Flood Rainfall Accumulation Calculator (mm)
Estimates flood duration from accumulated rainfall in millimeters over a few days and the basin drainage capacity.
—
Flood Time and Rainfall Accumulation (mm)
Rainfall accumulation is the total depth of precipitation that piles up over a given stretch of time, measured in millimetres (1 mm = 1 L/m²). Cities usually put out an urban flood alert once the total goes past 100 mm/24h, with the severe ones running above 150 mm/24h. The accumulation time is how long it takes from the first real downpour until the runoff outpaces what the drainage can handle.
A common way to estimate urban runoff is the Rational Method, Q = C · i · A / 360. Here Q is the flow in m³/s, C the runoff coefficient (0.10–0.95), i the rainfall intensity in mm/h, and A the contributing area in hectares. In Brazil, CEMADEN (National Centre for Monitoring and Early Warning of Natural Disasters) runs more than 4,700 pluviometers and puts out flood and landslide alerts in real time.
Applications
It shows up in storm-water drainage design under the Brazilian standard NBR 10844, in the flood risk maps that civil defence agencies put together, in agriculture as a way to set soil-saturation thresholds, and in insurance underwriting for climate-related claims.
FAQ
How much rain causes urban flooding? In Brazilian cities, totals of ≥ 50 mm in 1 h or ≥ 100 mm in 24 h are usually enough to swamp the drainage and trigger localised flooding.
What does 1 mm of rain mean? Picture 1 litre of water spread evenly across 1 m² of ground. That's 1 mm, and it works out to 10,000 L per hectare.
Where can I check official rainfall data? For Brazil, both real-time and historical pluviometric data are published by CEMADEN (cemaden.gov.br), INMET (portal.inmet.gov.br) and the municipal Civil Defence agencies.
Related Tools
River Flood Return Period Calculator (Years)
Computes the return period of a flood in years from the annual exceedance probability by the formula T equals one over P.
Marathon Time Projected from Half
Projects full marathon time from half marathon using Riegel exponent.
CNH Renewal Time BR
Estimates total CNH renewal time in Brazil including exams and document issuance.
Solidification Time (Chvorinov)
Calculate the solidification time of a casting by Chvorinov's rule, t = B × (V ÷ A)², from the mold constant B (min/cm², depending on the mold material and metal) and the ratio of the part's volume V to its surface area A. The result, in minutes, is the time for the metal to fully solidify. The rule shows that parts with a higher volume/area ratio (more 'massive') solidify more slowly — a fundamental casting design principle: risers (metal reservoirs) must have a larger modulus than the part to solidify last and feed the shrinkage. Enter the mold constant, the volume and the part area.
Taxi Time on Taxiway
Calculate an aircraft's taxi time on a taxiway, t = distance ÷ speed, from the distance to cover (m) and the taxi speed (m/s). Taxiing is the aircraft's ground movement between the runway and the apron (gate), under its own engines, at low speed. Taxi time is an important component of total operation time and cost: long taxis (at large airports with runways far from the terminal) burn fuel, generate emissions and delays, and occupy capacity-limited taxiways. Taxi speed is typically 5-15 m/s (about 20-50 km/h) on straights, slowing in curves and crossings. Taxi time feeds ground-traffic modeling, taxiway system sizing, ground fuel-burn and emissions estimates, and airport capacity studies. Efficient airports minimize taxi distances and conflicts with good geometry, well-placed runway exits and ground-traffic management. Enter the taxi distance and speed.
Pace ⇄ Time ⇄ Distance Calculator
Solve the triad pace (min/km), time (h:m:s) and distance (km). Provide any two and compute the third.
The results provided by this tool are for general informational and educational purposes only and do not constitute professional, financial, medical, legal, tax or accounting advice. Always confirm important decisions with a qualified professional and official sources.