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1.
The mathematical properties of the normalized diffusive hydrograph allow for easy determination of intrinsic basin characteristics. These include lag times between storm events and peak flow, recession rate, and the total, temporally integrated flow volume, all in terms of a single parameter, the basin time constant “b”. This simple function displays surprising fidelity to measured hydrographs of springs and hundreds of streams and small rivers. We explain this fidelity by showing that the curvature of the theoretical hydrograph matches that of the natural hydrographs better than several alternate models, and by demonstrating that the simple hydrograph function can be integrated over a range of time constants (0 to b max ) to represent the hierarchy of flow paths of varying lengths that exist in real watersheds. Surprisingly, the unwieldy analytical results from this integration are almost numerically indistinguishable from a simple hydrograph using a single, suitably-weighted average for the time constant. The peak flow times are shifted slightly. The accuracy with which the simple hydrograph approximates the integrated results for hierarchies of hydrographs representing individual flow paths explains why the former can realistically describe the discharge behaviors of complex natural watersheds.  相似文献   

2.
The concentrations of total suspended sediments (TSS), dissolved organic carbon (DOC) and particulate organic carbon (POC) were measured in water samples taken monthly in the Apure, Caura and Orinoco rivers during a hydrological cycle (between Sept. 2007 and Aug. 2008). The DOC concentration values ranged between 1.5 and 6.8 mgC l−1 in the Apure River; 2.07 and 4.9 mgC l−1 in the Caura River and 1.66 and 5.35 mgC l−1 in the Orinoco River. The mean concentration of DOC was 3.9 mgC l−1 in the Apure River, 3.24 mgC l−1 in the Caura River and 2.92 mgC l−1 in the Orinoco River at Puerto Ordaz. The three rivers showed a similar temporal pattern in the concentrations of DOC, with higher DOC values during the increasing branch of the hydrograph due to wash-out processes of the organic material stored in soils. The mean concentration values of POC were 1.33 mgC l−1; 0.77 mgC l−1 and 0.91 mgC l−1 in the Apure, Caura and Orinoco rivers, respectively. The inverse relationship found between the percentage in weight of the POC and the concentrations of TSS in the three rivers fits a logarithmic model, as it has been previously reported for other worldwide rivers. The POC concentrations in the Orinoco River showed a positive relationship with the TSS, suggesting that the POC in the Orinoco is the result of terrestrially organic matter. Although the fluxes of organic carbon (OC) in the three studied rivers are dependent on the values of water discharge, the fluxes of DOC during the increasing branch of the hydrograph are higher than those found during the decreasing stage, due to the yield of organic material accumulated in soils during the preceding dry season. The mean annual flux of total organic carbon (TOC) of the Orinoco River at Puerto Ordaz was about 4.27 × 106 TonC yr−1. Of this, 3.28 × 106 TonC yr−1 (77%) represents the flux of DOC and about 0.99 TonC yr−1 (23%) represents the flux of POC. The mean annual input of TOC from the Apure River to the Orinoco River was about 4.92 × 105 TonC yr−1 (11.5%), while the contribution of TOC from the Caura River to the Orinoco River was estimated at 3.05 × 105 TonC yr−1 (7.1%).The values of annual transport of TOC calculated for the Apure, Caura and Orinoco rivers were lower than those reported twenty years ago. This could be related to interannual variations of precipitation in the Orinoco Basin, due to runoff variations can have a strong effect on the fluxes of OC from land to rivers.  相似文献   

3.
Zinc, major ion, and other trace metal (V, Cr, Co, Ni, Cu, Cd, and Pb) concentrations were measured within 172 street and stream runoff samples in the Atlanta metropolitan region and in relatively undeveloped watersheds within the Georgia Piedmont and Blue Ridge Provinces. Peachtree Creek, draining a densely populated area of Atlanta, was the primary sampling location and samples were acquired under a wide range of hydrological conditions. Zinc concentrations within street runoff [median (Zn)urban street runoff=905 µg/l] were significantly greater than zinc concentrations within storm runoff [median (Zn)Peachtree Creek=60 µg/l], which were, in turn, greater than zinc concentrations within non-storm runoff [median (Zn)Peachtree Creek=14 µg/l]. Zinc concentrations were not significantly greater within urban base flow than within non-urban base flow, indicating that the primary source of pollution is "event water" or street runoff. Zinc was the only heavy metal present in greater than "background" concentrations (i.e., >10 µg/l), which is likely the result of automotive pollution that is omnipresent within the study area. Analysis of storm alkalinity dilution trends indicate that simple mixing between polluted street runoff and groundwater cannot account for the zinc concentrations observed within storm and recession flows. A two end member mass balance model suggests that a large proportion of the zinc present in the street runoff is adsorbed and transported on surfaces of the suspended sediment. Adsorption is readily possible at the near neutral pH (~6.5) of turbid storm discharge.  相似文献   

