Water accounting is the application of a consistent and structured approach to identifying, measuring, recording and reporting information about water. Water accounting involves the regular preparation of water accounting sheets using minimum standards. There are parallels between the envisaged approach to water accounting and the financial accounting discipline. Financial accounting is at its core concerned with providing information to users competing for scarce resources. Water accounting should do the same.
Robust and reliable water accounting facilitates informed water-related decision making. Water accounting is also concerned with providing information to users concerned with the management and use of a resource. Similar to the way financial accounting assists financial and business decision making, water accounting reports will provide information that is relevant, reliable, comparable and understandable.
Water accounting was described by the CGIAR International Water Management Institute (IWMI) in Sri Lanka during 1997. The IWMI publications are presented in the list of references below.
Water accounting includes the description of quantitative water flows and management practices in an understandable manner. It is a standard procedure (i) to quantify the major water flows, (ii) the consumption of water resources and (iii) the productivity resulting from water consumption in river basins.
The water accounts should be prepared by independent organizations that have documented skills to prepare these accounting sheets.
The water accounting exists of the following sheets:
- Water balance sheet
- Water consumption sheet
- Water productivity sheet
The input data need to be specified by land use classes. Land use classes are the guiding mechanism for specifying net water producers and net water consumers. Three types of water user categories are discerned:
- Natural land cover
- Managed land use
- Managed water use
Land use classes determine whether the water flows are natural, or are manipulated by human interventions in land use and water use. Land use affects the water balance by means of rainfed farming, urban growth, construction of recreational areas. Water use is adaptable through diversions, drainage, floods, groundwater abstractions etc. It is mandatory to specify land surface actual evapotranspiration rates in the input folder. The latter implies that these values must be pre-processed from remote sensing data or from hydrological modelling. All input data can be generated from remote sensing technologies.
More information can be acquired from w.bastiaanssen(at)waterwatch.nl