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August 1987 - December 2014
Publications
Publications (81)
Mountains play key roles in the world’s water cycle. They interact with the atmosphere to capture water and, as the world’s “water towers,” store and transform water and deliver it to lower regions. Human actions and warming climates alter mountain waterscapes. Mountain waterscapes symbolize the ever-evolving connection between nature and society,...
For millennia, humans have deliberately altered the geomorphology of the world's mountains to obtain resources, create transportation routes, and develop infrastructure for economic, agricultural, recreational, and spiritual activities. Road building, agriculture, mining, logging, dams, environmental restoration efforts, and other actions influence...
A synthesis of the rapidly growing field of anthropic geomorphology is presented that includes impacts on geomorphic systems, impacts of climate change, effects of geomorphic systems on society, and natural hazards. Conceptual models of anthropogenic geomorphic impacts that join human and physical factors are narrow in scope relative to the broad s...
As the world's top two economies, the United States (U.S.) and China face a number of similar water resource problems. Yet, few studies have been done to systematically compare policies and approaches on water resources management between China and the U.S. This study compares water resource policies of China and the U.S. in the areas of national a...
Physical geography is a process, conducted by people, of integration and synthesis of ideas and observations to advance scientific understanding of Earth’s surface and atmosphere and to apply this knowledge to the greater good of the planet and its people. Therefore, physical geography matters; that is, physical geography makes a difference to peop...
This article begins with a historical perspective of knowledge of and research on the effects of vegetation clearance on channel change, and reviews examples, first from North America and then more globally, of channel changes associated with vegetation clearance. Over the long term, the fluvial system, itself, provides an archive of channel change...
In-channel large wood (LW) plays an important role in the eco-morphological functionality of many river systems. This importance has been widely recognized, yet there continues to be a poor understanding of relationships between morphodynamics and locations of wood deposition within the channel, particularly in low-gradient, semi-confined rivers. T...
Páramo grasslands are important carbon sinks in the Ecuadorian Andes. Although carbon content of páramo Andisols is correlated with high water retention, the effects of differences in soil moisture under different types of land use on soil carbon processes have not been explicitly tested in the Ecuadorian Andes. This study assessed the relationship...
SUMMARY Andean grasslands ( páramos ) are highly valued for their role in regional water supply as well as for their biodiversity and large soil carbon stocks. Several Payment for Ecosystem Services (PES) programmes promote either afforestation or alteration of traditional burning regimes under the assumption that these land management strategies w...
Addition of large woody debris (LWD) to rivers has increasingly become a popular stream restoration strategy, particularly in river systems of the Midwestern United States. However, our knowledge of LWD dynamics is mostly limited to high gradient montane river systems, or coastal river systems. The LWD-related management of low-gradient, Midwestern...
Estimates of annual streamflow in connection with key natural and anthropogenic factors are necessary and
important for different purposes, such as water resource planning and management, sediment and nutrient
loading in streams and rivers, hydropower, and navigation. This study is an attempt to use the spatial statistical
regression approach to de...
The global biodiversity crisis has invigorated the search for generalized patterns in most disciplines within the natural sciences. Studies based on organismal functional traits attempt to broaden implications of results by identifying the response of functional traits, instead of taxonomic units, to environmental variables. Determining the functio...
Deliberately or indirectly, most of the terrestrial surface has been affected by the actions of human beings. For that reason, geomorphologists have needed to broaden their scope of inquiry to encompass the human-landscape system. Four themes related to human actions emerge in recent research in geomorphology: (1) human impacts on geomorphic system...
Bank failure is a common fluvial process and can be a pervasive fluvial response to natural and anthropogenic disturbances. Previous research has identified causes and types of bank failure, but the conditions that lead to the cessation of bank failure remain poorly explained. This research examines differences between banks with active bank failur...
Field research enables a researcher to view geomorphic systems in
broader contexts than those envisioned while at a desk and can yield
unanticipated insights that change the course of an investigation or
affect the interpretation of results. Geomorphological field research
often produces 'aha!' moments, epiphanies that enhance understanding and
lea...
This article summarizes the primary outcomes of an interdisciplinary workshop in 2010, sponsored by the U.S. National Science Foundation, focused on developing key questions and integrative themes for advancing the science of human-landscape systems. The workshop was a response to a grand challenge identified recently by the U.S. National Research...
The 1993 rockslide at La Josefina, Ecuador, killed many people, displaced thousands, and dramatically altered a populated mountain landscape. The author's field research in this area, before and after the rockslide, yields new insights into the volume of sediment moving through tributary river systems in this Andean environment and into the ongoing...
