Refereed Articles Chapters and Abstracts by Sheryl Luzzadder-Beach
In the 1970s scholars began to accept Maya terracing as the manifestation of ancient intensive a... more In the 1970s scholars began to accept Maya terracing as the manifestation of ancient intensive agriculture and large populations. We examine many ancient terraces and berms excavated in the Three Rivers region of Belize, synthesize the geography and suggest the intent of terracing across the Maya Lowlands, and analyze the history of terracing and soil erosion. Terraces occur in several slope positions and diverted and slowed runoff, to build up planting surfaces that could maximize soil moisture. The first accelerated soil erosion occurred during the Preclassic period (1500 b.c.-a.d. 250). Maya terracing started in the Early Classic period (a.d. 250–600) and spread across the Lowlands with the great population expansion of the Late/Terminal Classic period (a.d. 600–900). Thereafter, the Maya would largely forsake terracing. Though abandoned for a millennium, many terraces still function in today's tropical forests and burning milpas.
Quaternary Science Reviews, 2009
In the Maya Lowlands of Mexico, Belize, and Guatemala two main types of wetlands have played impo... more In the Maya Lowlands of Mexico, Belize, and Guatemala two main types of wetlands have played important roles in human history: bajos or intermittently wet environments of the upland, interior Yucatá n and perennial wetlands of the coastal plains. Many of the most important Maya sites encircle the bajos, though our growing evidence for human-wetland interactions is still sparse. The deposits of these wetlands record two main eras of slope instability and wetland aggradation: the Pleistocene-Holocene transition as rainfall increased and forests eclipsed savannas and the Maya Preclassic to Classic as deforestation, land-use intensity, and drying increased. The ancient Maya adapted with terraces around these bajo margins but retracted in the Late Preclassic in some areas. The perennial wetlands of the coastal plains have different histories, and the first conceptual model of human-wetland interaction described intensive wetland agriculture in the Preclassic through Classic based on raised fields and canals. But a second model arose that interpreted the wetland stratigraphy and canals as more indicative of natural aggradation by accelerated erosion and gypsum precipitation that buried Archaic and Preclassic fields and there was little Classic era use. We present new data on a third and fourth model in this study. The third is a hybrid of the models one and two, including the Archaic to Preclassic aggradation of the second model, and the first model's Classic period fields and canals as piecemeal attempts by the Maya to adapt to these and other environmental changes. The fourth conceptual model describes a very Late/Terminal Classic, preplanned project on a floodplain. These wetland fields were short-lived, aggraded rapidly but with some reoccupation in the Postclassic. All of these new models display the burgeoning evidence for intricate Maya interactions with wetlands, and the diversity of evidence from the relatively few studies underscores the infancy of our understanding of Maya interaction with tropical wetlands.
Perspectives on the Archaeology of Chetumal Bay, 2016
This chapter used remote sensing as a proxy for ancient Maya agricultural production and contextu... more This chapter used remote sensing as a proxy for ancient Maya agricultural production and contextualizes the data via comparison with ethnographic data to argue that large scale, intensive agricultural systems were present in the Rio Hondo floodplain during the classic Maya period.
Antiquity, 2016
In recent years, a growing body of research
has focused on the importance of water
management for... more In recent years, a growing body of research
has focused on the importance of water
management for ancient Maya societies, and
more generally on the cultural and economic
significance of water as a resource. But how
did this change across the centuries as cycles
of drought and sea level rise, together with
the growingMaya footprint on the landscape,
presented new challenges? As the resolution
of climatic records improves, the authors can
begin to show in detail how Maya water
management responded and adapted to such
shifts. This included the manipulation of
aguadas and the development of wetland field
systems, in the process transforming large areas
of the Maya landscape.
