PREDICTING PEAK STREAM FLOW FROM AN UNDISTURBED WATERSHED IN THE CENTRAL APPALACHIANS1

ABSTRACT: Data from a small forested catchment were used to model peak stream flow as a function of basic hydrologic variables associated with 112 rain storms. Rainfall depth and initial stream flow rate accounted for 87.1 percent of peak flow variability. Forty expressions of rainfall intensity (describing both the temporal sequence of intensity for 20 equal storm intervals, and maximum intensity for 20 separate interval lengths) were used in an attempt to improve the predictability of basic models. None of the intensity parameters improved predictability by as much as 2 percent, apparently because the most intense rainfall bursts generally occurred near the beginning of storm periods. Mean rainfall intensity for entire storms was generally as effective as any of the shorter interval intensities, and its use helped to linearize the relationship between peak flow and rainfall depth and duration.     

What are expert systems and how can they contribute to Planning?

The possible role of computer‐based expert systems in town and country planning has yet to be formalised and many planners are not aware of the potential and limitations of software developments in this area. This paper defines expert systems for planners, explains their operation and outlines a possible area, within the development control process, where such systems could provide a beneficial contribution to planning.     

Increased persistence of antifouling paint biocides when associated with paint particles

Current regulatory risk assessment procedures only assess the impact of antifouling paint biocides that are released through leaching from a painted surface. Hull cleaning activities can lead to particles of antifouling paint containing biocides to enter the environment. Comparative pseudo-first order anaerobic degradation rate constants and half-lives were determined for a selection of common antifouling paint booster biocides, their degradation products, and associated with paint particles. Anaerobic half-lives of <0.5 days were calculated for chlorothalonil, dichlofluanid, and SeaNine 211, between 1 and 3 days for DCPMU and DCPU, between 14 and 35 days for diuron and CPDU, and over 226 days for GS26575 and Irgarol 1051. Increased persistence was observed when the compounds were introduced to sediments associated with antifouling paint particles. When present as antifouling paint particles, an increased half-life of 9.9 days for SeaNine 211 and 1.4 days was calculated for dichlofluanid, no significant degradation was observed for diuron. It is suspected that this is due to much of the biocide being initially bound within the matrix of the paint particle that is slowly released through dissolution processes into the sediment pore water prior to degradation. The release of booster biocides associated with paint particles into marinas has the potential to lead to their accumulation unless activities such as hull cleaning are strictly regulated.     

Characterisation of Acid Mine Drainage Using a Combination of Hydrometric, Chemical and Isotopic Analyses, Mary Murphy Mine, Colorado

The legacy of mining continues to affect stream water quality throughout the western United States. Traditional remediation, involving treatment of acid mine drainage from portals, is not feasible for the thousands of abandoned mines in the West as it is difficult and expensive. Thus, the development of new methods to address acid mine drainage is critical. The purpose of this study was two fold; to identify and test new tools to identify sources of metal pollution within a mine and to identify low-cost treatment alternatives through the use of these tools. Research was conducted at the Mary Murphy Mine in Colorado, a multiple-level underground mine which produced gold, silver, copper, lead and zinc from 1870 to 1951. Source waters and flowpaths within the mine were characterised using analysis of hydrogen and oxygen isotopes of water (water isotopes) in combination with solute analysis and hydrometric techniques. Hydrometric measurements showed that while discharge from a central level portal increased by a factor of 10 during snowmelt runoff (from 0.7 to 7.2 Ls^–1), Zn concentrations increased by a factor of 9 (from 3,100 to 28320gL^–1). Water isotopes were used as conservative tracers to represent of baseflow and snowmelt inputs in a hydrologic mixing model analysis. The results showed that less than 7% of peak discharge was from snowmelt. Within the mine, approximately 71% of the high-flow Zn loading was caused by a single internal stream characterised by extremely high Zn concentrations (270600gL^–1) and low pH (3.4). Somewhat surprisingly, hydrologic mixing models using water isotopes showed that new water contributed up to 79% of flow in this high-Zn source during the melt season. Diversion of this high-Zn source within the mine resulted in a decrease in Zn concentrations at the portal by 91% to 2,510gL^–1, which is lower than the base-flow Zn concentration. The results suggest that in some mines remediation efforts can be concentrated on specific areas within the mine itself. Using the characterisation techniques demonstrated in this study, problem areas can be identified and contaminated flows diverted or isolated. The results also suggest that it may be possible to dewater contamination areas, greatly reducing costs of remediation.     

