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1.
A single parameter index method, in which ground temperature and air temperature is the sole input variable, respectively, is used to evaluate and compare the glacial runoff in three typical glacier catchments, Dongkemadi glacier catchment in Tibetan plateau, Koxkar glacier catchment and the headwater catchment of Urumqi River catchment in Tianshan Mountains in West China. The method based on ground temperature is an attempt to evaluate glacier runoff in elevated terrains, as few studies have focused specifically on the association between glacier runoff and ground temperature. The results identify ground temperature versus a certain depth, which is a critical factor that affected glacier hydrological processes and showed that runoff data is much better correlated with ground temperature than air temperature. Especially, at the latter two catchments, the largest coefficients of exponential relationship R 2 between glacier runoff and ground temperature are 0.9 and 0.83, respectively. The accuracy of the method makes it possible to estimate the glacier runoff with a certain depth ground temperature at a certain site, which may provide a new approach to evaluate the glacier runoff for areas where there is a lack of observation data.  相似文献   

2.
1960—2010年中国主要流域径流量减小原因探讨分析   总被引：1，自引：0，他引：1       下载免费PDF全文
针对1960—2010年径流量显著减少的中国主要流域,包括松花江、辽河、海河、黄河和汉江等,选择其上游地区受人类直接取用水影响较少的山区小流域,分析径流变化及其原因.采用基于Budyko假设的流域水热耦合平衡方程,估计了流域年径流量变化的气候弹性系数和下垫面弹性系数,并对各流域径流变化进行了归因分析.结果表明,在气候较为湿润的地区,径流对气候和下垫面变化均不敏感;在气候较为干燥的地区,径流对气候和下垫面变化都更为敏感,且区域差异性明显.潜在蒸散发的变化对径流减少的影响微弱,降水减少和下垫面变化是径流减少的主导因素,其中人类活动导致的下垫面变化对径流减少的影响尤为显著.对比两个阶段的径流变化归因分析结果,近10年间流域下垫面变化对年径流量的影响程度较前20年有显著增加.通过分析近30年的归一化植被指数(NDVI)数据发现,植被覆盖改善是下垫面变化的重要原因,说明中国水土保持工程发挥了显著生态效益的同时也导致了流域径流减小.  相似文献   

3.
Travel times and flow paths of groundwater from its recharge area to drinking-water production wells will govern how the quality of pumped groundwater responds to contaminations. Here, we studied the 180 km2 Ammer catchment in southwestern Germany, which is extensively used for groundwater production from a carbonate aquifer. Using a 3-D steady-state groundwater model, four alternative representations of discharge and recharge were systematically explored to understand their impact on groundwater travel times and flow paths. More specifically, two recharge maps obtained from different German hydrologic atlases and two plausible alternative discharge scenarios were tested: (1) groundwater flow across the entire streambed of the Ammer River and its main tributaries and (2) groundwater discharge via a few major springs feeding the Ammer River. For each of these scenarios, the groundwater model was first calibrated against water levels, and subsequently travel times and flow paths were calculated for production wells using particle tracking methods. These computed travel times and flow paths were indirectly evaluated using additional data from the wells including measured concentrations of major ions and environmental tracers indicating groundwater age. Different recharge scenarios resulted in a comparable fit to observed water levels, and similar estimates of hydraulic conductivities, flow paths and travel times of groundwater to production wells. Travel times calculated for all scenarios had a plausible order of magnitude which were comparable to apparent groundwater ages modelled using environmental tracers. Scenario with groundwater discharge across the entire streambed of the Ammer River and its tributaries resulted in a better fit to water levels than scenario with discharge at a few springs only. In spite of the poorer fit to water levels, flow paths of groundwater from the latter scenario were more plausible, and these were supported by the observed major ion chemistry at the production wells. We concluded that data commonly used in groundwater modelling such as water levels and apparent groundwater ages may be insufficient to reliably delineate capture zones of wells. Hydrogeochemical information relating only indirectly to groundwater flow such as the major ion chemistry of water sampled at the wells can substantially improve our understanding of the source areas of recharge for production wells.  相似文献   