4.
We examined the short-term (<1 month post-storm) impact of storms [Tropical Storm (TS) Helene in 2000, Hurricane (H) Isabel in 2003, H Alex, Tropical Depression (TD) Bonnie and TS Charley in 2004] varying in their trajectory, wind and rainfall characteristics, on water column structure, nutrients, and phytoplankton biomass in North Carolina’s Neuse R. Estuary (NRE). Data are presented from two sampling programs, ModMon (biweekly) and FerryMon (measurements made every 3 min daily). Helene’s winds mixed the previously stratified water column, delivering sediment-bound nutrients to the euphotic zone, and localized freshwater input from Helene was also evident. Mean chlorophyll a concentrations in the mesohaline portion of the NRE, where N was strongly limiting before the storm (molar DIN:DIP < 1), more than doubled after the storm. Unlike with Helene, the water column was well mixed before passage of Isabel, and nutrient concentrations were high. As a result, minimal impact on phytoplankton biomass was detected despite Isabel’s high winds and significant freshwater input. In fact, conditions became less favorable for phytoplankton growth after the storm. Alex was fast moving and relatively small, but its winds were sufficient to mix the water column. Although data from ModMon suggest that chlorophyll a was only slightly higher after passage of Alex, FerryMon detected an ephemeral bloom that was missed by ModMon. Overall, these results suggest that relatively small tropical storms and hurricanes can lead to significant increases in phytoplankton biomass. However, the phytoplankton response depends on both the characteristics of a particular storm and the physical–chemical conditions of the water column before storm passage. Finally, the ephemeral bloom that developed as a result of Alex, the strong response of phytoplankton in the mesohaline portion of the estuary to nutrient inputs, and their patchiness on several other occasions suggests that storms may create “hot spots” for trophic transfer and biogeochemical dynamics in estuaries. Adaptive sampling is necessary to capture these features and to fully understand the impact of perturbations such as storms on estuarine ecosystem functioning.  相似文献   

5.
The area lies between Hugli river in the northwest and Bidyadhari river in the east and includes the East Kolkata Wetlands. The East Kolkata Wetlands is included in the List of Wetlands of International Importance (“Ramsar List”), as per the Convention on Wetlands signed in Ramsar, Iran, in 1971. This wetland has been declared as a Ramsar site on the 19th August 2002 (Ramsar site no. 1208) and therefore has acquired an international status. The area is a part of the lower deltaic plain of the Bhagirathi–Ganga river system and is generally flat in nature. The sub-surface geology of the area is completely blanketed by the Quaternary fluviatile sediments comprising a succession of clay, silty clay, sand and sand mixed with occasional gravel. The Quaternary aquifer is sandwiched between two clay sequences. The confined aquifer is made up of moderately well sorted sand and reflects fluviatile environment of deposition. The regional groundwater flow direction is from east to west. Detailed geochemical investigations of 40 groundwater samples along with statistical analysis (for example, correlation and principal component analysis) on these chemical data reveal: (i) four types of groundwater quality, for example, good, poor, very poor and water unsuitable for drinking purpose, (ii) four hydrochemical facies which may be assigned to three broad types such as “fresh”, “blended”, and “brackish” waters, (iii) the evolution of the “blended” water is possibly due to hydraulic mixing of “fresh” and “brackish” waters within the aquifer matrix and/or in well mixing, and (iv) absence of Na–Cl facies indicates continuous flushing of the aquifer.  相似文献   

6.
Hydrograph Separation of the Amazon River: A Methodological Study   总被引：1，自引：0，他引：1  
The hydrograph separation of the Amazon river was performed using three different methodologies. Were applied isotopic, filter-separation, and mixing methods to estimate the contributions of the surface runoff (event water) and baseflow (pre-event water) components to the total river flow, during the 1973–1974 hydrological years. The importance of the baseflow contribution, mainly during the peak discharge, suggesting that the groundwater plays a much more active and important role in the storm dynamics, was verified. Similar results were obtained for all the methods used, and the applicability of each one was discussed in detail. For the Amazon river basin, the average contribution of the baseflow was 56% of the total river flow, at peak discharge. The average surface runoff contribution, which represents the water capable of mechanical erosion in drainage basins, expressed in terms of the surface runoff coefficient (Kr), was 31.9%, while the mean contribution of the baseflow, expressed by the baseflow coefficient (Kb), was 68.1%.  相似文献   

