Skip to main content
Advanced Search

Filters: Tags: modeling (X)

1,476 results (133ms)   

Filters
Date Range
Extensions
Types
Contacts
Categories
Tag Types
Tag Schemes
View Results as: JSON ATOM CSV
Due to the recent warming trend, the arctic regions have experienced significant land cover and hydrology changes which include extended shrub coverage, shrinking water bodies and melting permafrost. All these changes have and will certainly continue to affect the carbon cycles of those regions which have the largest soil organic carbon pools in the world. Of these large soil organic carbon pools, we selected the portion of the Yukon River Basin in the state of Alaska to investigate the dynamic in land cover changes and methane (CH 4 ) emission from 1980s onwards. We also developed a dissolved organic carbon (DOC) transport model to analyze the DOC trends for a watershed in the Yukon River Basin. We used the newly-released...
Near-surface air temperature inversions are a common element of northern environments. Seasonal and inter-annual variations of low-level inversion characteristics were examined using 47 years of twice-daily radiosonde data from Whitehorse airport (1956-2003). Nocturnal low-level inversion events occurred throughout the year in 68% of the 0400h PST radiosonde ascents. Afternoon (1600h PST) inversion events, in contrast, were primarily a winter phenomena, limited to 24% of the readings between October and March, and were deepest and strongest during the winter months. Shorter, weaker, lower magnitude inversions appeared progressively more frequently during the 1974-2003 warming at Whitehorse. The impact (1956-2003)...
The Arctic is in transition from climate-driven thawing of permafrost. We investigate satellite-derived water equivalent mass changes, snow water equivalent with in situ measurements of runoff and ground-survey derived geoid models from 1999 through 2009. The Alaskan Arctic coastal plain groundwater storage (including wetland bog, thaw pond and lake) is increasing by 1.15 ± 0.65 km3/a (area-average 1.10 ± 0.62 cm/a), and Yukon River watershed groundwater storage is decreasing by 7.44 ± 3.76 km3/a (area‑average 0.79 ± 0.40 cm/a). Geoid changes show increases within the Arctic coastal region and decreases within the Yukon River watershed. We hypothesize these changes are linked to the development of new predominately...
The evolution of permafrost in cold regions is inextricably connected to hydrogeologic processes, climate, and ecosystems. Permafrost thawing has been linked to changes in wetland and lake areas, alteration of the groundwater contribution to streamflow, carbon release, and increased fire frequency. But detailed knowledge about the dynamic state of permafrost in relation to surface and groundwater systems remains an enigma. Here, we present the results of a pioneering 1,800 line-kilometer airborne electromagnetic survey that shows sediments deposited over the past 4 million years and the configuration of permafrost to depths of 100 meters in the Yukon Flats area near Fort Yukon, Alaska. The Yukon Flats is near the...
Black spruce (Picea mariana) forests represent the dominant vegetation type throughout the North American and Siberian taiga and are generally considered to be pristine, N-limiting environments. The aim of this study was to investigate the fundamental underlying mechanisms which control N availability in these soils with particular reference to the dynamics of dissolved organic nitrogen (DON). Our results showed that in these highly organic and low pH soils, soluble N is dominated by organic forms with correspondingly low concentrations of ammonium and nitrate. Amino acids, which are known to be directly taken up by plants growing in these soils, were calculated to constitute 10–20% of the total DON pool. The microbial...
thumbnail
Map of Sage sparrow density (birds/ha) in relation to vegetation, abiotic, and anthropogenic features. These data were released prior to the October 1, 2016 effective date for the USGS’s policy dictating the review, approval, and release of scientific data as referenced in USGS Survey Manual Chapter 502.8 Fundamental Science Practices: Review and Approval of Scientific Data for Release.
thumbnail
Map of Brewer's sparrow distribution developed from an abundance map created using multi-scale vegetation, abiotic, and anthropogenic features. These data were released prior to the October 1, 2016 effective date for the USGS’s policy dictating the review, approval, and release of scientific data as referenced in USGS Survey Manual Chapter 502.8 Fundamental Science Practices: Review and Approval of Scientific Data for Release.
Ecological models facilitate evaluation and assessment of alternative approaches to restore the Greater Everglades ecosystem. However, the provision of useful and accessible models is a challenge because there is often a disconnect between model output and its use by decision makers. Joint Ecosystem Modeling (JEM) meets this challenge by providing ecological model output tailored to management decisions. JEM is a partnership among federal and state agencies, universities and other organizations. Ecological models (i.e., ecological planning tools) were developed and used by JEM during the Central Everglades Planning Project to evaluate potential effects to natural resources in the impacted areas. There is a desire...