PNAS, 2019
We report on a large area of ancient Maya wetland field systems
in Belize, Central America, based... more We report on a large area of ancient Maya wetland field systems
in Belize, Central America, based on airborne lidar survey coupled
with multiple proxies and radiocarbon dates that reveal ancient
field uses and chronology. The lidar survey indicated four main areas
of wetland complexes, including the Birds of Paradise wetland field
complex that is five times larger than earlier remote and ground
survey had indicated, and revealed a previously unknown wetland
field complex that is even larger. The field systems date mainly to
the Maya Late and Terminal Classic (∼1,400–1,000 y ago), but with
evidence from as early as the Late Preclassic (∼1,800 y ago) and as
late as the Early Postclassic (∼900 y ago). Previous study showed
that these were polycultural systems that grew typical ancient
Maya crops including maize, arrowroot, squash, avocado, and other
fruits and harvested fauna. The wetland fields were active at a time
of population expansion, landscape alteration, and droughts and
could have been adaptations to all of these major shifts in Maya
civilization. These wetland-farming systems add to the evidence for
early and extensive human impacts on the global tropics. Broader
evidence suggests a wide distribution of wetland agroecosystems
across the Maya Lowlands and Americas, and we hypothesize the
increase of atmospheric carbon dioxide and methane from burning,
preparing, and maintaining these field systems contributed to the
Early Anthropocene.
Diálogo Andino, 2013
Historia de dos colapsos: Variabilidad ambiental e interrupción cultural en las tierras bajas may... more Historia de dos colapsos: Variabilidad ambiental e interrupción cultural en las tierras bajas mayas nicholas p. dunning a , timothy beach b , liwy Grasiozo sierra c , john G. jones d , david l. lentz e , sheryl luzzadder-beach f , Vernon l. scarborough g , michael p. smyth h An expanding array of data is becoming available on past climate changes affecting the Maya Lowlands region. We examine the strengths and weaknesses of these data sets, both in terms of identifying general trends and specific events. We then use these data to develop a model based on adaptive cycles that addresses both environmental and cultural changes that occurred in the Terminal Preclassic and the Terminal Classic periods in several areas of the Maya Lowlands. In particular, we compare the variable experiences and trajectories of several ancient communities located in the elevated interior region with others situated on lower elevation coastal plains. In general, communities in lower elevation areas proved more resilient to environmental and cultural perturbations than those in the higher elevation interior. Key words: maya lowlands, maya archaeology, paleoclimate. un expansivo ordenamiento de la información sobre los pasados cambios climáticos que afectaron a la región de las tierras bajas mayas se está haciendo disponible. examinamos las fortalezas y debilidades sobre estos conjuntos de datos, tanto para identificar corrientes generales como eventos específicos. posteriormente utilizamos esta información para desarrollar un modelo basado en ciclos adaptativos que tratan de cambios ambientales y culturales que ocurrieron durante los períodos preclásico terminal y clásico terminal en algunas áreas de las tierras bajas mayas. en particular, comparamos las experiencias y trayectorias variables de algunas comunidades antiguas localizadas en la región elevada del interior con otras situadas en elevaciones más bajas de las planicies costeras. en general, las comunidades en las áreas de elevaciones de menor altura probaron tener mayor habilidad de recuperación y adaptación a las perturbaciones ambientales y culturales que aquellas situadas en lugares con mayor altura del interior. Palabras claves: tierras bajas mayas, arqueología maya, paleoclima.
PNAS, 2012
Getting at the Maya Collapse has both temporal and geographic dimensions, because it occurred ove... more Getting at the Maya Collapse has both temporal and geographic dimensions, because it occurred over centuries and great distances. This requires a wide range of research sites and proxy records, ranging from lake cores to geomorphic evidence, such as stratig-raphy and speleothems. This article synthesizes these lines of evidence , together with previously undescribed findings on Maya wetland formation and use in a key region near the heart of the central Maya Lowlands. Growing lines of evidence point to dryer periods in Maya history, which correlate to major periods of transition. The main line of evidence in this paper comes from wetland use and formation studies, which show evidence for both large-scale environmental change and human adaptation or response. Based on multiproxy studies, Maya wetland fields had a long and varied history, but most evidence indicates the start of disuse during or shortly after the Maya Terminal Classic. Hence, the perva-siveness of collapse extended into a range of wetlands, including perennial wetlands, which should have been less responsive to drought as a driver of disuse. A synthesis of the lines of evidence for canal infilling shows no attempts to reclaim them after the Classic Period. Mesoamerica | proxies | wetland agriculture S cholars have explored many proxy lines of evidence to understand the environmental change and timing of societal transitions in the Maya Lowlands of Mesoamerica. These proxies include lake and ocean cores; speleothems; geomorphic evidence; architecture; modeling; and, recently for Mesoamerica, tree rings. One repository of evidence we examine here comes from ancient Maya wetland field systems and their canals. Over the past decade , we have studied more than 50 of these systems, which can provide unique insights into site abandonment because their canals started to fill with sediment and proxy evidence after the Maya ceased maintaining them. We can thus date the infill of sediment and use multiple proxies to study ecological change from near the time of abandonment forward. These canals also provide