4.
This study aimed at investigating the first flush phenomenon from residential, commercial and industrial catchments. Stormwater was grab sampled and the flow rate was measured during 52 storm events. The dimensionless cumulative pollutant mass and runoff volume were used to determine the runoff volume needed to transport 50 and 80 % of total pollutant mass. Almost all the constituents did not satisfy this first flush definition except for total suspended solids (TSS) in the commercial catchment. The averages first runoff volume required to remove 50 and 80 % of the total pollutant mass were 37 and 67, 35 and 65, and 36 and 64 % for the residential, commercial and industrial catchments, respectively. It seemed that less runoff is required to transport the same amount of pollutant loadings in tropical urban catchments than in temperate regions. BOD, COD, NH3-N, SRP and TP consistently showed strong first flush effects in all catchments. The first flush strengths of TSS, BOD, COD, NH3-N and TP in the commercial catchment were strongly correlated with total rainfall, rainfall duration, max 5 min intensity, runoff volume and peak flow, but not with antecedent dry days. Management of the first 10 mm runoff depth would be able to capture about half of the total pollutant mass in stormwater runoff that would otherwise goes to drains.  相似文献   

5.
Biogeochemical processes were investigated in alpine river—Kamni?ka Bistrica River (North Slovenia), which represents an ideal natural laboratory for studying anthropogenic impacts in catchments with high weathering capacity. The Kamni?ka Bistrica River water chemistry is dominated by HCO3 ?, Ca2+ and Mg2+, and Ca2+/Mg2+ molar ratios indicate that calcite weathering is the major source of solutes to the river system. The Kamni?ka Bistrica River and its tributaries are oversaturated with respect to calcite and dolomite. pCO2 concentrations were on average up to 25 times over atmospheric values. δ13CDIC values ranged from ?12.7 to ?2.7 ‰, controlled by biogeochemical processes in the catchment and within the stream; carbonate dissolution is the most important biogeochemical process affecting carbon isotopes in the upstream portions of the catchment, while carbonate dissolution and organic matter degradation control carbon isotope signatures downstream. Contributions of DIC from various biogeochemical processes were determined using steady state equations for different sampling seasons at the mouth of the Kamni?ka Bistrica River; results indicate that: (1) 1.9–2.2 % of DIC came from exchange with atmospheric CO2, (2) 0–27.5 % of DIC came from degradation of organic matter, (3) 25.4–41.5 % of DIC came from dissolution of carbonates and (4) 33–85 % of DIC came from tributaries. δ15N values of nitrate ranged from ?5.2 ‰ at the headwater spring to 9.8 ‰ in the lower reaches. Higher δ15N values in the lower reaches of the river suggest anthropogenic pollution from agricultural activity. Based on seasonal and longitudinal changes of chemical and isotopic indicators of carbon and nitrogen in Kamni?ka Bistrica River, it can be concluded that seasonal changes are observed (higher concentrations are detected at low discharge conditions) and it turns from pristine alpine river to anthropogenic influenced river in central flow.  相似文献   

6.
辽河大伙房水库汇水区农业非点源污染入库模拟   总被引：1，自引：0，他引：1  
利用输出系数法和SWAT模型,对大伙房水库汇水区农业非点源污染(ANSP)进行了入库模拟研究,并用2006—2009年的水文和水质监测数据对模型进行了校准和验证。研究结果表明:汇水区年均输入到水库的泥沙量、总氮和总磷负荷分别为82.65×103 t、1 873.49t和81.97t;月入库泥沙量、总氮和总磷负荷与径流量有着较强的相关性,ANSP的产生和迁移受降水、径流过程影响很大,每年7、8月份的氮、磷和泥沙流失量达到年内最大值,分别占全年流失总量的42.64%、44.42%和67.91%。水库汇水区各流域对水库氮、磷污染的贡献率由大到小依次为:浑河流域(清原段)、苏子河流域、社河流域和水库周边小流域。  相似文献   

