摘要:

This paper briefly summarizes the results of a four-year research project carried out for the Federal Ministry of Agriculture and Forestry in Vienna, Austria. The main objective was the development of a deterministic model for the estimation of the distribution of extreme precipitation in complex terrain. The orographic component of precipitation is conceptually divided into a part directly generated by dynamic uplift and a part originating from convective activity. The model for the first type of precipitation enhancement is based on the theory of linear two-dimensional air flow over mountains. A dynamically consistent flow field and explicit simulation of the seeder-feeder mechanism are the main improvements compared to an earlier version of this model (Haidenet al., 1990). The assessment of convective precipitation is based on a new parameterization using results of an analytical model of thermally induced upslope flow. A comparison of model results with observations shows reasonable agreement regarding the structure of the precipitation fields.

ISSN:0262-6667    

DOI:10.1080/02626669209492609

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

The method of regularization for estimating unit hydrographs is expanded to allow the inclusion of prior information about the unit hydrograph shape. This may give smooth estimates without any loss in volume. The method is illustrated with prior information from a regression on catchment characteristics and with catchment lag determined from the data. A computer program to implement the method is given together with a sample calculation.

ISSN:0262-6667    

DOI:10.1080/02626669209492610

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

The method of regularization with additional information proposed by the authors is evaluated in a split sample test which compares it with the least squares and ordinary regularization methods. Data from 30 catchments are used. Additional information is provided by a simple conceptual model either fitted by a regression on physical characteristics of the catchment or fitted to the catchment lag determined from the data. The method is very useful when only a few rainfall/runoff events are available for analysis. When a large number of events is available, the ordinary regularization method is sufficient.

ISSN:0262-6667    

DOI:10.1080/02626669209492611

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

From 1967 until 1986, uranium mine dewatering increased dissolved gross alpha, gross beta, uranium and radium activities and dissolved selenium and molybdenum concentrations in the Puerco River as indicated by time trends, areal patterns involving distance from the mines and stream discharge. Additionally, increased dissolved uranium concentrations were identified in groundwater under the Puerco River from where mine discharges entered the river to approximately the Arizona-New Mexico State line about 65 km downstream. Total mass of uranium and gross alpha activity released to the Puerco River by mine dewatering were estimated as 560 Mg (560 × 106g) and 260 Ci, respectively. In comparison, a uranium mill tailings pond spill on 16 July 1979, released an estimated 1.5 Mg of uranium and 46 Ci of gross alpha activity. Mass balance calculations for alluvial ground water indicate that most of the uranium released did not remain in solution. Sorption of uranium on sediments and uptake of uranium by plants probably removed the uranium from solution.

ISSN:0262-6667    

DOI:10.1080/02626669209492612

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

A conceptual basin model of the instantaneous unit sediment graph was developed for sediment graph prediction from arid upland basins by routing mobilized sediments through a series of linear reservoirs. The sediment graphs generated by convolution of the instantaneous unit sediment graph compared reasonably well with the observed ones for four representative arid upland sub-basins in the Luni basin, India. The mobilized sediment during a storm was related to effective precipitation and the parameters of the model were estimated from observed events. The model can be applied to ungauged flow events through parameterization.

ISSN:0262-6667    

DOI:10.1080/02626669209492613

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

Field data on drainage basin response have a characteristic scale which is determined by the size of the basin investigated. As a rule, information obtained at one particular scale can be extrapolated over a limited scale range only. This study identifies the nature of constraints on spatial scale transference in a series of semiarid badland drainage basins ranging in area from < 1 to 202 260 m2. Research focussed on the rainfall-runoff relationship during a single rainstorm so that the temporal scale was kept constant. Spatial scale transference between systems of differing scale was restricted by morphological and functional constraints. Morphological constraints are caused by morphological elements present in large scale systems but absent in small scale ones. Functional constraints arise solely from the characteristics of the matter and energy flows in the systems of interest. Limits imposed upon spatial scale transferences by morphological and functional constraints are fuzzy rather than sharp in character.

ISSN:0262-6667    

DOI:10.1080/02626669209492614

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

The new Swedish guidelines for the estimation of design floods for dams and spillways are presented, with emphasis on high-hazard dams. The method is based on a set of regional design precipitation sequences, rescaled for basin area, season and elevation above sea level, and a full hydrological model. A reservoir operation strategy is also a fundamental component of the guidelines. The most critical combination of flood generating factors is searched by systematically inserting the design precipitation sequence into a ten year climatological record, where the initial snowpack has been replaced by a statistical 30-year snowpack. The new guidelines are applicable to single reservoir systems as well as more complex hydroelectric schemes, and cover snowmelt floods, rain floods and combinations of the two. In order to study the probabilities of the computed floods and to avoid regional inconsistencies, extensive comparisons with observed floods and frequency analyses have been carried out.

ISSN:0262-6667    

DOI:10.1080/02626669209492615

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

摘要:

The recently developed guidelines for design flood calculation in Sweden are based on simulation with a hydrological model. Several meteorological and hydrological conditions are prescribed as input to the model. The sensitivity of the floods according to the new guidelines with respect to those prescriptions is checked as well as the sensitivity to the modelling procedure. In this paper, the HBV hydrological model is used. It is shown that the most sensitive input factor is the design 14-day precipitation sequence. For autumn floods, the scaling relation between the precipitation sequence and the generated floods is in the order of 1:1. For spring floods on the other hand, snowmelt influences the flood magnitude and reduces the sensitivity to precipitation to about 1:0.6. Soil moisture modelling was important in basins with high evapotranspiration. Model calibration could have a large effect on the design flood magnitude. The most sensitive parameter was the high flow recession coefficient,K0. The water stage development in a multi-reservoir system is further influenced by the regulation strategy and spillway capacity. An increased spillway capacity can improve the situation considerably for a particular dam but could at the same time worsen the situation for downstream dams. After the filling of the reservoir there was a clear relation between inflow peak and maximum water stage. The study shows that it is difficult to assess the integrated effects of extreme precipitation, snowmelt, soil moisture status and regulation in a system beforehand.

ISSN:0262-6667    

DOI:10.1080/02626669209492616

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

ISSN:0262-6667    

DOI:10.1080/02626669209492617

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor

ISSN:0262-6667    

DOI:10.1080/02626669209492618

出版商:Taylor & Francis Group    

年代:1992

数据来源: Taylor