Cartographica: The International Journal for Geographic Information and Geovisualization, 2013
Remote sensing (RS) techniques based on multispectral satellite-acquired data have demonstrated a... more Remote sensing (RS) techniques based on multispectral satellite-acquired data have demonstrated an unequalled potential to detect, quantify, monitor, and map land degradation. However, RS data alone do not provide information on how land degradation affects the socio-political aspects and the economy of the population living in the affected regions. We developed the Continuous Cycle of Land Degradation (CCoLD) to quantify the severity of the land degradation in the Upper East Region (UER) of Ghana and combined it with the RS-based Normalized Difference Vegetation Index (NDVI) using Global Inventory Modeling and Mapping Studies (GIMMS) NDVI, ground data, and food-production data. In addition, we carried out a field study in the UER, a semi-arid transitional region that plays an important food-production role in Ghana, and compared the results with multi-temporal RS imagery. As well as the general ground measurements, the field study included questionnaires asking local residents to assess the impact of land degradation on their quality of life. The RS data show widespread localized degradation; the field study, supported by crop-production data, also suggests overall extensive land degradation. However, field evidence suggests ecological succession where locally adapted horsetail grasses were displaced by environmentally efficient, short-lived, quick-maturing, and dense grasses. A convergence of evidence suggests that land degradation is in the advanced stage and that more focused, community-based efforts would be needed to combat land degradation and restore the ecosystem's integrity.
Geoarchaeology and Hydrology of the Chunchucmil and Uci-Cansahcab Maya Archaeology Sites, Yucatan, Mexico
2011 GSA Geological Society of America Annual Meeting in Minneapolis, 2011
Water supply and accessibility are often studied as factors in human settlements. However, few ar... more Water supply and accessibility are often studied as factors in human settlements. However, few archaeological studies have considered the quality of those water supplies, and the opportunities and limitations the water quality may have imposed on ancient peoples’ land and water use. Although water quality mainly reflects conditions of today, often the mineralogical characteristics of water reflect the geologic conditions under which it occurs. Therefore mineral characteristics can be a proxy for expected water quality. We present two geoarchaeological case studies of water supply and quality in Ancient Maya Sites in the northern Yucatan, Mexico region. Chunchucmil was a Classic period Maya city located southwest of the modern city of Merida, just outside of the Ring of Cenotes. Uci and Cansahcab, northeast of Merida, were Classic period settlements linked together by a causeway, or sacbe, located just inside the Ring of Cenotes. Modern Maya villages are located near each site today. Both sites have limited surface water availability and intense dry seasons, and are dependent upon groundwater for their principal permanent water supply. They are also near the hydrogeologic influence of the Ring of Cenotes, which traces the edge of the Chicxulub Impact Crater of northwestern Yucatan. This research compares these two sites, and demonstrates that the ancient Maya of northern Yucatan confronted significant hydrologic challenges in addition to those encountered by the Ancient Maya of the broader Maya Lowlands Region.
Cartographica: The International Journal for Geographic Information and Geovisualization, 2013
Remote sensing (RS) techniques based on multispectral satellite-acquired data have demonstrated a... more Remote sensing (RS) techniques based on multispectral satellite-acquired data have demonstrated an unequalled potential to detect, quantify, monitor, and map land degradation. However, RS data alone do not provide information on how land degradation affects the socio-political aspects and the economy of the population living in the affected regions. We developed the Continuous Cycle of Land Degradation (CCoLD) to quantify the severity of the land degradation in the Upper East Region (UER) of Ghana and combined it with the RS-based Normalized Difference Vegetation Index (NDVI) using Global Inventory Modeling and Mapping Studies (GIMMS) NDVI, ground data, and food-production data. In addition, we carried out a field study in the UER, a semi-arid transitional region that plays an important food-production role in Ghana, and compared the results with multi-temporal RS imagery. As well as the general ground measurements, the field study included questionnaires asking local residents to assess the impact of land degradation on their quality of life. The RS data show widespread localized degradation; the field study, supported by crop-production data, also suggests overall extensive land degradation. However, field evidence suggests ecological succession where locally adapted horsetail grasses were displaced by environmentally efficient, short-lived, quick-maturing, and dense grasses. A convergence of evidence suggests that land degradation is in the advanced stage and that more focused, community-based efforts would be needed to combat land degradation and restore the ecosystem's integrity.
Annals of The Association of American Geographers, 2002
The conjunctive use of paleoecological and archaeological data to document past human-environment... more The conjunctive use of paleoecological and archaeological data to document past human-environment relationships has become a theoretical imperative in the study of ancient cultures. Geographers are playing leading roles in this scholarly effort. Synthesizing both types of data, we argue that large karst depressions known as bajos in the Maya Lowlands region were anthropogenically transformed from perennial wetlands and shallow lakes to seasonal swamps between 400 bc and ad 250. This environmental transformation helps answer several questions that have long puzzled scholars of Maya civilization: (1) why many of the earliest Maya cities were built on the margins of bajos, (2) why some of these early centers were abandoned between 100 bc and ad 250, and (3) why other centers constructed elaborate water storage systems and survived into the Classic period ( ad 250-900). The transformation of the bajos represents one of the most significant and long-lasting anthropogenic environmental changes documented in the pre-Columbian New World.
Geomorphology, Jan 1, 2008
This paper begins to differentiate the major drivers and chronology of erosion and aggradation in... more This paper begins to differentiate the major drivers and chronology of erosion and aggradation in the fluvial and fluviokarst landscapes of the southern and central Maya Lowlands. We synthesize past research on erosion and aggradation and add new data from water, soils, radiocarbon dating, and archaeology to study the quantity, timing, and causes of aggradation in regional landscape depressions. Geomorphic findings come from many excavations across a landscape gradient from upland valleys, karst sinks, and fans into the coastal plain floodplains and depressions. Findings from water chemistry show that sources in the uplands have low quantities of dissolved ions but water in the coastal plains has high amounts of dissolved ions, often nearly saturated in calcium and sulfate. We found significant geomorphic complexity in the general trends in upland karst sinks. In a few instances, sediments preserve Late Pleistocene paleosols, buried 2–3 m, though many more have distinct middle to late Holocene paleosols, buried 1–2 m, after c. 2300 BP (Maya Early to Late Preclassic). From 2300–1100 BP (Late Preclassic to Classic Periods), the landscape aggraded from five main mechanisms: river flooding, climatic instability, accelerated erosion, ancient Maya landscape manipulation, and gypsum precipitation from a rise in a water table nearly saturated in calcium and sulfate ions. Evidence exists for two or three high magnitude floods, possibly driven by hurricanes. Moreover, lake-core and geophysical studies from the Petén Lakes region have shown high rates of deposition of silicate clays (‘Maya Clays’) starting and peaking during the Maya Preclassic and continuing to be high through the Late Classic. The main driver on upland karst depressions, the Petén lakes, upland valleys, and fans was accelerated soil erosion, but water table rise, probably driven by sea-level rise, was the main driver on the wetlands of the coastal plain because the aggraded sediments here are dominantly composed of gypsum, precipitated from the groundwater. This latter mechanism represents a little recognized mechanism of aggradation over a large region. These large scale environmental changes occurred during periods of intensive ancient Maya land use and climatic instability, both of which may have contributed to erosion by increasing runoff. Despite these geomorphic changes, ancient Maya farmers adapted in several key cases.
Fuel and Energy Abstracts, 2011
This article provides new data and synthesizes earlier findings on the carbon isotope ratios of t... more This article provides new data and synthesizes earlier findings on the carbon isotope ratios of the humin part of soil organic matter from a range of sites in the central Maya Lowlands. Changes down the soil profile in carbon isotope ratios can provide an important line of evidence for vegetation change and erosion over time, especially in well dated aggrading profiles. Research thus far has provided substantial evidence for significant inputs from C 4 vegetation in buried layers from the Ancient Maya periods in depositional soils but equivocal evidence from sloping soils. We present new findings from soil profiles through ancient Maya wetland fields, upland karst wetlands, ancient Maya aguadas (reservoirs), and ancient Maya terraces. Most of the profiles exhibited δ 13 C enrichment greater than the 2.5-3‰ typical from bacterial fractionation. Seven of nine ancient Maya wetland profiles showed δ 13 C enrichment ranging from 4.25 to 8.56‰ in ancient Maya-dated sediments that also contained phytolith and pollen evidence of grass (C 4 species) dominance. Upland karst sinks and ancient reservoirs produced more modest results for δ 13 C enrichment. These seasonal wetland profiles exhibited δ 13 C enrichment ranging from 1 to 7.3‰ from the surface to ancient Maya-period sediments. Agricultural terraces produced mixed results, with two terraces having substantial δ 13 C enrichment of 5.34 and 5.66‰ and two producing only equivocal results of 1.88 and 3.03‰ from modern topsoils to Maya Classicperiod buried soils. Altogether, these findings indicate that C 4 plants made up c. 25% of the vegetation at our sites in the Maya Classic period and only a few percent today. These findings advance the small corpus of studies from ancient terraces, karst sinks, and ancient wetland fields by demonstrating substantial δ 13 C and thus C 4 plant enrichment in soil profile sections dated to ancient Maya times. These studies are also providing a new line of evidence about local and regional soil and ecological change in this region of widespread environmental change in the Late Holocene.