Hydrologic and soil erosion models, even distributed models, require some degree of generalization of land surface characteristics. Because generalization typically depends on the areal extent of parameter values, surfaces that affect geomorphic/erosional processes out of proportion to their areal extent require special consideration. Increased ero...
We describe a framework called Regional Hydrologic Modeling for Environmental Evaluation (RHyME2) for hydrologic modeling across scales. Rooted from hierarchy theory, RHyME2 acknowledges the rate-based hierarchical structure of hydrological systems. Operationally, hierarchical constraints are accounted for and explicitly described in models put tog...
Mountain environments, including the Andean páramo grasslands of Ecuador, are important water source areas. They are often sites of programs and policies intended to achieve multiple management objectives, such as carbon sequestration, biological conservation, and water resource protection; yet such environments are often data poor. This creates ch...
Anthropogenic geomorphology is an emerging systematic field that overlaps with climate change and natural hazards research. Collectively, these three topics form a human dimension of geomorphology that should gain increasing prominence in the twenty-first century with mounting concerns over the ability to reconcile population growth, dwindling reso...
This chapter begins with a historical perspective of the knowledge of and research on the effects of vegetation clearance on channel change, and reviews examples, first from North America and then more globally, of channel changes associated with vegetation clearance. Over the long term, the fluvial system, itself, offers a dependable archive of ch...
Ecuadorian páramo grasslands have become the focus of Payment for Ecosystem Services programs that have promoted land-use changes such as afforestation and reduction of burning, grazing of cattle or sheep, and agricultural expansion. However, limited information exists on the relationships between land use in páramos and the production of ecosystem...
Ways in which geographers have framed research on human–environment interactions have changed over time. This review emphasizes the limitations of previous ways of framing human–environment research and indicates new opportunities to be pursued by reframing the research questions. It begins with the research and influence of W. M. Davis and follows...
Ecosystem services programmes have been advocated for their potential to join conservation and poverty alleviation efforts, integrate working landscapes, and provide a flow of ecosystem services upon which populations rely. Ecuadorian paramo grasslands have rapidly become the focus of compensation for ecosystem services (CES) programmes intended to...
As part of a larger effort to improve water quality in the Little River watershed, we installed and monitored 45 erosion pins on 12 banks of tributaries of this east Tennessee river. Here, we examine changes in exposure of individual erosion pins and compare measurements made after 2.5 years to those made at the end of the first year (2007). No str...
Accelerated soil erosion is a common and environmentally destructive consequence of development, especially in mountain regions. Soil erosion is of special concern in agricultural lands, but agriculture is only one of many development activities that greatly accelerates soil erosion processes. Road building, trail use, excavation, extractive activi...
Erosion pins were installed on 32 banks in five tributaries of the Little River, eastern Tennessee, to quantify the contributions of streambanks to stream sediment loads and better understand the processes of streambank erosion. In the first two years of monitoring, erosional losses from streambanks were readily measurable, with a median loss of 1...
The landscape of Cajas National Park in the Andes mountains of southern Ecuador offers an opportunity to study the dynamics of Pleistocene glaciers in the tropics without interference from the Holocene glaciers or massive ash deposits that characterize the highest Ecuadorian peaks. This study of soil profiles along two transects in the Llaviucu gla...
Characteristics of low-order stream channels, and of the waters they convey, depend on characteristics of contributing area land surfaces, yet land-surface and stream processes are often treated separately. Land uses influence the amount and rate of water delivery to a stream and the chemical, biological, and particulate constituents of streamwater...
People have manipulated the natural environments of South America for agricultural purposes for several millennia. While agriculture is strongly affected by the physical attributes of a place—soil, water, climate, biota, and topography—agriculture changes a landscape’s physical and biological characteristics and processes. Agriculture may involve s...
Human-induced changes to the channel and 18·6 km2 catchment of Second Creek, in Knox County, Tennessee (USA), have included deliberate channel realignment, channelization of some reaches in culverts or cement-lined channels, the addition of coarse particles, and intentional and unintentional changes in catchment hydrology. Field observations and me...
South America delivers more freshwater runoff to the ocean per km2 land area than any other continent, and much of that water enters the fluvial system from headwaters in the Andes Mountains. This paper reviews ways in which human occupation of high mountain landscapes in the Andes have affected the delivery of water and sediment to headwater river...
Land-use change in the Southern Appalachian region has followed broader social and economic trends over the past century, from unregulated resource exploitation to economic development and conservation. In the early 20th century, land degradation resulting from exploitative land uses in the Southern Appalachian region provoked "corrective" conserva...
Water is well established as a major driver of the geomorphic change that eventually reduces mountains to lower relief landscapes. Nonetheless, within the altitudinal limits of continuous vegetation in humid climates, water is also an essential factor in slope stability. In this paper, we present results from field experiments to determine infiltra...
The landscape of the 130 km2 Copper Basin, in the southeastern USA, became extremely degraded during more than a century of logging, mining, acidification, grazing, and fire. In the twentieth century, the Copper Basin became the focus of a series of reforestation programs and is now largely tree-covered again. To investigate the effects of over 50...
The landscape of the 130 km2 Copper Basin, in the southeastern USA, became extremely degraded during more than a century of logging, mining, acidification, grazing, and fire. In the twentieth century, the Copper Basin became the focus of a series of reforestation programs and is now largely tree-covered again. To investigate the effects of over 50...
Accelerated soil erosion is a common and environmentally destructive consequence of development, especially in mountain regions. Soil erosion is of special concern in agricultural lands, but agriculture is only one of many development activities that greatly accelerates soil erosion processes. Road building, trail use, excavation, extractive activi...
Copper Basin in southeastern Tennessee became the site of increasingly extensive and successful reforestation efforts. To
determine the effectiveness of more than 50 years of reforestation efforts, we compared rainfall infiltration, sediment detachment,
and soil organic matter of reforested sites to those properties of unvegetated sites and foreste...
The Copper Basin, Tennessee, is unique in the southeastern United States for the extent and persistence of its treeless landscape. Reclamation has been slow and costly, but the basin has finally lost the appearance of a desert and is now green again. Reviewing the environmental history of the Copper Basin since 1847, we find a treeless landscape to...
Although accelerated rainfall runoff and soil erosion in inhabited mountain regions are often linked to cultivation practices on steep hillsides, fields that have been abandoned can pose an even greater risk of rapid runoff and soil erosion. This paper presents new evidence of land degradation resulting from land abandonment in the Ecuadorian Andes...
Using McQueen-type portable rainfall simulators, we simulated rainfall on trail surfaces and adjacent, off-trail forest sites at two reserves in the humid neotropics. Our results confirm that rates of runoff generation and soil particle detachment are significantly higher on trails and that runoff occurs frequently on trails, but only rarely off-tr...
Frequent wedge failure rock slides along Interstate 40 between Hartford, Tennessee, and the Tennessee/North Carolina state line have led to traffic flow disruption, expensive clearing efforts, and extensive corrective measures. Because previous studies have not critically examined the influence of meteorological events on wedge failures, this study...
Rapid sedimentation is a major problem at the reservoir of the Amaluza dam on the Paute river where more than half of Ecuador's electric power is produced. With this in mind extensive small-plot experiments were conducted with portable rainfall simulators to investigate the runoff dynamics and erosional responses of different soils and land uses in...
This preliminary effort toward developing a sediment budget for the primarily agricultural 3531 km2 upper and middle drainage basin of the Rio Paute in Andean Ecuador focuses on the geographic locations of potential upland nonpoint sediment sources and compares upland soil erosion estimates based on the Universal Soil Loss Equation (USLE) with othe...
Field research with portable rainfall simulators in the 5186 km2 Paute River basin in highland Ecuador indicates that footpaths generate runoff more rapidly and more often than adjacent fields and that pasture and abandoned crop lands are frequently important runoff source areas. Differential runoff production allows run-on water to play an importa...
Field observations and simulated rainfall experiments in two watersheds in the Ecuadorian Andes show high rates of soil erosion in both, although soil, climatic, agricultural, and cultural factors differ between the two. Intra-watershed variability of infiltration and runoff is high, and compacted surfaces, such as roads and trails, play a key role...
A new approach to evaluating hillslope soil erosion was developed when conventional erosion assessment strategies were found to be inappropriate to a $1,300\ {\rm km}^{2}$ intensively cultivated drainage basin in highland Ecuador. Methods used in this project enabled relatively rapid and inexpensive estimates of soil erosion on agricultural lands t...
Thesis (Ph. D.)--University of Colorado, 1987. Includes bibliographical references (leaves [177]-204). Photocopy of typescript.
The primary problem encountered in extrapolating soil erosion rates to the mesoscale is that of spatial heterogeneity. Physical and cultural aspects of tropical landscapes present dimensions of environmental parameters and landscape heterogeneity previously underrepresented in soil erosion studies in temperate environ ments. A new approach to the...
Thesis (M.A.)--University of Colorado, 1975. Includes bibliographical references (leaves [74]-78). Typescript. Map inserted in pocket.