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1.
《水文科学杂志》2013,58(6):971-984
Abstract

The identification of the turbidity mechanisms in two karstic springs (Ribaa and Bittit) located in the Middle Atlas Plateau in Morocco was performed by means of correlation and spectral analyses applied to time series of rainfall, flow rates, and turbidity. Time series analyses of rainfall and discharges revealed high inertia and storage capacities of the karstic systems. However, the occurrence of turbidity in the springs proved independent of discharges. A causal relationship between rainfall and the occurrence of turbidity in the form of waves was established. Accordingly, turbidity was assumed to be related to the hydrodynamic conditions prevailing in the karst. Turbulent quickflows in the karst transmissive conduits, following heavy rainfall, are thought to provoke the resuspension of solid particles deposited in the conduits, as well as their transport towards outlets. An external origin has also been contemplated, concerning infiltration waters may be loaded with suspended matters washed from the watershed.  相似文献   

2.
Karstic watersheds are highly complex hydrogeological systems that are characterized by a multiscale behaviour corresponding to the different pathways of water in these systems. The main issue of karstic spring discharge fluctuations consists in the presence and the identification of characteristic time scales in the discharge time series. To identify and characterize these dynamics, we acquired, for many years at the outlet of two karstic watersheds in South of France, discharge data at 3‐mn, 30‐mn and daily sampling rate. These hydrological records constitute to our knowledge the longest uninterrupted discharge time series available at these sampling rates. The analysis of the hydrological records at different levels of detail leads to a natural scale analysis of these time series in a multifractal framework. From a universal class of multifractal models based on cascade multiplicative processes, the time series first highlights two cut‐off scales around 1 and 16 h that correspond to distinct responses of the aquifer drainage system. Then we provide estimates of the multifractal parameters α and C1 and the moment of divergence qD corresponding to the behaviour of karstic systems. These results constitute the first estimates of the multifractal characteristics of karstic spingflows based on 10 years of high‐resolution discharge time series and should lead to several improvements in rainfall‐karstic springflow simulation models. Copyright © 2012 John Wiley & Sons, Ltd.  相似文献   

3.
Springs and seeps occur in the spaces around Po Hing Fong Street in the Mid‐Levels area, Hong Kong. Most of the springs occur through the drainage weepholes on retaining walls at the street. This paper first examines the geology and history of the springs. The paper then reports the findings from a 1‐year comprehensive spring monitoring programme. The temporal variations of flow rate, physiochemical parameters and hydrochemistry of the springs are discussed. The average temperatures of the springs were close to the mean air temperature, although there was a systematic lag time of 40 to 50 days between the peak air temperature and highest water temperatures. Spring waters from two rows of weepholes in the retaining wall showed significantly different physical and hydrochemical responses to the changes in rainfall and temperature, though their vertical distance is only about 1 m. The results suggest that water from the upper row of weepholes may represent a recharge source that is shallow or close to the spring outlets, whereas that from the lower row of weepholes may represent a recharge source that is much deeper or further up the hill. Although the spring flows increased rapidly after rainstorms, analysis of the total dissolved solids showed a delayed response to rainstorm events. The concentration of individual ions in the spring water varied in a unique way in response to rainstorm events. It is clear that the presence of underground man‐made drainage systems and the leakage from water mains in the study area may add complexity to the solute responses and transport mechanisms. Further studies are required to constrain the impacts of these man‐made structures on the hydrogeology of the springs. Copyright © 2007 John Wiley & Sons, Ltd.  相似文献   

4.
Spring Creek Springs and Wakulla Springs are large first magnitude springs that derive water from the Upper Floridan Aquifer. The submarine Spring Creek Springs are located in a marine estuary and Wakulla Springs are located 18 km inland. Wakulla Springs has had a consistent increase in flow from the 1930s to the present. This increase is probably due to the rising sea level, which puts additional pressure head on the submarine Spring Creek Springs, reducing its fresh water flow and increasing flows in Wakulla Springs. To improve understanding of the complex relations between these springs, flow and salinity data were collected from June 25, 2007 to June 30, 2010. The flow in Spring Creek Springs was most sensitive to rainfall and salt water intrusion, and the flow in Wakulla Springs was most sensitive to rainfall and the flow in Spring Creek Springs. Flows from the springs were found to be connected, and composed of three repeating phases in a karst spring flow cycle: Phase 1 occurred during low rainfall periods and was characterized by salt water backflow into the Spring Creek Springs caves. The higher density salt water blocked fresh water flow and resulted in a higher equivalent fresh water head in Spring Creek Springs than in Wakulla Springs. The blocked fresh water was diverted to Wakulla Springs, approximately doubling its flow. Phase 2 occurred when heavy rainfall resulted in temporarily high creek flows to nearby sinkholes that purged the salt water from the Spring Creek Springs caves. Phase 3 occurred after streams returned to base flow. The Spring Creek Springs caves retained a lower equivalent fresh water head than Wakulla Springs, causing them to flow large amounts of fresh water while Wakulla Springs flow was reduced by about half.  相似文献   

5.
Despite its location in the rain shadow of the southern Sierra Nevada, the Panamint Range hosts a complex mountain groundwater system supporting numerous springs which have cultural, historical, and ecological importance. The sources of recharge that support these quintessential desert springs remain poorly quantified since very little hydrogeological research has been completed in the Panamint Range. Here we address the following questions: (i) what is the primary source of recharge that supports springs in the Panamint Range (snowmelt or rainfall), (ii) where is the recharge occurring (mountain-block, mountain-front, or mountain-system) and (iii) how much recharge occurs in the Panamint Range? We answer questions (i) and (ii) using stable isotopes measured in spring waters and precipitation, and question (iii) using a chloride mass-balance approach which is compared to a derivation of the Maxey–Eakin equation. Our dataset of the stable isotopic composition (δ18O and δ2H) of precipitation is short (1.5 years), but analyses on spring water samples indicate that high-elevation snowmelt is the dominant source of recharge for these springs, accounting for 57 (±9) to 79 (±12) percent of recharge. Recharge from rainfall is small but not insignificant. Mountain-block recharge is the dominant recharge mechanism. However, two basin springs emerging along the western mountain-front of the Panamint Range in Panamint Valley appear to be supported by mountain-front and mountain-system recharge, while Tule Spring (a basin spring emerging at the terminus of the bajada on the eastern side of the Panamint Range) appears to be supported by mountain-front recharge. Calculated recharge rates range from 19 mm year−1 (elevations < 1000 mrsl) to 388 mm year−1 (elevations > 1000 mrsl). The average annual recharge is approximately 91 mm year−1 (equivalent to 19.4 percent of total annual precipitation). We infer that the springs in the Panamint Range (and their associated ecosystems) are extremely vulnerable to changes in snow cover associated with climate change. They are heavily dependent on snowmelt recharge from a relatively thin annual snowpack. These findings have important implications for the vulnerability of desert springs worldwide.  相似文献   

6.
The spectral method is based on the assumption of exponential forms of autocorrelation functions of the input and output time series. The results of practical applications of the spectral method on several karst springs in Croatia show that this assumption cannot always be reliably applied to the time series of rainfall and spring discharge, especially if short time periods are analysed. For this reason, the method is modified. The scale factor between the transfer function of total rainfall and the transfer function of groundwater recharge is considered as an additional model parameter which is determined in the optimization procedure. In addition to the theoretical background, this paper also presents the results of application of the modified spectral method on the springs Jadro and ?rnovnica located in the Dinaric karst area in Croatia. The parameters of groundwater recharge model are determined separately for both the springs and the obtained values are discussed and compared with the results of previous investigations. The values of the scale factors determined in the optimization procedure are compared to the values calculated using the theoretical equation. The comparison shows that the theoretical equation underestimates the optimal values of the scale factor. The underestimations are especially evident for periods of one year. Finally, the characteristics of rainfall–runoff relations of two springs are compared using the identified transfer functions and the results of simulations of the periodogram of observed discharge by the parametric periodogram. Copyright © 2008 John Wiley & Sons, Ltd.  相似文献   