ABSTRACT: The measure of the “Mayacene,” a microcosm of the Early Anthropocene that occurred from... more ABSTRACT: The measure of the “Mayacene,” a microcosm of the Early Anthropocene that occurred from c. 3000 to 1000 BP, comes from multiple Late Quaternary paleoenvironmental records. We synthesized the evidence for Maya impacts on climate, vegetation, hydrology and the lithosphere, from studies of soils, lakes, floodplains, wetlands and other ecosystems. Maya civilization had likely altered local to regional ecosystems and hydrology by the Preclassic Period (3000-1700 BP), but these impacts waned by 1000 BP. They altered ecosystems with vast urban and rural infrastructure that included thousands of reservoirs, wetland fields and canals, terraces, field ridges, and temples. Although there is abundant evidence that indicates the Maya altered their forests, even at the large urban complex of Tikal as much as 40% of the forest remained intact through the Classic period. Existing forests are still influenced by ancient Maya forest gardening, particularly by the large expanses of ancient stone structures, terraces, and wetland fields that form their substrates. A few studies suggest deforestation and other land uses probably also warmed and dried regional climate by the Classic Period (1700-1100 BP). A much larger body of research documents the Maya impacts on hydrology, in the form of dams, reservoirs, canals, eroded soils and urban design for runoff. Another metric of the “Mayacene” are paleosols, which contain chemical evidence for human occupation, revealed by high phosphorus concentrations and carbon isotope ratios of C4 species like maize in the C3–dominated tropical forest ecosystem. Paleosol sequences exhibit “Maya Clays,” a facies that reflects a glut of rapidly eroded sediments that overlie pre-Maya paleosols. This stratigraphy is conspicuous in many dated soil profiles and marks the large-scale Maya transformation of the landscape in the Preclassic and Classic periods. Some of these also have increased phosphorous and carbon isotope evidence of C4 species. We synthesize and provide new evidence of Maya-period soil strata that show elevated carbon isotope ratios (δ13C), indicating the presence of C4 species in typical agricultural sites. This is often the case in ancient Maya wetland systems, which also have abundant evidence for the presence of several other economic plant species. The “Mayacene” of c. 3000 to 1000 BP was thus a patchwork of cities, villages, roads, urban heat islands, intensive and extensive farmsteads, forests and orchards. Today, forests and wetlands cover much of the Maya area but like so many places, these are now under the onslaught of the deforestation, draining, and plowing of the present Anthropocene.
“Mayacene’ Floodplain and Wetland Formation in the Rio Bravo Watershed of Northwestern Belize"
ABSTRACT: This is the first article to characterize the soil and fluvial geomorphology of the Rio... more ABSTRACT: This is the first article to characterize the soil and fluvial geomorphology of the Rio Bravo’s fluviokarst watershed in the Rio Bravo Conservation and Management Area, northwestern Belize. Although the watershed has had little-altered tropical forest cover since c. 1000 BP, humans inhabited it for millennia, especially during the Maya Preclassic and Classic, c. 3000–1000 BP. We studied soils and floodplain formation in four excavation transects in the Rio Bravo to understand long-term human impacts on this watershed. Archaic to Preclassic (c. 3000–1700 BP) sedimentation rates ranged from 0.82 mm yr−1 at Chawak But’o’ob to 1.5 mm yr−1 on the Gran Cacao floodplain. The late Preclassic through Classic (c. 2300–1000 BP) rates rose 0.98–2.03 mm yr−1, and the Classic (c. 1700–1000 BP) rates ranged from 1 mm yr−1 to as high as 9.12 and 16.27 mm yr−1 at ancient Maya wetland field sites.Post Classic rates dropped back in the one dated profile, and the well-developed topsoils indicate long-term surface stability. Older soils at the edges and higher islands of the valley had more vertic features and full Vertisols, whereas Vertic Mollisols and Aquerts have formed in younger sediments. We also present new evidence for late Classic Maya wetland field formation at Chawak But’o’ob, which shows field raising with canalization in this wetland of low ionic water. All the soil profiles with dating and stable carbon isotope evidence exhibited increased δ13C in the profiles through the Classic period sediments, although some were equivocal. The two wetland field δ13C profiles through the Classic period sediments increase by c. 6‰ at Chawak But’o’ob and 3‰ at the Birds of Paradise (BOP) Field center, although earlier BOP profiles increased by as much as 7‰. Hence, this watershed exhibits three large diachronic shifts: from lower to higher and again to lower deposition over pre-Maya, Maya, and post-Maya times. These changes along with earlier evidence for ancient intensive agriculture from 3000 and 1000 BP lie sandwiched between the ancient and contemporary little-altered tropical forest.
Ancient Maya impacts on the Earth's surface: An Early Anthropocene analog?
The measure of the “Mayacene,” a microcosm of the Early Anthropocene that occurred from c. 3000 t... more The measure of the “Mayacene,” a microcosm of the Early Anthropocene that occurred from c. 3000 to 1000 BP, comes from multiple Late Quaternary paleoenvironmental records. We synthesized the evidence for Maya impacts on climate, vegetation, hydrology and the lithosphere, from studies of soils, lakes, floodplains, wetlands and other ecosystems. Maya civilization had likely altered local to regional ecosystems and hydrology by the Preclassic Period (3000-1700 BP), but these impacts waned by 1000 BP. They altered ecosystems with vast urban and rural infrastructure that included thousands of reservoirs, wetland fields and canals, terraces, field ridges, and temples. Although there is abundant evidence that indicates the Maya altered their forests, even at the large urban complex of Tikal as much as 40% of the forest remained intact through the Classic period. Existing forests are still influenced by ancient Maya forest gardening, particularly by the large expanses of ancient stone structures, terraces, and wetland fields that form their substrates. A few studies suggest deforestation and other land uses probably also warmed and dried regional climate by the Classic Period (1700-1100 BP). A much larger body of research documents the Maya impacts on hydrology, in the form of dams, reservoirs, canals, eroded soils and urban design for runoff. Another metric of the “Mayacene” are paleosols, which contain chemical evidence for human occupation, revealed by high phosphorus concentrations and carbon isotope ratios of C4 species like maize in the C3–dominated tropical forest ecosystem. Paleosol sequences exhibit “Maya Clays,” a facies that reflects a glut of rapidly eroded sediments that overlie pre-Maya paleosols. This stratigraphy is conspicuous in many dated soil profiles and marks the large-scale Maya transformation of the landscape in the Preclassic and Classic periods. Some of these also have increased phosphorous and carbon isotope evidence of C4 species. We synthesize and provide new evidence of Maya-period soil strata that show elevated carbon isotope ratios (δ13C), indicating the presence of C4 species in typical agricultural sites. This is often the case in ancient Maya wetland systems, which also have abundant evidence for the presence of several other economic plant species. The “Mayacene” of c. 3000 to 1000 BP was thus a patchwork of cities, villages, roads, urban heat islands, intensive and extensive farmsteads, forests and orchards. Today, forests and wetlands cover much of the Maya area but like so many places, these are now under the onslaught of the deforestation, draining, and plowing of the present Anthropocene.
Environmental Management, 1995
What size sample is sufficient for spatially sampling ambient groundwater quality? Water quality ... more What size sample is sufficient for spatially sampling ambient groundwater quality? Water quality data are only as spatially accurate as the geographic sampling strategies used to collect them. This research used sequential sampling and regression analysis to evaluate groundwater quality spatial sampling policy changes proposed by California's Department of Water Resources. Iterative or sequential sampling of a hypothetical groundwater basin's water quality produced data sets from sample sizes ranging from 2.8% to 95% coverage of available point sample sites. Contour maps based on these sample data sets were compared to an original (control), mapped hypothetical data set, to determine at which point map information content and pattern portrayal are not improved by increasing sample sizes. Comparing series of contour maps of ground water quality concentration is a common means of evaluating the geographic extent of groundwater quality change. Comparisons included visual inspection of contout maps and statistical tests on digital versions of these map files, including correlation and regression products. This research demonstrated that, down to about 15% sample site coverage, there is no difference between contour maps produced from the different sampling strategies and the contout map of the original data set.
