Estimating Hydraulic Properties of Volcanic Aquifers Using Constant‐Rate and Variable‐Rate Aquifer Tests1

Abstract: In recent years the ground‐water demand of the population of the island of Maui, Hawaii, has significantly increased. To ensure prudent management of the ground‐water resources, an improved understanding of ground‐water flow systems is needed. At present, large‐scale estimations of aquifer properties are lacking for Maui. Seven analytical methods using constant‐rate and variable‐rate withdrawals for single wells provide an estimate of hydraulic conductivity and transmissivity for 103 wells in central Maui. Methods based on constant‐rate tests, although not widely used on Maui, offer reasonable estimates. Step‐drawdown tests, which are more abundantly used than other tests, provide similar estimates as constant‐rate tests. A numerical model validates the suitability of analytical solutions for step‐drawdown tests and additionally provides an estimate of storage parameters. The results show that hydraulic conductivity is log‐normally distributed and that for dike‐free volcanic rocks it ranges over several orders of magnitude from 1 to 2,500 m/d. The arithmetic mean, geometric mean, and median values of hydraulic conductivity are respectively 520, 280, and 370 m/d for basalt and 80, 50, and 30 m/d for sediment. A geostatistical approach using ordinary kriging yields a prediction of hydraulic conductivity on a larger scale. Overall, the results are in agreement with values published for other Hawaiian islands.     

Mathematical Model on Flow Regime and Water Harvesting in Inundation Plains1

Abstract: A mathematical model on flow regime and water harvesting in inundation plains is presented. The flow profile is a free over‐fall at the end of the desired inundation. The flow front in the plain is on‐line for the entire coverage, in a sense that there is initiation of flow mass after each small reach of the flow traverse, and it is continuing to the extreme point of coverage. The water‐harvesting phenomenon depends upon the occurrences of the hydrologic events, the nature of surface flows in the valley, the expected favorable time of flood incidence, and the soil characteristics of the plains. The model has been tested for three micro‐watersheds of different soil characteristics. It is best suited to platykurtic nature of flood phenomenon in the study area, with the correlation co‐efficient in‐between computed and observed amount of water harvesting above 0.90.     

Calibration and Validation of ADAPT and SWAT for Field‐Scale Runoff Prediction1

Abstract: The pollutant reduction possible with a given agricultural best‐management practice (BMP) is complex and site‐specific. Water‐quality models can evaluate BMPs, but model results are often limited by the lack of calibrated parameters for a given BMP. This study calibrated runoff prediction of two models (ADAPT and SWAT) for individual field plots having one till and two no‐till management practices. The factors used for runoff calibration were curve number II (CN_II) and saturated hydraulic conductivity (Ksat) for ADAPT, and CN_II, Ksat, and available water capacity for SWAT. Results were evaluated using coefficient of determination (R²), Nash‐Sutcliffe efficiency (E_f), root‐mean square error, median‐based E_f, and sign tests. Results indicated that for ADAPT, the best‐fit CN_II was 66 for the NT/SB (no‐till plot with surface‐broadcast fertilizer) treatment, 68 for the NT/DB (no‐till with deep‐banded fertilizer) treatment, and 70 for the tilled plot, whereas for SWAT the best‐fit CN_II was much higher, 86, for all treatments. Neither agreed with the textbook CN_II, 78, for sorghum in silty clay loam soil. The best‐fit model parameters for both runoff calibration phases had excellent correlation to monthly totals and moderate correlation to individual events.     

Finding Water for Growth: New Sources,New Tools,New Challenges1

Abstract: Rapidly growing regions such as the western United States face difficult challenges in mobilizing new water supplies to meet new demands. Environmental concerns have curtailed the scope for large new surface storage projects, and widespread basin overdraft has limited ground water’s potential as a source of expansion. Drawing on the California experience, this article explores modern water planning approaches, which focus on a portfolio of options including nontraditional sources (recycling, desalination, underground storage) and more efficient use of existing supplies (conservation and water marketing). It reviews the advantages and drawbacks of the elements of the portfolio, provides examples of innovative planning approaches, and assesses the role for supportive government policies.     

Hydrologic Model Framework for Water Resources Planning in the Santa Cruz River,Southern Arizona1

Abstract: The authors develop a model framework that includes a set of hydrologic modules as a water resources management and planning tool for the upper Santa Cruz River near the Mexican border, Southern Arizona. The modules consist of: (1) stochastic generation of hourly precipitation scenarios that maintain the characteristics and variability of a 45‐year hourly precipitation record from a nearby rain gauge; (2) conceptual transformation of generated precipitation into daily streamflow using varied infiltration rates and estimates of the basin antecedent moisture conditions; and (3) surface‐water to ground‐water interaction for four downstream microbasins that accounts for alluvial ground‐water recharge, and ET and pumping losses. To maintain the large inter‐annual variability of streamflow as prevails in Southern Arizona, the model framework is constructed to produce three types of seasonal winter and summer categories of streamflow (i.e., wet, medium, or dry). Long‐term (i.e., 100 years) realizations (ensembles) are generated by the above described model framework that reflects two different regimes of inter annual variability. The first regime is that of the historic streamflow gauge record. The second regime is that of the tree ring reconstructed precipitation, which was derived for the study location. Generated flow ensembles for these two regimes are used to evaluate the risk that the regional four ground‐water microbasins decline below a preset storage threshold under different operational water utilization scenarios.     

