THE EFFECTS OF ARTIFICIAL CIRCULATION ON A HYPEREUTROPHIC LAKE1

ABSTRACT: Crystal Lake, a small urban lake in Robbinsdale, MN, had been artificially circulated for 12 years before a detailed water quality evaluation was undertaken. In 1986, the circulation system was shut off for a two-year assessment. Although the lake remained hypereutrophic, the use of the lake, which included shoreline fishing and feeding ducks and geese, did not appear to be seriously impaired by the absence of artificial circulation. The circulation system was returned to service in October 1987 (there are 16 diffusers in this 0.31 km^?2 lake). Continuous limnological data from October 1987 through October 1988, plus several sampling dates in 1989, compares to the two non-circulation years (1986 and 1987) as follows: there was a two- to three-fold increase in the lake's concentration of total phosphorus, total Kjeldahl nitrogen, and chlorophyll and a similar decrease in Secchi disk transparency. The surface oxygen concentration was reduced and the deep waters were nearly anoxic. In fact, following a wind storm in 1988, the entire lake became anoxic due to the mixing of high BOD throughout the water column, and a summertime fish-kill resulted. All of these occurrences are related to the artificial circulation of the lake.     

Soluble Mineral Content in Surficial Alluvium and Associated Mancos Shale1

ABSTRACT: The Mancos Shale area of the Upper Colorado River basin produces large quantities of solutes. In order to develop an understanding of the mechanism of salt production and to determine the source of salinity, a study of the soluble mineral content (SMC) of Mancos Shale and associated alluvium was undertaken. SMC is highly variable in alluvium and associated surficial Mancos Shale. However, lithomorphological units can be identified in terms of their SMC. Results from this study demonstrate that crusts are leached in deep alluvial fills and they contain somewhat less soluble minerals than underlying Mancos Shale on hillslopes. The crusts are saline, sometimes efflorescent, in shale bedrock channels or where channels abutt against the shale. SMC increases in alluvium with decrease in depth of alluvial fill, does not vary significantly with depth in deep of alluvial fills, and increases with depth in shallow ones.     

FLUVIAL SEDIMENT STORAGE IN WETLANDS1

ABSTRACT: The important ecological and hydrological roles of wetlands are widely recognized, but the geomorphic functions of wetlands are also critical. Wetlands can be defined in geomorphic, as well as in hydrological or biological terms, and a geomorphic definition of wetlands is proposed. An analysis of fluvial sediment budget studies shows that wetlands typically serve as short-term sediment sinks or longer-term sediment storage sites. In ten study basins of various sizes, an estimated 14 to 58 percent of the total upland sediment production is stored in alluvial wetland or other aquatic environments. Of the sediment reaching streams, 29 to 93 percent is stored in alluvial wetland or channel environments. For basins of more than 100 km², more than 15 percent of total upland sediment production and more than 50 percent of sediment reaching streams is deposited in wetlands. The data underestimates the magnitude of wetland sediment storage due to the lack of data from large river systems. A theoretical analysis of river channel sediment delivery shows that wetland and aquatic sediment storage is inevitable in fluvial systems and systematically related to basin size. Results suggest that wetlands should be managed in the context of drainage basins, rather than as discrete, independent units.     

GRADUATE EDUCATION IN WATER RESOURCES: AN INNOVATIVE APPROACH Part II: Post-Production Techniques1

ABSTRACT: The production of a documentary video in a graduate seminar offers advantages over the traditional term paper. These advantages derive from the nature of the videotape medium. The most distinct difference between a written document and a video production is the use of the video camera to record events. In using the camera, the student is required to become involved both in front of the video camera, for example, as an interviewer, and behind the camera as a camera operator. Next, as an editor, the student is required to review the events that she/he has taped for inclusion in the final product. By participating in these three roles, the student has the opportunity to learn interviewing skills while interacting with professionals in the field, to learn videotaping skills, and to see him/herself as he/she appears to others. The student can use the video feedback to improve his/her professional presentation; posture, dress, gestures, speech, and facial expressions all have an impact on how we are perceived by others. Additionally, the painstaking process of reviewing the taped material leads to an intimate knowledge of the topic, and the process of choosing portions out of entire interviews hones the ability to select the crucial or central themes and ideas from any discussion. Finally, the power of video lies in its ability to communicate information to a wide audience. Although the nature of video for the general public does not permit highly detailed or rigorous coverage of any topic, it is a major source of information. Accordingly, video is an important tool that can be used to inform the public about the importance of wise water resource management.     

