Page 108 - CIWA Water Data Revolution Overview Report

measured directly, because the depletion of water (through ET) can be obtained from the

satellite measurements. The WA+ approach relies on a range of open access remote sensing

datasets, in conjunction with open access GIS data and global hydrological model outputs to

calculate basin water balances on a regular basis, and to communicate water resource related
information for different land use categories. Consistent water balance parameters and

water accounts can be calculated through the framework for a river basin and its sub-basins,

avoiding data discrepancies between adjacent regions (or across transboundary river basins),
and quantifying indicators related to water use and availability based on measured data

where local data is insufficient.

2.0 The Scale Invariant Water Accounting Plus (SIWA+) Approach

Water accounting requires complete accounting for all sources (rainfall, groundwater, surface
water, runoff, other climate-resilient sources such as wastewater, recycled, desalination),

uses of water (evaporation, transpiration, runoff, recharge, flow to sinks, inter-basin

diversions, industrial users, irrigation and environmental uses) and change in storage capacity

(including soil moisture and surface and groundwater reserves) as water assets for further

accessibility.
The Scale-Invariant Water Accounting Plus (SIWA+) approach is designed to generate water

accounts for any boundary, including catchments, counties, countries, or continents.

Built on the conventional WA+ method, SIWA+ allows users to avoid rerunning complex

models by clipping data based on user-defined boundaries using a Boundary Data Extractor

(BDE). Additionally, it includes a Discharge Extractor (DISE) for managing inflow and outflow

data, especially in cases where in-situ data is unavailable. The DISE features sub-modules to

manage discharge for various boundaries, from river basins to administrative regions. The
SIWA+ also incorporates desalination data extraction (DDE) for regions with desalination

plants, and it streamlines the creation of water sheets through the Rapid Optimized Sheet

Extractor (ROSE). This approach provides flexibility and scalability, enabling efficient water
accounting at various scales.