摘要:

AbstractDepletion and recharge dynamics of soil water were studied at two forest sites in Northern and Southern Sweden during three growing seasons. At each site, having a stand of Norway spruce (Picea abies(L.) Karst), soil water potential was measured with 90 gypsum blocks in 30 profiles at depths of 6, 20, and 50 cm from the soil surface. The size of the rectangular plots was 250 m2. The large variation in soil water potential during desiccation periods extended throughout the measuring range of the gypsum blocks. The soil water potentials, at different times and depths, were log‐normally distributed during only parts of the desiccation periods. Due to the large variation and skewed distribution of soil water potentials the nonparametric Spearman rank correlation statistics was used to analyse the pattern of desiccation and rewetting of the soil.In the beginning of a dry period the topsoil was more efficiently desiccated than the subsoil at both sites. This difference lasted throughout all droughts at the southern site and was explained by a higher root density in the topsoil. At the northern site, however, there was no difference in the degree of desiccation at different soil depths during an extended desiccation period. While certain microsites tended to be more depleted than others during desiccation periods, this did not prove to be significantly correlated to the rewetting of the soil after the different droughts. There was a vertical relationship in soil water desiccation in which an accentuated water depletion at the 6 cm soil depth was followed by a similar strong depletion 14 cm lower in the same observation profile. Strongly desiccated observation profiles were not necessarily situated close to each other but seemed randomly spread over the site. There was no relationship between extracted water at any of the three soil depths in the different observation profiles and proximity to trees or tree siz

ISSN:0885-6087    

DOI:10.1002/hyp.3360040302

出版商:John Wiley&Sons, Ltd    

年代:1990

数据来源: WILEY

摘要:

AbstractField instrumentation was designed and installed to quantify the influence of forest interception on the spatial and temporal distribution of water fluxontoandintothe forest soil at the plot scale. An application is presented which demonstrates that the instrumentation has the required resolution to monitor the spatial variability and dynamics of the flux processes. The observations show that spatial variability of interception may play an important role, not only in small scale soil moisture heterogeneity, but also in the hydrological response of a forested catchment at the hillslope scale. They also highlight the need of gathering more field information on the effects of vegetation on the spatial variability of soil surface water input.

ISSN:0885-6087    

DOI:10.1002/hyp.3360040303

出版商:John Wiley&Sons, Ltd    

年代:1990

数据来源: WILEY

摘要:

AbstractDissolved organic carbon (DOC) was measured at hourly or two‐hourly intervals during more than 30 events in one forested and two moorland subcatchments of the Loch Fleet catchment in southwest Scotland. The dominantly peaty soils in the catchments resulted in small discharge‐related DOC variations within individual events, with a maximum range of about 2 mg 1−1. Seasonal variations were larger with an amplitude of 8‐9 mg 1−1and maximum concentrations in the summer months. The forested stream had the highest mean DOC, twice as large as the comparable moorland stream in the preliming phase. Applications of lime to the catchments increased stream DOC concentrations, with the largest increases in the moorland c

ISSN:0885-6087    

DOI:10.1002/hyp.3360040304

出版商:John Wiley&Sons, Ltd    

年代:1990

数据来源: WILEY

摘要:

AbstractSeasonal soil water dynamics were measured on a hillslope transect in the jarrah forest of southwest Western Australia over the period 1984‐86 using mercury manometer tensiometers, gypsum blocks, and a neutron moisture meter. The soil water potential gradients indicated downward vertical drainage flux through winter and spring. There was generally a change to an upwards flux in early summer which was sustained through to autumn. A shallow ephemeral saturation zone was identified in and above a duricrust layer, lasting up to three days after heavy, late winter rainfall. The annual maximum to minimum unsaturated soil water storage on the hillslope was approximately 400 mm to 6 m depth and 480 mm to 15 m depth. This did not change significantly in years of substantially different winter rainfall. The magnitude of seasonal soil water storage was similar to other forested areas with deep soil profiles. The depth of observable infiltration was dependent on annual rainfall. This was consistent with the observation that groundwater levels responded to rainfall over the whole hillslope in wet years but only responded on the lower slopes in dry years. The average summer drying rate of the soil profile to 6 m depth of 3.5 mm day−1was within the range of values reported for forests elsewhere. In late summer, following an extended drought period, the drying rate decreased downslope but increased midsl

ISSN:0885-6087    

DOI:10.1002/hyp.3360040305

出版商:John Wiley&Sons, Ltd    

年代:1990

数据来源: WILEY

摘要:

