摘要:

AbstractThe processes of stormflow generation were studied in a hill pasture catchment near Hamilton, New Zealand. Although rainfall was relatively evenly distributed throughout the year, stormflow was highly seasonal and over 65 per cent occurred during the winter. Three main processes contributing to stormflow were identified which could be related to soil type and physiographic position. On gleyed soils derived from rhyolitic colluvium, saturation overland flow was the dominant process. Hydrographs from ‘Whipkey’ throughflow troughs also indicated that there was a subsurface response (saturated wedge) from this soil type. On steeper convex slopes, more permeable soils were derived from weathered greywacke. The presence of ephemeral springs on the hillslopes and direct observation during storm events indicated that storm runoff was generated as return flow from this soil.It was noted that nitrate concentrations from subsurface sources were 5–10 times higher than surface runoff. This difference in concentration was utilized in a chemical mixing equation which partitioned stormflow sources. This was compared with the stormflow predicted from rain falling on to saturated areas. There was good agreement between the two models for winter‐spring events with respect to the volumes of surface runoff predicted, however the saturated areas model underestimated total stormflow.The results of the study are briefly discussed in terms of the potential for water quality man

ISSN:0885-6087    

DOI:10.1002/hyp.3360020202

出版商:John Wiley&Sons, Ltd    

年代:1988

数据来源: WILEY

摘要:

AbstractThe management of the riparian zone has been suggested as a technique for controlling the amounts of phosphorus (P) entering watercourses draining pasture catchments. A study was therefore made of P entering a stream from various sources (rainfall, surface and subsurface derived runoff, direct fallout from aerial topdressing), with the object of providing a rational basis for the design of effective riparian management schemes.P entrained in surface runoff could account for virtually all of the P entering the stream during storms. Approximately 20 per cent of the annual P export from the catchment could be accounted for by direct aerial input of P to the stream during autumn fertilizer topdressing. More than 85 per cent of the P was exported from the catchment as particulate P. Stream sediment had higher P sorption capacities, and were enriched with P relative to the soils from which they were derived. There was a pronounced seasonal variation in sediment enrichment which could be predicted (r2= 0.92) by the logarithm of the rainfall since fertilizer topdressing (LNFERT) and flood intensity. The amount of P lost in streamflow during any flood event was predicted (r2= 0.94) by peak flow, seven day antecedent peak flow and LNFERT. Approximately 40 per cent of the 1.3 kg P ha−1exported during 1981 occurred in four storms with recurrence intervals of more than three months. From a P budget compiled from nine events it was hypothesized that the stream acted as a net sink for P at baseflow and low‐medium intensity floods but was a source of P at higher flood intensities.It was concluded that P losses from hill pasture catchments could be reduced by avoidance of direct application of P fertilizer to the stream channel, and by fencing out stock from seasonally saturated areas during periods of saturation. The ultimate success of the latter technique would depend on whether buffer vegetation could retain accumulated P during extreme storm eve

ISSN:0885-6087    

DOI:10.1002/hyp.3360020203

出版商:John Wiley&Sons, Ltd    

年代:1988

数据来源: WILEY

摘要:

AbstractA study was made of the nitrogen (N) inputs to, and exports from, a stream draining a pasture catchment near Hamilton, New Zealand, in order to plan measures for minimizing N losses to natural waters.An estimated 7 kg N ha−1was exported from the catchment during 1981 of which 86 per cent was in reduced forms (Kjeldahl‐N, TKN) and the remainder as nitrate‐N (NO3‐N). Virtually all of the reduced N inputs came from saturated overland flow whereas NO3‐N inputs were dominantly subsurface derived. The TKN exported by individual storm events could be predicted (R2= 0.97) from peak flow and from the peak flow rate in the seven days preceding the storm. A TKN balance for eight events showed that except for large floods (return period approximately a year) the stream system was a net sink for TKN. During large floods, scouring of the organic rich seepage areas resulted in the stream system itself being a net source of TKN.Microbial assays for nitrification and denitrification activity indicated that the main nitrate source was the well‐aerated greywacke and ash soils and that the permanently saturated seepage zones were a significant nitrate sink. An in‐stream nitrate addition experiment showed that up to 20mg N m−2h−1was removed from the stream. Simultaneous measurements ofin situdenitrification activity demonstrated that only about 1 per cent of this removal could be accounted for by denitrification. It was inferred that plant uptake was responsible for the remainder.Retention of near‐stream seepage areas is suggested as a measure for minimizing NO3‐N export, whilst removal of stock from seasonally saturated areas during periods of saturatior should reduce soil loss and hence TKN

