Improved water efficiency control based on advanced remote sensing technologies (IWACA-TECH)

Short general project overview

In Mozambique, the increasing competing demands for water in river basins poses a problem. Agriculture is the largest water consumer and its expanding water requirements threaten the water availability for other users. By increasing the water use efficiency of agriculture the water security of other users will be enhanced. The pilot project concerns the application of a dynamic socio-technical system that combines model predictive control technology for open water systems, soil water status and crop water demand estimation by satellite remote sensing and human in the loop measurements and control actions. The location of the project is the Xinavane irrigation system of the Tongaat Hullet sugar company (18,000 ha) along the lower Incomati River in the South of Mozambique.

The methodology consist of three elements:

1. Automated model of predictive control for canal systems,
2. Estimating near real-time water availability and crop water demand using satellite remote sensing, and
3. Optimal human in the loop decision-making using smartphone technology.

Human operators, guided by these different technology components, will perform measurements and control actions at specific locations. With these actions they will balance water demand and supply by means of mobile predictive control techniques in combination with the steering information of the soil water status and crop demand as derived from satellite sensors. This will result in more accurate water demand predictions and a more optimized control of the canal irrigation systems.

Initial activities and results of the project

This project will develop:

• A hydraulic model of the system which includes all relevant dimensions of the open canals and all dimensions and specification of the various engineering structures.
• Control system that distributes the available water with humans in the loop as sensors and actuators, and that adequately handles the uncertainties due to human inaccuracy.
• Algorithms that directly integrate the satellite based soil water status and water demand for crops in the modelling control system.
• An application that enables operators to conduct validated measurements, gives them insight into the irrigation system, and enables them to do adequate open-channel control.
• A quantified estimation of the total water use efficiency and operational efficiency for the Tongaat Hulett sugarcane plantation.
• A study, advice and implementation on an economic system behind the control system.

Sugar industry and agricultural water users: The water users in Xinavane irrigation system benefit because the water demand of their crop is estimated more accurately, which will increase their profits (less pumping costs and/or higher crop yields, higher water productivity). The downstream water users will benefit from a fairer water distribution, and it is likely that more water will become available to them. The main benefit of ARA-Sul, the regional water authority, is regular and reliable water level data in a key "hot-spot" stretch of the Incomati river. This data enables them to manage the water in an adequate way, and charge consumers rightfully.

What makes the technology, product, method or approach used innovative?

The satellite images with high-resolution hydrological information are integrated with local observations in the overall model/system. This way of integrating and opening up advanced knowledge to the local situation in Mozambique seems innovative.

What are the results of the project?

During a few fieldwork weeks in March and July 2018 the project partners created a database. VanderSat gathered data on yield, water use, meteorological data, and other relevant agronomic data. It was concluded that the infrastructure is poorly maintained; therefore, predictions of the flow are very difficult. Because of these difficulties a functional hydraulic model for the Model Predictive Controller could not be created, nor the gauge application of Mobile Water Management (MWM) could be used. As an alternative strategy MWM developed two new applications that could potentially assist the project. The mobile applications that were created were the Mobile Irrigation Monitor and the Soil Moisture Monitor. These applications suited Xinavane’s situation better. Combining satellite data and meteorological data a high spatial and temporal resolution evaporation product was produced by VanderSat. It was deducted, that groundwater contributes to the transpiration flux within the sugarcane plantation. Groundwater had to be taken into consideration. In the last phase of the project we performed a principal component analysis on yield with all the collected data available to assess the main limiting factor to productivity in the plantation. The preliminary results from this analysis showed that the main limiting factor is not drought, as would be expected in an area facing a rainfall deficit for the last six years, but poor subsurface drainage. All partners successfully piloted and further developed their product.