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Hydrological and weather tools

Free calculators for professionals, students, and the curious: streamflow in channels, flood risk, unit converter, and monthly water balance.

Flood and alert map

Real-time interactive map with reservoirs, SAIH flow rates, AEMET warnings, and T10/T100/T500 flood-prone zones on a Ventusky-style dark basemap.

Open advanced map

Streamflow calculator (Manning)

Calculate flow rate in channels and rivers using the Manning formula with rectangular, trapezoidal, or circular cross sections.

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Flood risk assessor

Estimate, as a guideline, the flood risk of a location based on rainfall, distance to the riverbed, elevation, and SNCZI zoning.

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Unit converter

Convert wind speed, precipitation, temperature, pressure, flow rate, and reservoir volume in real time.

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Water balance (Thornthwaite)

Calculate monthly PET and water balance (P-PET) with presets for Spanish cities and an SVG P/PET chart.

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Live weather webcams

Watch real-time conditions from hundreds of beach, mountain, reservoir and city webcams across Spain and Europe.

Watch webcams

Marine and wave forecast

Wave height, period, direction and sea temperature for 100+ beaches. Made for surfers, sailors and sport fishing.

View sea

Model comparator GFS / ICON / ECMWF

Compare forecasts from the major numerical models (GFS, ICON, ECMWF) side by side. Find the most reliable one.

Compare

Professional multilayer map

Animated wind, temperature, pressure, waves, clouds, lightning and more. 12 layers with 10-day forecast (Ventusky/Windy style).

Open map

What these tools are for

These calculators complement the real-time data on the HidroAlerta24 map. They let you size flow rates in drainage projects, quickly assess flood exposure, convert between common units in hydrology and meteorology, and characterize a region's climate through the monthly water balance.