摘要:

A package of simulation models has been developed to study the hydrological processes controlling runoff and to predict flow hydrographs in the Indian arid zone. The models describe rainfall-runoff in the upland phase and the interaction between runoff and transmission losses in the channel phase, so as to derive the drainage basin outflow hydrograph. In the upland phase the rising limb of the hydrograph is predicted through a regression model and the recession through a conceptual analogue of discharge from a single leaky reservoir. The leaky reservoir is described by a continuity equation and by discharge-stage and storage-stage relationships at the outlet. In the channel phase the governing equations for movement of a flood wave subjected to the transmission losses are simplified through a time averaging process to develop an ordinary differential equation describing transmission losses as a function of distance, inflow, channel width, time parameters of flow and effective hydraulic conductivity. These models are simplified and developed to require a minimum of observed data for calibration. The package of models can be applied to ungauged drainage basins through parameterization.

ISSN:0262-6667    

DOI:10.1080/02626669809492130

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

After analysing the Wiener process characteristics of reservoir storage capacity in flood regulation, an Ito stochastic differential equation including a random input term is proposed to describe and estimate the stochastic reservoir level hydrograph in a flood routing process. An expression of risk for flood release is given and the probability density functions of the reservoir level hydrograph, which are related to the risk of overtopping failure, are computed using a Fokker-Planck equation. Analysed and calculated results indicate that, by using the stochastic differential equations, the uncertainty influence of various random factors on the reservoir level hydrograph can be taken into account in the flood routing process. Therefore, the procedure of evaluating the risk of dam overtopping failure developed in this paper provides an improvement over existing methods.

ISSN:0262-6667    

DOI:10.1080/02626669809492131

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

Microscale-averaged inter-rill area sheet flow and rill flow equations (Tayfur & Kavvas, 1994) are averaged along the inter-rill area length and rill length to obtain local areally-averaged inter-rill area sheet flow and rill low equations (local-scale areai averaging). In this averaging, the local areally-averaged flow depths are related to the microscale-averaged flow depths at the outlet sections (downstream ends) of a rill and an inter-rill area by the assumption that the flow in these sections has the profile of a sine function. The resulting local areally-averaged flow equations become time dependent only. To minimize computational efforts and economize on the number of model parameters, local areally-averaged flow equations are then averaged over a whole hillslope section (hillslope-scale areal averaging). The expectations of the terms containing more than one variable are obtained by the method of regular perturbation. Comparison of model results with observed data is satisfactory. The comparison of the model results with those of previously developed models which use point-scale and large-scale (transectionally) averaged technology indicates the superiority of this model over them.

ISSN:0262-6667    

DOI:10.1080/02626669809492132

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

A survey of the River Kali in western Uttar Pradesh (India) has been carried out to assess the contribution of point and non-point sources of pollution to the river. The river shows strong seasonal dependence for various constituents and the water quality deteriorates sharply as it flows through Muzaffarnagar city. The important characteristic associated with the pollution of the river is the depletion of oxygen over a stretch of about 25 km. High values of BOD and COD indicate a high degree of organic pollution in the river. A chemical mass balance approach has been used for measuring changes in the concentration and/or load to the river, which develops an interesting concept to discriminate between point and non-point sources of pollution to the river. The resulting differential loadings, if adjusted for uncharacterized non-point contribution to the load, may represent the total point source load to the river minus any losses due to volatilization, settling, and/or degradation. Mass balance calculations conducted for certain water quality constituents indicated that additional inputs are needed to account for the observed differences in load along the river. The sources may include non-point sources of pollution due to agricultural activities, sediment remobilization or entrainment, groundwater intrusion or a combination of these sources. The difference may also be attributed to some point sources of pollution which could not be identified in the course of these investigations.

ISSN:0262-6667    

DOI:10.1080/02626669809492133

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

Studies using data from a general circulation model (GCM) and from numerical weather prediction models (NWP) as inputs to a hydrological model have produced useful results but were limited by the coarse resolution of the GCM data on the one hand and, on the other hand, by the relatively short period of high-resolution NWP data available. This paper describes an alternative approach using long-term (96 years) daily data from a high resolution atmospheric boundary layer model. The data from the atmospheric model were used as inputs to a daily distributed hydrological model of the Upper Columbia Basin in western Canada. The hydrological model was calibrated for five years and verified using streamflow and other data for a further 18 years. It was found that the hydrological model was able to simulate snowpack and streamflow data for the total period of 96 years of available atmospheric model output with good success. This method provides the opportunity for analysis of water resources systems under alternative climate and land-use scenarios.

