WaPOR, remote sensing for water productivity

Introduction

Transparent and comprehensive information of water resources is needed for sustainable integrated water resources management. Water accounting is the systematic analysis of the current status and trends in water supply, demand, distribution, accessibility and use in time and space within specified domains, producing a basis for evidence-based water policy decision-making (FAO, 2017). Water accounting outputs reveals how water is used across different sectors and help shape an understanding of the benefits and existing trade-offs of the water allocations and use patterns. The integrated and cross sectoral presentation of the information in water accounting helps the users to see the bigger picture and cross linkages in water management.

Understanding the current status of water resources systems globally requires detailed information on the source of water in space and time as well as detailed information on the utilisation of those water resources. Unavailability of sufficient observed data is a big issue in most parts of the world to be able to fully assess available water resources and its utilisation. Fortunately, more and more remote sensing based products are becoming available, providing information on various components of the water cycle, such as precipitation, actual evapotranspiration and storage variations.

Water accounting using open access remote sensing data and other open data sets has been and will be applied to assess the water resources situation and the extent to which water productivity increases have an effect on different water users. Increasing water productivity upstream, while maintaining existing levels of withdrawal, will increase the productive efficiency of water use, but, at the same time, may deprive downstream water users who depend on return flow in rivers or groundwater aquifers fed from these returns. Changes in the availability of water resources and its use should be described by Measurement - Reporting - Verification (MRV) in the local river basin context.

The output consists mainly of water accounting which are being carried out by IHE Delft with inputs from FAO. IHE Delft will apply water accounting through Remote Sensing to assess the extent to which water productivity increases have an effect on different water users (including the environment). The major deliverables of this output are:

  • Design of a Measurements-Reporting-Verification mechanism for the land and water productivity database developed under output 1.
  • Quality control of associated spatial data components such as biomass production, actual and reference evapotranspiration and rainfall.
  • Quantifying the role of agricultural water flows (e.g. rainfall, irrigation, evapotranspiration, drainage, and recharge) in a river basin context with competing uses.

FAO will provide inputs to this output with regard to earlier project experiences with water accounting.