Spatial extrapolation of soil characteristics using whole-soil particle size distributions

Soils support ecosystem functions such as plant growth and water quality because of certain physical, chemical, and biological properties. These properties have been studied at different spatial scales, including point scales to satisfy basic research needs, and regional scales to satisfy monitoring needs. Recently, soil property data for the entire USA have become available in the State Soil Geographic Data Base (STATSGO), which is appropriate for regional-scale research. We analyzed and created models of STATSGO data in this study to serve as a research tool, for example, for linking the soil to regional water quality monitoring data in our companion paper. Map units in STATSGO define geographic land areas by soil characteristics (SCs) of similar soil series. We selected 27 SCs that influenced water properties (in varying degrees), aggregated the layer and component SCs to map unit SCs, and used SCs to calculate relationships among map units. The relationships were defined by equations of conditional mean for the qth SC (SCq), while using the remaining 26 SCs as predictors. The relative standard errors for 22 of the 27 SCs were less than 10%, and less than 22% for the remaining five. We conclude that spatial extrapolation of SCs is feasible and the procedures are a first step toward extrapolating information across a region using SC-water property relationships. Although our procedure is for regional scale monitoring, it is also applicable to finer spatial scales commensurate with available soil data.     

Behaviour and transport of radionuclides in soil and vegetation of a sand dune ecosystem

A sand dune ecosystem in the vicinity of the British Nuclear Fuels reprocessing plant at Sellafield, Cumbria, UK was used to examine the spatial, temporal and depth distributions of 134Cs, 137Cs, 238Pu, 239 + 240Pu and 241Am in soil and in two species of vegetation (Festuca rubra, Ammophila arenaria). Core samples showed evidence of the accumulation of radionuclides derived mainly from sea-to-land transfer. Accumulated deposits of radioactivity (0-0.1 m) lie within the range: 1.1-3.4 Bq kg-1 (134Cs), 260-440 Bq kg-1 (137Cs), 31-40 Bq kg-1 (238Pu), 150-215 Bq kg-1 (239 + 240Pu) and 190-240 Bq kg-1 (241Am). Soil profiles showed greater activity concentrations in their deeper regions and this is attributed to leaching of radionuclides in percolating drainage water accentuated by the coarse texture, low organic matter and clay mineral content of coastal sands. Radionuclide activity concentrations in F. rubra and A. arenaria were similar, in the ranges 20-70 Bq kg-1 (137Cs), 1-5 Bq kg-1 (238Pu), 10-30 Bq kg-1 (239 + 240Pu) and 10-65 Bq kg-1 (241Am). Clear temporal and spatial variations were observed in both species of vegetation, reflecting the weather conditions antecedent to the sampling period and the influence of sea-to-land transfer. Concentration ratios (vegetation:soil) for activity concentrations in the two species were similar, in the ranges: 0.05-0.14 (137Cs), 0.025-0.097 (238Pu), 0.022-0.057 (239 + 240Pu) and 0.025-0.212 (241Am).     

Toward efficient riparian restoration: integrating economic, physical, and biological models

This paper integrates economic, biological, and physical models to explore the efficient combination and spatial allocation of conservation efforts to protect water quality and increase salmonid populations in the Grande Ronde basin, Oregon. We focus on the effects of shade on water temperatures and the subsequent impacts on endangered juvenile salmonid populations. The integrated modeling system consists of a physical model that links riparian conditions and hydrological characteristics to water temperature; a biological model that links water temperature and riparian conditions to salmonid abundance, and an economic model that incorporates both physical and biological models to estimate minimum cost allocations of conservation efforts. Our findings indicate that conservation alternatives such as passive and active riparian restoration, the width of riparian restoration zones, and the types of vegetation used in restoration activities should be selected based on the spatial distribution of riparian characteristics in the basin. The relative effectiveness of passive and active restoration plays an important role in determining the efficient allocations of conservation efforts. The time frame considered in the restoration efforts and the magnitude of desired temperature reductions also affect the efficient combinations of restoration activities. If the objective of conservation efforts is to maximize fish populations, then fishery benefits should be directly targeted. Targeting other criterion such as water temperatures would result in different allocations of conservation efforts, and therefore are not generally efficient.     

MAPPING REGIONAL PRECIPITATION INTENSITY DURATION FREQUENCY ESTIMATES1

ABSTRACT: For regional precipitation frequency analyses, methods are needed to spatially interpolate or smooth point intensity duration frequency (IDF) estimates at gage sites for the purposes of visualization and estimation at ungaged sites. In this study to update IDF estimates for Michigan, the assumption is made that for practical purposes, the entire state may be treated as a homogeneous region in which annual maximum precipitation is identically distributed at each site apart from a site‐specific scaling factor, commonly known as the index flood. Several interpolation and smoothing techniques are evaluated for IDF estimation at ungaged sites, including trend surface analysis, thin plate splines, inverse distance weighting, and several kriging algorithms. Ordinary block kriging is recommended as a practical and objective method for smoothing the variability in the index flood values and developing isopluvial maps.     

