摘要:

The large quantities of sediment eroded from the Sydney F3 Expressway extension and the lack of defined channels within the catchment presented several problems of discharge and sediment load sampling. The monitoring equipment at the catchment outlet, namely pump samplers and capacitance-based water level sensors, was computer controlled, but for partial area monitoring manual methods were used together with Gerlach traps and erosion pins. The monitoring at the catchment outlet was cost-effective because of the use of electronic equipment. The sampling strategies are described and recommendations for future sampling programs are presented. Coarse sand and silt-clay concentrations in many samples were more than 10 g 1−1at the outlet. In some samples the silt-clay concentrations exceeded 30 g 1−1and the coarse sand concentrations 100 g 1−1.

ISSN:0262-6667    

DOI:10.1080/02626669009492440

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

An integrated model for the simulation and prediction of both snowmelt quantity and quality from seasonal snow cover in a mountain basin has been developed at the Institute of Hydrology and Hydraulics SAS in cooperation with the Geological Institute of Dionyz Štur. The model will be used for both the simulation and forecast of snow accumulation and the accumulation of SO2-4washout. At the present time it is mostly used for simulation of the SO2-4concentration and water supply in snow. In this paper the results of SO2-4modelling in a brook are also presented.

ISSN:0262-6667    

DOI:10.1080/02626669009492441

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

Ten candidate models of the Auto-Regressive Moving Average (ARMA) family are investigated for representing and forecasting monthly and ten-day streamflow in three Indian rivers. The best models for forecasting and representation of data are selected by using the criteria of Minimum Mean Square Error (MMSE) and Maximum Likelihood (ML) respectively. The selected models are validated for significance of the residual mean, significance of the periodicities in the residuals and significance of the correlation in the residuals. The models selected, based on the ML criterion for the synthetic generation of the three monthly series of the Rivers Cauvery, Hemavathy and Malaprabha, are respectively AR(4), ARMA(2,1) and ARMA(3,1). For the ten-day series of the Malaprabha River, the AR(4) model is selected. The AR(1) model resulted in the minimum mean square error in all the cases studied and is recommended for use in forecasting flows one time step ahead.

ISSN:0262-6667    

DOI:10.1080/02626669009492442

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

Wetlands, as defined by the Ramsar Convention, are productive ecosystems providing goods and services for people. Negative effects of “development” on wetlands are exemplified through adverse climatic effects (Aral Sea, USSR), inadvertent environmental changes (Canadian Prairie Potholes), non-sustainable alternative uses (South Chad Irrigation Scheme, Nigeria), exacerbation of problems (Garaet El Haouaria, Tunisia), detri-mental effects on rare species (Mikri Prespa, Greece), social disruption (Kissingin Fadama, Nigeria), international obligations (Ichkeul, Tunisia), and sub-optimal management (Weija-Panbros, Ghana). The functions and values of wetlands, following the Adamus approach, are described and exemplified for the Hadejia-Nguru wetlands (Nigeria) and Lake Hula (Israel). Threats to wetlands from agricultural intensification, pollution, engineering schemes and urban development are discussed. Since the societies and institutions that degrade wetlands are themselves complex systems, an understanding of hydrology and ecology is insufficient for a wetland manager. Wetland destruction can be aided by mis-perceptions, public subsidy, international funds, local-scale planning, sectoral approaches, and narrow disciplinary thinking. National Wetland Strategies are needed and a lengthy prescription is presented and amplified with examples. Hydrologists should be more involved in wetlands and their sustainable utilization. “Political hydrology” must complement “scientific hydrology”.

ISSN:0262-6667    

DOI:10.1080/02626669009492443

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

The probability distributions of annual rainfall totals at 18 stations from north coastal Peru to the southern highlands and Altiplano are examined. Most stations exhibit high interannual variability which cannot be satisfactorily modelled by a single lognormal distribution. Indices of the El Niño-Southern Oscillation (ENSO) suggest that two precipitation regimes may be identified, the ENSO regime and the non-ENSO regime. Simple descriptive statistics of rainfalls within the two sub-samples indicate that during ENSO years the Altiplano and southern highland regions experience drought, with an average reduction of mean annual precipitation of 18%, while the north coastal region is receiving over 88% above non-ENSO rainfall. A mixed lognormal model of annual precipitation is successfully fitted at all stations. The estimated parameters reflect the contrasting response of the two regions to ENSO events. Pearson product-moment correlation matrices generated between stations for each subsample further support the hypothesized negative relationship between conditions on the northern coast and the Altiplano. The resulting model describes the stochastic nature of annual precipitation in the area and illustrates regional differences in the influence of ENSO.

ISSN:0262-6667    

DOI:10.1080/02626669009492444

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

A real-time operational methodology has been developed for multipurpose reservoir operation for irrigation and hydropower generation with application to the Bhadra reservoir system in the state of Karnataka, India. The methodology consists of three phases of computer modelling. In the first phase, the optimal release policy for a given initial storage and inflow is determined using a stochastic dynamic programming (SDP) model. Streamflow forecasting using an adaptive AutoRegressive Integrated Moving Average (ARIMA) model constitutes the second phase. A real-time simulation model is developed in the third phase using the forecast inflows of phase 2 and the operating policy of phase 1. A comparison of the optimal monthly real-time operation with the historical operation demonstrates the relevance, applicability and the relative advantage of the proposed methodology.

ISSN:0262-6667    

DOI:10.1080/02626669009492445

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

ISSN:0262-6667    

DOI:10.1080/02626669009492446

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

ISSN:0262-6667    

DOI:10.1080/02626669009492447

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

ISSN:0262-6667    

DOI:10.1080/02626669009492448

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

ISSN:0262-6667    

DOI:10.1080/02626669009492449

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor