Integrated Water Science (IWS) Basins

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The U.S. Geological Survey is integrating its water science programs to better address the Nation’s greatest water resource challenges. At the heart of this effort are plans to intensively study at least 10 Integrated Water Science (IWS) basins — medium-sized watersheds (10,000-20,000 square miles) and underlying aquifers — over the next decade. The IWS basins will represent a wide range of environmental, hydrologic, and landscape settings and human stressors of water resources to improve understanding of water availability across the Nation.

Illustration of integrated science process stages overlaid onto blurred map of national hydrological network

Each of these science processes—observe, understand, predict, and deliver—are necessary for acquiring reliable and actionable information about water availability. If one process is overlooked, the others are limited. For example, if observing systems are not advanced, understanding is limited as is the ability to build better models for prediction. This is why science integration is critical and why it is a priority at the USGS.

State-of-the-art water-availability models—supported by high-density innovative monitoring and cutting-edge research—will be developed and applied in each IWS basin in ways that are extensible to larger regions represented by the basins and ultimately to the entire Nation. Water availability here is defined as the spatial and temporal distribution of water quantity and quality in both surface and groundwater, as related to human and ecosystem needs and as affected by human and natural influences. Together, various USGS water science programs, including the Next Generation Water Observing System (NGWOS), Integrated Water Availability Assessments (IWAAs), and Integrated Water Prediction programs, are providing the observations, understanding, predictions, and information delivery necessary for sound decision-making related to emergency response, flood forecasting, reservoir management, drinking water delivery, permit compliance, water-quality improvement, recreational safety and more. 

A regional framework was developed and is being used to ensure that basins selected from different hydrologic regions collectively represent the range in major drivers of the hydrologic cycle across the contiguous United States. A quantitative ranking scheme, primarily based on human stressors of water resources, is being used to ensure that the selected basins also address important water-resource challenges (Van Metre et. al., 2020). To date (2020), IWS basin activities are underway in the Delaware River Basin, where the impact of the drought of record under current water supply and demand restrictions is being studied, and in the Upper Colorado River Basin, where cold-region processes of snow, ice and frozen soils are being studied. Beginning in 2021, planning will begin for IWS basin activities in the Illinois River Basin, where the relation between an overabundance of nutrients (primarily nitrogen and phosphorus), associated harmful algal blooms (HABs), and water availability will be studied.

Key questions the USGS can address with Integrated Water Science

  1. What is the quality and quantity of atmospheric, surface, and subsurface water, and how do these vary spatially and temporally?
  2. How do human activities affect water quantity and quality?
  3. How can water accounting be done more effectively and comprehensively to provide data on water availability and use?
  4. How does changing climate affect water quality, quantity, and reliability, as well as water-related hazards and extreme events?
  5. How can long-term water-related risk management be improved?


Map of national reference basins with three selected IWS basins highlighted

Selected reference basins—referred to as Integrated Water Science (IWS) basins (labeled watersheds outlined in gray)—are serving as regional focus areas for intensive observation, understanding, prediction, and delivery of data and information in support of deep, integrated assessments of water availability that can be extended to the broader region (colored areas) and ultimately to the Nation. To date (2020), three basins have been selected for intensive study, the Delaware River Basin, the headwaters of the Colorado and Gunnison River Basin (Upper Colorado River Basin) and the Illinois River Basin.