Assessment of a hybrid system that uses small modular reactors (SMRs) to back up intermittent renewables and desalinate water

Introduction The July 23, 1972 launch of the Earth Resources Technology Satellite (ERTS), later renamed Landsat 1, marks the first milepost of the Landsat journey. While the inception of the Landsat program began several years earlier (Goward et al. 2017), that first launch and the subsequent launches of eight more Landsat satellites define a timeline that leads us to celebrate the 50th anniversary of an ongoing satellite program with profound impacts on our observation and understanding of the Earth. Prior histories have addressed technical, programmatic, and scientific aspects of the Landsat program in a more-or-less chronological order (Mack 1990; Goward et al. 2017). Here, we briefly address the cumulative impacts of the Landsat program on key Earth science and environmental topics.

Seeing Our Planet Anew: Fifty Years of Landsat

Agriculture is the largest user of water in the United States. Yet, we do not understand the spatially resolved sources of irrigation water use (IWU) by crop. The goal of this study is to estimate crop‐specific IWU from surface water withdrawals (SWW), total groundwater withdrawals (GWW), and nonrenewable groundwater depletion (GWD). To do this, we employ the PCR‐GLOBWB 2 global hydrology model to partition irrigation information from the U.S. Geological Survey Water Use Database to specific crops across the Continental United States (CONUS). We incorporate high‐resolution input data on agricultural production and climate within the CONUS to obtain crop‐specific irrigation estimates for SWW, GWW, and GWD for 20 crops and crop groups from 2008 to 2020 at county spatial resolution. Over the study period, SWW decreased by 20%, while both GWW and GWD increased by 3%. On average, animal feed (alfalfa/hay) uses the most irrigation water across all water sources: 33 from SWW, 13 from GWW, and 10 km3/yr from GWD. Produce used less SWW (43%), but more GWW (57%), and GWD (27%) over the study time‐period. The largest changes in IWU for each water source between the years 2008 and 2020 are: rice (SWW decreased by 71%), sugar beets (GWW increased by 232%), and rapeseed (GWD increased by 405%). These results present the first national‐scale assessment of irrigation by crop, water source, and year. In total, we contribute nearly 2.5 million data points to the literature (3,142 counties; 13 years; 3 water sources; and 20 crops).

Irrigation by Crop in the Continental United States From 2008 to 2020

Water scarcity threatens the well-being of individuals, the natural environment, and economic systems that function within society. Faced with growing and evolving water supply concerns, many utilities and industries have relied on nontraditional water sources to mitigate severe shortages and combat water quality concerns. Treated municipal wastewater can serve as a reliable supply of water at a predictable quality and quantity and is especially well-suited for nonpotable end uses. In this work, we identify areas within the contiguous United States where water reuse projects are possible on the basis of existing supplies of treated wastewater at known qualities and quantities, estimated nonpotable demands, and state-level policies that outline water quality requirements for reuse. We use publicly available data to develop a geographic information system-based supply-demand assessment that identifies spatial trends and areas of interest for locally focused water reuse analysis. We find that the feasibility of water reuse is highly sensitive to existing state-level policies and the level of wastewater treatment currently in place. Nonpotable recycled water can potentially offset significant water withdrawals within communities where specific policy and technical criteria are met. 

Identifying Opportunities for Nonpotable Water Reuse Based on Potential Supplies and Demands in the United States

The production of food, electricity, and treated water is often tracked and managed along political or infrastructure boundaries. Yet, water resources, a critical input in the production of these goods, are delineated along natural landscape features (i.e., watersheds). The boundary mismatch between water resources and the associated production of economic goods conceals hydrologic dependencies and vulnerabilities in the provisioning of Food‐Energy‐Water (FEW) resources. In this study, we pair economic, infrastructure, and hydrologic data to evaluate the production of food, electricity, and treated water within watersheds of the conterminous United States. The US FEW sectors produced 950 million tonnes of crops, 3,973 million MWh of electricity, and supplied water to 263 million people in 2017. FEW production consumed 128 km3 of blue water (18%) and 583 km3 of green water (82%). Watersheds in central and southern California, the Midwest, and the Southwest have the largest FEW blue water consumption and the greatest exposure to water stress. Nearly three‐fifths of FEW production occurs in regularly water‐stressed watersheds. FEW production in watersheds in the Great Plains and Midwest relies heavily on groundwater to buffer against intra‐ and inter‐annual streamflow variability, while surface reservoir storage buffers against water shortages in all watersheds. We show where FEW production may be susceptible to curtailments due to ongoing groundwater depletion or known infrastructure deficiencies. This study adds to our understanding of how a nation's water resources and associated infrastructure support economic activity, as well as areas where economic activity is exposed to hydrological and infrastructure risks.

Food, Energy, and Water Production Within Watersheds of the United States

In the United States, greater attention has been given to developing water supplies and quantifying available waters than determining who uses water, how much they withdraw and consume, and how and where water use occurs. As water supplies are stressed due to an increasingly variable climate, changing land‐use, and growing water needs, greater consideration of the demand side of the water balance equation is essential. Data about the spatial and temporal aspects of water use for different purposes are now critical to long‐term water supply planning and resource management. We detail the current state of water‐use data, the major stakeholders involved in their collection and applications, and the challenges in obtaining high‐quality nationally consistent data applicable to a range of scales and purposes. Opportunities to improve access, use, and sharing of water‐use data are outlined. We cast a vision for a world‐class national water‐use data product that is accessible, timely, and spatially detailed. Our vision will leverage the strengths of existing local, state, and federal agencies to facilitate rapid and informed decision‐making, modeling, and science for water resources. To inform future decision‐making regarding water supplies and uses, we must coordinate efforts to substantially improve our capacity to collect, model, and disseminate water‐use data.

https://onlinelibrary.wiley.com/doi/pdfdirect/10.1111/1752-1688.13004

Water‐Use Data in the United States: Challenges and Future Directions

Some parts of the U.S. have strained or insufficient local water supplies to meet the demands of population, industry and agriculture located in the region. Some areas with insufficient water supply have long implemented measures to address the shortfall through transferring water from other basins. New York City obtains almost 97% of its water and Los Angeles over 90% from interbasin transfers (IBTs).With climate change affecting precipitation and temperature patterns across the U.S., coupled with growth in population and the economy leading to changes in demand, planning for risks to water supplies is critical to ensuring continued supply of water for all U.S. regions. Assessment of areas of high and low water risk can provide insights into potential changes in availability for existing supply, and aid in decision making for mitigating forecasted risks to local water supply. Implementation of IBTs historically has been one approach for addressing water supply risks.The overarching goal of this research was to examine the role of IBTs for water resource supply and management in the U.S. Specific objectives were as follows:1. Quantify the number of IBTs that exist at a defined hydrologic unit code (HUC) level in the U.S. and examine the distribution of IBTs and potential causes associated with any observed clustering of IBTs. 2. Characterize and classify IBTs, and examine the development drivers for a subset of IBTs in the U.S through sampling in different climate regions of the U.S.3. Examine the water risks in the U.S. by county, considering both current and future conditions and accounting for natural water importation through streams and rivers, and consider the role of IBTs in mitigating these risks.As part of the first objective, the definition of what constitutes a “basin” was required to assess man-made transfers that cross those basin boundaries. There are several definitions utilized by different states, with no federal definition. The most recent inventory of IBTs was conducted by the USGS in 1985 and 1986 using the HUC4 level. To build a new inventory of IBTs in the U.S., the National Hydrography Dataset (NHD) was utilized, combined with the Watershed Boundary Dataset (WBD). Man-made transfers across basin boundaries at the HUC6 level were considered to be interbasin. Geographic Information Systems (GIS) analysis showed that as of 2016 there were 2,161 IBTs crossing HUC6 boundaries in the U.S. These were located across the country, although over 50% of those identified were located in Florida, Texas or North Carolina. Some clustering of IBTs was observed in various states and analysis of the clustering suggested a variety of reasons for IBT construction, including population, drainage and agricultural factors. However, the flow volumes associated with the IBTs identified could not be evaluated due to a lack of available data at both the state and federal level.The second objective expanded upon this analysis, examining a subset of 109 (5%) of the identified IBT reaches within the various climate regions of the U.S. To characterize and classify the IBTs each was labeled as being near irrigated agricultural land, near cities, or rural for those not near either cities or irrigated land. IBTs in proximity to both cities and irrigated agricultural lands were given the designation city+irrigated agriculture. Selection of IBTs for this