Article by Mathew Lippincott and Don Blair for Community Science Forum: Water

Design Philosophy

The Riffle is a design for an open source hardware water monitor. While water monitors are put to many uses, the Riffle project has focused on monitoring indicators of pollution to identify changing water conditions. Temperature, Conductivity, Depth, and Turbidity indicate changes in water flow and content rather than specific pollutants, providing the baseline information needed to pinpoint sources of pollution.

Motivation

The initial concept for the Riffle came out of conversations with Mark Green, a Professor of Hydrology at Plymouth State, and Don Blair, a Public Lab Fellow, about 1) the current technologies used for water monitoring and 2) an assessment of existing field temperature loggers by forest ecologist Chris Fastie. Mark identified several challenges presented by existing commercial designs:

• Proprietary data formats: Data can only be decoded by a manufacturer's proprietary software.
• Proprietary software suites: Hardware is locked to software and platforms supported by the manufacturer. Software can be discontinued, or new versions must be purchased to keep using hardware.
• Proprietary hardware: Special hardware interfaces are required to load data off of devices. Devices are not extensible with new sensors, and sensor designs are not documented.
• Single-use devices: Chris Fastie identified that many long-term systems lack the ability to log multiple sensor measurements at the same time and may even have non-replaceable batteries, making them essentially disposable.

Goals

As a result, we decided to begin a project to develop an "open hardware water monitor" useful for some common water monitoring applications. We sought to make something which would have the following characteristics:

• Open and accessible data formats: Data is recorded in a common data format, such as Comma Separated Value (CSV), using accessible data storage media such as SD cards.
• Rich software ecosystem: Build on platforms with modular, open source software, so that the platform does not require much software expertise to extend.
• Open Sensor designs: Sensors should be built around analog electronics and accessible materials, so that sensing projects are not dependent on a single manufacturer.
• Accessible materials: The waterproof enclosure and other parts should be broadly available and repairable locally.
• Low power: Capable of monitoring at a remote locations for many days ---weeks, at least --- on a rechargeable or interchangeable battery.

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