Drought planning and water allocation: an assessment of local capacity in Minnesota

Water allocation systems are challenged by hydrologic droughts, which reduce available water supplies and can adversely affect human and environmental systems. To address this problem, drought management mechanisms have been instituted in jurisdictions around the world. Historically, these mechanisms have involved a crisis management or reactive approach. An important trend during the past decade in places such as the United States has been a shift to a more proactive approach, emphasizing drought preparedness and local involvement. Unfortunately, local capacity for drought planning is highly variable, with some local governments and organizations proving to be more capable than others of taking on new responsibilities. This paper reports on a study of drought planning and water allocation in the State of Minnesota. Factors facilitating and constraining local capacity for drought planning were identified using in-depth key informant interviews with state officials and members of two small Minnesota cities, combined with an analysis of pertinent documentation. A key factor contributing to the effectiveness of Minnesota's system is a water allocation system with explicit priorities during shortages, and provisions for restrictions. At the same time, the requirement that water suppliers create Public Water Supply Emergency Conservation Plans (PWSECP) clarifies the roles and responsibilities of key local actors. Unfortunately, the research revealed that mandated PWSECP are not always implemented, and that awareness of drought and drought planning measures in general may be poor at the local level. From the perspective of the two cities evaluated, factors that contributed to local capacity included sound financial and human resources, and (in some cases) effective vertical and horizontal linkages. This analysis of experiences in Minnesota highlights problems that can occur when senior governments establish policy frameworks that increase responsibilities at the local level without also addressing local capacity.     

Spatial Modeling of Harvest Constraints on Wood Supply Versus Wildlife Habitat Objectives

We studied the effects of spatial and temporal timber harvesting constraints on competing objectives of sustaining wildlife habitat supply and meeting timber harvest objectives in a boreal mixedwood forest. A hierarchical modeling approach was taken, where strategic and tactical level models were used to project blocking and scheduling of harvest blocks. Harvest block size and proximity, together with short- and long-term temporal constraints, were adjusted in a factorial manner to allow creation of response–surface models. A new measure of the habitat mosaic was defined to describe the emergent pattern of habitat across the landscape. These models, together with multiple linear regression, were used to provide insight on convergence or divergence between spatial objectives. For example, green-up delay (defined as time required before a harvest block adjacent to a previously logged block can be scheduled for harvest) had an adverse effect on the amount of annual harvest area that could be allocated and blocked spatially, and habitat supply responded in an opposite direction to that of wood supply, where caribou, moose wintering, and marten habitat supply increased when harvest blocks were further apart, maximum block size smaller, and both a green-up delay and mesoscale stratification were applied. Although there was no solution space free of conflicts, the analysis suggests that application of the mesoscale stratification, together with a diversity of harvest block sizes and a between-harvest block proximity of 250 m, will perform relatively well with respect to wood supply objectives, and at the same time create a less fragmented landscape that better reflects natural forest patterns.     

A soil-site evaluation index of productivity in intensively managed Pinus radiata (D. Don) plantations in South Australia

A limiting-factor, environmental model for radiata pine (Pinus radiata (D. Don)) has been developed using landform and soil morphological features that influence site productivity. The model focuses on soil and landscape constraints to productivity and predicts the native productivity of land and tree species. It permits the integration of land-use objectives for a catchment through forest management and use of silvicultural practices which increase productivity. The soil site evaluation index (SSEI) is an index of forest productivity found when silviculture extends only to the minimum amount of site disturbance needed to establish a plantation of radiata pine. The impacts of intensive silvicultural practices were deducted from the Site Quality productivity survey rating to calculate the unimproved yield class (uYC). We calculated SSEI by range standardising uYC values from 0 to 1. SSEI was correlated with the environmental factors in a regression tree model using readily available analytical software. The model accurately predicts unimproved forest productivity from observed soil horizon and land surface properties. The environmental constraints in low lying areas relate to waterlogging, soil sodicity and gravel content. In elevated areas, plant available water storage, rock weathering, landform, ironstone gravel and aspect are recognised factors for pine growth.     

Sperm count in earthworms (Lumbricus terrestris) as a biomarker for environmental toxicology: effects of cadmium and chlordane

Earthworms, Lumbricus terrestris, exposed in artificial soil to sublethal concentrations of technical chlordane (6.25, 12.5, and 25 ppm) and cadmium nitrate (100, 200, and 300 ppm) exhibited significant reduction in spermatozoa from testes and seminal vesicles. The onset time of reduction varied with exposure concentration, but absolute depression in sperm count was independent of exposure concentration or exposure duration after reduction was first manifested, demonstrating a threshold effect. Earthworm sperm counts show potential as a rapid-measurement endpoint biomarker for measuring sublethal effects of chemical pollutants on reproduction.     

