A MONTHLY WATER BALANCE MODEL INCLUDING DEEP INFILTRATION AND CANAL LOSSES / Un modèle mensuel du bilan hydrologique inclusive l'infiltration profonde et les pertes des canaux

Abstract

A monthly water balance model is being successfully applied to the Grote Nete test basin (553 km²) in the North of Belgium. This low region has a complex geological structure, its boundaries are more or less unknown and deep infiltration into a deep aquifer is most likely to occur. Moreover, the area is crossed by several navigation canals which import and export an unknown volume of water.

The inputs are monthly precipitation and Penman potential evapotranspiration values. The model computes actual evapotranspiration, water storage in the basin, direct runoff and infiltration, baseflow and total stream discharge, deep infiltration loss into the underlying aquifer and constant seepage from the canals. The ‘pattern search’ procedure has been used for automatic optimization of the six model parameters. All parameters have a physical meaning and can be evaluated initially.

For the calibration period 1967–1972, total stream discharge has been calculated with a precision of 0.2 per cent compared to total measured volume. The correlation coefficient is 92 per cent for the same calibration period. Prediction for the period 1973–1974 gave a volume precision of 8.7 per cent and a correlation coefficient of 93 per cent.     

The effects of climate variability on discharge as dependent on catchment characteristics in the Upper Loire basin,France

Abstract

The effects of climatically deviating periods of at least four years on discharge were investigated employing flow duration curves in the Upper Loire basin, France. The periods were determined using the standardized cumulative yearly deviation from the mean precipitation for ten climate stations. Flow duration curves from 27 catchments were determined and parameterized for each period. Results show that the effect of precipitation on discharge is more pronounced than the effect of temperature. They also show that the parameter values that determine the flow duration curve differ significantly between dry and wet periods. Furthermore the effect of drought on discharge is larger than the effect of wetness. Catchments with a high variability of discharge are more sensitive to changes of precipitation than catchments with a low variability of discharge.     

A modern oceanic hardground on the Carnegie Ridge in the eastern Equatorial Pacific

Fossil surfaces of erosion and non-deposition are common in limestone sequences from the Mesozoic in western Europe and in the Tethys and have been described under the name ‘hardgrounds’. They are of shallow water as well as of oceanic origin. A modern example in the Pacific is described in this paper. The Carnegie Ridge, an east-west trending shallow ridge between South America and the Galapagos Islands, has a central, deeper saddle where erosion has removed most of the sediment cover down to a hard chalk and chert bed (acoustic basement), and has cut intricate channel patterns on the south flank and two deep canyons on the north. The erosion has produced a karst-like relief of steep-walled channels, cliffs, and corroded chalk remnants. The floors of the channels are covered with ferromanganese oxide crusts or crust fragments over which loose sediment is being transported. In the two canyons on the north flank, this sediment consists of foraminiferal sand travelling downslope in the form of barchan dunes. All sediment down to acoustic basement has been stripped from the Carnegie Ridge crest except where it is protected behind basement ridges and pinnacles. Surface features of the eroded chalk are strongly reminiscent of features observed in Mesozoic hardgrounds. Current measurements over several days indicate a net northward movement, slow but possibly adequate to keep the sea floor free of fresh deposits. The rates, however, seem inadequate to explain the formation of the deep channels, and there is no evidence for the southward flow which is implied by the southern channel system. A process of combined carbonate dissolution and removal by the current of fresh sediment and dissolution residues can account for the required erosion in about two million years. Regional unconformities identifiable in seismic reflection profiles and dated in cores are of middle to late Pliocene age, suggesting that the formation of the erosion surface began 2-3 million years ago. Buried Miocene unconformities of local extent show that the present erosion period had minor precursors possibly related to short-lived increases in current action and carbonate dissolution.     

Technology transfer in the Clean Development Mechanism

Technology transfer is often mentioned as an ancillary benefit of the Kyoto Protocol's Clean Development Mechanism (CDM), but this claim has hardly been researched or substantiated. The question of technology transfer is important, both for developing countries in need for new technology and knowledge and for industrialized countries, as it provides export potential for climate-friendly technologies. To determine what technology transfer means, whether it is occurring through the CDM, and what the value of the associated capital flows is, this article examines technology transfer in the 63 CDM projects that were registered up until 1 January 2006. Technology hardware originates from outside the host country in almost 50% of the evaluated projects, particularly in non-CO₂ greenhouse gas projects, wind energy projects, and a substantial share of the hydropower projects. Bioenergy and projects in the agricultural sector mainly use local technology. The investment value associated with the CDM projects that transferred technology is estimated to be around €470 million, with about €390 million coming from the EU. As the non-CO₂ greenhouse gas projects had very low capital costs, the investment value was highest in the more capital-intensive wind energy and hydropower projects. We also found substantial soft technology transfer, but uncertainties for this finding are greater.     