7.
The chemical property of groundwater depends largely on the mineralogical composition of the rocks through which the water has moved and the rate of movement and these characteristics of surface water depend on organic and inorganic reactions, industrial effluents, rainfall and temperature etc. The underground water tends to contain more dissolved materials than those in surface water because of their more intimate and longer contact with organic materials of soil and rock particles. The groundwater of the studied area is dominant of alkaline earth’s (Ca2+ and Mg2+) and weak acids (HCO3 −) which may be classified as Magnesium-Bicarbonate and Calcium Carbonate types. Genetically, the groundwater of the area belongs to both “Normal Chloride” “Normal Sulphate” and “Normal Carbonate” to “Super Carbonate” group. Based on EC, SAR and RC, the groundwater of the area varies from good–excellent quality for irrigation purposes with low alkali hazard and medium salinity hazard.  相似文献   

8.
Three sequential hurricanes in the fall of 1999 provided the impetus for assessing multi-annual effects on water quality and phytoplankton dynamics in southwestern Pamlico Sound, North Carolina. Two and a half years of post-hurricane data were examined for short- and long-term impacts from the storms and >100 year flooding. Salinity decreased dramatically and did not recover until May 2000. Inorganic nitrogen and phosphorus concentrations were briefly elevated during the flooding, but later returned to background levels. Dissolved organic carbon concentrations declined through the whole study period, but did not appear to peak as was observed in the Neuse River estuary, a key tributary of the Sound. Light attenuation was highest in the fall to spring following the storms and was best correlated with chlorophylla concentrations. Phytoplankton biomass (chla) increased and remained elevated until late spring 2000 when concentrations returned to pre-storm levels and then cycled seasonally. Phytoplankton community composition varied throughout the study, reflecting the complex interaction between physiological optimal and combinations of salinity, residence time, nutrient availability, and possibly grazing activity. Floodwater advection or dilution from upstream maxima may have controlled the spatial heterogeneity in total and group-specific biomass. The storms produced areas of shortterm hypoxia, but hypoxic events continued during the following two summers, correlating strongly with water column stratification. Nitrogen loading to the southwestern sound was inferred from network analysis of previous nitrogen cycling studies in the Neuse River estuary. Based on these analyses, nutrient cycling and removal in the sub-estuaries would be decreased under high flow conditions, confirming observations from other estuaries. The inferred nitrogen load from the flood was 2–3 times the normal loading to the Sound; this estimate was supported by the substantial algal bloom. After 8-mos, the salinity and chla data indicated the Sound had returned to pre-hurricane conditions, yet phytoplankton community compositional changes continued through the multi-year study period. This is an example of long-term aspects of estuarine recovery that should be considered in the context of a predicted 10–40 yr period of elevated tropical storm activity in the western Atlantic Basin.  相似文献   

9.
An extra-thick high-quality brown coal was found to have accumulated in the Xianfeng basin in Yunnan Province, China. There are also abundant sedimentary marks of allochthonous genesis in the extra-thick coalbeds. These genesis indicators reveal a new submodel about allochthonous accumulation, which is: the long-distance river transportation of detrital plant and inorganic matter → the sedimentation of detrital plant fan delta + the hypautochthony accumulation of local lakeshore swamp peat → the autochthonous accumulation of local lacustrine peat + the sedimentation of fine inorganic matter → the mixing and transportation by flood current or weak storm flow or underwater gravity flow → the mechanical differentiation and their resedimentation between detrital plant and inorganic matter. This submodel can be called “the double accumulation of lacustrine detrital plant fan delta and underwater gravity flow” or “Xianfeng submodel”, which supplements the “allochthonous-hypautochthony lacustrine combination accumulation model” of the extra-thick coalbeds. The combination accumulation model is based on the Fuxin submodel and Fushun submodel in the Chinese Mesozoic and Cenozoic intarcontinental fault basin. Translated from Acta Sedimentologica Sinica, 2006, 24(1): 1–9 [译自: 沉积学报]  相似文献   