7.
Integration of vegetation processes in rain–runoff (RR) models significantly affects runoff response by influencing evapotranspiration in mesoscale catchments. However, it is impossible to interpret the impacts of vegetation processes on runoff simulations in macroscale catchments using results from mesoscale catchments. Few studies involved vegetation process impacts on hydrological simulations by integrating daily vegetation information into conceptual RR models of macroscale catchments. In this study, we integrated the remotely sensed leaf area index (LAI) from the Moderate Resolution Imaging Spectroradiometer (MODIS) into a daily Distributed Time-Variant Gain Model (DTVGM). Then, this study assessed the performances of two DTVGM versions, with and without vegetation processes, in the Wei River catchment, China. The results showed that: (1) Integration of MODIS-LAI into the DTVGM model improved the calibration and runoff simulation results of the initial DTVGM model. (2) Inclusion of vegetation processes in the DTVGM changed the simulated proportions of water balance components in the hydrological model and made the simulation of water balance components more accurate. (3) The fact that inclusion of vegetation processes could improve the hydrological simulation performance of the daily conceptual RR model in the macroscale catchment was consistent with studies in mesoscale catchment.  相似文献   

8.
The Ballenera Creek has 160 km2 being a small catchment in the Pampa Plain in Argentina. This area has been deeply modified by human action through agricultural activities. From 2013 to 2017, electrical conductivity, stable isotopes of water and nitrate concentration monitoring program were conducted. The sampling included weekly and bimonthly samples in two sites along the stream, several groundwater wells and monthly precipitation. Chemical and isotopic tracers are used to discriminate the streamflow components and to evaluate their incidence in the nitrate concentration. The easiest conceptual model for gaining streams contemplates two main elements: direct runoff and groundwater (baseflow and pre-event water). The direct runoff has the lowest electrical conductivity and 18Ow variable content. The baseflow component is characterized by the highest electrical conductivity and isotope composition quite constant. Finally, pre-event water has an intermediate electrical conductivity and isotopic content close to the rainfall-weighted average composition. The nitrate concentration obtained was in general related to the different stream stages and was a useful indicator to evaluate the fertilization in agricultural zones.  相似文献   

9.
A field study was conducted to determine the effect of landscape spatial pattern and micro-topography on nutrient transfer via runoff from two catchments into Yuqiao Reservoir in north China. The surface runoff discharge was measured during rainfall events and water samples were analyzed in 2004 and 2005. The mean annual total nitrogen (TN) and total phosphorus (TP) exports per unit area from Caogezhuang catchment (C catchment) were 1.048 and 0.561 kg ha−1 year−1, respectively, while the TN and TP exports from Taohuasi catchment (T catchment) were 0.158 and 0.027 kg ha−1 year−1. In both catchments, village and vineyard shared the highest nutrient export ability due to the accumulated animal waste and heavy application of fertilizer and manure. In T catchment, the distance of village and vineyard was about 1,500 m away from the receiving water and in between were woodland and cropland. In the hydrological pathway, there were sink landscape structures of small stone dams, roadside swale, vegetated filter strip and dry ponds, which could detain water and nutrients. In C catchment, the distance between the village and the receiving water was about 200 m, and the hydrological pathway was compacted roads and ditches with no sink structures. It is suggested that the distance between the pollution source area and the receiving water and the micro-topographical features were the main factors to control the great difference in nutrient export rates.  相似文献   

10.
Statistical approach to the analysis of the relationship between the frequency of flood events and land cover (LC) changes in small catchments of Slovakia is presented in this paper. The data for identification of LC changes were taken from the 1990 and 2006 CORINE LC (CLC) data layers. They were derived by computer-aided visual interpretation of satellite images under the CLC Projects. The data about frequency of flood events in small catchments are from the period 1996–2006. Two hypotheses were formulated: (1) the greater the area of LC changes, the more frequent flood events; (2) in catchments where LC changes accelerating formation of direct runoff (e.g. urbanization, deforestation, farming) dominates, flood events are more frequent than in catchments where the prevailing LC changes (e.g. afforestation) reduce formation of direct runoff. Validity of hypotheses was tested in the framework of flood potential of catchments by two-factor ANOVA method. The obtained results indicate that (1) flood event frequency increases with the increasing total area of LC changes in a catchment. This tendency clearly manifests itself in catchments with very high flood potential. It is somewhat less distinct in catchments with moderate and high flood potentials. (2) There were no differences in flood event frequency between the group of catchments, where LC changes accelerating the formation of the direct runoff prevailed and the group of catchments where LC changes decelerating the formation of direct runoff were dominated.  相似文献   

