hydrological models	SWAT, GR4J, LSTM model
Spatial resolution	Gauging station
Temporal resolution	Daily to annual (1951–2100)
Variables	River discharges
Format	NetCDF, GeoTIFF, or vector (shapefile)

Hydrological indicators

The following table presents the main hydrological indicators available in the Hydros database. These indicators assist in decision-making, risk assessment, and the definition of resilience strategies across all sectors worldwide. Additional indicators can be developed upon request to meet regional, sectoral, or project-specific needs.

No.	Hazard	Indicator	Definition
01	Water management : mean flow	Qs	Specific discharge: average runoff value
		Q50	Average discharge
		QAV	Median discharge
02	High flows	QJXA	Maximum discharge: annual maximum daily flow (flood flow)
		QJXAT	Return period of the annual maximum daily discharge
		tQJXA	Date of the annual maximum daily discharge
		VCXn	Annual maximum of the n-day mean daily discharge
		Q90	High discharge
		Q95	Very high discharge
03	Low flows	QMNA	Annual minimum monthly discharge
		QMNA5	Five-year low flow: mean monthly minimum discharge with a 5-year recurrence
		VCNn	Annual minimum mean discharge over n consecutive days (3, 10, 30 days)
		QMNocc	Low-flow occurrence: number of low-flow days per year
		Q05	Very low discharge
		Q10	Low discharge