摘要:

Remote sensing (RS) applications have become an important tool for the rapid evaluation of water resources. This paper deals with the utilization of RS data as the main input in an integrated approach for groundwater targeting. The Mulug Taluk, with an areal extent of 3200 km2, is one of the poor taluks in the Warangal District, Andhra Pradesh, India. A hydrogeomorphological study based on remote sensing (Landsat 5, TM) helped in establishing: (i) a broad demarcation of different lithologicalunitsviz., old Pakhals, Vindhyans, Gondwanas and recent alluvium; (ii) erosional landforms (96%)viz., denudational hills, structural hills, mesa/buttes, linear ridges, a pediment inselberg complex, a shallow weathered pediplain, a moderately weathered pediplain and depositional landforms (4%) such as flood plain areas; and (iii) delineation of minor and major lineaments. The investigations revealed that the potential for groundwater development is in the preferential order of alluvium, Gondwanas and Puranas. A statistical treatment of the data also confirmed that wells on lineaments yield more than wells away from lineaments. NE-SW structural trends cutting across the regional trend appeared to be more favourable for the exploitation of baseflow for shallow groundwater development.

ISSN:0262-6667    

DOI:10.1080/02626669609491488

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

The hysteresis (η) of the non-dimensional site-specific rating curve is used to describe the occurrence of a kinematic wave (KW), a diffusion wave (DW) or a dynamic wave (DYW) in the downstream valleys of the Teton dam, USA, and the Machhu dam II, India. Criteria are developed for the occurrence of these waves. The study reveals that the hysteresis is the energy loss occurring at a particular site and is related to the speed of travel, wave number, phase difference and attenuation characteristics of the flood wave. The role of η is shown to be of vital importance in: (i) choosing a suitable downstream boundary for improving the results; and (ii) identifying the wave zones where approximate models can substitute the complete DYW model.

ISSN:0262-6667    

DOI:10.1080/02626669609491489

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

Spatial properties of field soils vary in a complex manner. Especially in arid and semiarid areas, this variability affects plant quality and crop production. An experimental field plot was extensively sampled regarding soil water (378 gravimetrical samples), soil chemical content (314 samples), and crop yield and chemical content (26 samples) at the Cherfech agricultural field research station in Tunisia. Geostatistical analyses were made to gain a better understanding of thein situvariability of soil water, soil chemical and crop properties. Ranges of correlation were found to vary over distances between 5 and over 40 m. Nugget and sill values for semivariograms were almost an order of magnitude larger for crop samples compared to soil samples. The crop yield components appeared to have larger variability as compared to crop chemical components.

ISSN:0262-6667    

DOI:10.1080/02626669609491490

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

Le débit d'une rivière est lié, par des relations complexes, à une multitude de variables dont les valeurs sont difficilement disponibles. Le but de cet article était de construire un modèle de prévision du débit basé sur la seule connaissance de valeurs débimétriques et pluviométriques. Les modèles proposés ont été implémentés pour l'utilisation combinée de deux méthodes: une méthode de réseaux connexionnistes permettant de tenir compte de la non-linéarité de la relation pluie-débit et une technique adaptative, le filtre de Kalman, permettant la correction des prévisions en temps réel. La relation pluie-débit a été ainsi modélisée pour deux rivières du nord de la France. Les modèles établis à pas de temps journalier ou hebdomadaire ont permis des prévisions satisfaisantes et ceci pour différents horizons de prévision.

ISSN:0262-6667    

DOI:10.1080/02626669609491491

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

Based on the kinematic wave equations, formulae for the wave celerity along an overland plane subject to uniform rainfall excess and with a constant upstream inflow together with the corresponding average wave celerity and time to equilibrium for the entire plane are derived. The formulae are further developed in terms of both the Darcy-Weisbach resistance coefficient and the Manning resistance coefficient. By comparing the wave celerities, the average wave celerities and the time to equilibrium for planes with and without upstream inflow show that the upstream inflow causes the wave celerity and the average wave celerity to be faster and the times to equilibrium to be shorter. The effect of upstream inflow is greater with increasing inflow, but the marginal effect decreases with increasing inflow. The effect is greatest for laminar flow and least for turbulent flow. For the wave celerity, the effect is also greatest at the upstream end of the plane and least at the downstream end of the plane.