SURFACE ROUGHNESS EVOLUTION OF SOILS CONTAINING ROCK FRAGMENTS

Soil surface roughness is a dynamic property which determines, to a large extent, erosion and infiltration rates. Although soils containing rock fragments are widespread in the Mediterranean region, the effect of the latter on surface roughness evolution is yet poorly understood. Therefore, laboratory experiments were conducted in order to investigate the effect of rock fragment content, rock fragment size and initial moisture content of the fine earth on the evolution of interrill surface roughness during simulated rainfall. Surface elevations of simulated plough layers along transects of 50 cm length were measured before and after simulated rainfall (totalling 192.5 mm, I = 70 mm h⁻¹) with a laser microreliefmeter. The results were used to investigate whether systematic variations in interrill surface roughness along stony hillslopes in southeastern Spain could be attributed to rock fragment cover and rock fragment size. Soil surface elevations were measured along the contour lines (50 cm long transects) with a contact microreliefmeter. Roughness was expressed by two parameters related to the height and frequency of roughness elements, respectively: standard deviation of de-trended surface elevations (random roughness: RR), and correlation length (L) derived from exponential fits of the autocorrelation functions. The frequently used assumption that surface roughness (RR) of cultivated topsoils decreases exponentially with cumulative rain is not valid for soil surfaces covered by rock fragments. The RR of soils containing small rock fragments (1.7–2.7 cm) increased with cumulative rainfall after an initial decrease during the first 17.5 mm of rainfall. For soils containing large rock fragments (7.7 cm), RR increased with rainfall above a threshold rock fragment content by mass of 52 per cent. For a given rainfall application, RR increased non-linearly with rock fragment content. The correlation length for soils containing small rock fragments decreases with rock fragment content and is significantly lower than for soils with large rock fragments. Soils covered with small rock fragments (large RR and small L) are thus well protected against raindrop impact by a water film in the depressions between the rock fragments. On abandoned agricultural fields along hillslopes in southeastern Spain, rock fragments cover increases non-linearly with slope owing to selective erosion of finer particles on steep slopes. The increase of surface cover by large rock fragments (>25 mm) is even more pronounced. The simultaneous increase of rock fragment cover and rock fragment size with slope explains the non-linear increase of RR with slope. These relationships differ for soils covered by platy misaschists and those covered with cubic andesites. The variations in correlation length along the hillslopes are not clear, probably owing to a simultaneous increase in rock fragment cover and rock fragment size. These findings may provide a better prediction of soil surface roughness of interrill areas covered by rock fragments using slope angle and lithology.     

ESTIMATING INFILTRATION PARAMETERS FROM BASIC SOIL PROPERTIES

Infiltration data were collected on two rectangular grids with 25 sampling points each. Both experimental grids were located in tropical rain forest (Guyana), the first in an Arenosol area and the second in a Ferralsol field. Four different infiltration models were evaluated based on their performance in describing the infiltration data. The model parameters were estimated using non-linear optimization techniques. The infiltration behaviour in the Ferralsol was equally well described by the equations of Philip, Green–Ampt, Kostiakov and Horton. For the Arenosol, the equations of Philip, Green–Ampt and Horton were significantly better than the Kostiakov model. Basic soil properties such as textural composition (percentage sand, silt and clay), organic carbon content, dry bulk density, porosity, initial soil water content and root content were also determined for each sampling point of the two grids. The fitted infiltration parameters were then estimated based on other soil properties using multiple regression. Prior to the regression analysis, all predictor variables were transformed to normality. The regression analysis was performed using two information levels. The first information level contained only three texture fractions for the Ferralsol (sand, silt and clay) and four fractions for the Arenosol (coarse, medium and fine sand, and silt and clay). At the first information level the regression models explained up to 60% of the variability of some of the infiltration parameters for the Ferralsol field plot. At the second information level the complete textural analysis was used (nine fractions for the Ferralsol and six for the Arenosol). At the second information level a principal components analysis (PCA) was performed prior to the regression analysis to overcome the problem of multicollinearity among the predictor variables. Regression analysis was then carried out using the orthogonally transformed soil properties as the independent variables. Results for the Ferralsol data show that the parameters of the Green–Ampt and Kostiakov model were estimated relatively accurately (maximum R² = 0.76). For the Arenosol, use of the second information level together with PCA produced regression models with an R² value ranging from 0.38 to 0.68. For the Ferralsol, most of the variance was explained by the root content and organic matter content. In the Arenosol plot, the fractions medium and fine sand explained most of the observed variance.     

Relict Majoritic Garnet Microstructures from Ultra-Deep Orogenic Peridotites in Western Norway

Protogranular, porphyroclastic and equigranular (or equant-polygonal)garnet microstructures from Mg–Cr type orogenic garnetperidotites, Otrøy, Western Gneiss Region, Norway, havebeen studied using naked eye, light-optical, electron-opticaland confocal laser (fluorescence) microscopy techniques. Protogranularand porphyroclastic garnets contain microstructural evidencefor the former existence of majoritic (or super-silicic) garnet.The microstructural evidence consists of exsolution texturesinvolving pyroxene. Two types of exsolution microstructuresoccur—needles parallel to <111>_grt and interstitialgrains. The maximum volume percentage for intra-crystallinepyroxene exsolution is 2·7, and 3·6 for inter-crystallinepyroxene exsolution. The maximum pyroxene total volume percentagemeasured in one single protogranular or porphyroclastic garnetis 4·0. This value, at 1200°C, corresponds to minimumpressures of 6·4 GPa (     

Growth, Production, and a Partial Energy Budget for the Amphipod, Talorchestia capensis (Crustacea; Talitridae) in the Eastern Cape, South Africa

Abstract. .A population of Talorchestia capensis was sampled in dune slacks over the period of one year. Two hatching periods, one in March and one in September, were observed. Growth was rapid, the amphipods reaching a size of 8.4 mm standard length in 18 months. Maximum growth occurred in spring and minimum growth in winter. Annual mortality rates for summer- and winter-hatched individuals were low, 0.22-y“¹ and 0.16-y”¹. Average production for the summer classes was 7.2g-y?‘ (dry mass) and for the winter classes 2.9-y“¹, with a P/B ratio of 2.25-y”’. Production values peaked during autumn and summer. Abundance and biomass estimates showed maxima during summer and minima in early spring. Reproductive output was low, 0.1 kJ ? m^-2 y“¹, indicating that 7 % of the total production is used for reproduction and 93 % for somatic production. The assimilated energy flow through the population was estimated to be 16.3 kJ m?² y?‘ and consumption about 81.6 kJ m^-2 y^_’.