SIMULATION AND MAPPING OF SOIL-WATER CONDITIONS IN THE GREAT PLAINS1

ABSTRACT: Soil-water conditions provide valuable insight into the hydrologic system in an area. A soil-water balance quantitatively summarizes soil-water conditions and is based on climatic, soil, and vegetation characteristics that vary spatially and temporally. Soil-water balances in the Great Plains of the central United States were simulated for 1951–1980. Results of the simulations were mean annual estimates of infiltration, runoff, actual evapotranspiration, potential recharge, and consumptive water and irrigation requirements at 152 climatic data stations. A method was developed using a geographic information system to integrate and map the simulation results on the basis of spatially variable climatic, soil, and vegetation characteristics. As an example, simulated mean annual potential recharge was mapped. Mean annual potential-recharge rates ranged from less than 0.5 inch in much of the north-central and southwestern Great Plains to more than 10 inches in parts of eastern Texas and southwestern Arkansas.     

The modelling of pool vaporization

This paper describes a mathematical model which calculates the time dependencies of the flow rate and composition of the vapour emerging from a pool. A large variety of accidental cases can be covered: continuous or instantaneous spills, on confined or unconfined ground, ideal or non-ideal liquid mixtures in boiling or evaporating conditions. The boiling, when present, is modelled through an equation system comprising the Rachford-Rice relation and the energy balance of the pool, which is assumed to be well-mixed. In the case of a volatile pool, interfacial mass rates are determined taking into account the Stefan flux, and the thermal resistance inside the liquid phase is also considered. In all situations, the energy balance includes the contribution of ground, sun and air. Known experimental data have been used to validate the model.     

ESTIMATED CONSUMPTIVE LOSS FROM MAN-MADE SNOW1

ABSTRACT: Consumptive loss of water attributable to man-made snowmaking was estimated using an energy balance model and a mass balance procedure. Data from nine field experiments at Colorado ski areas were collected and used in these models. The mean consumptive loss using the energy balance model for the nine experiments was 6.0 percent and 5.8 percent for the mass balance model A thermodynamic relationship and a regression equation were developed to provide a procedure to estimate consumptive loss as a linear function of atmospheric temperature.     

WATER BALANCE OF PACIFIC ATOLLS1

ABSTRACT: This study presents an estimate of water balance components for Pacific atolls under average dimatological conditions. Figures show annual potential evapotranspiration, annual recharge for rain-fed and aquifer-fed vegetated areas, and the number of months that potential evapotranspiration exceeds actual evapotranspiration (indicating water stress) under average conditions. The method relies on the assumption that small islands have minimal influence on cloudiness and precipitation. The potential evapotranspiration is computed using the equilibrium evaporation concept, and estimates of monthly soil water storage and recharge follow Thornthwaite's bookkeeping method. Gradients in potential evapotranspiration run primarily north-south, though for the equatorial zone potential evapotranspiration declines from east to west, opposing the trend in rainfall. Recharge estimates range from 250 mm in the central Tuamotu Archipelago and zero in eastern Kiribati to over 2000 mm per year in the southern Caroline Islands (U.S. Trust Territory) and Solomon Islands. The sensitivity of the model to intra-month rainfall variability and a range of available soil moisture values is discussed.     

ESTIMATING THE WATER RESOURCE FOR A HIGH SIERRA WATERSHED1

ABSTRACT: Competition for water, concerns for maintaining ground water quality, and compliance with legislative action require quantification of the water resource for high elevation watersheds in the Sierra Nevada. However, meager hydroclimatic data frequently hinder runoff assessments needed for formulating water development policies, and the selection of watershed models for estimating the water resource is limited to those requiring a minimum of observational data. A climatic water budget model and an energy slope and aspect model are employed to estimate the water resource for a small watershed in Sierra Valley north of Lake Tahoe. The models employ different assumptions and computational procedures, but the total water available estimated by both models is very similar. Measured runoff is estimated satisfactorily by the models, but streamflow is not representative of the total water resource because a substantial portion of the available water enters the regional ground water system. This conclusion is supported by hydrologic and geochemical evidence, and ground water recharge is estimated to be at least as great as measured runoff during dry years and nearly twice as large during wet years.     

