The National Forest Climate Change Maps project was developed by the Rocky Mountain Research Station (RMRS) and the Office of Sustainability and Climate to meet the needs of national forest managers for information on projected climate changes at a scale relevant to decision making processes, including forest plans. The maps use state-of-the-art science and are available for every national forest in the contiguous United States with relevant data coverage. Currently, the map sets include variables related to precipitation, air temperature, snow (including snow residence time and April 1 snow water equivalent), and stream flow.Historical (1975-2005) and future (2071-2090) precipitation and temperature data for the contiguous United States are ensemble mean values across 20 global climate models from the CMIP5 experiment (https://journals.ametsoc.org/doi/abs/10.1175/BAMS-D-11-00094.1), downscaled to a 4 km grid. For more information on the downscaling method and to access the data, please see Abatzoglou and Brown, 2012 (https://rmets.onlinelibrary.wiley.com/doi/full/10.1002/joc.2312) and the Northwest Knowledge Network (https://climate.northwestknowledge.net/MACA/). We used the MACAv2- Metdata monthly dataset; monthly precipitation values (mm) were summed over the season of interest (annual, winter, or summer). Absolute and percent change were then calculated between the historical and future time periods.Raster data are also available for download from RMRS site (https://www.fs.usda.gov/rm/boise/AWAE/projects/NFS-regional-climate-change-maps/categories/us-raster-layers.html), along with pdf maps and detailed metadata (https://www.fs.usda.gov/rm/boise/AWAE/projects/NFS-regional-climate-change-maps/downloads/NationalForestClimateChangeMapsMetadata.pdf).

The National Forest Climate Change Maps project was developed by the Rocky Mountain Research Station (RMRS) and the Office of Sustainability and Climate to meet the needs of national forest managers for information on projected climate changes at a scale relevant to decision making processes, including forest plans. The maps use state-of-the-art science and are available for every national forest in the contiguous United States with relevant data coverage. Currently, the map sets include variables related to precipitation, air temperature, snow (including snow residence time and April 1 snow water equivalent), and stream flow.Historical (1975-2005) and future (2071-2090) precipitation and temperature data for the state of Alaska were developed by the Scenarios Network for Alaska and Arctic Planning (SNAP) (https://snap.uaf.edu). Monthly precipitation values (mm) were summed over the season of interest (annual, winter, or summer). These datasets have several important differences from the MACAv2-Metdata (https://climate.northwestknowledge.net/MACA/) products, used in the contiguous U.S. They were developed using different global circulation models and different downscaling methods, and were downscaled to a different scale (771 m instead of 4 km). While these cover the same time periods and use broadly similar approaches, caution should be used when directly comparing values between Alaska and the contiguous United States.Raster data are also available for download from RMRS site (https://www.fs.usda.gov/rm/boise/AWAE/projects/NFS-regional-climate-change-maps/categories/us-raster-layers.html), along with pdf maps and detailed metadata (https://www.fs.usda.gov/rm/boise/AWAE/projects/NFS-regional-climate-change-maps/downloads/NationalForestClimateChangeMapsMetadata.pdf).

The National Forest Climate Change Maps project was developed by the Rocky Mountain Research Station (RMRS) and the Office of Sustainability and Climate to meet the needs of national forest managers for information on projected climate changes at a scale relevant to decision making processes, including forest plans. The maps use state-of-the-art science and are available for every national forest in the contiguous United States with relevant data coverage. Currently, the map sets include variables related to precipitation, air temperature, snow (including snow residence time and April 1 snow water equivalent), and stream flow.\Historical (1975-2005) and future (2071-2090) precipitation and temperature data for the contiguous United States are ensemble mean values across 20 global climate models from the CMIP5 experiment (https://journals.ametsoc.org/doi/abs/10.1175/BAMS-D-11-00094.1), downscaled to a 4 km grid. For more information on the downscaling method and to access the data, please see Abatzoglou and Brown, 2012 (https://rmets.onlinelibrary.wiley.com/doi/full/10.1002/joc.2312) and the Northwest Knowledge Network (https://climate.northwestknowledge.net/MACA/). We used the MACAv2- Metdata monthly dataset; monthly precipitation values (mm) were summed over the season of interest (annual, winter, or summer). Absolute and percent change were then calculated between the historical and future time periods.Historical (1975-2005) and future (2071-2090) precipitation and temperature data for the state of Alaska were developed by the Scenarios Network for Alaska and Arctic Planning (SNAP) (https://snap.uaf.edu). These datasets have several important differences from the MACAv2-Metdata (https://climate.northwestknowledge.net/MACA/) products, used in the contiguous U.S. They were developed using different global circulation models and different downscaling methods, and were downscaled to a different scale (771 m instead of 4 km). While these cover the same time periods and use broadly similar approaches, caution should be used when directly comparing values between Alaska and the contiguous United States.Raster data are also available for download from RMRS site (https://www.fs.usda.gov/rm/boise/AWAE/projects/NFS-regional-climate-change-maps/categories/us-raster-layers.html), along with pdf maps and detailed metadata (https://www.fs.usda.gov/rm/boise/AWAE/projects/NFS-regional-climate-change-maps/downloads/NationalForestClimateChangeMapsMetadata.pdf).

