摘要:

This paper presents a model for forecasting daily changes of water level in Lake Kinneret during flood periods. The model is based on the water budget equation. Its parameters are calibrated by multiple regression using inflow, outflow and rainfall for the preceding day. A correction factor which takes into account the errors of forecasts for the preceding two days is added to the model. Split-sample calibrations and applications yield results which are accurate to within 10 to 20 mm.

ISSN:0262-6667    

DOI:10.1080/02626669509491400

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

The artificial neural network (ANN) approach described in this paper for the synthesis of reservoir inflow series differs from the traditional approaches in synthetic hydrology in the sense that it belongs to a class of data-driven approaches as opposed to traditional model driven approaches. Most of the time series modelling procedures fall within the framework of multivariate autoregressive moving average (ARMA) models. Formal statistical modelling procedures suggest a fourstage iterative process, namely, model selection, model order identification, parameter estimation and diagnostic checks. Although a number of statistical tools are already available to follow such a modelling process, it is not an easy task, especially if higher order vector ARMA models are used. This paper investigates the use of artificial neural networks in the field of synthetic inflow generation. The various steps involved in the development of a neural network and a ultivariate autoregressive model for synthesis are presented. The application of both types of model for synthesizing monthly inflow records for two reservoir sites is explained. The performance of the neural network is compared with the statistical method of synthetic inflow generation.

ISSN:0262-6667    

DOI:10.1080/02626669509491401

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

The principle of maximum entropy (POME) is employed to derive a new method of parameter estimation for the 3-parameter generalized Pareto (GP) distribution. Monte Carlo simulated data are used to evaluate this method and compare it with the methods of moments (MOM), probability weighted moments (PWM), and maximum likelihood estimation (MLE). The parameter estimates yielded by the POME are either superior or comparable for high skewness.

ISSN:0262-6667    

DOI:10.1080/02626669509491402

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

Multiple Nonlinear Standardized Correlation (MNSC) analysis has been used for the development of three mathematical models for: (a) monthly streamflow data interpolation; (b) extrapolation; and (c) transfer to ungauged sites. This paper reports the application of MNSC to two different regions in Manitoba, Canada: the Red-Assiniboine basin (southern) and the Interlake district (central). The aim of the analysis is to test how appropriate MNSC is in Manitoba. The results of the MNSC applications to Manitoba's streams were enhanced by the introduction of various physical parameters.

ISSN:0262-6667    

DOI:10.1080/02626669509491403

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

The Gedaref basin in eastern Sudan is believed to be a great tectonic depression filled mainly with continental deposits and Tertiary basalt lava flows. The main aquifers are the Gedaref sandstone aquifer system and the basalts. 70 wells drilled in the Gedaref basin were sampled and analysed for the major cations, major anions, total dissolved solids, alkalinity and hardness. The data were treated with simple statistics, represented with Piper trilinear plots and were the subject of cluster analysis. The interpretations of the applied methods confirm each other and the groundwater was classified into two groups. The water in the sandstone aquifer was dominated by NaHCO3while the water in the basalts was partially dominated by alkaline earth.

ISSN:0262-6667    

DOI:10.1080/02626669509491404

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

Having verified the decrease in surface water resources observed over the last twenty years in West Africa, changes planned for the Sassandra basin, Côte d'Ivoire, are described. The methods used to generate two hundred year data series, the basis of previous studies, are presented. The generated time series allow the development of long term working patterns for cases similar to the climatic conditions pertaining before and since the drought of the late 1960s. The results demonstrate a clear drop in the performance of the water system, related to climatic conditions experienced since the start of the drought. The conclusions drawn from the comparisons and analyses indicate that, if the present conditions were to persist in West Africa, surface water resources would no longer meet needs which were identified and planned for on the basis of data records presenting characteristics different from those currently observed. The frequency of failures would then become much greater, leading to a serious decline in the output of existing facilities. Modifications made to the operation of the Buyo reservoir are also analysed.

ISSN:0262-6667    

DOI:10.1080/02626669509491405

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

On a regional scale, some of the most profound impacts of climate change due to increases in greenhouse gases would probably be major changes in the hydrological cycle, in water availability, in agricultural production and in the use of energy. This paper gives a brief overview of studies carried out on climate change and possible impacts on hydrology and water resources in India, covering also the agricultural aspect. The need is emphasized for carrying out further studies in this important subject area at the national level, keeping in view the data and computing facilities available.

ISSN:0262-6667    

DOI:10.1080/02626669509491406

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

Observations of discharge, temperature and suspended sediment made at a gauging site established near the snout of the Dokriani glacier in the western Himalayan region are presented. These observations were made during a scientific expedition to this glacier over 21 days (23.8.1992–12.9.1992). Because of harsh weather conditions, observations could not be made for a longer period. The minimum streamflow in the glacier melt stream was observed at 0700 h whereas the maximum was observed at 1800 h. The ratio of maximum to minimum flow was computed to be 1.81 from the continuous hourly observations. Based on an analysis of the recession of the hydrograph, it was found that the meltwater time lag from the accumulation zone of the glacier was more than seven times higher than that from the ablation zone. No specific relationship was observed between suspended sediment and discharge. The average values of the suspended sediment concentration and load were found to be 350 ppm and 180 t day−1, respectively, for the study period. Weathering processes in different zones of the glacier were also studied to find out the source of the sediment transported by the meltwater into the melt stream. A high correlation coefficient (r= 0.89) was found between the glacier specific runoff and the air temperature at the gauging site. It showed that temperature alone can represent the melting of the glacier and may be considered for the hydrological modelling of glacier melt runoff. Based on observations over three days under clear weather conditions for isolated snow blocks, the average snowmelt factor was computed to be 5.4 mm/(°C. 6 h).

ISSN:0262-6667    

DOI:10.1080/02626669509491407

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

The distributed parameter model ANSWERS was used to predict runoff and soil loss from three agricultural watersheds in the arid zone of India. Model input parameters such as landform, drainage, soil and land use/land cover were derived from Landsat Thematic Mapper false colour composites and limited ground truth. The model predicted hydrographs and sediment graphs within acceptable limits. ANSWERS underpredicted the total soil loss by factors of 2.6 to 3.6. Reasons for these results are discussed.

ISSN:0262-6667    

DOI:10.1080/02626669509491408

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

A key component of a sediment yield prediction is an estimate of the sediment deposition between erosion sources and a drainage basin outlet. This technical note presents methods requiring a minimum of data which can be used to assess the importance of sediment deposition within the river system of a basin. The methods were applied to a 4123 km2basin in the Philippines. Results indicated that sediment deposition within this river system had no significant effects on the overall sediment yield.

ISSN:0262-6667    

DOI:10.1080/02626669509491409

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor