摘要:

This paper describes a stochastic rainfall model which has been developed to generate synthetic sequences of hourly rainfalls at a point. The model has been calibrated using data from Farnborough in Hampshire, England. This rainfall data series was divided into wet and dry spells; analysis of the durations of these spells suggests that they may be represented by exponential and generalized Pareto distributions respectively. The total volume of rainfall in wet spells was adequately fitted by a conditional gamma distribution. Random sampling from a beta distribution, defining the average shape of all rainfall profiles, is used in the model to obtain the rainfall profile for a given wet spell. Results obtained from the model compare favourably with observed monthly and annual rainfall totals and with annual maximum frequency distributions of 1, 2, 6, 12, 24 and 48 hours duration at Farnborough. The model has a total of 22 parameters, some of which are specific to winter or summer seasons.

ISSN:0262-6667    

DOI:10.1080/02626669009492414

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

Regional flood frequency entails the pooling of data from sites within a defined region to enhance the estimation of at-site quantiles. Conventional regionalization techniques normally identify a fixed set of stations forming a contiguous region. An approach to regional flood frequency analysis that involves each site having a potentially different set of stations included for the at-site estimation of extremes was compared with a more traditional regionalization technique. The characteristics of the stations identified as being of relevance for the purposes of at-site estimation using the two approaches were contrasted and also the extreme flow values obtained were compared. The results indicated that the region of influence approach results in a group of stations with greater homogeneity than was the case for the regionalization technique and also leads to extreme flow estimates which are more accurate.

ISSN:0262-6667    

DOI:10.1080/02626669009492415

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

The scale-adjusted probability density functions of the two-parameter gamma and the three-parameter beta distributions were shown to fit reasonably well to ten observed unit hydrographs in Anatolia, the gamma exhibiting slightly better fits. As a result, a method making use of this curve is suggested for the synthetic unit hydrograph.

ISSN:0262-6667    

DOI:10.1080/02626669009492416

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

The estimated overall annual runoff for Costa Rica is 2200 mm which corresponds to an outflow of 3557 m3s−1. Gross water utilization by hydroelectricity, irrigation, navigation and potable-industrial uses has increased significantly during recent decades. During the period 1970–1987 the percentage of available water used doubled from 6% to 12%. An estimate for the year 2000 indicates that the degree of gross water utilization will increase to about 20%. Water resources availability, therefore, is not a problemper se.There are, however, water scarcity and allocation conflicts due primarily to water pollution and uneven water distribution in time and area. Specific environmental and policy issues are discussed. Among these are the lack of institutional coordination, inadequate water legislation, accelerated environmental degradation and absence of watershed management programmes. A significant change in the national policy toward natural resource management has taken place in the last two years with the creation of the new Ministry of Natural Resources and the development of the National Strategy for Sustainable Development. These changes in policy are giving an opening for a new water resources management response that, in conjunction with other productive sectors such as energy, agriculture and forestry, will lead to a sound approach in the planning and management of the resource. Multilateral and bilateral development agencies, as well as international private and voluntary organizations sponsoring development activities in the country, must support the implementation of this National Strategy so that the desired objectives may be accomplished.

ISSN:0262-6667    

DOI:10.1080/02626669009492417

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

Proceeding from the well-known infiltration model by Mein & Larson (1973) and several extensions, explicit equations for time-dependent infiltration rate and cumulative infiltration are proposed in this paper. Although the time-range of validity is limited due to the chosen mode of derivation, the formulae seem well suited for application in the course of storm runoff modelling for small catchments. Major advantages of the proposed equations are constituted by the comparatively simple structure and by a high degree of versatility allowing a considerable number of effects to be explicitly accounted for. The parameters involved can be identified from measurements. Rules of thumb regarding the range of applicability are given.

ISSN:0262-6667    

DOI:10.1080/02626669009492418

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

摘要:

The amount of groundwater recharge to an aquifer depends on the amount of precipitation and its seasonal distribution, the air temperature, the land use, and other factors; direct measurements of the recharge components are not possible. Because of these factors, determining the recharge to aquifers is a difficult problem in all water resource studies. A project for determining quantitative groundwater recharge is illustrated by the computation of the groundwater balance of the Kirkgöz springs area in the Mediterranean region of Turkey.

ISSN:0262-6667    

DOI:10.1080/02626669009492419

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

ISSN:0262-6667    

DOI:10.1080/02626669009492420

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

ISSN:0262-6667    

DOI:10.1080/02626669009492421

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

ISSN:0262-6667    

DOI:10.1080/02626669009492422

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor

ISSN:0262-6667    

DOI:10.1080/02626669009492423

出版商:Taylor & Francis Group    

年代:1990

数据来源: Taylor