11.
Water quality in less-developed countries is often subject to substantial degradation, but is rarely studied in a systematic way. The concentration and flux of major ions, carbon, nitrogen, silicon, and trace metals in the heavily urbanized Bagmati River within Kathmandu Valley, Nepal, are reported. The concentrations of all chemical species increased with distance downstream with the exceptions of protons and nitrate, and showed strong relationships with population density adjacent to the river. Total dissolved nitrogen (TDN), dominated by NH4, was found in high concentrations along the Bagmati drainage system. The export of dissolved organic carbon (DOC) and TDN were 23 and 33 tons km?2 year?1, respectively, at the outlet point of the Kathmandu Valley, much higher than in relatively undeveloped watersheds. The cationic and silica fluxes were 106 and 18 tons km?2 year?1 at the outlet of the Bagmati within Kathmandu Valley, and 36 and 32 tons km?2 year?1 from the relatively pristine headwater area. The difference between headwaters and the urban site suggests that the apparent weathering flux is three times higher than the actual weathering rate in the heavily urbanized Bagmati basin. Fluxes of cations and silica are above the world average, as well as fluxes from densely populated North American and European watersheds. End-member composition of anthropogenic sources like sewage or agricultural runoff is needed to understand the drivers of this high rate of apparent weathering.  相似文献   

12.
The aim of this study is to apply an integrated approach to determine nitrate sources and fate in the alluvial aquifer of the River Vibrata (Abruzzi, central Italy) by coupling the Isotope and the Component approaches. Collected data include concentration and nitrogen isotope composition of groundwater samples from the alluvial aquifer and nitrogen loads arising from agricultural and non-agricultural sources. The adopted methodology identified synthetic fertilizers as main sources of nitrate in the Vibrata alluvial aquifer. At the catchment scale, two different zones have been identified: the Upper Valley, where infiltration to groundwater is dominant and nitrogen easily migrates into the aquifer; in this area, nitrate content in groundwater is stable and normally higher than EU requirements. Moreover, streamwaters are fed by groundwater with a nitrate content likely lowered by denitrification processes occurring in the hyporheic zone. In the Lower Valley, runoff processes dominate and the nitrate content in surface waters is higher. Nevertheless, groundwater is locally affected by denitrification that breaks down the nitrate content, which often reaches values consistent with law limits.  相似文献   

13.
Pollution and overexploitation of scarce groundwater resources is a serious problem in the Zarqa River catchment, Jordan. To estimate this resource’s potential, the amount and spatial distribution of groundwater recharge was calculated by applying the hydrological model J2000. The simulation period is composed of daily values gathered over a 30-year period (July 1977 to June 2007). The figure finally obtained for estimated groundwater recharge of the Zarqa River catchment is 105 × 106 m3 per year (21 mm a?1). This is 19 % higher than the value previously assumed to be correct by most Jordanian authorities. The average ratio of precipitation to groundwater recharge is 9.5 %. To directly validate modelled groundwater recharge, two independent methods were applied in spring catchments: (1) alteration of stable isotope signatures (δ18O, δ2H) between precipitation and groundwater and (2) the chloride mass balance method. Recharge rates determined by isotopic investigations are 25 % higher, and recharge rates determined by chloride mass balance are 9 % higher than the modelled results for the corresponding headwater catchments. This suggests a reasonably modelled safe yield estimation of groundwater resources.  相似文献   

14.
潘钊  孙自永  马瑞  常启昕  胡雅璐  刘源  王旭 《地球科学》2018,43(11):4226-4236
为揭示中、低纬度高寒山区降雨-径流的形成过程,指导水资源的合理开发利用,选择黑河上游红泥沟小流域为研究区,基于河道径流量及雨水和河水稳定同位素的观测数据,构建二元混合模型,计算了2013年7月23日及8月21日两次典型降雨-径流事件中事件水（降雨）和事件前水（流域前期储水）对河道径流的贡献及其动态变化.结果显示:两次降雨事件中事件前水的贡献比例分别为68.69%和54.46%;事件前水的贡献比例在涨水阶段减小,在退水阶段增大.结合河水电导率的观测结果,进一步分析了降雨-径流的形成过程:河道径流的形成主要受饱和区蓄满产流、河岸带地下径流和山坡地下径流3种产流机制控制;事件水主要源于蓄满产流,事件前水主要源于河岸带和山坡地下径流;事件初期和末期以河岸带地下水补给为主,涨水阶段后期和退水阶段前期转为以蓄满产流和山坡地下水补给为主,洪峰期间蓄满产流的贡献达到最大.两次事件的对比表明,事件前的湿度条件和降雨强度对降雨-径流的形成过程有着重要影响:前期越湿润,流域储水能力越弱,导水能力越强,事件水的贡献越大,河道径流对降雨的响应越迅速;降雨强度越大,蓄满产流及其中的事件水比例越高,河道径流中事件水的比例也越高.   相似文献   

15.
For the sustainable utilization of rivers in the mid and downstream regions, it is essential that land surface hydrological processes are quantified in high cold mountains regions, as it is in these regions where most of the larger rivers in China acquire their headstreams. Glaciers are one of the most important water resources of north-west China. However, they are seldom explicitly considered within hydrological models, and climate-change effects on glaciers, permafrost and snow cover will have increasingly important consequences for runoff. In this study, an energy-balance ice-melt model was integrated within the Variable Infiltration Capacity (VIC) macroscale hydrological model. The extended VIC model was applied to simulate the hydrological processes in the Aksu River basin, a large mountainous and glaciered catchment in north-west China. The runoff components and their response to climate change were analyzed based on the simulated and observed data. The model showed an acceptable performance, and achieved an efficiency coefficient R 2 ≈ 0.8 for the complete simulation period. The results indicate that a large proportion of the catchment runoff is derived from ice meltwater and snowmelt water. In addition, over the last 38 years, rising temperature caused an extension in the snow/ice melting period and a reduction in the seasonality signal of runoff. Due to teh increased precipitation runoff, the Aksu catchment annual runoff had a positive trend, increasing by about 40.00 × 106 m3 per year, or 25.7 %.  相似文献   

16.
Due to differences in rainfall regimes and management practices, tropical urban catchments are expected to behave differently from temperate catchments in terms of pollutant sources and their transport mechanism. Storm Water Management Model (SWMM) was applied to simulate runoff quantity (peakflow and runoff depth) and quality (total suspended solids and total phosphorous) in residential, commercial and industrial catchments. For each catchment, the model was calibrated using 8?C10 storm events and validated using seven new events. The model performance was evaluated based on the relative error, normalized objective function, Nash?CSutcliffe coefficient and 1:1 plots between the simulated and observed values. The calibration and validation results showed good agreement between simulated and measured data. Application of Storm Water Management Model for predicting runoff quantity has been improved by taking into account catchment??s antecedent moisture condition. The impervious depression storages obtained for dry and wet conditions were 0.8 and 0.2?mm, respectively. The locally derived build-up and wash-off parameters were used for modelling runoff quality.  相似文献   