POLLUTANT RUNOFF MODELS: SELECTION AND USE IN DECISION MAKING1

Models for pollutant runoff can be useful in water quality management planning if appropriately structured for the problem at hand. Accordingly, a “top-down” approach is proposed for the examination of extant pollutant runoff models. The approach consists of the identification of objectives and attributes that reflect the needs of planners and decision makers when these models are used for water quality management planning. Ideally, the attributes should concern the effect of model information on improved decision making and the cost of model application. Practical difficulties with the first attribute necessitates substitution of surrogate attributes reflecting model appropriateness, resolution, and uncertainty. Common pollutant runoff models, in particular export coefficients and hydrology-driven simulation models, are found to have serious weaknesses on some of the attribute scales. The “top-down” approach leads to a set of desirable pollutant runoff model attributes; alternate modeling techniques are thus examined in order to identify promising future directions for model development. The focus of this examination is phosphorus, due to its importance in the eutrophication of surface waters. Models for both sediment-attached and dissolved phosphorus are considered. Among the conclusions is the belief that the partial contributing area concept can yield an effective yet simple simulation despite the variable and complex nature of runoff.     

VALIDATION OF POLITICAL SIMULATION MODELS -WATER RESOURCE PROJECTS1

ABSTRACT. The critical role of political processes in water resource projects has recently been placed in a new perspective [Hall, 1970]. The “political hassle” period of institutional interaction which serves to resolve political conflicts over such aspects as organizational growth and survival, responsibility for economic liabilities, and responsibility for economic benefits, requires systematic analysis in order to improve our capability to implement water projects. Failure to properly assess the political aspects of a proposed water project may result in extensive delays with significant economic losses. The complexities associated with water use and re-use have created the need for new institutional arrangements which can more effectively function to implement policies and programs. One tool which has recently become available for the research investigator concerned with institutional interactions and political processes associated with water resource projects is the technique of computer simulation of such institutional interaction. In theory, this new approach will enable the investigator to assess the political feasibility or political acceptability of a proposed water project given existing institutional structures. Furthermore, the investigator has the opportunity to experiment with new and innovative institutional arrangements which may in turn enhance the political acceptability of a proposed project. The specific material presented within this paper reports upon the validation of an existing computer simulation model designed to replicate political interactions in resource allocation problems-including water resource problems. This validation effort is done by taking an actual water problem and comparing what the political simulation models predicts in terms of political outcomes with what actually takes place. The case study in question is the formulation and legislative development of the Michigan Bond Issue for Water Pollution Control.     

The influence of personal protection equipment,occupant body size,and restraint system on the frontal impact responses of Hybrid III ATDs in tactical vehicles

Objective: Although advanced restraint systems, such as seat belt pretensioners and load limiters, can provide improved occupant protection in crashes, such technologies are currently not utilized in military vehicles. The design and use of military vehicles presents unique challenges to occupant safety—including differences in compartment geometry and occupant clothing and gear—that make direct application of optimal civilian restraint systems to military vehicles inappropriate. For military vehicle environments, finite element (FE) modeling can be used to assess various configurations of restraint systems and determine the optimal configuration that minimizes injury risk to the occupant. The models must, however, be validated against physical tests before implementation. The objective of this study was therefore to provide the data necessary for FE model validation by conducting sled tests using anthropomorphic test devices (ATDs). A secondary objective of this test series was to examine the influence of occupant body size (5th percentile female, 50th percentile male, and 95th percentile male), military gear (helmet/vest/tactical assault panels), seat belt type (3-point and 5-point), and advanced seat belt technologies (pretensioner and load limiter) on occupant kinematics and injury risk in frontal crashes.

Methods: In total, 20 frontal sled tests were conducted using a custom sled buck that was reconfigurable to represent both the driver and passenger compartments of a light tactical military vehicle. Tests were performed at a delta-V of 30 mph and a peak acceleration of 25 g. The sled tests used the Hybrid III 5th percentile female, 50th percentile male, and 95th percentile male ATDs outfitted with standard combat boots and advanced combat helmets. In some tests, the ATDs were outfitted with additional military gear, which included an improved outer tactical vest (IOTV), IOTV and squad automatic weapon (SAW) gunner with a tactical assault panel (TAP), or IOTV and rifleman with TAP. ATD kinematics and injury outcomes were determined for each test.

