Articles (9)
Product · 6 min read
Designing early-warning apps for low bandwidth
Why a warning app has to work on a weak connection, and the design rules that keep the message small, fast and readable.
Product · 5 min read
Reading a live river dashboard during a flood
Five checks that turn a live river water level dashboard from a screen of numbers into a decision aid when the river is rising.
Technology · 9 min read
Cell broadcast alerts in India: SACHET and CAP
How one alert written in the Common Alerting Protocol reaches phones by SMS and by cell broadcast, and what each government source says about the rollout.
Solutions · 10 min read
Urban flood early warning systems in Indian cities
What a city flood warning system has to do differently from a river warning, what Mumbai, Chennai and Bengaluru have built, and what the NDMA guidelines ask every city to put in place.
Technology · 12 min read
Hydrological data formats: CSV, WaterML 2.0 and APIs
Why the format of a water-level record decides whether another agency can use it, what CSV, WaterML 2.0 and a JSON API each carry, and what to ask for in a tender.
Technology · 13 min read
MQTT vs HTTP for IoT, or SMS: how should a station report?
What a broker, a topic and a QoS level actually do, what each protocol costs in bytes and battery, and which one to use when the mobile signal comes and goes.
Technology · 13 min read
IoT device security: updates, keys and access control
Why unattended river gauges, rain gauges and sirens are a target, what can go wrong, and the controls a buyer should write into a specification.
Technology · 9 min read
From sensor to screen: how hydromet data reaches a dashboard
Following one river-level reading from the sensor, through the logger, modem and network, to a server and a dashboard, and adding up the delay at each step.
Technology · 12 min read
Time stamps you can trust: clocks, time zones and synchronisation in data loggers
Why every hydromet reading is only as good as the clock that labelled it, how logger clocks drift, and how to set, store and correct time without damaging the record.