10.
In recharge areas, the Heihe River flow was separated into components of ice-snowmelt and precipitation according to 14 gauging stations and to monthly hydrograph using oxygen-18. As shown by the result of the two-component mixing model, on average, 19.8% of the runoff comes from ice-snowmelt. At three stations which are closer to glaciers and with headstream of ice-snow melted water, the ice-snowmelt runoff is larger than 28% of stream water. In addition, because most of the ice-snowmelt infiltrates the groundwater, which later discharges into the river at mountain outlets, the ice-snowmelt percentage in runoff is lower than average at these stations with the elevation higher than 3,600 m. According to monthly hydrograph, the lowest percentage of ice-snowmelt in runoff is in July (6.46%), whereas during November it is the largest (26.1%). In the middle basin, the fraction of groundwater in runoff had a marked increase from 23.57% near Zhangye City to 60.28% near Gaotai City, and then a dramatic drop to 13.61% near Zhengyixia Station because of agricultural flood irrigation in Zhangye Basin.  相似文献   

11.
The preliminary study of streams and rivers from the Roşia Montană area revealed that the concntration of heavy metals— Cd, Mn, Cu, Pb, and Zn—are above accepted limits. The gold extraction method is based on flotation. The most important pollution sources are mine tailings. The determinations were performed for samples collected in: April 2004, July 2004, September 2004, November 2004, February 2005 and May 2005. The highest concentrations were found for cadmium in September 2004: 0.17 mg/L; for copper in September 2004: 1.38 mg/L; for manganese in July 2004: 239.4 mg/L; for lead in May 2005: 0.54 mg/L; and for zinc in September 2004: 35.37 mg/L;. This study involved three small rivers (streams) that flow into the Mureş River and finally into the Danube River, having a great impact on human health and environmental stability in the area. In May 2005, a sample of drinking water from the mining district was also collected.  相似文献   

12.
Anomalous high fluoride concentration up to 7.59 mg/dm3 is found in groundwater from “La Victoria” area. This water is used to supply drinking water to Hermosillo City, Sonora. Geochemistry of groundwater, relationship between physicochemical parameters, hydrogeology and geologic setting were correlated to define the origin and the geochemical mechanisms of groundwater fluorine enrichment. High fluoride concentration is associated with high bicarbonates, pH and temperature, and it decreases toward the west and south of the area. Fluoride is in negative correlation to calcium concentration. Sodium sulphate facies of regional deep water flow are related to high fluoride concentration. High electric resistivity rocks associated with granites from the Sierra Bachoco basement might be the deep source of fluoride. Outcropping of Sierra Bachoco in the west causes upward regional flow. Groundwater of longer residence time can be pumped there. The anomalous area is restricted to “La Victoria” because calcareous paleozoic rocks outcrop to the south.  相似文献   

13.
The study was designed to establish the distributions of trace metals, dissolved organic carbon, and inorganic nutrients as well as to assess the extent of anthropogenic inputs into the Narmada and Tapti rivers. Water and sediment qualities are variable in the rivers, and there are major pollution problems at certain locations, mainly associated with urban and industrial centers. The metal concentrations of samples of the aquatic compartments investigated were close to the maximum permissible concentration for the survival of aquatic life, except for higher values of Cu (5–763 μg l−1), Pb (24–376 μg l−1), Zn (24–730 μg l−1), and Cr (70–740 μg l−1) and for drinking water except for elevated concentrations of metals such as Pb, Fe (850–2,060 μg l−1), Cr, and Ni (20–120 μg l−1). In general, the concentrations of trace metals in the rivers vary down stream which may affect the “health” of the aquatic ecosystem and may also affect the health of the rural community that depends on the untreated river water directly for domestic use. The assessment of EF, I geo, and PLI in the sediments reveals overall moderate pollution in the river basins.  相似文献   