Results: Maximum excursions were generally greater in the 95th percentile male compared to the 50th percentile male ATD and in ATDs wearing TAP compared to ATDs without TAP. Pretensioners and load limiters were effective in decreasing excursions and injury measures, even when the ATD was outfitted in military gear.

Conclusions: ATD injury response and kinematics are influenced by the size of the ATD, military gear, and restraint system. This study has provided important data for validating FE models of military occupants, which can be used for design optimization of military vehicle restraint systems.     

Mitigating Groundwater Impacts of Residential Wells through Small‐Scale Distributed Storage in the Skagit River Basin

The exemption for groundwater wells for residential uses from the prior appropriations system, common in the western United States, has eroded in Washington State since about 2000 due to a series of legal cases. Water markets can allow the transfer of an existing water right, typically from an agricultural use, to compensate for the effect of a new residential well. But water must be legally and physically available in a way suitable to satisfy mitigation requirements. A recent court case in the Skagit basin in Northwestern Washington State has effectively halted residential development in rural areas of the basin because no suitable water rights are available to purchase for mitigation. This paper presents and examines the cost‐effectiveness of various water supply mitigation strategies. We find a small‐scale, distributed stream‐side storage system for augmenting instream flow purchased from downstream sources is relatively cost‐effective to mitigate against the effects of domestic groundwater use compared to more common alternatives. We consider transporting water to storage sites by both small‐gauge pipe and by truck. Overall, trucking water to stream‐side storage and release points tends to be more cost‐effective to mitigate against indoor‐use only given current subbasin housing densities, whereas piping for direct streamflow augmentation is more cost‐effective for higher mitigation needs associated with indoor and outdoor use and higher housing densities.     

Occurrence, distribution and possible sources of organochlorine pesticide residues in tropical coastal environment of India: an overview

Organochlorine pesticides (OCPs) are an important potential component of chemical pollutants used extensively for agriculture and sanitation purposes in India as these are comparatively cheap and effective. These persistent organic compounds such as HCH isomers, DDT and its metabolites are the predominant chemical contaminants found along the Indian coast and thus constitute both alluring and grave areas of scientific research. Our objective in the paper is to provide a comprehensive account of the distribution of organochlorine pesticides in biotic and abiotic compartments of the Indian coastal environment, make some comments on their environmental sources, their movement through the food chain and possible ecotoxicological risk of health in biota including humans. The prevalent HCH, DDT and HCB concentrations differ markedly in eastern and western coast of India reflecting differing agricultural and other usage and their ultimate input into the coastal environment by several rivers and the bioturbation activities of macrozoobenthos (bivalve mollusks, polychaetous annelids, etc.). In several cases, the DDT levels exceeded the effects range-low (ER-L) and could thus cause acute biological impairments, in comparison with the sediment quality guidelines. Contributions of DDT metabolites (DDT, DDD and DDE residues) vary in different Indian coastal regions predominated by pp'-DDT and pp'-DDD. Measured concentrations of HCHs were lower than DDTs that might be due to higher water solubility, vapor pressure and biodegradability of the latter. HCH and DDT residues in fish in India were lower than those in the temperate countries indicating a lower accumulation in tropical fish, which might be related to rapid volatilization of this insecticide in the tropical environment. The concentrations of other chlorinated pesticides (aldrin, dieldrin, eldrin, methoxychlor, endosulfan sulphate) were lower and not generally of great concern.     

Sperm motility and longevity in the giant cuttlefish, Sepia apama (Mollusca: Cephalopoda)

The sperm kinetics and fertilisation literature in marine invertebrates is heavily biased toward free-spawning species. Nonetheless, many species (e.g. cephalopods) transfer and/or fertilise gametes in confined external spaces or internally, creating very different selective pressures on sperm storage, sperm longevity and hence sperm competition. Here we report the results of an investigation into the effects of sperm age, water temperature and sperm concentration on sperm motility in the giant cuttlefish (Sepia apama). Significant positive correlations were found between percent motility and sperm concentration, and between sperm motile speed and sperm concentration. Mean percent motility of cuttlefish sperm suspension was still 9% eight hours after being released from the spermatophore and diluted into filtered seawater at 12°C (ambient field temperature during the spawning season). Sperm resuspended from spermatangia taken from (mated) females in the field were motile for up to 100 hours. When spermatophores were stored at 4°C motility was still observed in resuspended sperm after two months. Our results show that spermatangia and spermatophores can retain and release live sperm for long periods. The observed longevity of sperm in S. apama greatly increases the potential for sperm competition in this species.