17.
西山岩溶水作为北京市重要的供水水源,在区域水文地质调查过程中发现西山岩溶水补给区一些样品硝酸盐浓度偏高,然而其周围岩溶水中硝酸盐浓度并未见明显变化（浓度均值为18.81 mg/L）,具点状硝酸盐源特征。岩溶含水层中硝酸盐分布特征和影响因素具有重要的研究意义。文章利用岩溶水化学和同位素分析结果研究了岩溶水硝酸盐分布和来源,利用IsoSource软件计算各来源的贡献率。结果表明:军庄—永丰屯径流区和军庄—古城—玉泉山泉径流区岩溶水中硝酸盐主要来源于生活废水、土壤有机氮矿化和大气沉降,贡献率值分别为37.1%、36.3%、26.6%;潭柘寺—四季青岩溶水中硝酸盐在潭柘寺补给区有养殖场废水下渗影响,径流区中硝酸盐含量低并发生反硝化降解作用。永定河水源硝酸盐不是岩溶水硝酸盐的主要来源。研究成果对西山岩溶水中硝酸盐的控制具有重要参考价值。  相似文献   

18.
Increasing sediment loads entering the Lake Tanganyika ecosystem are hastening the need for improved understanding of the linkages between catchment characteristics and influent sediment transport and loading. Sediment loads of two catchments at the southern end of the lake were estimated for October 1998–December 1999, and catchment characteristics determined using GIS. It was found that both sediment yields and loads were higher from the catchment of the Lunzua River (19.8 t km?2 and 20,114 t, respectively) compared with that of the Kalambo (4.1 t km?2 and 12,197 t) in 1999. These differences were both attributed to the smaller size and higher road density of the Lunzua catchment, and suggest that previous recommendations regarding the positioning of underwater lake reserves fail to take into account the low sediment retention capacity of small mountainous rivers. Differences between the study rivers in the transport of suspended sediments, organic matter, and bedload sediments into the lake were also found, the latter determined by the novel application of the 'McLaren Model'.  相似文献   

19.
Time histories of riverine water discharge, nitrate concentration, and nitrate, flux have been analyzed for the Mississippi and Atchafalaya rivers. Results indicate that water discharge variability is dominated by the annual cycle and shorter-time-scale episodic events presumably associated with snowmelt runoff and spring or summer rains. Interannual variability in water discharge is relatively small compared to the above. In contrast, nitrate concentration exhibits strongest variability at decadal time scales. The interannual variability is not monotonic but more complicated in structure. Weak covariability between water discharge and nitrate concentration leads to a relatively “noisy” nitrate flux signal. Nitrate flux variations exhibit a low-amplitude, long-term modulation of a dominant annual cycle. Predictor-hindcastor analyses indicate that skilled forecasts of nitrate concentration and nitrate flux fields are feasible. Water discharge was the most reliably hindcast (on seasonal to interannual time scales) due to the fundamental strength of the annual hydrologic cycle. However, the forecasting effort for this variable was less successful than the hindcasting effort, mostly due to a phase shift in the annual cycle during our relatively short test period (18 mo). Nitrate concentration was more skillfully predicted (seasonal to interannual time scales) due to the relative dominance of the decadal-scale portion of the signal. Nitrate flux was also skillfully forecast even though historical analyses seemed to indicate that it should be more difficult to predict than either water discharge or nitrate concentration.  相似文献   

20.
李耕  韩志伟  申春华  曾祥颖 《地球科学》2019,44(9):2899-2908
岩溶流域水环境极易受到人为活动的影响,而硝酸盐污染是岩溶流域面临的最突出最普遍的问题之一,把握岩溶流域中硝酸盐的来源及其在不同水体中的分布特征与成因,可为岩溶流域硝酸盐污染的防治提供依据.以贵州普定后寨河流域为研究对象,于2017年5月采集地下水和地表水样品共53件,测定主要水化学参数,分析NO3-来源,并结合区域土地利用类型,沿流动路径阐明其影响.结果表明,研究区主要阴、阳离子浓度从大到小依次为HCO3- > SO42- > NO3- > Cl-、Ca2+ > Mg2+ > Na+ > K+,水化学类型以HCO3-Ca型为主.水体NO3-的主要来源为化肥,有6个采样点水体明显受到硝酸盐污染,NO3-浓度变化主要受混合过程控制,硝化作用和反硝化作用影响不明显.流域水体NO3-浓度受土地利用方式影响明显,流经以农田或村寨为主的区域时NO3-浓度升高,流经以林地灌木等自然植被繁茂的区域时NO3-浓度降低.   相似文献   

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