Snowmelt Simulation

The rapid growth in recent years of a variety of demands upon available water resources has lead to an increasing interest in more fundamental approaches to the science of hydrology. Accompanying this growth has been a need for an increased understanding of the snowmelt process. A completely adequate description of the entire physical process of snowmelt under all conditions is not yet available. The complex interrelated and variable nature of the snowmelt processes that occur simultaneously complicate the problem. A preliminary mathematical model of the snowmelt process has been developed in which processes such as pack settlement rates and energy flow in the pack by means of both conduction and liquid movement are considered. Factors such as an temperature, surface albedo, and degree and direction of slope are also included. A temperature criterion is applied to predict the form of precipitation input (snow or rain) to the model. Equations of the various processes are synthesized into a dynamic model of the total system by means of an electronic analog computer. This computer was utilized primarily because of its ability to (1) perform repetitive operations at very high speeds and (2) solve directly the several time-dependent partial differential equations included in the model. Field data from snow laboraties operated by the Corps of Engineers and highly instrumented watersheds of the Agricultural Research Service are being used to test and verify the model. Inital results have indicated close agreement between observed and computed results. Sensitivity studies have been conducted, and work is continuing to further test and improve the model

Hybrid Computer Simulation of the Accumulation and Melt Processes in a Snowpack

This study represents the first phase of an investigation to develop an operational simulation model of the point snowmelt process based on a time increment of one day or less. Mathematical relationships for various phenomena involved in the snowmelt process were proposed and tested. These relationships were combined into a model which is applicable to any geographic locations by determining appropriate constants for certain relationships. The model was synthesized on a hybrid computer and calibrated using field data from the Central Sierra Snow Laboratory. It was then tested with data from other well instrumented locations. Sensitivity tests were also conducted to study the relative effects of the various basic parameters and functions upon the melting process. Initial tests of the model proved encouraging and suggested merit in perusing a proposed subsequent phase of the project to incorporate the watershed runoff hydrographs resulting from a melting snowpack will be simulated

Reviews

The following publications have been reviewed by the mentioned authors;A Compendium of Craft Books, reviewed by John EgglestonDesign and Designing by I. Burden, J. Morrison and J. Twyford, reviewed by Jeff HardmanThe Establishment and Management of Wildflower Meadows by the Nature Conservancy Council, reviewed by Derek WellsTelephone Boxes by Gavin Stamp, reviewed by John EgglestonShop Fronts by Alan Powers, reviewed by John EgglestonTroughs & Drinking Fountains by Philip Davies, reviewed by John EgglestonSIMCAD Computer Aided Design by OWL Micro Systems, reviewed by Marshall HughesTechnical Drawing by Susan Peach, reviewed by Keith Vicker

Is an Epic Pluvial Masking the Water Insecurity of the Greater New York City Region?

Six water emergencies have occurred since 1981 for the New York City (NYC) region despite the following: 1) its perhumid climate, 2) substantial conservation of water since 1979, and 3) meteorological data showing little severe or extreme drought since 1970. This study reconstructs 472 years of moisture availability for the NYC watershed to place these emergencies in long-term hydroclimatic context. Using nested reconstruction techniques, 32 tree-ring chronologies comprised of 12 species account for up to 66.2% of the average May–August Palmer drought severity index. Verification statistics indicate good statistical skill from 1531 to 2003. The use of multiple tree species, including rarely used species that can sometimes occur on mesic sites like Liriodendron tulipifera, Betula lenta, and Carya spp., seems to aid reconstruction skill. Importantly, the reconstruction captures pluvial events in the instrumental record nearly as well as drought events and is significantly correlated to precipitation over much of the northeastern United States. While the mid-1960s drought is a severe drought in the context of the new reconstruction, the region experienced repeated droughts of similar intensity, but greater duration during the sixteenth and seventeenth centuries. The full record reveals a trend toward more pluvial conditions since ca. 1800 that is accentuated by an unprecedented 43-yr pluvial event that continues through 2011. In the context of the current pluvial, decreasing water usage, but increasing extra-urban pressures, it appears that the water supply system for the greater NYC region could be severely stressed if the current water boom shifts toward hydroclimatic regimes like the sixteenth and seventeenth centuries

Reviews

The following publications have been reviewed by the mentioned authors;Art Students Observed by Charles Madge and Barbara Weinberger, reviewed by R. J. PlummerThe Modern Blacksmith by Alexander G. Weygas, reviewed by R. W. MillardOrmolu: The work of Matthew Bolton by Nicholas Goodison, reviewed by John EgglestonCraft Education, Presentation of Design by T. Pettit, reviewed by Keith GentleApproaches to Clay Modelling by John Scott and Erich Fisher, reviewed by Michael PaffardWorking in Collage by John Portschmouth, reviewed by Keith GentleChina, A History of Art by Bradley Smith & Wan-go Weng, reviewed by John EgglestonArt Techniques for Children by Gottfried Tritten, reviewed by Keith GentleJB Design Data Sheets by J. B. Designs, reviewed by M. Saye