AbstractSeasonal soil water dynamics were measured at a fine‐textured, upslope site within the jarrah forest of southwest Western Australia and compared to the results from a coarse‐textured hillslope transect. Gravity drainage dominated during winter and early spring. This reversed in early summer and an upward potential gradient was observed to 7 m depth. A shallow ephemeral saturation zone was observed above a clay pan at 1.5 m depth. This saturation zone persisted through late winter and early spring, contrasting with the short‐lived saturation in the duricrust on the hillslope transect. The annual maximum to minimum unsaturated soil water storage was about 530 mm, 50 mm greater than the hillslope transect and higher than most values reported elsewhere in Australia. Significant soil water content changes following winter rain were generally restricted to 6 m but at one site occurred to 9 m. These depths were significantly less than the coarser‐textured hillslope transect. Soil water drying rates averaged 5 mm day−1during extended dry periods compared to 3.5 mm day−1on the hillslope transect. The drying rate occurred uniformly through the profile until late summer when a significant decrease in the upper 3 m w

ISSN:0885-6087    

DOI:10.1002/hyp.3360040306

出版商:John Wiley&Sons, Ltd    

年代:1990

数据来源: WILEY

摘要:

AbstractA two‐dimensional finite element model for density dependent groundwater flow was calibrated to simulate sea water intrusion in Nauru Island in the Central Pacific Ocean. Nauru Island occupies an area of 22 km2and supports a population of 8500. The island has been mined for its phosphate deposits and current reserves indicate that the mine has about eight years life remaining. The water supply of the island is about one third dependent on imported water which is also used as ballast on the phosphate ships. Imported water will not be available in the future, and a hydrogeological investigation shows that the island is underlain by a fresh water layer, less than 5 m thick. The freshwater layer overlies a thick transition zone of brackish water which in turn overlies sea water. Simulation of several management options shows that it is possible to substitute current importation of fresh water by careful extraction from the groundwater resources of the islan

ISSN:0885-6087    

DOI:10.1002/hyp.3360040307

出版商:John Wiley&Sons, Ltd    

年代:1990

数据来源: WILEY

摘要:

AbstractA single large volume water sample taken at the mouth of the Upper Rhone River on Lake Geneva was processed directly in parallel through two continuous flow centrifuges, a Westphalia and an Alfa‐Laval. Sediment was recovered from the Westphalia, and separately from the bowl and brass core of the Alfa‐Laval. The three sediment samples were analyzed for particle size and the following elements: Zn, Cu, Mn, Cr, P, Co, B, V, Be, Sr, Na, Pb, Ni, Ba, Fe, Ca, and Mg. Results indicate that the particle size recovery of both machines is similar when sediment from the brass core and bowl of the Alfa‐Laval are combined, and that the recovery for all elements other than Cu, V, B, and Pb are the same when the particle size differences are taken into account. Sediment from the Alfa‐Laval brass core is clearly contaminated by Cu, B and is also elevated in V and Pb but not to a significant extent. The sediment recovered from the bowl of the Alfa‐Laval is contaminated only with Cu, with a 10 ppm increase over the 52 ppm recovered in the Westphalia sediment. Operating procedures involve the discarding of the brass core sediment and the mixing of the Alfa‐Laval bowl sediment with that from the Westphalia. The consequent increase in Cu is estimated at less than 5 ppm or within the confidence level of the analysis. These procedures are recommended to all operators of non modified Alfa

ISSN:0885-6087    

DOI:10.1002/hyp.3360040308

出版商:John Wiley&Sons, Ltd    

年代:1990

数据来源: WILEY

摘要:

AbstractThe heat pulse method was used to estimate stand transpiration from a radiata pine (Pinus radiata) plantation in southeastern Australia over a period of four days. The diurnal pattern of sapflow was related to net radiation with a time lag of about 1.5 hours. Despite high soil moisture levels, sapflow did not keep up with evaporative demand in the afternoon. Sapflow estimates of transpiration exceeded estimates for evaporation based on Bowen ratio measurements for all four days of the study.

ISSN:0885-6087    

DOI:10.1002/hyp.3360040309

出版商:John Wiley&Sons, Ltd    

年代:1990

数据来源: WILEY

ISSN:0885-6087    

DOI:10.1002/hyp.3360040301

出版商:John Wiley&Sons, Ltd    

年代:1990

数据来源: WILEY