Effects of changes in canopy interception on stream runoff response and recovery following clear-cutting of a Japanese coniferous forest in Fukuroyamasawa Experimental Watershed in Japan     

Tomoki Oda  Tomohiro Egusa  Nobuhito Ohte  Norifumi Hotta  Nobuaki Tanaka  Mark B. Green  Masakazu Suzuki 《水文研究》2021,35(5):e14177

Understanding changes in evapotranspiration during forest regrowth is essential to predict changes of stream runoff and recovery after forest cutting. Canopy interception (Ic) is an important component of evapotranspiration, however Ic changes and the impact on stream runoff during regrowth after cutting remains unclear due to limited observations. The objective of this study was to examine the effects of Ic changes on long-term stream runoff in a regrowth Japanese cedar and Japanese cypress forest following clear-cutting. This study was conducted in two 1-ha paired headwater catchments at Fukuroyamasawa Experimental Watershed in Japan. The catchments were 100% covered by Japanese coniferous plantation forest, one of which was 100% clear-cut in 1999 when the forest was 70 years old. In the treated catchment, annual runoff increased by 301 mm/year (14% of precipitation) the year following clear-cutting, and remained 185 mm/year (7.9% of precipitation) higher in the young regrowth forest for 12–14 years compared to the estimated runoff assuming no clear-cutting. The Ic change was −358 mm/year (17% of precipitation) after cutting and was −168 mm/year (6.7% of precipitation) in the 12–14 years old regrowth forest compared to the observed Ic during the pre-cutting period. Stream runoff increased in all seasons, and the Ic change was the main fraction of evapotranspiration change in all seasons throughout the observation period. These results suggest that the change in Ic accounted for most of the runoff response following forest cutting and the subsequent runoff recovery in this coniferous forest.  相似文献   

Long-term hydrology and aquatic biogeochemistry data from H. J. Andrews Experimental Forest,Cascade Mountains,Oregon     

Sherri L. Johnson  Don Henshaw  Greg Downing  Steve Wondzell  Mark Schulze  Adam Kennedy  Greg Cohn  Stephanie A. Schmidt  Julia A. Jones 《水文研究》2021,35(5):e14187

The H. J. Andrews Experimental Forest (HJA) encompasses the 6400 ha Lookout Creek watershed in western Oregon, USA. Hydrologic, chemistry and precipitation data have been collected, curated, and archived for up to 70 years. The HJA was established in 1948 to study the effects of harvest of old-growth conifer forest and logging-road construction on water quality, quantity and vegetation succession. Over time, research questions have expanded to include terrestrial and aquatic species, communities and ecosystem dynamics. There are nine small experimental watersheds and 10 gaging stations in the HJA, including both reference and experimentally treated watersheds. Gaged watershed areas range from 8.5 to 6242 ha. All gaging stations record stage height, water conductivity, water temperature and above-stream air temperature. At nine of the gage sites, flow-proportional water samples are collected and composited over 3-week intervals for chemical analysis. Analysis of stream and precipitation chemistry began in 1968. Analytes include dissolved and particulate species of nitrogen and phosphorus, dissolved organic carbon, pH, specific conductance, suspended sediment, alkalinity, and major cations and anions. Supporting climate measurements began in the 1950s in association with the first small watershed experiments. Over time, and following the initiation of the Long Term Ecological Research (LTER) grant in 1980, infrastructure expanded to include a set of benchmark and secondary meteorological stations located in clearings spanning the elevation range within the Lookout Creek watershed, as well as a large number of forest understory temperature stations. Extensive metadata on sensor configurations, changes in methods over time, sensor accuracy and precision, and data quality control flags are associated with the HJA data.  相似文献   

Geology ‘far from the madding crowd’, along the northern border of Vietnam     

Mark Williams  Toshifumi Komatsu  Phong Nguyen Duc  Tom Harvey  Thijs Vandenbroucke 《Geology Today》2019,35(6):217-220

To the north of Hanoi, about a day's drive by car, lies Ha Giang Province, the northernmost region of Vietnam. Ha Giang is remote from the hustle and bustle of daily life, and beyond its eponymous provincial capital towards the border with China, mountains rise quickly to Quan Ba, ‘Heaven's Gate’. The mountains form an uneven landscape of steep‐sided karst rising from deep river‐cut gorges and form a formidable barrier on the northern frontier of Vietnam. Beyond ‘Heaven's Gate’ lies the little travelled region of Dong Van, with its majestic mountains of Palaeozoic strata rising precipitously to the sky. Here, a century ago, the French geologists Henri Mansuy and Jacques Deprat documented early finds of fossils from lower Palaeozoic strata on the border with China.  相似文献   