Conflict, the Continuum and Chronic Emergencies: A Critical Analysis of the Scope for Linking Relief, Rehabilitation and Development Planning in Sudan

The concept of the ‘relief-to-development continuum’ has been the subject of renewed interest in recent years. Concerned by the rise in relief budgets over the past decade and the absolute fall in development aid resources, support has been growing for the concept of developmental relief. In the context of complex political emergencies, it has been argued further that as effective development aid can reduce vulnerability to the impact of natural hazards, so it might also be used to contribute to a process of conflict prevention. In this way, the concept of the relief-development continuum has become entwined with broader discussions about the contribution of official development assistance to conflict management. Drawing on a Review of Operation Lifeline Sudan (OLS), this paper cautions against uncritical application of the concept of the continuum in complex political emergencies, and of rehabilitation in particular, in the current Sudanese context. It argues that in order to move legitimately from relief aid programming to development aid programming, three fundamental conditions must be in place: first, a minimum level of security, respect for human rights and humanitarian access. Second, empirical evidence from the field needs to demonstrate that the emergency is over. Finally, moving from relief to development aid programming is contingent on donor governments accepting the legitimacy of national governmental structures and of the rebel movements. In other words, for donor governments, moving along the continuum is in significant part determined by foreign policy considerations, not only technical ones. Consideration needs to be given to the actual and perceived legitimation of the different movements that a move to rehabilitation might be seen to imply. The paper argues that none of these conditions had been satisfied in Sudan by mid-1997. Instead of a process of normalisation paving the way to long-term development, the current situation in Sudan is better described as a chronic political emergency. In such a context, uncritical pursuit of developmental strategies may negatively affect the welfare of conflict-affected populations.     

THE FLOOD OF '96 AND ITS SOCIOECONOMIC IMPACTS IN THE SUSQUEHANNA RWER BASIN1

ABSTRACT: The meteorology flood hydroclimatolog and socioeconomic impacts of the Flood of January 1996 in the Susquehanna River Basin are explored. The analysis explains how an unusual storm system brought high humidities, high temperatures, strong winds, and heavy rain to the basin. The rapid melt of the deep snowpack, combined with the heavy rainfall, produced the sudden release of large volumes of water. Because the ground surface was frozen or saturated, this water moved primarily as overland flow. Thus, the flood waters were not restricted to areas immediately adjacent to stream channels and, consequently, some of the largest impacts were on people, property, and infrastructure in areas not normally prone to flooding. Socioeconomic patterns of flooding over time and space are investigated to put this flood into context and to highlight its impacts. The analysis concludes that if such overland flooding is a more common feature of climate change, then the current vulnerability to this form of flooding and its economic implications must be considered carefully.     

Forest planning in an Oregon case study: Defining the problem and attempting to meet goals with a spatial-analysis technique

Five major management goals were identified for the upper Grande Ronde River Basin on the Wallowa-Whitman National Forest in northeastern Oregon: to produce high-quality fish habitat, to maintain elk habitat, to restore and maintain forest conditions within the natural range of viability, and to contribute to community economic stability. From the broad goals, specific goals for stream temperature, habitat effectiveness index (HEI), habitat corridors, maintenance of land in late or old seral stages, and a nondeclining even flow of timber were selected. A case study was undertaken in a small watershed that is under typical societal constraints to determine whether one decisionsupport tool, SNAP II+, could evaluate the selected goals in a single planning exercise. Three riparian management strategies and two forest road scenarios were used. The exclusion of harvest and road-building from riparian zones in order to increase habitat protection decreased harvest levels and net present value but maintained preactivity stream temperatures. Other resources were generally maintained within prescribed management levels. Although the technique has limitations (e.g., it does not account for riparian zones in calculations of forage and cover for HEI, and it can use the maximum but not minimum acreage goal for some resources), it shows promise for evaluating management tradeoffs in watershed analysis.This is Paper 3069 of the Forest Research Laboratory, Oregon State University, Corvallis, Oregon.     

Enhanced intrinsic bioremediation of hydrocarbons using an oxygen-releasing compound

An “oxygen barrier” was formed by depositing an oxygen-releasing compound in a series of wells that were placed perpendicular to the direction of groundwater flow at a site in Belen, New Mexico. The objective was to enhance the intrinsic bioremediation of dissolved phase BTEX contamination in the aquifer and to quantify the results. The oxygen was supplied by a controlled release formulation of magnesium peroxide called Oxygen Release Compound (ORC®), a virtually insoluble powder that is packaged in polyester filter socks. The areal distributions of the initial concentrations of dissolved oxygen and BTEX were measured and compared to the concentration changes at various times in the first 93 days of system operation. The concomitant reduction in BTEX can be seen in a series of contour plots. In 93 days, dissolved oxygen had dispersed at least 20-feet downgradient from the ORC source wells based on the pattern of decreasing BTEX concentrations.     

OPTICAL IMPACTS AND SOURCES OF SUSPENDED SOLIDS IN ONONDAGA CREEK,U.S.A.1

ABSTRACT: The degradation of the optical aesthetics in the mouth of Onondaga Creek, New York, that occurs during high flow periods as a result of the influx of large quantities of suspended solids, is documented. Features of the degradation include very low clarity (Secchi disc minimum of approximately 0.1 m) and a brown ‘muddy’ appearance. The reduced clarity is mostly a result of increased light scattering. Loading and concentration profiles obtained for an approximately 35 km interval above the creek mouth over a wide range of flow indicates most of the suspended solids received during runoff events is resuspended stream sediment and eroded bank material. Application of microscopy-based individual particle analysis techniques indicates that the origin of most of these deposits and much of the suspended solids during runoff events is point source inputs, termed ‘mud boils,’ located approximately 32 km upstream of the creek mouth.