摘要:

The principles and the establishment of the Danish ground-water monitoring network (67 areas) are outlined. The operation and the protocol of the sampling system are described as is the storage of data in decentralized and centralized systems. The Nyborg monitoring area is used as an example with main limestone and secondary sand aquifers. The first three years' results are evaluated, including an evaluation of the technical function and chemical analyses (inorganics, trace elements and organic micropollutants).

ISSN:0262-6667    

DOI:10.1080/02626669409492716

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

Several types of streamflow droughts in northern Nigeria can be distinguished, including short droughts which cluster in the rainy season, long droughts which span the dry season, and multiyear droughts. The latter are not analysed in this paper because of limited record length. The duration of short droughts follow a Weibull distribution while the durations of long droughts are normally distributed. As drought duration and deficit are highly correlated, similar probability distributions apply to the deficits. The starting date of droughts can be described by normal distributions. It is suggested that while the occupants of the desert fringe have adapted to long droughts that last the dry seasons, improved knowledge of short drought occurrences is beneficial to the planning of activities for the rainy period.

ISSN:0262-6667    

DOI:10.1080/02626669409492717

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

This paper deals with the dynamic characteristics of the siphon which is usually applied to control the movement of rain water from the collecting funnel of a raingauge to the compartments of the tipping bucket. Since commercially available tipping bucket raingauges suffer from nonlinearity, a modified siphon has been tested. The dimensions of its elements have been designed to meet linearity requirements up to a certain maximum rainfall intensity. The raingauge achieved linearity for the chosen range of intensities.

ISSN:0262-6667    

DOI:10.1080/02626669409492718

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

Water balance models have been used to examine trends in the level of Lake Victoria over this century. A monthly model developed in a previous study for the period 1925 to 1978 has been improved and the simulation period extended to 1990. Also, an annual model has been used to extend the water balance back to the start of the century. The simulations confirm the results from previous studies which showed that the observed variations in lake level can be explained primarily in terms of natural variations in rainfall over the lake and surrounding basin. An idealized interpretation of these variations is presented which illustrates the long response time of this large lake and which is used to speculate on the likely future behaviour of the lake.

ISSN:0262-6667    

DOI:10.1080/02626669409492719

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

摘要:

This paper presents a comparison between anL2estimator and anL1estimator for solving parameter identification problems in groundwater flow and solute transport simulation. TheL1estimator is formulated using a weightedL1-norm as the error measure between the vector of the observed hydraulic heads and solute concentrations and the vector of the simulated heads and concentrations. The simulation model is comprised of a finite element formulation for steady-state groundwater flow and solute transport in a two-dimensional vertically averaged aquifer system. The gradients of the state variables with respect to the parameters are computed using a state sensitivity method. Posterior statistical inferences are conducted. The solutions to two sets of hypothetical groundwater parameter estimation problems illustrate that theL1estimator is more robust than theL2estimator in handling observation data containing certain outliers.

ISSN:0262-6667    

DOI:10.1080/02626669409492720

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

ISSN:0262-6667    

DOI:10.1080/02626669409492721

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

ISSN:0262-6667    

DOI:10.1080/02626669409492722

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

ISSN:0262-6667    

DOI:10.1080/02626669409492724

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

ISSN:0262-6667    

DOI:10.1080/02626669409492725

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor

ISSN:0262-6667    

DOI:10.1080/02626669409492715

出版商:Taylor & Francis Group    

年代:1994

数据来源: Taylor