蚯蚓有机废水土地处理试验研究

利用蚯蚓的有机废水土地处理是一种符合生态平衡的新的处理技术，在这种处理工艺中，含有蚯蚓的土壤对废水中的COD的吸附去除百分数和有机物负荷均比常规的污水土地处理高两倍以上。这一处理过程的机理符合吸附，再生过程的一级反应动力学。     

灾害生态学问题研究

灾害生态学是从生态进化的角度上研究灾害问题，其目的在于通过对生态灾害的界定，生态灾害成因分析，来寻求防止或减轻生态灾害的有效途径．文章从灾害与生态进化的关系入手，阐述了研究灾害生态学问题的重要意义，提出了当前灾害生态学研究的主要问题，为灾害生态学的研究提供了一条新的思路。     

浅谈城市房价与地价

地价与房价作为房地产市场的两个重要指标，其水平高低对房地产市场的正常、有序发展起者重要作用。房价与地价在一定范围内、一定条件下相互作用，相互影响。正确分析和处理房价与地价的关系，促进房地产业健康发展，可采取以下措施：土地交易信息公开、透明；土地及时开发，及时入市；加强对土地市场供需结构的宏观调控和经济适用房、廉租房体系的建设等。     

Degradation Kinetics of Biodegradable Fiber Composites

In a composite, fast degradable fibers determine the degradation of the slowly degradable matrix. Such biodegradable composites consisting of degummed hemp fibers and a polyester amide matrix were produced with fiber mass fractions between 0 and 0.48. The hot-pressed plates, 1-mm thick, were incubated in a standard soil. The degradation kinetics was quantified by the measurement of CO₂ production. Furthermore, after termination of experiment, the carbon balance was uncovered. The results were fitted to an exponential law taking into account the degradation of fibers. The increased amount of pores realized by high fiber contents induces pronounced degradation. The degradation is fully characterized by the time constant , which is correlated to the fiber mass fraction. The model allows to predict the degradation kinetics of composites with a few well-defined experiments.     

Modelling nitrogen cycles of farming systems as basis of site- and farm-specific nitrogen management

The paper describes a model designed for analysing interrelated nitrogen (N) fluxes in farming systems. It combines the partial N balance, farm gate balance, barn balance and soil surface balance, in order to analyse all relevant N fluxes between the subsystems soil–plant–animal–environment and to reflect conclusive and consistent management systems. Such a system approach allows identifying the causes of varying N surplus and N utilisation.The REPRO model has been applied in the experimental farm Scheyern in southern Germany, which had been subdivided into an organic (org) and a conventional (con) farming system in 1992. Detailed series of long-term measuring data are available for the experimental farm, which have been used for evaluating the software for its efficiency and applicability under very different management, yet nearly equal site conditions.The organic farm is multi-structured with a legume-based crop rotation (N₂ fixation: 83 kg ha⁻¹ yr⁻¹). The livestock density is 1.4 LSU ha⁻¹. The farm is oriented on closed mass cycles.The conventional farm is a simple-structured cash crop system based on mineral N (N input 145 kg ha⁻¹ yr⁻¹). Averaging the years 1999–2002, the organic crop rotation reached, with regard to the harvested products, about 81% (6.9 Mg ha⁻¹ yr⁻¹) of the DM yield and about 93% (140 kg ha⁻¹ yr⁻¹) of the N removal of the conventional rotation. Related to the cropped area, the N surplus calculated for the organic rotation was 38 kg ha⁻¹ yr⁻¹ versus 44 kg ha⁻¹ yr⁻¹ for the conventional rotation. The N utilisation reached 0.77 (org) and 0.79 (con), respectively. The different structure of the farms favoured an enhancement of the soil organic nitrogen stock (35 kg ha⁻¹ yr⁻¹) in the organic crop rotation and caused a decline in the conventional system (−24 kg ha⁻¹ yr⁻¹). Taking account of these changes, which were substantiated by measurements, N surplus in the organic rotation decreased to 3 kg ha⁻¹ yr⁻¹, while it increased to 68 kg ha⁻¹ yr⁻¹ in the conventional system. The adjusted N utilisation value amounted to 0.98 (org) and 0.69 (con), respectively.