ISSN:0885-6087    

DOI:10.1002/hyp.3360020204

出版商:John Wiley&Sons, Ltd    

年代:1988

数据来源: WILEY

摘要:

AbstractThree instruments recently developed for use in the Runoff Formation Laboratory of the Institute of Geography, Academia Sinica are briefly described. The experimental data obtained indicate that all of them meet the design requirements and they are being successfully used in the Laboratory.

ISSN:0885-6087    

DOI:10.1002/hyp.3360020205

出版商:John Wiley&Sons, Ltd    

年代:1988

数据来源: WILEY

摘要:

AbstractVariations in the concentration of Cl in rainfall and stream runoff are presented for two catchments in the Hafren forest of mid‐Wales, Great Britain. Despite the large fluctuations in rainfall concentrations, Cl in the streamwater remains relatively constant. Using the two‐reservoir Birkenes model, an attempt was made to simulate observed Cl in streamwater. The original model was unable to reproduce the observations and several modifications are suggested to provide better simulations. The resulting model is not the only one capable of reproducing the observations; other hydrochemical models will most probably also achieve this although emphasis will in each case be placed on different aspects. In this paper, it is suggested that the stochastic properties of water movement and chemical processes can account for the streamwater chemistry responses observed. On the catchment scale these processes will lead to an apparently deterministic behaviour that may well be described by simple relationsh

ISSN:0885-6087    

DOI:10.1002/hyp.3360020206

出版商:John Wiley&Sons, Ltd    

年代:1988

数据来源: WILEY

摘要:

AbstractA model for quantitatively expressing the hydrological cycle in a forested mountain catchment is proposed as a HYCYMODEL. HYCYMODEL is able to predict both short‐ and long‐term hydrographs because the model parameters remain independent of time. It shows a good applicability for ten years of continuous data at both hourly and daily intervals for the Kiryu catchment—a forested mountain basin. Since HYCYMODEL does not need hydrograph separation between storm flow and base flow, it is a particularly attractive

ISSN:0885-6087    

DOI:10.1002/hyp.3360020207

出版商:John Wiley&Sons, Ltd    

年代:1988

数据来源: WILEY

摘要:

AbstractNumerical models for simulation of multidimensional unsaturated flow are becoming increasingly available, but relatively little has been reported on the detailed analysis of numerical errors associated with such schemes. For unsaturated‐saturated flow, further complexity is introduced to the highly non‐linear unsaturated problem as the form of governing equation changes within the flow field. In this paper, two‐dimensional simulation of infiltration to a water table is considered. Numerical errors associated with selection of time step, grid geometry, convergence criteria, and the representation of internodal hydraulic conductivity are discussed with respect to moisture content profiles and mass balance error. Although solution sensitivity to numerical parameters is problem specific, the results presented indicate the nature and magnitude of numerical effects which should not be overlooked in model applica

ISSN:0885-6087    

DOI:10.1002/hyp.3360020208

出版商:John Wiley&Sons, Ltd    

年代:1988

数据来源: WILEY

ISSN:0885-6087    

DOI:10.1002/hyp.3360020209

出版商:John Wiley&Sons, Ltd    

年代:1988

数据来源: WILEY

ISSN:0885-6087    

DOI:10.1002/hyp.3360020201

出版商:John Wiley&Sons, Ltd    

年代:1988

数据来源: WILEY