7.
We applied graphical methods and multivariate statistics to understand impacts of an unsewered slum catchment on nutrients and hydrochemistry of groundwater in Kampala, Uganda. Data were collected from 56 springs (groundwater), 22 surface water sites and 13 rain samples. Groundwater was acidic and dominated by Na, Cl and NO3. These ions were strongly correlated, indicating pollution originating from wastewater infiltration from on‐site sanitation systems. Results also showed that rain, which was acidic, impacted on groundwater chemistry. Using Q‐mode hierarchical cluster analysis, we identified three distinct water quality groups. The first group had springs dominated by Ca‐Cl‐NO3, low values of electrical conductivity (EC), pH and cations, and relatively high NO3 values. These springs were shown to have originated from the acidic rains because their chemistry closely corresponded to ion concentrations that would occur from rainfall recharge, which was around 3.3 times concentrated by evaporation. The second group had springs dominated by Na‐K‐Cl‐NO3 and Ca‐Cl‐NO3, low pH but with higher values of EC, NO3 and cations. We interpreted these as groundwater affected by both acid rain and infiltration of wastewater from urban areas. The third group had the highest EC values (average of 688 μS/cm), low pH and very high concentrations of NO3 (average of 2.15 mmol/l) and cations. Since these springs were all located in slum areas, we interpreted them as groundwater affected by infiltration of wastewater from poorly sanitized slums areas. Surface water was slightly reducing and eutrophic because of wastewater effluents, but the contribution of groundwater to nutrients in surface water was minimal because o‐PO4 was absent, whereas NO3 was lost by denitification. Our findings suggest that groundwater chemistry in the catchment is strongly influenced by anthropogenic inputs derived from nitrogen‐containing rains and domestic wastewater. Copyright © 2013 John Wiley & Sons, Ltd.  相似文献   

8.
Rainfall data collected on and around the Soufriere Hills Volcano, Montserrat between 1998 and 2003 were analysed to assess the impact on primary volcanic activity, defined here as pyroclastic flows, dome collapses, and explosions. Fifteen such rainfall-triggered events were identified. If greater than 20 mm of rain fell on a particular day, the probability of a dome collapse occurring on that day increased by a factor of 6.3% to 9.2%, compared to a randomly chosen day. Similarly, the probability of observing pyroclastic flows and explosions on a day with > 20 mm of rainfall increased by factors of 2.6 and 5.4, respectively. These statistically significant links increased as the rainfall threshold was increased. Seventy percent of these rainfall-induced dome collapse episodes occurred on the same calendar day (most within a few hours) as the onset of intense rainfall, but an extra 3 occurred one or two calendar days later. The state of the volcano was important, with the rainfall–volcanic activity link being strongest during periods of unstable dome growth and weakest during periods of no dome growth or after a recent major collapse.Over 50% of the heavy rain days were associated with large-scale weather systems that can potentially be forecast up to a few days ahead. However, the remaining heavy rain days were associated with small-scale, essentially unpredictable weather systems. There was significant variability in the amount of rainfall recorded by different rain gauges, reflecting topographic variations around the volcano but also the inherent small-scale variability within an individual weather system. Hence, any monitoring/warning program is recommended to use a network, rather than just a single gauge. The seasonal cycle in rainfall was pronounced, with nearly all the heavy rain days occurring in the May–December wet season. Hence, the dome was at its most vulnerable at the beginning of the wet season after a period of uninterrupted growth. Interannual variability in rainfall was related to tropical Pacific and Atlantic sea surface temperature anomalies, and holds out the prospect of some limited skill in volcanic hazard forecasts at even longer lead times.  相似文献   