Yearly effective energy and mass transfer (EEMT) (MJ m−2 yr−1) was calculated for the Catalina Mountains by summing the 12 monthly values. Effective energy and mass flux varies seasonally, especially in the desert southwestern United States where contemporary climate includes a bimodal precipitation distribution that concentrates in winter (rain or snow depending on elevation) and summer monsoon periods. This seasonality of EEMT flux into the upper soil surface can be estimated by calculating EEMT on a monthly basis as constrained by solar radiation (Rs), temperature (T), precipitation (PPT), and the vapor pressure deficit (VPD): EEMT = f(Rs,T,PPT,VPD). Here we used a multiple linear regression model to calculate the monthly EEMT that accounts for VPD, PPT, and locally modified T across the terrain surface. These EEMT calculations were made using data from the PRISM Climate Group at Oregon State University (www.prismclimate.org). Climate data are provided at an 800-m spatial resolution for input precipitation and minimum and maximum temperature normals and at a 4000-m spatial resolution for dew-point temperature (Daly et al., 2002). The PRISM climate data, however, do not account for localized variation in EEMT that results from smaller spatial scale changes in slope and aspect as occurs within catchments. To address this issue, these data were then combined with 10-m digital elevation maps to compute the effects of local slope and aspect on incoming solar radiation and hence locally modified temperature (Yang et al., 2007). Monthly average dew-point temperatures were computed using 10 yr of monthly data (2000–2009) and converted to vapor pressure. Precipitation, temperature, and dew-point data were resampled on a 10-m grid using spline interpolation. Monthly solar radiation data (direct and diffuse) were computed using ArcGIS Solar Analyst extension (ESRI, Redlands, CA) and 10-m elevation data (USGS National Elevation Dataset [NED] 1/3 Arc-Second downloaded from the National Map Seamless Server at seamless.usgs.gov). Locally modified temperature was used to compute the saturated vapor pressure, and the local VPD was estimated as the difference between the saturated and actual vapor pressures. The regression model was derived using the ISOHYS climate data set comprised of approximately 30-yr average monthly means for more than 300 weather stations spanning all latitudes and longitudes (IAEA).

This web map is a component of the Cordova, Alaska StoryMap. This map uses data from PRISM to show Alaska's average annual precipitation, with values averaged from 1981 - 2010.

This resource contains data inputs and a Jupyter Notebook that is used to introduce Hydrologic Analysis using Terrain Analysis Using Digital Elevation Models (TauDEM) and Python. TauDEM is a free and open-source set of Digital Elevation Model (DEM) tools developed at Utah State University for the extraction and analysis of hydrologic information from topography. This resource is part of a HydroLearn Physical Hydrology learning module available at https://edx.hydrolearn.org/courses/course-v1:Utah_State_University+CEE6400+2019_Fall/about

In this activity, the student learns how to (1) derive hydrologically useful information from Digital Elevation Models (DEMs); (2) describe the sequence of steps involved in mapping stream networks, catchments, and watersheds; and (3) compute an approximate water balance for a watershed-based on publicly available data.