Ecological models facilitate evaluation and assessment of alternative approaches to restore the Greater Everglades ecosystem. However, the provision of useful and accessible models is a challenge because there is often a disconnect between model output and its use by decision makers. Joint Ecosystem Modeling (JEM) meets this challenge by providing ecological model output tailored to management decisions. JEM is a partnership among federal and state agencies, universities and other organizations. Ecological models (i.e., ecological planning tools) were developed and used by JEM during the Central Everglades Planning Project to evaluate potential effects to natural resources in the impacted areas. There is a desire...
thumbnail
This USGS data release presents tabular data and a model archive used to estimate seepage rates at 19 locations on the Truckee Canal for the 2018 and 2019 irrigation seasons. This supplemental data release consists of two child items: (1) Model archive of two-dimensional variably saturated heat and flow models (VS2DH) used to examine seepage rates in the Truckee Canal at 19 transect locations (model archive), and (2) ​Tabular data of site locations, sediment and water temperature, and canal head or stage in the Truckee Canal (tabular data).
thumbnail
A proof-of-concept MODFLOW 6 groundwater model was developed to represent the bedrock, delta, and alluvially-deposited aquifers underlying the Mekong River Basin approximately between Phnom Penh, Cambodia and Cao Lanh, Vietnam. The model was constructed using square grid cells measuring 2,200 meters on each side. The proof-of-concept groundwater model was used to simulate environmental baseline conditions, representative of a 20-year period with stresses from November 1990 through October 2010. Additionally, a 20-year period of drier conditions with sea-level rise was also simulated that approximates the Mekong River Commission C3 climate scenario (drier climate with sea level rise; Mekong River Commission, 2019)....
thumbnail
To understand potential climate change impacts on ecosystems, water resources, and numerous other natural and managed resources, climate change data and projections must be downscaled from coarse global climate models to much finer resolutions and more applicable formats. This project conducted comparative analyses to better understand the accuracy and properties of these downscaled climate simulations and climate-change projections. Interpretation, guidance and evaluation, including measures of uncertainties, strengths and weaknesses of the different methodologies for each simulation, can enable potential users with the necessary information to select and apply the models.
thumbnail
The USGS, in cooperation with the U.S. Bureau of Land Management (BLM), created a series of geospatial mapping products of the Scotts Creek Watershed in Lake County, California, using National Agriculture Imagery Program (NAIP) imagery from 2018, 2020 and 2022 and Open Street Map (OSM) from 2019. The imagery was downloaded from United States Department of Agriculture (USDA) - Natural Resources Conservation Service (NRCS) Geospatial Data Gateway (https://datagateway.nrcs.usda.gov/) and Geofabrik GmbH - Open Street Map (https://www.geofabrik.de/geofabrik/openstreetmap.html), respectively. The imagery was classified using Random Forest (RF) Modeling to produce land cover maps with three main classifications - bare,...
thumbnail
The USGS, in cooperation with the U.S. Bureau of Land Management (BLM), created a series of geospatial products of the Scotts Creek Watershed in Lake County, California, using National Agriculture Imagery Program (NAIP) imagery from 2018, 2020 and 2022. The imagery was downloaded from United States Department of Agriculture (USDA) - Natural Resources Conservation Service (NRCS) Geospatial Data Gateway (https://datagateway.nrcs.usda.gov). The NAIP imagery from 2018, 2020 and 2022 was classified using Random Forest Modeling to produce land cover maps with three main classifications – bare, vegetation, and shadows. A total of 600 independent reference points were used in the accuracy assessment. The overall accuracy...
thumbnail
This dataset includes model inputs (specifically, meteorological inputs to the predictive models and flags for predicted ice-cover) and is part of a larger data release of lake temperature model inputs and outputs for 2,332 lakes in the U.S. states of North Dakota, South Dakota, Minnesota, Wisconsin, and Michigan (https://doi.org/10.5066/P9PPHJE2).
thumbnail
A simple water budget includes precipitation, streamflow, change in storage, evapotranspiration, and residuals: P=Q + ET + ΔS + e. It is essential to include the managed component (i.e., the “human” component) to close the water budget and reduce the magnitude of the residuals from “natural” water budgets. Some of the largest components of managed water withdraws are public supply, irrigation, and thermoelectric. The modified water budget is: P=Q + ET + ΔS + (PS + Irr + TE) + e, where PS is public supply, Irr is irrigation, and TE is thermoelectric water use. This data release contains both the natural and managed components of the water budget for a region within the Apalachicola-Chattahoochee-Flint (ACF) River...
thumbnail
The travel time map was generated using the Pedestrian Evacuation Analyst model (version 1.0.1 for ArcGIS 10.5) from the USGS (https://geography.wr.usgs.gov/science/vulnerability/tools.html). The travel time analysis uses ESRI's Path Distance tool to find the shortest distance across a cost surface from any point in the hazard zone to a safe zone. This cost analysis considers the direction of movement and assigns a higher cost to steeper slopes, based on a table contained within the model. The analysis also adds in the energy costs of crossing different types of land cover, assuming that less energy is expended walking along a road than walking across a sandy beach. To produce the time map, the evacuation surface...
In support of mapping ecological conditions (e.g. invasive annual grass) in sagebrush-dominated landscapes of the western United States, we developed weekly (starting from week 7 to week 42 and Week 1 starts January 1 or Day of the year 1 to 7, week 2 is from Day of year 8 to 14, and so on) 30-m cloud-free Normalized Difference Vegetation Index (NDVI) from 2016 to 2019. The data was generated with machine-learning techniques (i.e., regression tree [RT]) and harmonized Landsat and Sentinel -2 (HLS) data. The geographic coverage includes areas in the Great Basin, the Snake River Plain, the state of Wyoming, and contiguous areas. This NDVI collection allows for local-scale detection and analysis such as, fuel breaks...
map background search result map search result map Analysis of Downscaled Climate Simulations and Projections and Their Use in Decision Making for the Southwest Tsunami evacuation time map for American Samoa predicted maximum tsunami (PMT) inundation zone and fast run speed Natural and managed components of the water-budget from 2008–2012 for 43 HUC10s in the Apalachicola-Chattahoochee-Flint River Basin, Georgia, U.S. Weekly cloud free Harmonized Landsat Sentinel (HLS) Normalized Difference Vegetation Index (NDVI) estimates for western United States (2016 – 2019) Ecological Model Support for the Western Everglades Restoration Project (WERP) Round Four of Four, 2020 Ecological Model Support for the Western Everglades Restoration Project (WERP) Round Two of Four, 2018 Supplemental data and documentation of VS2DH seepage models: Incorporating temperature into seepage loss estimates for a large irrigation canal MODFLOW 6 proof-of-concept groundwater model for the Mekong River Basin between Phnom Penh, Cambodia and Cao Lanh, Vietnam Sage sparrow density in the Wyoming Basins Ecoregional Assessment area Brewer's sparrow distribution in the Wyoming Basins Ecoregional Assessment area Geospatial mapping products derived from 2018, 2020, and 2022 NAIP aerial imagery for the Scotts Creek Watershed, Lake County, CA Land Cover Maps for the Scotts Creek Watershed, Lake County, California for 2018, 2020, and 2022 Geospatial mapping products derived from 2018, 2020, and 2022 NAIP aerial imagery for the Scotts Creek Watershed, Lake County, CA Land Cover Maps for the Scotts Creek Watershed, Lake County, California for 2018, 2020, and 2022 Supplemental data and documentation of VS2DH seepage models: Incorporating temperature into seepage loss estimates for a large irrigation canal Ecological Model Support for the Western Everglades Restoration Project (WERP) Round Four of Four, 2020 Ecological Model Support for the Western Everglades Restoration Project (WERP) Round Two of Four, 2018 Natural and managed components of the water-budget from 2008–2012 for 43 HUC10s in the Apalachicola-Chattahoochee-Flint River Basin, Georgia, U.S. MODFLOW 6 proof-of-concept groundwater model for the Mekong River Basin between Phnom Penh, Cambodia and Cao Lanh, Vietnam Sage sparrow density in the Wyoming Basins Ecoregional Assessment area Brewer's sparrow distribution in the Wyoming Basins Ecoregional Assessment area Analysis of Downscaled Climate Simulations and Projections and Their Use in Decision Making for the Southwest Weekly cloud free Harmonized Landsat Sentinel (HLS) Normalized Difference Vegetation Index (NDVI) estimates for western United States (2016 – 2019)