Differentiating work autonomy facets in a non‐Western context

Work autonomy is one important component of job design theory which in recent decades has been elaborated upon by a number of researchers who have argued that it may be disaggregated into separate work method, work schedule and work criterion autonomy facets. Breaugh (1985) developed the Work Autonomy Scales as measures of each of these. This article reports the results of two studies carried out in Egypt that explored the validity of Breaugh's scales in relation to job design theory. In Study 1, in which Breaugh's scales were administered to 534 employees in two large Egyptian organizations, the Work Autonomy Scales' three‐factor structure was verified using exploratory and confirmatory factor analyses. In Study 2, using a sample of 120 managers from four organizations, the associations between the three facets of work autonomy and other variables with which they would be expected to correlate, along with their relationships with a number of outcome variables, were explored. Statistically significant correlations were observed between certain of the work autonomy scales and task interdependence, Hackman and Oldham's autonomy scale and job complexity. In terms of outcomes, work schedule autonomy was associated with job commitment, while work criterion autonomy was associated with job satisfaction. The results are discussed in the light of previous findings and some suggestions for future research are offered. Copyright © 2003 John Wiley & Sons, Ltd.     

Designing and implementing an urban river remediation

In 2017, Consumers Energy completed a sediment response action in the Flint River to address manufactured gas plant‐related impacts in sediments and at the groundwater‐surface water interface. The project site is located in an urban, channelized, developed reach of the river. Multiple property owners and site constraints presented unique challenges for the remedial design, including the presence of Hamilton Dam at the downstream edge of the site which was considered a high‐hazard dam in “very poor condition.” An additional consideration was the City of Flint water crisis which was initially exposed in 2014. The sediment response action was not related to the water crisis because the site is located approximately two miles downstream of the City's water intake, but design, permitting, and construction began after 2014, so the timing added a heightened sense of awareness from the public stakeholders. The successful completion of the sediment response action was the result of deliberate planning, iterative engineering, and open communication with stakeholders that enabled a careful balancing of objectives with sometimes competing interests.     

Nitrate Concentrations in Springs Flowing into the Lower Flint River Basin,Georgia U.S.A.1

Allums, Stephanie E., Stephen P. Opsahl, Stephen W. Golladay, David W. Hicks, and L. Mike Conner, 2012. Nitrate Concentrations in Springs Flowing Into the Lower Flint River Basin, Georgia U.S.A. Journal of the American Water Resources Association (JAWRA) 48(3): 423-438. DOI: 10.1111/j.1752-1688.2011.00624.x Abstract: Analysis of long-term data from (2001-2009) in four springs that discharge from the Upper Floridan aquifer into the Flint River (southwestern Georgia, United States) indicate aquifer and surface-water susceptibility to nutrient loading. Nitrate-N concentrations ranged from 1.74 to 3.30 mg/l, and exceeded historical levels reported for the Upper Floridan aquifer (0.26-1.52 mg/l). Statistical analyses suggest increasing nitrate-N concentration in groundwater discharging at the springs (n = 146 over eight years) and that nitrate-N concentration is influenced by a dynamic interaction between depth to groundwater (an indicator of regional hydrologic conditions) and land use. A one-time synoptic survey of 10 springs (6 springs in addition to the 4 previously mentioned) using stable isotopes generated δ¹⁵N-NO₃⁻ values (4.8-8.4‰ for rural springs and 7.7-13.4‰ for developed/urban springs) suggesting mixed sources (i.e., fertilizer, animal waste, and soil organic nitrogen) of nitrate-N to rural springs and predominantly animal/human waste to urban springs. These analyses indicate a direct relation between nitrate-N loading since the 1940s and intensification of agricultural and urban land use. This study demonstrates the importance of evaluating long-term impacts of land use on water quality in groundwater springs and in determining how rapidly these changes occur.     

The availability of copper in soils historically amended with sewage sludge, manure, and compost

Metals in soils amended with sewage sludge are typically less available compared with those in soils spiked with soluble metal salts. However, it is unclear if this difference remains in the long term. A survey of copper (Cu) availability was made in soils amended with sewage sludge, manure, and compost, collectively named organic amendments. Paired sets of amended and control soils were collected from 22 field trials where the organic amendments had aged up to 112 yr. Amended soils had higher total Cu concentrations (range, 2-220 mg Cu kg; median, 15 mg Cu kg) and organic C (range, 1-16 g kg; median, 4 g kg) than control soils. All samples were freshly spiked with CuCl, and the toxicity of added Cu to barley was compared between amended and control soils. The toxicity of added Cu was significantly lower in amended soils than in control soil in 15 sets by, on average, a factor of 1.4, suggesting that aged amendments do not largely increase Cu binding sites. The fraction of added Cu that is isotopic exchangeable Cu (labile Cu) was compared between control soils freshly spiked with CuCl and amended soils with both soils at identical total Cu concentrations. Copper derived from amendments was significantly less labile (on average 5.9-fold) than freshly added Cu in 18 sets of soils. This study shows that Cu availability after long-term applications of organic amendments is lower than that of freshly added Cu salts, mainly because of its lower availability in the original matrix and ageing reactions than because of increased metal binding sites in soil.