Horizons Regional Council ( www.horizons.govt.nz) operate an extensive network of floodwarning sites.
ESL assist with the operation of some of these sites, as well as providing technical support for councils hydrology technicians as required.
Generally, Horizons use the Campbell Scientific CR10 datalogger, with Hilltop radio modems and conventional two-way radio communications for remote or critical sites.
Non critical sites use GPRS over the cellular phone network. The GPRS network failed during the last floods (Feb 2004) but the flood monitoring network operated OK via conventional two way radio.
Water level is measured using float and counter weight inside a well next to the river, or with a pressure transducer which is either directly submersed, or utilises a bubbling gas line to measure water pressure and hence derives water height, and flow.