Geomorphology, 2008
We examined the alluvial history of the plain near Kinet Höyük, an archaeological mound (or Tell)... more We examined the alluvial history of the plain near Kinet Höyük, an archaeological mound (or Tell) with a sequence of six millennia of occupation on the southeast Mediterranean coast of Turkey, through 17 excavations over a 1000 m transect near the Mound. Excavations ranged from 2 to 6 m deep and up to 20 m across. This low gradient, alluvial plain shows significantly different rates and processes of near-Mound sedimentation, with one unit having nearly 4 m of Late Bronze Age habitation and flood deposits and another having 4 m of Hellenistic channel and floodplain deposition. This flat, alluvial surface turns out to be a rich geoarchaeological landscape that shrouds Early and Late Bronze Age settlements, Hellenistic walls, and two epochs of Roman Roads. One widespread phenomenon was a Hellenistic or earlier paleosol and occupation level covered by channel gravels and overbank deposits mostly from the Hellenistic to the Late Roman period. These channel and floodplain deposits filled in and flattened out the off-Mound settlements, blanketing the Pre-Hellenistic topography and silting in a long active port. This glut of alluvium correlates in time with drier conditions and the most intensive land uses in the watershed, where Roman and Hellenistic sites today are severely eroded.
Professional Geographer, 1997
Accurately mapping a region's ground water quality depends upon the spatial sampling strategies e... more Accurately mapping a region's ground water quality depends upon the spatial sampling strategies employed, including where and how often field data are collected. This study compares the relative values of three field sampling strategies for mapping a known migrating plume of volcanic ground water in Sierra Valley, California. The first strategy sampled wells once each year during 1957, 1972, and 1980 (n=63, 45, and 57, respectively) and portrayed spatial-temporal changes in ground water quality more clearly on maps than did two alternative sampling strategies. One of these alternatives, Strategy 2, sampled one well per township per year during 1957, 1972, and 1980 (n=11) and did not detect the migrating plume, despite being a recommended strategy. The other alternative, Strategy 3, frequently sampled in time a small, fixed group of indicator wells (n=13) every four years for the same period, again producing maps with little correlation to the original pattern detected by Strategy 1. Key Words: ground water, water quality monitoring, spatialtemporal sampling, water quality maps, water management.
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Refereed Articles Chapters and Abstracts by Sheryl Luzzadder-Beach
has focused on the importance of water
management for ancient Maya societies, and
more generally on the cultural and economic
significance of water as a resource. But how
did this change across the centuries as cycles
of drought and sea level rise, together with
the growingMaya footprint on the landscape,
presented new challenges? As the resolution
of climatic records improves, the authors can
begin to show in detail how Maya water
management responded and adapted to such
shifts. This included the manipulation of
aguadas and the development of wetland field
systems, in the process transforming large areas
of the Maya landscape.
in Belize, Central America, based on airborne lidar survey coupled
with multiple proxies and radiocarbon dates that reveal ancient
field uses and chronology. The lidar survey indicated four main areas
of wetland complexes, including the Birds of Paradise wetland field
complex that is five times larger than earlier remote and ground
survey had indicated, and revealed a previously unknown wetland
field complex that is even larger. The field systems date mainly to
the Maya Late and Terminal Classic (∼1,400–1,000 y ago), but with
evidence from as early as the Late Preclassic (∼1,800 y ago) and as
late as the Early Postclassic (∼900 y ago). Previous study showed
that these were polycultural systems that grew typical ancient
Maya crops including maize, arrowroot, squash, avocado, and other
fruits and harvested fauna. The wetland fields were active at a time
of population expansion, landscape alteration, and droughts and
could have been adaptations to all of these major shifts in Maya
civilization. These wetland-farming systems add to the evidence for
early and extensive human impacts on the global tropics. Broader
evidence suggests a wide distribution of wetland agroecosystems
across the Maya Lowlands and Americas, and we hypothesize the
increase of atmospheric carbon dioxide and methane from burning,
preparing, and maintaining these field systems contributed to the
Early Anthropocene.