Irrigation redistributes natural water sources for primarily agricultural use. There are several consequences to this process that are unavoidable, but optimization of irrigation minimizes these issues. Here are a few of those problems.
Let start with a major source of irrigation – the river. Redirection of water from natural sources reduces water available to the natural ecosystem. An irrigation system drawing from a river reduces the downstream flow. This reduces the available volume of living space for organisms in the river ecosystem. It also reduces transport of natural sedimentation causing sediment buildup, which chokes river flow even further. If extreme enough, this poor management of water diversion can alter the ecosystem and lead to higher potential for flooding during heavy precipitation. In addition to this, increased distribution of river water into many tributaries, increases the total surface area of river water exposed to air. This causes more rapid evaporation which means loss of water to atmosphere and an increase in atmospheric moisture which leads to uncontrolled redistribution of this water in the form of unpredictable precipitation.
Now let’s discuss the irrigated area. Water redirected into a crop field is intended for use in growing the crop. Unfortunately, not all this water can be used as much is retained in the soil, evaporated, or drained. Water not used for the crop is typically in the range of 40-60% or redirected water. If not properly drained, that additional water will increase the ground water table level, recharge aquifers, and cause water logging. River water contains a variety of salts and all the additional water saturating a poorly drained field increases soil salinity and ultimately reduces crop yield. The higher water table also reduces soil oxygenation, further affecting yield. Salinity is a global problem and the UN estimates that up to 20% of the world’s irrigated land is affected – with India, China, and Pakistan some of the most afflicted nations.
There are a variety of ancillary problems associate with poor irrigation management. Stagnation of water tables from water logging create breeding grounds for diseases like malaria and yellow fever. Excess drainage into rivers can introduce agricultural chemicals and salts that damage the ecosystem and make the water unsuitable or unsafe for human consumption. Poor drainage control can affect downstream water users and excess irrigation draw can reduce water available for livestock, fishing, and household use.
Precision in irrigation draw and drainage is the key to optimizing the use of this critical resource. To start, we need to know the details and that means collecting data. Irrigation systems can be extensive and complex, so the task may seem daunting, but the IoT (Internet of Things) field can be tapped for a cost-effective way of collecting the detailed data needed to indicate where and what the problems are. An IoT sensor network could be used to detect flow rates for rivers, irrigation channels, and drainages. Soil sensors can be leveraged to measure salinity and oxygen levels. Submersible detectors can be used to assess chemical concentration in rivers. Weather stations can be linked to track changes in humidity. These metrics can be collected with strategically placed arrays of wireless sensors. The historical data from those devices can be stitched together and visualized as heat maps over-laid on digital property maps. This gives land owners and governments the ability to monitor the state of an irrigation system and the environment it is embedded in. It also highlights changes in both over time and allows for more accurate predictions, more effective proposed solutions, and the ability to simulate the results of multiple courses of action (or inaction).
IoT systems that leverage long-rage, low-power networks enable vast wireless networks of sensors connected back to gateways that aggregate that data and transmit it to the cloud. Once that data is collected, online data storage and analytics platforms can be used to make effective predictions and generate plausible solutions. These networks are easy to setup, require little additional infrastructure due to their wireless nature, are fairly maintenance free, and are remotely manageable. Web-based data handling platforms are also becoming more and more customizable and easier to use. With existing IoT technology, irrigation can be intelligent, resources can be preserved, and both short and long-term costs associate with poor water management can be brought down.