The “Induced Precipitation Recycling” (IPR) concept had its origins from a desire to help develop long-term solutions to ongoing water shortages observed in the western United States. Experts anticipate that temperatures in this region will continue to rise and rainfall—in particular in the summer months—will continue to decline¹. Weather trends have been in general agreement with these predictions. In fact, the problem is considered much greater when viewed from a global perspective:

Billions of people suffer the effects of inadequate access to water and extreme heat events. Climate change can exacerbate water shortages and threaten food security, triggering mass migrations and increasing social and political conflict. Strategies for mitigating and adapting to such outcomes are urgently needed. For large populations to remain where they are located without experiencing the extreme disruptions that can cause migrations, reliable access to water and tolerable atmospheric temperatures must be recognized as stable ingredients of life. ²

There is much in the news and literature that supports this statement, and the general consensus is that as populations in arid regions continue to increase the need for access to safe water becomes more pressing.

Traditional engineering approaches to providing water where it is needed have associated drawbacks. Significantly, there always appear to be “winners” and “losers”, because the water supply in arid regions is considered to be a scarce resource. This perspective has often been supported by the statement that water scarcity exists because we can’t increase the amount of rainfall. However, a growing body of research indicates that this is not the case. In fact, evidence from this research questions the conventional wisdom and suggests that we can indeed increase precipitation by favorably modifying the environment.

Conventional wisdom also says that a desert occurs when there isn’t enough water available. This can be framed slightly differently: when a component necessary to provide abundant water is missing, arid regions result. The missing component is precipitable atmospheric moisture (i.e. evaporated water that can condense, and fall as rain). Our solution approach is to supply this missing atmospheric moisture, to create abundance from scarcity. The IPR concept was developed to accomplish this. The article describing the approach, and a means to validate the concept, was published in the journal “Ecological Engineering” in 2016.³

IPR works by capitalizing on the natural interactions between forest cover and weather patterns. These interactions (described in detail here) are observed in mature forest ecosystems. However, the underlying processes can be initiated, or induced, by reforesting marginalized land using surplus water (such as waste-water in arid regions) for irrigation. If developed in a favorable location and managed correctly, the climate and environment are modified sufficiently to create an increase in regional precipitation.

Environmental Transformation

Because IPR transforms the regional environment, it provides additional services as beneficial side-effects, or co-benefits. If wastewater is used for irrigation, the evaporated water is purified naturally and any remaining contaminants may be retained and processed further (if necessary) in a localized area. Also, the trees remove carbon dioxide as well as pollutants from the atmosphere. These co-benefits come at essentially no extra cost, so IPR is considered an “integrated solution” because it simultaneously addresses multiple problems. This increases the value proposition of an IPR project from an economic perspective.

The demonstration project proposed in the original journal article³ is relatively small (about 1000 acres), however the size can be scaled up readily once the concept has been demonstrated. Larger projects are expected to have significantly greater effects over time, as envisioned in Figure 1.

However, when exploring the “art of the possible”, there is no reason to artificially constrain the size of a project, or the potential impact that IPR can have over a region. A co-benefit of considerable interest is carbon sequestration (removal of atmospheric CO2) to support climate change adaptation and mitigation strategies. The larger the region transformed to forest (or vegetative) cover, the greater the mitigating effect. Also, the greater the increase in the regional water supply. Part of our research will explore how large a region can be influenced by IPR.

As an example, the possibility that large desert regions such as the Arabian Peninsula can be transformed from extreme desert to a wetter, greener environment has been suggested.⁴ The left side of Figure 2 shows a map of surface water that may have existed a few thousand years ago. While speculative in nature, it was developed using satellite imagery, geological research, archeological discoveries and historical descriptions of the region as a basis.⁵

The northern river was described as being about a mile across, and the large lake was up to 300 feet deep. None of this exists today, as can be seen in the image on the right, and conventional wisdom infers that it can’t be returned to a greener, wetter climate. However, we have proposed exploring the possibility of doing just that. Our plan builds upon earlier research⁶ that supports this premise. A more in-depth discussion of how IPR can support large-scale environmental transformation projects such as this will be described in the next page: "How IPR Works".

Transitioning from Theory to Practice

A verification test campaign to demonstrate and validate the IPR concept is described in the "Project Verification" page. While there is strong evidence supporting the IPR methodology, we want confidence that it will work well in an area selected for a project. Once demonstrated as a “proof of concept”, full implementation of an operational IPR project can begin. In practice, designs (such as that proposed for IPR) which take advantage of natural processes are often more reliable and cost-effective than traditional engineered approaches. A successful IPR project will provide an alternative approach to supplement existing and typically far costlier plans to address regional water security.⁷ As an integrated solution, IPR will not only increase the regional water supply, but also provide additional eco-system services and end-products that add value and utility, thereby improving the project’s economic viability.