April 2021

D-CAT offers a variety of different imagery-derived water indices that are used in various applications, including agriculture monitoring where they offer food producers and farmers invaluable insights to help them sustainably manage their crops and soil.

Water indices are measures of moisture activity based on changes in spectral reflectance of the land which can be accurately measured by optical sensors on satellites. These changes are known to correspond to factors of importance to crop and pasture production, and so different water indices have been developed for agricultural, and other, applications. All provide relative measures on a scale of -1 to 1, which can be plotted to show variations over time, or mapped to highlight variations across land areas.

Water indices can be applied to provide a view of relative moisture levels in topsoil or vegetation, but they can also be used as part of a solution to a specific issue. One such example is the use of the modified normalised difference water index (MNDWI) alongside topographic information to help predict locations with high flood risks, and thereby allowing measures to be put in place to mitigate the impact of future floods.

Water indices therefore offer key decision support information to industries as diverse as agriculture, water and other utilities, and infrastructure or construction. A time-series analysis of water indices can provide further insights into changing conditions on the ground. In addition, intelligent processing of indices means that issues can be alerted before they are visible by eye, health assessments can be made efficiently, and benchmarking completed quickly and easily.

D-CAT offers three different water indices which are proven and ready to use worldwide. Whether for agricultural production applications, or as part of your sustainability plan, they have a part to play and real value to add.

As an example of how water indices can provide very wide area monitoring for macro-scale analysis of moisture trends, and not just local-level intelligence, the animation below shows an area of 100km by 100km over Argentina through its 2019/2020 growing season, and the variation in moisture throughout time is clear from sowing towards harvest. 


The graph below shows the changing moisture levels in this area during the 2019/2020 growing season.

The full set of this example data is available for free on AWS Data Exchange (ADX). D-CAT offers a service, fulfilled through ADX that can supply this data for any area or region.


By using this service clients:

Example Applications


From determining when best to irrigate, to detecting water-logging issues, monitoring crops with remote imagery gives farmers essential information to best manage their crops.

Flood Monitoring
The water indices are an excellent resource for cost-effectively detecting and monitoring areas that are susceptible to flooding. This provides valuable knowledge that can be used to support the prioritisation of flood mitigation plans from regional to local levels, ultimately reducing the impact of flood events.

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