Please note that this exercise is designed for the Logan River watershed, which drains to USGS streamflow gauge 10109000 located just east of Logan, Utah. However, this Jupyter Notebook and the analysis can readily be applied to other locations of interest. If running the terrain analysis for other study sites, you need to prepare a DEM TIF file, an outlet shapefile for the area of interest, and the average annual streamflow and precipitation data. - There are several sources to obtain DEM data. In the U.S., the DEM data (with different spatial resolutions) can be obtained from the National Elevation Dataset available from the national map (http://viewer.nationalmap.gov/viewer/). Another DEM data source is the Shuttle Radar Topography Mission (https://www2.jpl.nasa.gov/srtm/), an international research effort that obtained digital elevation models on a near-global scale (search for Digital Elevation at https://www.usgs.gov/centers/eros/science/usgs-eros-archive-products-overview?qt-science_center_objects=0#qt-science_center_objects). - If not already available, you can generate the outlet shapefile by applying basic terrain analysis steps in geospatial information system models such as ArcGIS or QGIS. - You also need to obtain average annual streamflow and precipitation data for the watershed of interest to assess the annual water balance and calculate the runoff ratio in this exercise. In the U.S., the streamflow data can be obtained from the USGS NWIS website (https://waterdata.usgs.gov/nwis) and the precipitation from PRISM (https://prism.oregonstate.edu/normals/). Note that using other datasets may require preprocessing steps to make data ready to use for this exercise.

Yearly effective energy and mass transfer (EEMT) (MJ m−2 yr−1) was calculated for the Valles Calders, upper part of the Jemez River basin by summing the 12 monthly values. Effective energy and mass flux varies seasonally, especially in the desert southwestern United States where contemporary climate includes a bimodal precipitation distribution that concentrates in winter (rain or snow depending on elevation) and summer monsoon periods. This seasonality of EEMT flux into the upper soil surface can be estimated by calculating EEMT on a monthly basis as constrained by solar radiation (Rs), temperature (T), precipitation (PPT), and the vapor pressure deficit (VPD): EEMT = f(Rs,T,PPT,VPD). Here we used a multiple linear regression model to calculate the monthly EEMT that accounts for VPD, PPT, and locally modified T across the terrain surface. These EEMT calculations were made using data from the PRISM Climate Group at Oregon State University (www.prismclimate.org). Climate data are provided at an 800-m spatial resolution for input precipitation and minimum and maximum temperature normals and at a 4000-m spatial resolution for dew-point temperature (Daly et al., 2002). The PRISM climate data, however, do not account for localized variation in EEMT that results from smaller spatial scale changes in slope and aspect as occurs within catchments. To address this issue, these data were then combined with 10-m digital elevation maps to compute the effects of local slope and aspect on incoming solar radiation and hence locally modified temperature (Yang et al., 2007). Monthly average dew-point temperatures were computed using 10 yr of monthly data (2000–2009) and converted to vapor pressure. Precipitation, temperature, and dew-point data were resampled on a 10-m grid using spline interpolation. Monthly solar radiation data (direct and diffuse) were computed using ArcGIS Solar Analyst extension (ESRI, Redlands, CA) and 10-m elevation data (USGS National Elevation Dataset [NED] 1/3 Arc-Second downloaded from the National Map Seamless Server at seamless.usgs.gov). Locally modified temperature was used to compute the saturated vapor pressure, and the local VPD was estimated as the difference between the saturated and actual vapor pressures. The regression model was derived using the ISOHYS climate data set comprised of approximately 30-yr average monthly means for more than 300 weather stations spanning all latitudes and longitudes (IAEA).

Precipitation Recharge/Discharge Areas: Kissimmee Basin/Floridan, and Lower West Coast/Sandstone-Tamiami. Protection of ground-water recharge areas against continued intrusion from urban expansion is becoming a primary concern among local governments within south Florida; a region whose population depends almost exclusively on ground water to meet its potable water demands. The Florida Legislature, by enacting various statutes, requires the water management districts to provide recharge area information to local governments in an effort to assist these agencies with the development and subsequent implementation of appropriate water resource policies.As a result, the South Florida Water Management District undertook a project to map recharge (as a consequence of infiltration and leakage) for all of the primary public water supply aquifer systems within its four planning regions.Recharge maps, at a scale of 1:300,000, were compiled for the unconfined Biscayne aquifer (Lower East Coast Planning Region), the unconfined Surficial aquifer system (Lower East Coast, Upper East Coast, and Lower West Coast Planning Regions), the semi-confined lower Tamiami and Sandstone aquifers (Lower West Coast Planning Region), and the semi-confined to confined upper Floridan aquifer (Kissimmee Basin Planning Region). The maps delineate average yearly rates of precipitation recharge or leakage, depending on the type of aquifer system(s) portrayed, as well as excess precipitation estimates (i.e. rainfall minus actual evapotranspiration losses) for each planning region. Recharge rates were determined from data sets extracted from existing regional numerical ground-water flow models representing a ten-year period (1980 through 1990), and standardized to long-term average or “normal” precipitation trends. A geographic information system (GIS) was employed to integrate the various data necessary in producing the final maps.Because of the large scale nature and the assumptions inherent within the data bases employed for completion of this project, the resulting map products are intended to be used as regional ground-water resource management planning aids only, and are not considered applicable for site-specific assessments.

Excess Precipitation - Kissimmee Basin, Upper East Coast, Lower East Coast and Lower West Coast Regions / Floridan Aquifer. Protection of ground-water recharge areas against continued intrusion from urban expansion is becoming a primary concern among local governments within south Florida; a region whose population depends almost exclusively on ground water to meet its potable water demands. The Florida Legislature, by enacting various statutes, requires the water management districts to provide recharge area information to local governments in an effort to assist these agencies with the development and subsequent implementation of appropriate water resource policies.As a result, the South Florida Water Management District undertook a project to map recharge (as a consequence of infiltration and leakage) for all of the primary public water supply aquifer systems within its four planning regions.Recharge maps, at a scale of 1:300,000, were compiled for the unconfined Biscayne aquifer (Lower East Coast Planning Region), the unconfined Surficial aquifer system (Lower East Coast, Upper East Coast, and Lower West Coast Planning Regions), the semi-confined lower Tamiami and Sandstone aquifers (Lower West Coast Planning Region), and the semi-confined to confined upper Floridan aquifer (Kissimmee Basin Planning Region). The maps delineate average yearly rates of precipitation recharge or leakage, depending on the type of aquifer system(s) portrayed, as well as excess precipitation estimates (i.e. rainfall minus actual evapotranspiration losses) for each planning region. Recharge rates were determined from data sets extracted from existing regional numerical ground-water flow models representing a ten-year period (1980 through 1990), and standardized to long-term average or “normal” precipitation trends. A geographic information system (GIS) was employed to integrate the various data necessary in producing the final maps.Because of the large scale nature and the assumptions inherent within the data bases employed for completion of this project, the resulting map products are intended to be used as regional ground-water resource management planning aids only, and are not considered applicable for site-specific assessments.

The 2021 National Hydrologic Assessment offers an analysis of flood risk, water supply, and ice break-up and jam flooding for spring 2021 based on late summer, fall, and winter precipitation, frost depth, soil saturation levels, snowpack, current streamflow, and projected spring weather. NOAA's network of 122 Weather Forecast Offices, 13 River Forecast Centers, National Water Center, and other national centers nationwide assess this risk, summarized here at the national scale. Overall, a reduced risk of spring flooding exists this year primarily due to a mainly dry fall and winter, along with limited snow still remaining on the ground. Major flooding is not expected this spring season. Minor to moderate flooding is ongoing across portions of the Lower Missouri River Basin with the flood risk predicted to continue through spring. The exception to the reduced risk is over the Coastal Plain of the Carolinas and Lower Ohio River Basin where flooding is predicted this spring, driven by above normal precipitation over the winter months, which has led to ongoing flooding, elevated streamflows, and highly saturated soil conditions. This wet pattern is expected to continue across the Coastal Plain of the Carolinas and Lower Ohio River Basin through spring, making these regions vulnerable to spring flooding. It is important to note that heavy rainfall at any time can lead to flooding, even in areas where overall risk is considered low. This assessment addresses only spring flood potential on the timescale of weeks to months, not days or hours. Debris flow and flash flooding often associated with burn scars and urban areas can form quickly and occur any time with heavy rainfall events. Nearly every day, flooding happens somewhere in the United States or its territories. Flooding can cause more damage than any other weather-related event...with an annual average direct damage impact of 8 billion dollars a year over the past 40 years, with these impact costs adjusted for inflation. Flooding is one of America's most underrated killers, causing nearly 100 fatalities per year… roughly half of which occur in vehicles. Flowing water can be particularly powerful and dangerous… with just six inches of water able to sweep a person off their feet… and two feet of rushing water able to carry a mid-size car downstream. No vehicle should ever attempt to cross a flooded roadway, and drivers are reminded to “Turn Around, Don’t Drown.” To be prepared, every American should know their flood risk and what to do before, during, and after a flood event. This information is available at www.ready.gov/floods. To remain apprised of your current flood risk, visit weather.gov for the latest official watches and warnings. For detailed hydrologic conditions and forecasts, go to water.weather.gov.