ISSN:0262-6667    

DOI:10.1080/02626669809492134

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

This study illustrates the association between annual and seasonal streamflow characteristics on six Costa Rican rivers and the Southern Oscillation Index (SOI). Annual discharge from rivers within the Pacific watershed are clearly positively associated with contemporary values of the SOI and experience significant reductions in both mean and variance in El Ninõ years. The considerable practical implications of this finding to a country in which over 60% of national electrical power comes from hydroelectric schemes is illustrated using quantile estimates from various models. Rivers draining towards the Caribbean show less clear and coherent patterns of associations. The observed associations with seasonal flows on some rivers appear to be the opposite of those on the Pacific, and may even vary during the course of a year at a site. The exact nature of the response seems to be closely related to the elevation of the gauge site. The larger the proportion of the basin at elevations above about 500–1000 m the greater the similarity to the Pacific pattern, suggesting that the marked topographic divide between the two coastal watersheds does not correspond to the divide in associations between streamflow and the SOI.

ISSN:0262-6667    

DOI:10.1080/02626669809492135

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

Both the theoretical basis of a distributed approach to sediment delivery and its agreement with basin sediment yield measurements are tested. At first, by using morphological data of five Apulian and four Calabrian basins, the applicability of a theoretically-based relationship for evaluating the sediment delivery ratio of each morphological unitSDRh, into which a basin is divided, is verified. Using the morphological data of the nine investigated basins, the sediment delivery relationship, i.e. the relationship of the basin sediment delivery ratioSDRWandSDRh, is tested. The analysis showed that the relationships, proposed by Ferro (1997), establishing the dependence of theacoefficient of the sediment delivery relationship on the median travel time and on a drainage density index are yet applicable. The influence of the scale of the basin topographic map on the sediment delivery distributed approach is also studied. The analysis showed that the ratio between theacoefficient and the median travel time is scale-invariable while the link between the coefficientaand the drainage density index has to be re-calibrated because the drainage density index is dependent on the map scale used. Finally, the predictive capability of the sediment delivery distributed model is validated using the sediment yield measurements carried out in three small Calabrian basins and in the Apulian Triolo basin. The analysis showed that the model accuracy is dependent on the temporal scale used and the model reliability increases from the event to the annual scale.

ISSN:0262-6667    

DOI:10.1080/02626669809492136

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

In this study we present the results of the comparison of three different algorithms: the Genetic Algorithm coupled with Sequential Quadratic Programming (GA-SQP), the Pattern Search also coupled with SQP (PS-SQP) and the Shuffled Complex Evolution (SCE-UA). The analyses were conducted using a conceptual rainfall-runoff model applied both to a single basin and to a complex basin. For both types of basin, a theoretical case without model and data errors was considered, in which the true values of the parameters are knowna priori, and several real-world cases where model and data errors exist. With reference to the single basin, the SCE-UA algorithm was the most reliable while the other two algorithms gave solutions equivalent to those of the SCE-UA in the theoretical case, but in the real-world cases they showed an increasing tendency (particularly the PS-SQP) to be trapped in local minima. With reference to the complex basin, none of the three algorithms identified the exact solution in the theoretical case. However, the SCEUA was the one which systematically approximated it better than the others. In the real-world case its solutions were stable but characterized by many parameter values set at the boundary of their own range. The other two algorithms produced a very unstable set of parameters.

ISSN:0262-6667    

DOI:10.1080/02626669809492137

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

The impact of various water management alternatives, resulting from the construction of the La Vinuela reservoir system (Málaga, Spain), on the hydrological regime of the coastal aquifer of the Vélez River has been analysed. In particular, steady-state simulations of the freshwater regime have been carried out under various possible management policies for this reservoir system. For this purpose, a finite element model was used, which was designed to take into account the relationship between the groundwater and surface water, the different hypotheses for the mixture of freshwater and saltwater, and the special treatment of the open boundaries of the aquifer at the coastline. The simulations consider average freshwater inputs as well as different water management and exploitation alternatives for surplus and deficit of freshwater. The accomplished simulations provide the phreatic levels, the active drainage network and the thicknesses of freshwater and saltwater as a result of the advance of the saltwater interface. The results of the simulations appear to be reliable according to the existing experimental data on the region. The simulation alternatives illustrate the main limitations of the aquifer for storing and transmitting freshwater, and preventing the advance of saltwater intrusion resulting from the exploitation by pumping in wells and water management policies in the La Vinuela reservoir system.

ISSN:0262-6667    

DOI:10.1080/02626669809492138

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor

摘要:

An integrated model is developed for short-term yearly reservoir operation for irrigation of multiple crops. The model optimizes a measure of annual crop production, starting from the current period in real time. Reservoir storage at the beginning of a period, inflow during the previous period, crop soil moisture values and crop production already achieved up to the beginning of the period are used as inputs to the model. The solution specifies the reservoir release and optimal irrigation allocations to individual crops during an intra-seasonal period. The model overcomes some of the limitations of an earlier model developed by Mujumdar & Ramesh (1997) by replacing the two dynamic programming (DP) formulations with a single linear programming (LP) formulation. Application of the model is studied through a case study in India.

ISSN:0262-6667    

DOI:10.1080/02626669809492139

出版商:Taylor & Francis Group    

年代:1998

数据来源: Taylor