Geography Deserts: State and Regional Variation in the Formal Opportunity to Learn Geography in the United States, 2005–2015     

Mark C. Jones  Marcos Luna 《The Journal of geography》2019,118(2):88-100

The formal opportunity to learn geography in the United States is unevenly distributed across space, creating possible geography deserts. Data on the number of exams taken in Advanced Placement Human Geography (APHG) and bachelor’s degrees earned in geography are mapped at the state and regional scales. Normalized rates are ranked and grouped into quintiles. For APHG exams, states in the southeastern region of the United States are in the uppermost quintiles while states in the northeastern region are in the lowermost quintiles. The pattern for bachelor’s degrees in geography is somewhat the spatial inverse of that for APHG.  相似文献   

Evaluating soil water routing approaches in watershed-scale,ecohydrologic modelling     

Garett Pignotti  Indrajeet Chaubey  Keith Cherkauer  Mark Williams  Melba Crawford 《水文研究》2021,35(3):e14034

Soil water dynamics are central in linking and regulating natural cycles in ecohydrology, however, mathematical representation of soil water processes in models is challenging given the complexity of these interactions. To assess the impacts of soil water simulation approaches on various model outputs, the Soil and Water Assessment Tool was modified to accommodate an alternative soil water percolation method and tested at two geographically and climatically distinct, instrumented watersheds in the United States. Soil water was evaluated at the site scale via measured observations, and hydrologic and biophysical outputs were analysed at the watershed scale. Results demonstrated an improved Kling–Gupta Efficiency of up to 0.3 and a reduction in percent bias from 5 to 25% at the site scale, when soil water percolation was changed from a threshold, bucket-based approach to an alternative approach based on variable hydraulic conductivity. The primary difference between the approaches was attributed to the ability to simulate soil water content above field capacity for successive days; however, regardless of the approach, a lack of site-specific characterization of soil properties by the soils database at the site scale was found to severely limit the analysis. Differences in approach led to a regime shift in percolation from a few, high magnitude events to frequent, low magnitude events. At the watershed scale, the variable hydraulic conductivity-based approach reduced average annual percolation by 20–50 mm, directly impacting the water balance and subsequently biophysical predictions. For instance, annual denitrification increased by 14–24 kg/ha for the new approach. Overall, the study demonstrates the need for continued efforts to enhance soil water model representation for improving biophysical process simulations.  相似文献   

Creating an isotopically similar Earth–Moon system with correct angular momentum from a giant impact     

Bryant M. Wyatt  Jonathan M. Petz  William J. Sumpter  Ty R. Turner  Edward L. Smith  Baylor G. Fain  Taylor J. Hutyra  Scott A. Cook  John H. Gresham  Michael F. Hibbs  Shaukat N. Goderya 《Journal of Astrophysics and Astronomy》2018,39(2):26

The giant impact hypothesis is the dominant theory explaining the formation of our Moon. However, the inability to produce an isotopically similar Earth–Moon system with correct angular momentum has cast a shadow on its validity. Computer-generated impacts have been successful in producing virtual systems that possess many of the observed physical properties. However, addressing the isotopic similarities between the Earth and Moon coupled with correct angular momentum has proven to be challenging. Equilibration and evection resonance have been proposed as means of reconciling the models. In the summer of 2013, the Royal Society called a meeting solely to discuss the formation of the Moon. In this meeting, evection resonance and equilibration were both questioned as viable means of removing the deficiencies from giant impact models. The main concerns were that models were multi-staged and too complex. We present here initial impact conditions that produce an isotopically similar Earth–Moon system with correct angular momentum. This is done in a single-staged simulation. The initial parameters are straightforward and the results evolve solely from the impact. This was accomplished by colliding two roughly half-Earth-sized impactors, rotating in approximately the same plane in a high-energy, off-centered impact, where both impactors spin into the collision.  相似文献   

Aging in Activity Spaces: How Does Individual Accessibility Compare across Age Cohorts?     

Brittany S. Wood  Mark W. Horner 《The Professional geographer》2019,71(1):1-14

The proportion of individuals age sixty-five and over is growing at an astronomical rate in the United States, and some estimate that this demographic age group will double by the year 2025. Older adults and adults nearing retirement age tend to reside in suburban neighborhoods and rely heavily on personal vehicles. This study uses travel diary data on automobile trips to construct activity spaces to explore whether or not travel patterns across age groups result in differential access to particular goods and services in the Orlando Metropolitan Statistical Area (MSA). Using an approach based on time geographic density estimation, this research identifies activity spaces across different age cohorts to identify differences in the automobility of different age groups. Results indicate that the geographic dispersion of activities with the Orlando MSA currently favors younger adults. Adults age fifty to sixty-four had the lowest accessibility scores compared to other age cohorts. If this preretirement group has poor access now, holding other effects constant, their access might only get worse as they get older and stop commuting. Transportation is an important consideration in planning for aging populations, and analyzing differences in how older adults travel compared to their younger counterparts can offer insight into the diverse needs of this group. Key Words: accessibility, aging populations, mobility, time geography, transportation.  相似文献   

Modelling population retention in Australia’s Northern Territory – how do current forms of migration contribute to population turnover and retention?     

James Thurmer  D. Carson  A. Taylor 《The Australian geographer》2019,50(4):435-452

ABSTRACT

In the past, population growth in Australia's Northern Territory, as in other peripheral parts of high-income countries, has been driven by internal labour migration and migration from outside of Australia. These have been contributing to the high population turnover experienced in peripheral areas. Since 2010, the Northern Territory has experienced low (and even negative) population growth, and public policy is currently focused on migration as a lever to reverse this trend. However, the extent to which the characteristics of migrants influence the potential for longer-term population growth is poorly understood. This paper uses a new method to analyse the contributions of various types of migrants to both population turnover and retention. Two major sets of findings emerge: First, the significance of separating newer in-migrants from longer-term residents when analysing migration patterns; and secondly, the contribution of age, gender, Indigenous status, international origin, wages and industry of employment to the Northern Territory's population turnover. The research suggests that current forms of migration favour people who are likely to stay for only short periods, and have high wage demands. The main policy inference is that long-term population growth will likely not eventuate unless new forms of migration can be stimulated.  相似文献   

Spatially explicit models for exploring COVID‐19 lockdown strategies     

David O'Sullivan  Mark Gahegan  Daniel J. Exeter  Benjamin Adams 《Transactions in GIS》2020,24(4):967-1000

This article describes two spatially explicit models created to allow experimentation with different societal responses to the COVID‐19 pandemic. We outline the work to date on modeling spatially explicit infective diseases and show that there are gaps that remain important to fill. We demonstrate how geographical regions, rather than a single, national approach, are likely to lead to better outcomes for the population. We provide a full account of how our models function, and how they can be used to explore many different aspects of contagion, including: experimenting with different lockdown measures, with connectivity between places, with the tracing of disease clusters, and the use of improved contact tracing and isolation. We provide comprehensive results showing the use of these models in given scenarios, and conclude that explicitly regionalized models for mitigation provide significant advantages over a “one‐size‐fits‐all” approach. We have made our models, and their data, publicly available for others to use in their own locales, with the hope of providing the tools needed for geographers to have a voice during this difficult time.  相似文献   

Distinguishing extensive and intensive properties for meaningful geocomputation and mapping     

Simon Scheider  Mark D. Huisjes 《International journal of geographical information science》2019,33(1):28-54

A most fundamental and far-reaching trait of geographic information is the distinction between extensive and intensive properties. In common understanding, originating in Physics and Chemistry, extensive properties increase with the size of their supporting objects, while intensive properties are independent of this size. It has long been recognized that the decision whether analytical and cartographic measures can be meaningfully applied depends on whether an attribute is considered intensive or extensive. For example, the choice of a map type as well as the application of basic geocomputational operations, such as spatial intersections, aggregations or algebraic operations such as sums and weighted averages, strongly depend on this semantic distinction. So far, however, the distinction can only be drawn in the head of an analyst. We still lack practical ways of automation for composing GIS workflows and to scale up mapping and geocomputation over many data sources, e.g. in statistical portals. In this article, we test a machine-learning model that is capable of labeling extensive/intensive region attributes with high accuracy based on simple characteristics extractable from geodata files. Furthermore, we propose an ontology pattern that captures central applicability constraints for automating data conversion and mapping using Semantic Web technology.  相似文献