A feature class depicting geographic locations where streamflow statistics have been modeled within the Great Smoky Mountains National Park. Locations are expressed in the form of point geometry. These point data have been digitized from Water resources of the Great Smoky Mountains National Park, Tennessee and North Carolina Hydrologic Atlas 420 (William M. McMaster, E.F. Hubbard), 1970 edition. The Great Smoky Mountains National Park is located on the Tennessee-North Carolina border in the southern part of the Appalachian Range. The park occupies an area of about 800 square miles which is divided almost equally between the two States. Because of its beauty, location, and wide appeal, this is the nation's most visited national park. The number of visitors increased from 600,000 in 1937 to 3,000.000 in 1959 and to 7,000,000 in 1968. To serve these visitors, the National Park Service has provided campgrounds, picnic areas, scenic overlooks, nature and pioneer museums,and many miles of foot and horse trails. Most of these facilities and services require potable water supplies.The recreational and service facilities are scattered throughout the park, and it is necessary to develop a separate water system for each. For many years, water supplies in the park were obtained mostly from springs and small streams. However, the increasing demand for water at some facilities has approached the yield of the springs. Although streams in most cases have afforded adequate supplies, the water requires treatment, which may be costly. For these reasons, ground-water supplies are being developed wherever possible to replace existing water supplies and for most new facilities. In those places where ground-water supplies are not practical, surface water may provide an adequate supply. The total volume of water removed from streams or from storage in the ground for use at park facilities is currently less than 500,000 gallons per day during the periods of heaviest usage. This water is only diverted briefly, as storage facilities are very small, and probably more than 90 percent of the water is not "consumed" but is returned either to the streams or to the ground-water system. Therefore no measurable effects on either the terrestrial or aquatic ecologic balance can be anticipated as a result of pumpage.In order to plan effectively for the development of new facilities, the enlargement of existing facilities, and the management of the park's resources, the Park Service needs information on how much water is available at different places in the park. Emphasis of this study was placed on evaluating the occurrence, availability, and quality of ground water. But ground water and surface water are so interrelated within an area, that one may not be examined fully without considering the other. It also must be anticipated that as park facilities are enlarged, the Park Service may find it necessary to obtain supplies for some facilities from surface-water sources. Thus, an important part of the study was devoted to the flow of streams, particularly low flows. Low flows arc a limiting factor when developing a stream for water supply. Low-flow data arc also essential in stream-pollution studies and for the protection of aquatic life and resident environment. Many recreational uses of the streams also depend on adequate low flows.The movement of water from the oceans, through the atmosphere, over and through the land, and back to the oceans is referred to as the hydrologic cycle. In the park, this cycle begins when water enters the area as moisture in the atmosphere and reaches the land surface as rain or snow. Part of this precipitation is either evaporated, transpired by plants, or temporarily stored in the soil and rocks. The remaining precipitation runs overland to join a stream. Streamflow during a flood consists almost entirely of overland runoff. However, most streams in the park flow continuously whether it has rained recently or not. During periods of no overland runoff, streamflow is sustained by ground-water discharge from springs and from seepage directly into the stream channels.Two climatic factors play a decisive role in the hydrologic cycle in the park. The most important of these is precipitation. The other is temperature, which largely determines the amount of water evaporated and that transpired by plants. (The combined total of evaporation and transpiration is called evapotranspiration.) The park is located in one of the wettest regions of the United States. Precipitation in the park as a whole averages 64 inches annually, which amounts to some 890 billion gallons. Of this, about 500 billion gallons is discharged from the park during the year through streams and rivers. The remaining 390 billion gallons is either evaporated, 'transpired by plants, or seeps from the area through permeable rocks beneath the ground.Precipitation at points within the park ranges from less than 50 to more than 80 inches per year (surface-water