ISSN:0262-6667    

DOI:10.1080/02626669609491492

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

Land cover classification in Kitami, which covers an area of 12 km X 9.6 km, was done using Landsat TM data immediately after geometric correction. For each of seven land cover categories, monthly mean albedo was estimated based on field measurements obtained by the Cold Region Meteorological Observation System (CRMOS) of the Kitami Institute of Technology (KIT) and Kotoda's (1986) suggested values. The permeable zone percentages for urban and residential areas were estimated using the normalized vegetation index obtained with Landsat TM data. The monthly mean areal évapotranspiration for Kitami was obtained by Kojima's (1979) equation in winter and by Morton's (1978) equation in other seasons. The annual variation in estimated monthly mean évapotranspiration, which reaches its maximum value in July, correlated reasonably well with the évapotranspiration in an observation field. The influences on évapotranspiration of land cover category, slope solar radiation and land development were examined.

ISSN:0262-6667    

DOI:10.1080/02626669609491493

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

Low-temperature scanning electron microscopy (SEM) was used to observe precipitated snow crystals. The newly-fallen snow crystals were obtained in storms at Beltsville, Maryland, and at Bearden Mountain near Davis, West Virginia, USA. The snow samples were mounted on modified SEM stubs, frozen in liquid nitrogen, sputter coated with platinum, and imaged with an electron beam. Many types of precipitated snow crystals were observed including hexagonal plates, columns, needles, stellar dendrites, bullets, graupel, and rimed crystals. The SEM techniques that were developed can be used for quantitative measurements of size, shape and structure of crystals. SEM of precipitated snow appears to have direct application for the inference of atmospheric and cloud conditions where the snow crystals formed and travelled to the ground and for the development of a relationship between snow crystal type and snowfall intensity and amount. The SEM technique provides a new procedure to record permanently snow crystal conditions during winter storms.

ISSN:0262-6667    

DOI:10.1080/02626669609491494

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

Low-temperature scanning electron microscopy (SEM) was used to observe metamorphosed snow crystals and grains obtained in the field. Metamorphosed snow was obtained from seasonal snowpacks in the Colorado Rocky Mountains and in Alaska. The snow samples obtained in snowpits were mounted on modified SEM stubs, frozen in liquid nitrogen, transported in Dewar flasks to the SEM facility, sputter coated with platinum, and imaged with an electron beam. Analysis of a representative set of snow samples revealed examples of metamorphosed stellar crystals, fine snow grains with sintering, rounded and faceted crystals, several types of depth hoar, rounded grains of melt metamorphism, and an ice lens. Some of the crystals exhibiting both rounding and facets indicated that both equitemperature and temperature gradient metamorphism influenced the snowpack. The SEM methods developed are operable in the field and can be used to quantify three-dimensionally size, shape and bonding characteristics of crystals. SEM appears to have direct application for better understanding of snow crystal metamorphism and snowpack processes, increasing knowledge of conditions leading to avalanche formation, and improving modelling of the transfer of microwave energy from the ground surface through the snowpack for eventual estimation of snow water equivalent.

ISSN:0262-6667    

DOI:10.1080/02626669609491495

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

摘要:

A river regime describes the average seasonal behaviour of flow. This seasonal pattern reflects climatic and physiographic conditions in the basin. An inherent characteristic of a flow regime is its stability, i.e. regularity or irregularity of the seasonal pattern. A temperature rise, as predicted by climatic models, might cause changes in the patterns and stability of river flow regimes. Sensitivity of the stability of flow regimes to small fluctuations in temperature (= ± 1°C) is investigated with the help of historical temperature and flow series for Scandinavia. The concept of entropy is utilized for quantification of the stability of the flow regimes conditioned on temperature which also allows forecasting of possible changes in this stability due to changes in temperature. The study shows that the stability of flow regime types with rain or mixed rain and snowmelt sources of flow formation is already sensitive to small changes in temperature, especially concerning flow minima.

ISSN:0262-6667    

DOI:10.1080/02626669609491496

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor

ISSN:0262-6667    

DOI:10.1080/02626669609491497

出版商:Taylor & Francis Group    

年代:1996

数据来源: Taylor