9.
River discharge in mountainous regions of the world is often dominated by snowmelt, but base flows are sustained primarily by groundwater storage and discharge. Although numerous recent studies have focused on base-flow discharge in mountain systems, almost no work has explicitly investigated the role of karst groundwater in these systems across a full range of flow conditions. We directly measured groundwater discharge from 48 karst springs in the Kaweah River and its five forks in the Sierra Nevada mountains, California, United States. Relationships between spring and river discharge showed that karst aquifers and springs provide significant storage and delayed discharge to the river. Regression models showed that, of all potential seasonal groundwater storage compartments in the river basin, the area of karst (0.1–4.4%) present provides the best explanation of base-flow recession in each fork of the Kaweah River (directly measured contributions from karst springs ranged from 3.5 to 16% during high-flow to 20 to 65% during base-flow conditions). These results show that, even in settings where karst represents a small portion of basin area, it may play an over-sized role in seasonal storage and water resources in mountain systems. Karst aquifers are the single most important non-snow storage component in the Kaweah River basin, and likely provide similar water storage capacities and higher base flows in other mountain river systems with karst when compared with systems without karst.  相似文献   

10.
While rainfall intermittency is a dynamical phenomenon, little progress has been made in the literature on the link between rainfall intermittency and atmospheric dynamics. We present the basic dynamical models of intermittency that are phenomenologically most similar to rainfall: Pomeau–Manneville Type-III and On–Off. We then illustrate each type with both a 1-D iterative map and a corresponding stochastic process stressing the appearance of these dynamics in high-dimensional (stochastic) systems as opposed to low-dimensional chaotic systems. We show that the pdf of rainfall intensities, the pdf of “laminar phases” (periods of zero rainfall intensity), and the spectrum of the rainfall series all have power-law behavior that is broadly consistent with intermittency in the classic types. Using a seasonal analysis, we find that summer convective rainfall at daily and sub-daily scales seems consistent with features of Type-III intermittency. The correspondence with Type-III intermittency and a preliminary entropic analysis further suggest that rainfall may be an example of sporadic randomness, blending deterministic and stochastic components.  相似文献   

11.
ABSTRACT

Karst aquifers and springs are important with respect to their potential for supplying drinking water in regions suffering from water scarcity in Iran. Accordingly, it is essential to determine the recharge potential of the catchment and the regions with higher obtainability potential. This study provides a road map for the Sheshpeer catchment in southern Iran. A recharge potential (RP) map was produced from which a recharge index (RI) was computed for several selected springs in the catchment. Furthermore, the unit discharge (q) – defined as the average annual discharge for a given catchment area and unit rainfall depth for each spring – was calculated. The plot of q versus RI for the springs showed a linear positive relationship between the two variables (R 2 = 0.9). Applying the trend equation of this plot to the whole Sheshpeer karstic catchment reveals that its long-term recharge coefficient is 0.74.  相似文献   

12.
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13.
Hydrogeologic field work in remote settings is often challenging: assessing spring behaviour and aquifer characteristics can be expensive in both time commitment and resources needed to assess these systems. In this study, we document the hydrology and geochemistry of 47 perennial karst springs in the Kaweah River, a mountain river basin in the Sierra Nevada, California. After preliminary hydrogeochemical characterization and grouping, selected springs were continuously monitored to further assess aquifer characteristics in each group. Later, in areas without previous dye‐tracing work, traces were conducted to establish connections between large sinking streams and springs. The springs have a wide range of inter‐spring and intra‐spring variability in discharge and geochemistry. We assessed this variability by performing statistical comparisons with spring chemistry and principal components analysis of all measured variables. Results show that springs can be divided into two distinct groups: high elevation springs of the Mineral King Valley and lower elevation springs throughout the rest of the basin. Continuous discharge, temperature and specific conductivity data from four springs (two from each group) were then used to characterize the hydrograph recession behaviour of springs in each group. Both groups showed statistically similar baseflow recession slopes, suggesting that both groups contain baseflow storage compartments with similar hydrogeologic properties. The biggest difference between each group is the variability in amount of water remaining in the aquifer during baseflow conditions. High elevation springs have lower baseflow discharges, relative to peak flow, than lower elevation springs, despite the fact that more precipitation falls at higher elevation. This is likely caused by differences in the amount of soil and epikarst storage, which are related to recent geomorphic events: high elevation aquifers were glaciated as recent as 41 thousand years ago (kya), while there is no evidence that low elevation aquifers were glaciated. As a result, lower elevations have developed thicker soils, weathered bedrock and epikarst. Copyright © 2016 John Wiley & Sons, Ltd.  相似文献   