availability map). In general, the amount of precipitation increases with increasing altitude. Differences in average annual precipitation of more than 25 inches between a rain gage in a valley and one on a peak less than 10 miles away are not uncommon. Precipitation also varies from year to year. For example, over the upper Little Tennessee River basin, which includes the southern part of the park, precipitation has ranged during the past 33 years from a low of 54 inches in 1952 to a high of 77 inches in 1964 (TVA, 1968). On a seasonal basis, the winter and spring tend to be much wetter than the summer and fall. March is usually the wettest month and October the driest; long-term averages indicate that only about half as much precipitation occurs in October as in March.The variations of evapotranspiration losses with time are related to seasonal changes in temperature. An example is the low streamflow generally experienced in late summer and early fall. This is caused. in part, by the higher temperatures of summer, which increase evaporation and transpiration, reducing the ground-water supplies. Areal variations in evapotranspiration, however, are related closely to altitude. This is due primarily to the decrease in average annual temperature of about 2° F for each J ,000 foot increase in altitude. (Shanks, 1954.). Many factors influencing the availability of water resources within an area are related to the nature of the land surface. These factors are mostly topography, such as altitude, slope, and drainage pattern, other factors also include vegetation and ground cover. The dominant topographic feature of the park is the northeastward trending ridgeline of the Great Smoky Mountains, which forms the boundary between North Carolina and Tennessee. Sixteen peaks along this ridge arc above 6,000 feet in altitude. Lesser ridges form radiating spurs from the central ridgeline. In broad aspect, the topography of the park consists of moderately sharp-crested, steep-sided ridges separated by deep, V -shaped valleys. Slopes of 50 percent ( 50 feet vertically in 100 feet horizontally) are common along the sides of ridges. Altitude ranges from 840 feet at the mouth of Abrams Creek at the extreme western end of the park to 6,642 feet at Clingmans Dome near the center of the park. The central ridgeline is a major drainage divide in the park, but it immediately beyond the park boundaries to the northeast by the Pigeon River and to the southwest by the Little Tennessee River.The streams of the park flow outward from the central ridgeline in every direction. All the streams are relatively small, none draining an area of more than 200 sq mi (square miles): most are much smaller than this where they flow from the park. The drainage system is characterized by a dense network of small streams flowing through steeply-sloping channels to the Tennessee River or its tributaries. Stream slopes average nearly 400 feet per mile of channel. The slopes increase to as much as 2,000 feet per mile in the headwaters. Most of the park is covered with forest : layers of leaves on the ground, tree roots, and ground vegetation reduce overland runoff, inhibit erosion, and cause a low sediment load, so that the streams are nearly always clear and sparkling. During the growing season, vegetation transpires a significant part of the ater resources of the region. Streamflow in the park is variable with respect to both time and location. The amount of flow passing a particular point may vary by as much as a factor of I 0,000 from minimum flow to maximum flood. The low-flow yield of two basins of equal size may differ by a factor of I 0 or more. The four principal factors that affect streamflow are drainage area, precipitation, evapotranspiration, and-for low flows-geology. Streamflow is usually reported in units of cubic feet per second (cfs) or of cubic feet per second per square miles (cfsm). This latter form represents the flow from each square mile of drainage basin, and is used to compare the yield of basins of different size. Average flow is a limiting factor in the design of a water supply. If all the water flowing past a point could be stored and no losses subsequently occurred, such as evaporation or seepage, then average flow would be the maximum constant rate at which water could be used. The average flows for selected sites are given in table I. The surface-water availability map shows the location of each of these sites by number.Average discharge shown in table 1 ranges from less than 2 to more than 4 cfsm. Thus, some streams in the park yield twice as much water per unit area as do other streams. This variability from place to place is the result of variations in precipitation and evapotranspiration. Ground water in the Great Smoky Mountains National Park comes from rain and snow. A part of the precipitation, even on the steepest mountain slopes, seeps into the ground. Water absorbed by the ground moves down to the water table