14.
Research on large northern rivers suggests that as permafrost thaws, deeper groundwater flowpaths become active, resulting in greater baseflow, increased concentrations of weathering ions and reduced concentrations of dissolved organic carbon in the streamflow. In contrast, at the headwater-catchment scale, where understanding of groundwater/surface-water interactions is developed, inter-annual variability in climate and hydrology result in complex hydrological and chemical responses to change. This paper reports on a 4-year runoff investigation in an alpine discontinuous permafrost environment in Yukon, Canada, using stable isotopes, major dissolved ions and hydrometric data, to provide enhanced insight into the inter-annual-variability runoff-generation processes. Stable isotope results suggest that pre-event (old) water stored within the catchment dominates the snowmelt hydrograph, and dissolved ion results reveal that groundwater pathways occur predominantly in the near-surface during freshet. Dissolved organic carbon varies inter-annually, reflecting changing melt patterns, whereas weathering ions generated from deeper flowpaths become diluted. The total snow-water equivalent does not have a major influence on the fraction of snowmelt water reaching the stream or the runoff ratio. Results from multiple years highlight the considerable variability over short time scales, limiting our ability to detect climate-change influences on groundwater at the headwater scale.  相似文献   

15.
极端降水条件下北京西山黑龙关泉响应研究   总被引：3，自引：0，他引：3       下载免费PDF全文
2012年7月21日,北京房山区发生特大暴雨,暴雨从21日10时开始到22日2时结束。总降雨量达228mm,是北京60年一遇暴雨。暴雨后,黑龙关泉域岩溶水系统内的各种水资源要素都对其形成积极响应。依据岩溶地下水位统测、区域地质构造以及地貌条件综合分析黑龙关泉地下水系统补、径、排。研究黑龙关泉地下水系统对7.21洪水响应。从地下水位、地表河流、泉水水量、岩溶地下水化学分析7.21洪水前后变化情况。降水后,大石河流量最大达221m~3/s,水化学类型中带硫酸根离子的样品数显著增加。7月15日,实测黑龙关泉水流量为0.31m~3/s,7月21日上午实测为0.30m~3/s,25日分别对大石河的黑龙关泉口上、下游进行实测,获得泉水流量为3.47m~3/s,到29日降至2.34m~3/s,流量变化较为剧烈,与大石河水对岩溶水的补给密切相关。为进一步研究北京黑龙关泉域岩溶水的变化规律和岩溶水资源评价及合理开发利用提供了科学依据。  相似文献   

16.
Tidal freshwater wetlands (TFW) alter nitrogen concentrations in river water, but the role of these processes on a river’s downstream nitrogen delivery is poorly understood. We examined spatial and temporal patterns in denitrification in TFW of four rivers in North Carolina, USA and evaluated the relative importance of denitrification rate and inundation on ecosystem-scale N2 efflux. An empirical model of TFW denitrification was developed to predict N2 efflux using a digital topographic model of the TFW, a time series of water level measurements, and a range of denitrification rates. Additionally, a magnitude-frequency analysis was performed to investigate the relative importance of storm events on decadal patterns in N2 efflux. Spatially, inundation patterns exerted more influence on N2 efflux than did the range of denitrification rate used. Temporal variability in N2 efflux was greatest in the lower half of the tidal rivers (near the saline estuary) where inundation dynamics exerted more influence on N2 efflux than denitrification rate. N2 efflux was highest in the upper half of the rivers following storm runoff, and under these conditions variation in denitrification rate had a larger effect on N2 efflux than variability in inundation. The frequency-magnitude analysis predicted that most N2 efflux occurred during low flow periods when tidal dynamics, not storm events, affected TFW inundation. Tidal hydrology and riparian topography are as important as denitrification rate in calculating nitrogen loss in TFW; we present a simple empirical model that links nitrogen transport in rivers with loss due to denitrification in TFW.  相似文献   

17.
Coastal flooding occurs due to storm surges generated by tropical and extra-tropical cyclones on the globe. The meteorological forcing fields for the generation of storm surges are the tangential surface wind stress on the ocean surface and the normal atmospheric pressure gradients associated with the weather systems. The large scale forcing from the cyclones is referred to as the synoptic scale and storm surge prediction from synoptic scale forcing is well developed and is reasonably satisfactory around the world. However, coastal flooding also occurs from weather systems, with forcing on a meso-scale and also from remote forcing. It is proposed here that the term “Storm surge” be used to only refer to coastal flooding from synoptic scale forcing and the terminology “Rissaga” be used for coastal flooding from meso-scale forcing. For flooding due to remote forcing, a new term “Kallakkadal” is proposed.  相似文献   