Influence of solvent and soil type on the pressurised fluid extraction of PAHs

Pressurised fluid extraction (PFE) of polycyclic aromatic hydrocarbons (PAHs) from a certified reference material (CRM) 524 has been firstly optimised following a central composite design. The instrumental parameters of the PFE (pressure, temperature, extraction time and number of solvent cycles) were studied in order to obtain maximum extraction yields. Neither pressure nor extraction time or temperature seemed to have any significant effect on the extraction yield, therefore one extraction cycle was enough to exhaustively extract all the PAHs from CRM 524. Once the instrumental conditions were established, the extraction yields obtained with eight different solvents or solvent mixtures [acetone, dichloromethane, acetonitrile, acetone-dichloromethane (1 + 1 v/v), acetone-isohexane (1 + 1 v/v), isohexane, methanol and toluene] from the CRM 524 were compared and showed that the best recoveries were obtained with acetone-isohexane (1 + 1 v/v). Finally, the effect of sand, silt, clay and the organic matter content of soil was investigated with respect to recovery of PAHs by PFE with different solvents or solvent mixtures for aged soil samples. In this case, eight soils with different sand, silt, clay and organic matter contents were slurry spiked with PAHs and aged for 19 days. Three aliquots of each slurry spiked soil were extracted with the previously mentioned solvents and the results were studied by means of principal component analysis (PCA) of the whole data set (soil composition, solubility parameter of the solvent and recoveries of all PAHs) and partial least squares (PLS). Clay and organic matter content and the squared solubility parameter have the highest correlation with the recovery of PAHs from soil samples.     

Effects of the organophosphorous insecticides temephos (Abate®) and chlorpyrifos (Dursban®) on populations of the salt-marsh snail Melampus bidentatus

The effects of 2 organophosphorous insecticides, temephos (Abate^®) and chlorpyrifos (Dursban^®), on populations of the salt-marsh snail Melampus bidentatus Say (Basommatophora: Melampidae) were investigated in a series of field experiments. These toxicants were aerially applied to mosquito breeding areas in New Jersey salt marshes in the manner normally used in biting-fly control operations. No significant change in the population density of M. bidentatus was observed in response to multiple treatments of granular formulations of either temephos or chlorpyrifos. However, there was a highly significant (P<0.01) depression in population density observed in the plot exposed to multiple treatments of a temephos emulsion. This depression was followed by a resurgence in density levels, beginning 3 weeks after the last treatment. The specific mechanism for thisperturbation is not known. However, it is hypothesized that it might involve some combination of indirect insecticide effects coupled with age-specific effects. Tests of age structure of the affected population using the chi-square distribution supported this hypothesis.Paper of the Journal Series, New Jersey Agricultural Experiment Station. This research was supported, in part, by a grant from the New Jersey Mosquito Control Commission.     

Evaluation of the effect of a cover layer on radon exhalation from uranium mill tailings: transient radon flux analysis

An experimental study concerning the transport of 222Rn in uranium mill tailings (UMTs) and in the cover layer was launched in 1997 with the participation of the French uranium mining company (COGEMA). Evaluation of the cover layer's effectiveness in reducing 222Rn flux emanating from UMTs was one of its objectives. In the first phase, the 222Rn flux densities were measured regularly on a UMT layer. In the second phase, the UMT was covered with a one-meter layer of compacted material consisting of crushed waste rock derived from mining activities. Radon-222 flux was then measured at the surface of this cover layer. Observations were compared with radon flux calculated using TRACI, a model for vertical water and gas flow and radon transport. The results show that the calculations bear a fair resemblance to the observations in both cases. They also show that the effectiveness of the cover layer calculated with TRACI, using the thickness and textural properties of the cover material, is very close to the measured effectiveness.     

EFFECTS OF MULTI‐SCALE ENVIRONMENTAL CHARACTERISTICS ON AGRICULTURAL STREAM BIOTA IN EASTERN WISCONSIN1

ABSTRACT: The U.S. Geological Survey examined 25 agricultural streams in eastern Wisconsin the determine relations between fish, invertebrate, and algal metrics and multiple spatial scales of land cover, geologic setting, hydrologic, aquatic habitat, and water chemistry data. Spearman correlation and redundancy analyses were used to examine relations among biotic metrics and environmental characteristics. Riparian vegetation, geologic, and hydrologic conditions affected the response of biotic metrics to watershed agricultural land cover but the relations were aquatic assemblage dependent. It was difficult to separate the interrelated effects of geologic setting, watershed and buffer land cover, and base flow. Watershed and buffer land cover, geologic setting, reach riparian vegetation width, and stream size affected the fish IBI, invertebrate diversity, diatom IBI, and number of algal taxa; however, the invertebrate FBI, percentage of EPT, and the diatom pollution index were more influenced by nutrient concentrations and flow variability. Fish IBI scores seemed most sensitive to land cover in the entire stream network buffer, more so than watershed‐scale land cover and segment or reach riparian vegetation width. All but one stream with more than approximately 10 percent buffer agriculture had fish IBI scores of fair or poor. In general, the invertebrate and algal metrics used in this study were not as sensitive to land cover effects as fish metrics. Some of the reach‐scale characteristics, such as width/depth ratios, velocity, and bank stability, could be related to watershed influences of both land cover and geologic setting. The Wisconsin habitat index was related to watershed geologic setting, watershed and buffer land cover, riparian vegetation width, and base flow, and appeared to be a good indicator of stream quality Results from this study emphasize the value of using more than one or two biotic metrics to assess water quality and the importance of environmental characteristics at multiple scales.