Impacts of Residential Development on Humid Subtropical Freshwater Resources: Southwest Florida Experience1

Abstract: The population of Collier and Lee Counties in southwestern Florida has increased 11‐fold from 1960 to 2004 with a concomitant increase in freshwater demand. Water levels and salinity within the water table aquifer over the past two to three decades have generally been stable, with more monitoring wells showing statistically significant temporal increases in water level than decreases. Residential development has had a neutral impact on the water table aquifer because the total annual evapotranspiration of residential communities is comparable to that of native vegetation and less than that of most agricultural land uses. Public water supply systems and private wells also result in net recharge to the water table aquifer with water produced from deeper aquifers. Confined freshwater aquifers have overall trends of decreasing water levels. However, with the exception of the mid‐Hawthorn aquifer, water levels in most areas recover to near background levels each summer wet season. Freshwater resources in humid subtropical areas, such as southwestern Florida, are relatively robust because of the great aquifer recharge potential from the excess of rainfall over ET during the wet season. Proper management can result in sustainable water resources.     

INFLUENCE OF HERBIVORY ON REGROWTH OF RIPARIAN SHRUBS FOLLOWING A WILDLAND FIRE1

Streamside vegetation frequently regenerates faster than upland vegetation following wildland fire and contributes to the recovery of riparian and stream ecosystems. Limited data are available, however, on the post‐fire growth of riparian species and the influence of herbivory on regeneration. To determine post‐fire regrowth of riparian vegetation, height, crown area, crown volume, and browse levels were measured for key riparian shrub species in streamside burned and unburned plots along second‐order streams in western Wyoming. Shrubs in the burned plots were subject to high levels of browse ‐ up to 84 percent of the leaders were browsed ‐ by native ungulates in 2002, the second post‐fire year (September 2001 to September 2002). In summer 2003, the burned watershed was also grazed by livestock, resulting in increased browse levels and decreased shrub heights for several species. In the third post‐fire year, September 2002 to September 2003, four of the six most common species showed no increase in crown area or crown volume, indicating that the combination of native ungulate and cattle browsing suppressed their growth. Potential impacts of grazing on post‐fire recovery of stream and riparian ecosystems are discussed.     

OPTIMUM USE OF PADDY FIELDS FOR FLOOD MITIGATION1

In Taiwan, the continuously increasing levels of rice imports are likely to result in surplus paddy fields. Hence, the surplus paddy fields may be developed into wetlands to increase ground water recharge, provide appropriate environments for wildlife, and most importantly, store flood water. This study developed a hydrological model incorporating the distributed rainfall‐runoff model based on the kinematics wave approach and the distributed tank model for simulation, respectively, in mountainous and flat areas. The hydrological model was found to simulate the rainfall‐runoff behavior well in the study area. Furthermore, a decision method based on the genetic algorithm concepts was proposed to give policy makers the optimal location and area size of paddy fields to construct wetlands for flood mitigation.     

The psychological contracts of violation victims: A post‐violation model

Organizations may fail to keep their commitments to their employees, at times leading to psychological contract violation. Although many victims of violation remain with their employer despite such adverse experiences, little research exists on their responses in the aftermath of violation. This paper develops a post‐violation model to explain systematically how violation victims respond to and cope with violation and the effects this process has on their subsequent psychological contract. Central to post‐violation are the victims' beliefs regarding the likelihood of violation resolution and the factors affecting it. The model specifies how the victim engages in a self‐regulation process that results in an array of potential psychological contract outcomes. Possible outcomes include reactivation of the original pre‐violation contract, the formation of a new contract that may be more or less attractive than the original, or a state of dissolution wherein the victim fails to form a functional psychological contract with the employer. The research and practical implications of this model are discussed. Copyright © 2015 John Wiley & Sons, Ltd.     

Fear of terror and increased job burnout over time: Examining the mediating role of insomnia and the moderating role of work support

While the prevalence of terrorism has increased substantially, there is a paucity of research on the effects of terrorism on employee behavior at work. Building on conservation of resources (COR) theory, and its extension, the conservation of social resources theory, we close gaps in the literature by investigating the effect of fear of terror on increased job burnout over time, the mediating effect of insomnia, and the moderating effect of supervisor and co‐worker support on these relationships. This longitudinal study followed a large sample of Israeli employees (n = 670) across three time measurements over 7 years, in a time period characterized by a high number of terror attacks. The results showed fear of terror to be related to elevated job burnout over time, even during a period in which terror attacks were reduced substantially. Further, insomnia mediated the relationship between fear of terror and increased burnout, while co‐worker support, but not supervisor support, moderated the relationships between fear of terror and increased insomnia and between increased insomnia and increased burnout. The results further support the notion of loss cycles in COR theory, as well as the importance of social resources, which are the cornerstones of conservation of social resources theory. Copyright © 2014 John Wiley & Sons, Ltd.