Water availability is a vital need for a wide range of agricultural activities . Long-term hydroclimatic changes may have significant impacts on regional water resources . The findings of this study can help decision-makers to be prepared and react appropriately to changes in regional hydroclimatic conditions of croplands and their potential consequences on water and food resources, particularly under ongoing severe situations like the COVID pandemic , water shortages [24, 26] and wildfires . Long-term hydroclimatic changes may force farmers to change their crops based on the new regional hydroclimate conditions. Future projections of hydroclimatic changes in U.S. croplands can help managers, planners, and decision-makers to maximize crop production and prioritize water resources allocation by improving water resource management . However, there are some important questions that should be addressed in this case as a prospect of this study.
The first question that can be raised here is how shifts in hydroclimatology of cropping regions may affect future crop productions. Although climate change may have positive impacts on agricultural productivity in some regions, it can reduce crop yields in regions that currently have optimal climate conditions [6, 28, 29]. For instance, Cho and McCarl (2017)  reported that cotton and sorghum are more appropriate under the warming temperature. Besides, sorghum, and spring wheat are more likely to be selected under drier conditions, while corn, cotton, and soybeans are better choices for wetter conditions . Additionally, it is worth mentioning that while an increase in precipitation may be beneficial for most growing regions, it can have negative impacts on some cropping regions because of water-logging and pest disasters .
Another important question that should be addressed here is how much irrigation requirement would change in response to hydroclimatic change for maintaining current crop yields. Irrigation has been commonly used as an adaptation tool to increase crop yields and decrease the impacts of climate changes [31–33]. Considerable research has investigated the effects of climate variability on crop yield . However, few studies have focused on the impacts of climate changes on irrigation water requirements . Crop production can be stabilized by increasing irrigation [6, 35–38]. An increase in irrigation helps crop production meets the current food demand, which may decrease in response to climate change . While irrigation plays a key role in agricultural productivity, the impact of hydroclimatic changes on irrigation water use has not been well studied . The impacts of climate change on irrigation water use have been rarely studied due to limited data availability .
Additionally, there is a few research on how irrigated and rainfed crop yields respond differently to climate change over five major US cropping regions . Assessing the response of both rainfed and irrigated crop yields to climate change can lead to the improved understanding of the role of irrigation on agricultural productions . Although precipitation plays an important role in dryland production systems, there is still a lack of studies evaluating the impacts of climate change on irrigated crops.
A national, spatially assessing the impacts of hydroclimatic shifts on U.S agricultural regions is needed to be done to provide insight into changes in crop productivity and dependence on irrigation .