The role of biomorphodynamics in estuarine evolution in New Zealand

Abstract:   Biomorphodynamic interactions, the feedback loops that operate between physical processes, biology and morphology, affect the long-term evolution of estuaries. This paper outlines how consideration of such interactions and implementation through innovative modelling techniques can become the next crucial step needed to advance understanding of estuarine evolution.     

Recording architecture at the archaeological site of Uxmal, Mexico: A historical and contemporary view

Architecture at the Maya archaeological site of Uxmal in Yucatan, Mexico has been documented since the 17th century by historians, archaeologists, illustrators, photographers, and most recently photogrammetrists. This paper reviews the work of the major contributors to recording of architecture at Uxmal with a particular focus on the 19th century stereophotography of Alice and Augustus Le Plongeon who worked to record all the standing architecture at Uxmal, and the close range stereophotogrammetric projects that recorded the Adivino Pyramid during the late 20th century.     

EFFECTS OF RIVER ICE ON STAGE-DISCHARGE RELATIONSHIPS——A CASE STUDY OF THE YELLOW RIVER

Using field observations at four gauging stations along the Inner Mongolia Reach of the Yellow River in China, this paper explores effects of the ice on the hydraulics of this river reach for four different conditions, namely: under open channel flow, during ice-running period, the ice-covered period, and the river break-up period. The rating curves were found to be well recognized under open channel situations, but were sometimes poorly defined and extremely variable under ice conditions. The results also show that the water level is insensitive to flowing ice prior to freeze-up. However, significant, but hardly surprising, variations were observed during ice-covered conditions. The rating curves for both the ice covered condition and river ice breakup period are developed and some related hydraulic issues are examined. Additionally, the impacts of the ice accumulation and associated riverbed deformation during ice period on the rating curves are discussed.     

Geometric assessment of the kodak DCS Pro back

This paper reports on an investigation into the suitability of the Kodak DCS Pro Back for use in close range photogrammetric measurement. The camera back, being used in conjunction with a medium-format non-metric camera, has been assessed with a view to using it for low- to medium-order photogrammetric work in architectural recording. Examinations centred upon the stability of the camera back with respect to the camera body and the effects of the removable infrared filter that is present immediately above the camera's focal plane. Ultimately the camera combination was deemed suitable for application in recording of this kind and is now in active use by the Metric Survey Team at English Heritage.     

Elevated stream trace and minor element concentrations in the foreland of receding tropical glaciers

Globally, the ongoing retreat of mountain glaciers will ultimately diminish fresh water supplies. This has already begun in watersheds with greatly reduced glacial coverage. Still unknown are the affects of glacial retreat on downstream water quality, including the threats to human and ecosystem health. In the Cordillera Blanca, retreating glaciers have exposed sulfide-rich rock outcrops, negatively affecting the quality of the glacial meltwater. This study has evaluated glacial melt stream hydrogeochemistry in the sulfide-bearing Rio Quilcay watershed (∼9°27′S, ∼77°22′W) during the 2008 dry season. Surface water samples were collected from the upper 12 km of the watershed during the 2008 dry season. Dissolved (0.4 μm) and unfiltered acidified (pH < 2) Al, Co, Cu, Fe, Ni, Mn, Pb, Zn and dissolved major ions and organic C (DOC) concentrations were quantified and pH and temperature were measured in the field. Twenty of 22 stream samples had pH values below 4, generating significantly (p < 0.01, α = 0.05) greater cation denudation normalized to discharge than other worldwide glacier-fed streams. Additionally, dissolved trace and minor element concentrations were comparable to acid mine drainage. Non-conservative dissolved element behaviors resulted from adsorption/desorption reactions in tributary mixing zones. At low pH values, hydrous Fe oxides acted as the dominant sorption surfaces. The poor water quality observed in Cordillera Blanca headwaters coupled with the likely exposure of additional sulfide-rich outcrops from ongoing glacial retreat may pose water quality challenges.     

Migration of Chlorophenolic Compounds at the Chemical Waste Disposal Site at Alkali Lake, Oregon —1. Site Description and Ground-Water Flow

The hydrogeology of the chemical waste disposal site in the closed basin at Alkali Lake, Oregon has been examined. Interest in the site is due to the burial (November 1976) of 25,000 drums of herbicide manufacturing residues in unlined trenches on the playa of the basin. Included in the wastes were large amounts of chlorophenols and polymeric chlorophenoxyphenols. The flow of the alkaline (pH ∼10) ground water in the site area is driven by: (1) springs which create a mound east of the site; and (2) the sump effect of “West Alkali Lake,” a topographic low to the west of the site. Porosity, bulk mass densities, and grain-size distributions were determined. At one piezometer, the depth to ground water ranged between 0.9 m and 2.2 m. With the bottoms of the trenches in which the chemicals were buried between 0.60 and 0.75 m below the level of the ground surface, the bottom portions of the trenches may, at least occasionally, be in direct contact with the ground water.     

The Cretaceous–Paleogene unconformity in England: Uplift and erosion related to the Iceland mantle plume

During the late Cretaceous to early Paleogene, the present-day area of Britain and Ireland emerged from nearly total submergence by the chalk sea. What mechanism was responsible for this major marine regression? Combined studies of Paleogene depositional sequences offshore and coeval igneous rocks onshore, show that significant episodic uplift of northern Britain was at that time largely controlled by the early development of the Iceland mantle plume. How far south did this influence of the Iceland plume extend across England, and even beyond? We present new maps of the structure and denudation of the chalk surface in southern England. Some 500 m thickness of chalk was removed from the crest of a Chilterns–East Anglia dome before deposition of the earliest Paleogene sediments. Allowing for isostatic amplification by erosion, minimum uplift of the chalk surface above sea level was c.125 m. Early Paleogene crustal shortening of that chalk surface was by a factor of at most 1.01, contributing a maximum uplift of 25 m of the floor of the chalk sea. Compressional forces were not the main cause of the Cretaceous–Paleogene unconformity in southern England, as in the interpretation of this event as a distant reflection of the development of the Alps to the south. Postulated contemporary changes in global sea-level are also inadequate to account for the development of the unconformity in southern England. Here we suggest with some confidence that the main vertical surface movements involved in creating the unconformity were controlled by the Iceland mantle plume, as in northern Britain. We speculate that another hotspot, in Central France, may have influenced Paleogene sedimentation in the Paris Basin in a comparable fashion. We consider how to distinguish between our proposed mantle control of regional relative sea-level and global controls of Paleogene sea level.     

EFFECTS OF RIVER ICE ON STAGE——DISCHARGE RELATIONSHIPS

Using field observations at four gauging stations along the Inner Mongolia Reach of the Yellow River in China, this paper explores effects of the ice on the hydraulics of this river reach for four different conditions, namely: under open channel flow, during ice-running period, the ice-covered period, and the river break-up period. The rating curves were found to be well recognized under open channel situations, but were sometimes poorly defined and extremely variable under ice conditions. The results also show that the water level is insensitive to flowing ice prior to freeze-up. However, significant, but hardly surprising, variations were observed during ice-covered conditions. The rating curves for both the ice covered condition and river ice breakup period are developed and some related hydraulic issues are examined. Additionally, the impacts of the ice accumulation and associated riverbed deformation during ice period on the rating curves are discussed.     

A Robust Surface Matching Technique for Integrated Monitoring of Coastal Geohazards

At the dynamic coastal fringe, numerous processes interact with local morphology. In soft-cliff environments, this can often lead to the occurrence of coastal geohazards. These can pose a major threat to property and cultural heritage, and an effective monitoring strategy is therefore essential. While contemporary monitoring techniques have been applied, these are often unsuitable in isolation. This paper presents an integrated approach, with the development of weighted surface matching software enabling reliable dataset fusion and multi-temporal change detection, even where significant surface differences exist. Evaluation of this approach is presented and discussed.