摘要:

This paper describes the development of a field-scale model that simulates the nitrogen (N) cycle in grazed grassland within a catchment-scale management model which can predict the loading and concentration of nitrate in rivers. The development is comprised of the addition of two sub-models of nitrate transport: one relating the amount of soil nitrate to its concentration in drainage water for different types of soil, and the second accounting for the proportion of permeable rock underlying the catchment. The sub-model that calculates the supply and transport of soil nitrate has been made sensitive to annual patterns of weather according to a classification based on the maximum soil water deficit. The model predictions were tested against best estimates of annual load and peak concentration of nitrate in rivers draining 11 small, predominantly grassland, catchments in the UK during the period 1974–1987.

ISSN:0262-6667    

DOI:10.1080/02626669509491431

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

The potential impacts of a hypothetical climate change induced by a rise of the concentration of greenhouse gases on the water cycle of the Sagana River basin (Central Kenya) have been assessed. For this purpose, by fitting the IRMB daily conceptual hydrological model to this basin, a water balance assessment for the period 1978–1988 was performed. The model parameters having been optimized, climate change scenarios were adopted, mainly from General Circulation Models. Three scenarios differing only by rainfall modification were considered (i.e. rises of 0%, 5% and 10%). New water balances under those assumptions were compiled and a sensitivity study performed. Conditional to the adopted climate change scenario, the results showed a general tendency towards improved water resources for this equatorial basin during the dry seasons in the 10% rainfall rise scenario. On the other hand, a reduction of the water resources was simulated if no rainfall increase was adopted in the climate scenario. Negative impacts could be feared in this case. The scenario with an intermediate 5 % rainfall increase led to a position of status quo.

ISSN:0262-6667    

DOI:10.1080/02626669509491432

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

The mobilization and biodegradation of 13 PAHs sorbed in a creosote-contaminated soil were assessed in the presence of sodium dodecyl sulphate (SDS). In a mobilization experiment, the soil was mixed with SDS solutions (0.005 to 1 % w/v) and the PAH concentrations in the aqueous phase were determined. In a biodegradation experiment, soil residual PAH concentrations were monitored during 45 weeks in the presence of 10, 100 and 500 mg kg−1SDS. The SDS was effective in mobilizing three- and four-ring PAHs. Increasing SDS concentration resulted in the mobilization of very low water-soluble five- and six-ring PAHs. The SDS (100 and- 500 mg kg−4) significantly decreased the biodegradation of fluorene, phenanthrene and all of the four-ring PAHs. PAHs with more than four rings were not biodegraded. The surfactant [α14C]SDS was readily biodegraded. Even if SDS may be efficient in mobilizing PAHs in soil pore water or groundwater, it will not improve PAH biodegradation. Such a result must be considered when using anionic surfactants in the perspective of biological treatment of PAHs.

ISSN:0262-6667    

DOI:10.1080/02626669509491433

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

In Brazil the cost of collecting hydrological data is very high because drainage basins are large, access is poorly developed and the terrain often difficult. Both inland areas and the more developed coastal regions require knowledge of water resources in terms of basin yield and flood discharges. This paper describes procedures established for the regionalization of flood peaks, mean flows and low flows, based upon existing literature and the kind of hydrological data available in Brazil. The procedures were prepared for use to be used in the Pantanal, a large swamp area in the basin of the Paraguay River (360 000 km2).

ISSN:0262-6667    

DOI:10.1080/02626669509491434

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

A model has been developed to estimate runoff volumes from generally available geophysical data. Most of the hydrological processes are modelled in a realistic manner and the model needs only one fitting parameter. Input to the model consists of monthly rainfall, evaporation and parameters. In the model, rainfall is partitioned, depending on soil water status, into soil water storage, groundwater recharge and surface runoff. Surface runoff and baseflow are separate outputs of the model and equal emphasis has been placed on estimating each of these flow components. To do this a technique has been developed for estimating recharge. The model has been shown to reproduce observed monthly flows in eastern Australian streams very well, both on catchments used to calibrate the model and in independent tests where it was used without any local calibration data. This ability to provide good estimates of volumes of flow on ungauged catchments with very modest requirements for input data means the model could find wide application. The evidence of accurate estimation of runoff volumes in an independent test in a wide range of climatic and geophysical environments is suggested to result from the physical realism of the model.

ISSN:0262-6667    

DOI:10.1080/02626669509491435

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

The discharge variability of some karst springs in Bulgaria has been investigated in detail within a region situated in the semiarid zone where most of the principal processes controlling spring outflow (evapotranspiration, snow accumulation, karstic functioning) are significant. While the karstification was notable in the Kotel and Bistretz springs with a predominance of quickflow, in the Beden system the baseflow was higher and had a behaviour similar to a porous aquifer. Univariate and bivariate spectral analyses were applied as a suitable tool in preparation for a further application of precipitation-discharge relationship models.

ISSN:0262-6667    

DOI:10.1080/02626669509491436

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

Data from 31 non-snowfed catchments in India having catchment areas less than 1515 km2have been analysed to develop a simple method for the estimation of monthly runoff for the monsoon months of June to October. One of the parameters of this method was found to vary with the catchment area, the percentage of forest cover in the catchment and the monthly average temperature. The value of another parameter of the proposed method was found to be constant during any one month in a hydrologically homogeneous region. The method proposed herein is useful for estimating the monthly runoff during the monsoon period from catchments having scarce data.

ISSN:0262-6667    

DOI:10.1080/02626669509491437

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

ISSN:0262-6667    

DOI:10.1080/02626669509491438

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

ISSN:0262-6667    

DOI:10.1080/02626669509491439

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

ISSN:0262-6667    

DOI:10.1080/02626669509491440

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor