摘要:

Real-time flow hydrograph forecasting models have been operational in Poland as a routine service since 1975. A trend in recent years is a shift away from complex conceptual catchment models to simple ones of the storage function type. Another approach has been to forecast the mass flow curve (S-curve) using an ARMA-type model the parameters of which are estimated via a linear Kalman filter algorithm. Examples are shown of the application of the latter approach to models of both the rainfall-runoff category and the channel routing category including estimation of ungauged lateral inflow in the latter models. Previous experience with the application of a linear Kalman filter to flow hydrograph forecasts is discussed. Derivation of the forecast flow hydrograph from the S-curve is done by converting flow volume increments into flow discharges assuming a linear shape for the flow hydrograph within the time step and a trend corresponding to the last observed trend. In the vicinity of the hydrograph peak, the forecast flow values are computed by means of a flood wave equation developed by Strupczewski (1964).

ISSN:0262-6667    

DOI:10.1080/02626668609491050

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

In the first of two papers the development of two statistical tests of region homogeneity for use in regional flood frequency analysis is described and the properties of the test statistics are examined. The preferred test is based on the distribution function of the regional parent and its power is shown to depend on region size, record length and choice of parent distribution.

ISSN:0262-6667    

DOI:10.1080/02626668609491051

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

The homogeneity statistic developed in the previous paper (Wiltshire, 1986) is applied here to geographical regions and to clusters of basins formed in a flow-statistic dataspace. Clusters are seen to offer several advantages over geographical regions and they are interpreted in terms of basin characteristics through the use of a multivariate linear discriminant analysis. The discriminant scores of each basin based on basin characteristics can be used to assess the performance of the original independent classification based on flow statistics. An ungauged basin for which a design flood is required can have a fractional membership of more than one cluster, and the desired quantile can then be estimated as a weighted average of quantile estimates from each cluster. Experiments with hypothetical ungauged basins show that the allocation of basins to clusters is in accord with physical reasoning.

ISSN:0262-6667    

DOI:10.1080/02626668609491052

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

Studies were conducted during the years 1977–1982 to determine the moisture and thermal regimes of the desert soils of western Rajasthan (India) and their management for better plant production. The results showed that during the high rainfall year of 1977 (628 mm) about 50% of the rainfall percolated down a 900 mm soil profile at Palsana, leading thereby to low moisture regimes and a moisture utilization by the the grass vegetation of only 276–294 mm. Wide variations in diurnal soil temperatures ranging from 28°C to 56°C at the surface and from 33°C to 37°C at 300 mm depth were observed at Jodhpur leading thereby to downward movement of moisture during the day-time (1400 h) and upward during the nighttime (0400 h). The moisture movement was predominantly in the vapour phase as observed by higher values of thermal vapour diffusivity. The monthly variations in soil temperature controlled the movement of moisture which was observed by the increase in the profile moisture storage during the winter month of December at Beechwal and Palsana. An integration of management techniques such as a subsurface moisture barrier of pond sediments, water harvesting, and the use of pond sediments and farmyard manure, increased the initial moisture storage of the 600 mm soil profile from 73 to 91 mm. It also significantly increased the height, canopy diameter and dry matter production of pruned material of Acacia tortilis tree seedlings from 980 to 1750 mm, from 594 to 1100 mm, and from 40.6 to 123.5 g respectively.

ISSN:0262-6667    

DOI:10.1080/02626668609491053

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

Soil physical studies were carried out in the black cotton soil areas of the Betwa basin, central India, to assess their role in partitioning monsoon rainfall into runoff and groundwater recharge. The regional and annual variations of soil moisture were studied first, followed by studies of the soil water flow mechanisms at representative sites. Measurements of soil water content were made by neutron probe and of soil water potential by porous pot tensiometer. Unsaturated conductivity characteristics were determined by the “instantaneous profile method”. Dry season recharge and evaporation were calculated by the zero-flux plane method. The studies suggested that significant recharge is possible only in the shallow soil areas, where structured clay/silts directly overlie the weathered basalt containing the surface aquifer.

ISSN:0262-6667    

DOI:10.1080/02626668609491054

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

As part of a wider study of the Betwa basin, central India, estimates of rainfall, potential transpiration, soil moisture and groundwater storage, and river flow are available for the Nion catchment in 1978 and 1979. These show that net rainfall is divided between soil moisture storage, groundwater storage and runoff in a sequence which is similar in 1978 with rainfall above average and in 1979 when rainfall was well below average. The knowledge acquired in process studies is incorporated in a conceptual model which reproduces reasonably not only the runoff but also the water stored in the catchment.

ISSN:0262-6667    

DOI:10.1080/02626668609491055

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

Methods of assessing the goodness-of-fit of hydrological simulation models are discussed. The methods generally compare the goodness-of-fit of a simulated hydrograph with an observed one and invariably have a bias towards one or another aspect of the hydrograph. It appears that no single parameter is sufficient to assess adequately the overall measure of fit between a computed and an observed hydrograph, particularly in view of the many objectives behind hydrological modelling. Previous research has concentrated on assessing the goodness-of-fit of long duration hydrographs resulting from continuous simulation. This paper discusses a number of criteria for hydrograph comparison in single event modelling studies and applies them to a specific stormwater modelling exercise. It is shown that particular criteria highlight particular aspects.

ISSN:0262-6667    

DOI:10.1080/02626668609491056

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

Hydrogeological parameters of an aquifer change by diagenetic processes due to water-rock interaction. The clay fraction which exists in the matrix of sedimentary aquifers even in minute quantity has great importance in these processes. The resulting change may influence the flow regime. One of the zones most affected by diagenesis is where two chemically different types of water meet. Numerous coastal aquifers, including the one in Israel, contain chemically different types of water, and, consequently, many interfaces. The degree of alteration of hydrogeological parameters was studied in the laboratory under the extreme conditions of a seawater/fresh-water interface; where a large decrease of hydraulic conductivity was observed. One can use the findings of this laboratory study in building a model of prediction for the influence of water-rock interaction on the flow in other interfaces of an aquifer.

ISSN:0262-6667    

DOI:10.1080/02626668609491057

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

Lake-sediment-based estimates of sediment yield are calculated from a210Pb and137Cs chronology for the period 1765–1983 for a small lake-catchment in the English Midlands. Based on a multiple coring exercise, synchronous sedimentation levels are identified on the basis of mineral magnetism because of the lack of a visual stratigraphy. The rates of sediment accumulation are adjusted for outflow losses, biogenic precipitation and atmospheric fallout and results are considered to reflect accurately sediment yields for the area. At best, these yields are averaged over 4–5 years in the recent past, and 50–60 years in previous centuries. It is suggested that analysis of sediment yields over the last 218 years provides data covering one of the most dramatic periods of change as a result of human activity and covers intermediate timescales often ignored in hydrological studies because they fall beyond the scope of direct process monitoring.

ISSN:0262-6667    

DOI:10.1080/02626668609491058

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

ISSN:0262-6667    

DOI:10.1080/02626668609491059

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor