The National Land Cover Database(NLCD)2016 products show that,between 2001 and 2016,nearly half of the land cover change in the conterminous United States(CONUS)involved forested areas.To ensure the quality of NLCD la...The National Land Cover Database(NLCD)2016 products show that,between 2001 and 2016,nearly half of the land cover change in the conterminous United States(CONUS)involved forested areas.To ensure the quality of NLCD land cover and land cover change products,it is important to accurately detect the location and time of forest disturbance.We designed a comprehensive strategy to integrate a continuous time series forest change detection method and a discrete 2-date forest change detection method to produce the NLCD 1986-2019 forest disturbance product,which shows the most recent forest disturbance date between the years 1986 and 2019 for every 2-to 3-year interval.This method,the Time-Series method Using Normalized Spectral Distance(NSD)index(TSUN),uses NSD to detect multi-date forest land cover changes and was shown to be easily extended to a new date even when new images were processed in a different way than previous date images.The discrete 2-date method uses the Multi-Index Integrated Change Analysis(MIICA)method to detect changes between 2-date images.A method based on confidence and object grouping was designed to combine the multiple MIICA outputs to improve change detection accuracy.Finally,an aggregation scheme was implemented to combine the TSUN output,the integrated MIICA results,and ancillary data to produce the NLCD 2019 forest disturbance 1986–2019 product.The initial accuracy assessments from 1,600 samples over 4 Landsat path/rows show that the producer’s and user’s accuracies of the 2001-2019 forest disturbance map are 76% and 74%,respectively.The final CONUS-wide forest disturbance product is provided at https://www.mrlc.gov/nlcd-2019-scienceresearch-products.展开更多
Floods have become increasingly prominent in recent decades causing devastating effects on lives and livelihoods worldwide.Efficient tools to assess the drivers of floods,such as increasing urbanization,could help to ...Floods have become increasingly prominent in recent decades causing devastating effects on lives and livelihoods worldwide.Efficient tools to assess the drivers of floods,such as increasing urbanization,could help to minimize flood hazards.Urbanization increases the design peak flow(maximum potential surface water flow from a precipitation event with an average probability of occurring once in a specific recurrence interval),which is a key information needed for designing stormwater management infrastructures such as culverts and storm sewers.A web-based application was developed to explore the potential changes(1985 to 2020)in design peak flow of urban areas across the conterminous United States driven by land cover change.The results indicate a potential increase in design peak flow in urban areas up to 126.6% in 2020 compared to 1985.Of the total 3,535 study urban areas,about 80%(2,840)urban areas increased design peak flow,and about 19%(654)decreased design peak flow.A general pattern of increasing design peak flow was observed during 1985 to 2010,and decreasing pattern was observed during 2010 to 2020,primarily driven by respective increasing(decreasing)and decreasing(increasing)developed areas(croplands).The application provides crucial information by visualizing both spatial and temporal data that could be useful for decision-makers in developing and improving urban stormwater management plans and policies for efficient resource allocations and reducing flood risks.展开更多
基金supported by the USGS-NASA Landsat Science Team Program for Toward Near Real-time Monitoring and Characterization of Land Surface Change for the Conterminous US(140G0119C0008).
文摘The National Land Cover Database(NLCD)2016 products show that,between 2001 and 2016,nearly half of the land cover change in the conterminous United States(CONUS)involved forested areas.To ensure the quality of NLCD land cover and land cover change products,it is important to accurately detect the location and time of forest disturbance.We designed a comprehensive strategy to integrate a continuous time series forest change detection method and a discrete 2-date forest change detection method to produce the NLCD 1986-2019 forest disturbance product,which shows the most recent forest disturbance date between the years 1986 and 2019 for every 2-to 3-year interval.This method,the Time-Series method Using Normalized Spectral Distance(NSD)index(TSUN),uses NSD to detect multi-date forest land cover changes and was shown to be easily extended to a new date even when new images were processed in a different way than previous date images.The discrete 2-date method uses the Multi-Index Integrated Change Analysis(MIICA)method to detect changes between 2-date images.A method based on confidence and object grouping was designed to combine the multiple MIICA outputs to improve change detection accuracy.Finally,an aggregation scheme was implemented to combine the TSUN output,the integrated MIICA results,and ancillary data to produce the NLCD 2019 forest disturbance 1986–2019 product.The initial accuracy assessments from 1,600 samples over 4 Landsat path/rows show that the producer’s and user’s accuracies of the 2001-2019 forest disturbance map are 76% and 74%,respectively.The final CONUS-wide forest disturbance product is provided at https://www.mrlc.gov/nlcd-2019-scienceresearch-products.
基金funded by the US Geological Survey Land Change Science program(contract number:140G0119C0001).
文摘Floods have become increasingly prominent in recent decades causing devastating effects on lives and livelihoods worldwide.Efficient tools to assess the drivers of floods,such as increasing urbanization,could help to minimize flood hazards.Urbanization increases the design peak flow(maximum potential surface water flow from a precipitation event with an average probability of occurring once in a specific recurrence interval),which is a key information needed for designing stormwater management infrastructures such as culverts and storm sewers.A web-based application was developed to explore the potential changes(1985 to 2020)in design peak flow of urban areas across the conterminous United States driven by land cover change.The results indicate a potential increase in design peak flow in urban areas up to 126.6% in 2020 compared to 1985.Of the total 3,535 study urban areas,about 80%(2,840)urban areas increased design peak flow,and about 19%(654)decreased design peak flow.A general pattern of increasing design peak flow was observed during 1985 to 2010,and decreasing pattern was observed during 2010 to 2020,primarily driven by respective increasing(decreasing)and decreasing(increasing)developed areas(croplands).The application provides crucial information by visualizing both spatial and temporal data that could be useful for decision-makers in developing and improving urban stormwater management plans and policies for efficient resource allocations and reducing flood risks.