analysis was based on the approximate proportional distribution of the total number of IBTs within each climate region and included representation of IBT clusters identified as part of the first objective. The results of the analysis showed that there have been four major drivers behind the construction of IBTs in the U.S.: irrigation for agriculture, municipal and industrial water supply, commercial shipping or navigation, and drainage or flood management. The most common factor for IBT construction has been to enable drainage or flood management. IBT development for agricultural needs has also been prevalent. The majority of IBTs examined were constructed between 1880 and 1980, with peaks in construction occurring between 1900-1910 and 1960-1970. The case studies examined showed that drivers of IBT development evolved through history, reflecting the changes in U.S. and regional economies, populations and needs.To examine the risks associated with the U.S. water supply a new Water Risk Index (WRI) was developed, building upon and advancing a prior risk analysis developed by Roy et al. (2012). The Roy et al. work utilized risk factors that focused upon local precipitation, demand and evapotranspiration, without examining the natural flow of water between counties. To produce the WRI the analysis utilized the 2015 USGS Water Use Report data and projected water use in 2050, assuming only municipal and domestic water demand and thermoelectric power water withdrawal demand would change over time as per Roy et al. (2012). To calculate the flow volumes for each county the Water Supply Sustainability Index (WaSSI) developed by the USDA Forest Service (Sun, 2008) was used. The WaSSI model allowed for the analysis to include changes in climate and related hydrology as well as the evolving water demand. The WRI calculated water supply risk for each county in the contiguous U.S. The WRI calculation includes comparisons of water withdrawal to local flow volume, the drought susceptibility during summer for both the present and future, the projected growth in water demand, and the proportion of groundwater use relative to total water demand. This risk index provides a scaled value system that provides context to each individual risk factor included. The results of this showed that while some counties are regarded as high or very high risk, there are significantly fewer than those identified by the Roy et al. (2012) analysis. A maximum of 36 counties were identified as high or very high risk within the scenarios examined as part of the WRI analysis, in comparison to over 400 in the previous analysis. The highest risk areas are located in the west, with most counties determined to be at very high risk located in California. Most of the counties with negligible risk are located in Montana and Wyoming, as well as Colorado west of the continental divide.This research provides insights into locations within the U.S. that may have high risks to their water supplies, and into the role that current or potential IBTs can have to mitigate those risks. In addition, the methods developed can help support planners to identify low risk locations to examine for their potential to support IBT water supply solutions while accounting for the downstream impacts such diversions may cause. To ensure that the U.S. maintains a consistent and secure water supply all options must be considered for their viability, including the potential for moving water from where it is plentiful to areas it is not.

Interbasin Transfers and Water Risk in the United States

Abstract Interbasin water transfers (IBTs) can have a significant impact on the environment, water availability, and economies within the basins importing and exporting water, as well as basins downstream of these water transfers. The lack of comprehensive data identifying and describing IBTs inhibits understanding of the role IBTs play in supplying water for society, as well as their collective hydrologic impact. We develop three connected datasets inventorying IBTs in the United States and Canada, including their features, geospatial details, and water transfer volumes. We surveyed the academic and gray literature, as well as local, state, and federal water agencies, to collect, process, and verify IBTs in Canada and the United States. Our comprehensive IBT datasets represent all known transfers of untreated water that cross subregion (US) or subdrainage area (CA) boundaries, characterizing a total of 641 IBT projects. The infrastructure-level data made available by these data products can be used to close water budgets, connect water supplies to water use, and better represent human impacts within hydrologic and ecosystem models. 

https://www.nature.com/articles/s41597-023-01935-4.pdf

Kerim Dickson

Papers

Water‐Use Data in the United States: Challenges and Future Directions

Interbasin Transfers and Water Risk in the United States

Interbasin water transfers in the United States and Canada