18.
为探讨河西地区内陆河径流对气候变化的响应, 选取1955-2008年石羊河、黑河和疏勒河的河流流量资料进行计算和分析. 结果表明: 50多年来, 石羊河年径流总体呈明显下降趋势, 黑河呈略有增加趋势, 疏勒河呈明显增加趋势, 地域上呈现愈往西部的河流年径流量增加愈明显. 三大河流进入1990年代后有下降趋势, 进入21世纪均有明显增多趋势. 三大河流径流对气候变化有不同响应, 石羊河流域主要受季风气候影响, 气候变暖, 蒸发加剧, 水分散失量大, 是造成径流减少的主要原因;黑河和疏勒河流域主要受西风带环流影响, 径流增多的重要原因是气候变暖降水明显增多. 为减缓气候变化对流域水资源利用的不利影响, 在分析三大内陆河流量对气候变化响应特征的基础上, 提出了适应性水资源管理的建议. 建议应提高水资源利用效率;改变生产方式, 调整农业种植业结构与布局;加大祁连山自然保护区建设, 搞好水资源可持续利用;积极开发祁连山丰富的空中云水资源、哺育祁连山冰川等流域适应性水资源管理对策, 对流域进行综合治理与开发利用, 这些措施和对策将为流域水资源开发提供科学依据.  相似文献   

19.
The significant role of the drainage area’s geological background in the formation of the groundwater runoff in the active water-exchange zone was revealed for the first time on the basis of long-term observations of streams of the Upper Kolyma River region during the autumn-winter low-water period, when the rivers are fed only by the groundwater recharge. The analysis of all the available data made it possible to define the characteristic periods in the autumn-winter low-water season. The waters of the seasonally thawed layer play the dominant role in the river’s recharge in September; the suprapermafrost water, in January; and the subgelisol water (nonfreezing water streams) during the 30-day-long period of the minimal flow. The quantitative parameters of the groundwater runoff corresponding to its module during this period reflect the water influx to the active water-exchange zone. It is established that the latter is minimal in the In’yali-Debin synclinorium, which consists of sedimentary rocks formed in deepwater trough environments. Their subsequent transformation proceeded under the action of subduction-accretionary and shear strains. The water availability in the active water-exchange in the Ayan-Yuryakh anticlinorium zone is substantially higher, although the Late Paleozoic and Early Mesozoic sedimentary formations of this area were also deposited in deepwater trough settings, but their subsequent evolution was related to the uplift of the anticlinorium. The maximal watering is observed in the active water-exchange zone of the Omulevka terrane, which is composed of Paleozoic terrigenous-carbonate and carbonate formations. The differences in the hydrogeological regimes of the terranes may be significant with respect to their geoecology.  相似文献   

20.
《Applied Geochemistry》2004,19(4):469-518
A periodic sampling (85 samples) collected fortnightly along 3 annual hydrological cycles (1990–1993) in the Niger River basin, at the outlet of Bamako (Mali), allowed the calibration of an hydrochemical model based on the hydrograph separation. As a first step, 5 reservoirs are identified: Rr the rapid runoff, Rs the superficial runoff, Rh the hypodermic or differred runoff, Ns the superficial ground water, and Np the deep ground water, also called base flow. In each reservoir, the physico-chemical composition of water is supposed to be constant with time. Along the hydrograph, or total discharge curves, and during 3 hydrological cycles, the relative proportions of each of the reservoirs fluctuate continuously. The methodology, processing step by step, is first calibrated, by using concentrations of specific tracers: dissolved Na+, HCO3−, and suspended sediments (TSS). Then, the proportions of Rr, Rs, Rh, Ns, and Np, contributing to the total flow measured at each instant of sampling, are calculated. As a second step, pH and the concentrations of aqueous species (K+, Ca2+, Mg2+, Cl−, SO42−, DOC, SiO2), are in turn calculated by regression analysis in each reservoir. Finally a test of validity of the method is presented as a very close correlation between measured and predicted fluctuating concentrations of each of the elements. From that satisfactory stage, the geochemical budget of weathering is conducted, with particular attention to SiO2 release and CO2 consumption. Parent-rock mineralogical compositions contributing to dissolved species in the total discharge as well as in the individual flow components have been reconstituted. Rates of both chemical erosion (soil profile formation by weathering), and mechanical erosion (soil profile and landscape denudation) have been evaluated. The methodology, successfully applied to the Niger basin, is proposed as a strategic tool for studying the watershed dynamics for any time and space scales. The model revealed its ability to extrapolate and predict the geochemical or the environmental behaviour of such basins, naturally submitted to large secular or annual, regular or even catastrophic climatic oscillations.  相似文献   

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