14.
Recent studies have reported very large accelerations after stiffness changes in nonlinear systems, particularly self‐centering systems. Some have attributed these accelerations to numerical modelling choices and have assumed that they could be eliminated if the modelling were refined. Others have concluded that self‐centering systems generally have much larger peak accelerations than more traditional systems. This paper demonstrates that accelerations at changes in stiffness are caused by physical phenomena but may be amplified by modelling decisions. This is done by examining the response of a two‐degree‐of‐freedom system after a change in stiffness and by developing a closed‐form mathematical model to characterize this response. The equation shows that acceleration spikes should be expected near small masses and near nonlinear springs that are initially nearly rigid, particularly when those springs change from low stiffness to high stiffness while moving at a high velocity. These acceleration spikes depend on system properties that are often not known precisely, so without physical testing, analytical estimates of the accelerations that occur in nonlinear systems after stiffness changes should be treated with skepticism. Copyright © 2010 John Wiley & Sons, Ltd.  相似文献   

15.
Classification of Thermal Patterns at Karst Springs and Cave Streams   总被引：1，自引：0，他引：1  
Thermal patterns of karst springs and cave streams provide potentially useful information concerning aquifer geometry and recharge. Temperature monitoring at 25 springs and cave streams in southeastern Minnesota has shown four distinct thermal patterns. These patterns can be divided into two types: those produced by flow paths with ineffective heat exchange, such as conduits, and those produced by flow paths with effective heat exchange, such as small fractures and pore space. Thermally ineffective patterns result when water flows through the aquifer before it can equilibrate to the rock temperature. Thermally ineffective patterns can be either event‐scale, as produced by rainfall or snowmelt events, or seasonal scale, as produced by input from a perennial surface stream. Thermally effective patterns result when water equilibrates to rock temperature, and the patterns displayed depend on whether the aquifer temperature is changing over time. Shallow aquifers with seasonally varying temperatures display a phase‐shifted seasonal signal, whereas deeper aquifers with constant temperatures display a stable temperature pattern. An individual aquifer may display more than one of these patterns. Since karst aquifers typically contain both thermally effective and ineffective routes, we argue that the thermal response is strongly influenced by recharge mode.  相似文献   

16.
The spatial and temporal discharge regime and its effects on benthic communities were studied in two small temporary karstic stream systems of the Paderborner Hochfläche (East Westphalia, Germany). Both streams are characterized by very small perennial springbrook sections. Benthic invertebrates were sampled three times at 12 sites and discharge was measured monthly from March to September 2000. The spatial extension of streamflow was observed regularly to evaluate the duration of drought. Both streams showed a longitudinal gradient of hydrological intermittency from very small perennial reaches with low intermittency to an extremely harsh hydrological situation. The benthic communities displayed a decreasing species richness at increasing intermittency. The different hydrological stream sections were colonized by different lotic communities, characterized by typical species of temporary streams and by several typical species of springs. Particularly the perennial springs and springbrooks are very important for the species richness in these karstic stream systems.  相似文献   

17.
The Hakata hot springs area is located in Fukuoka City, which is in the southwestern part of Japan. Gamma-ray and gravity surveys were conducted to understand the relationship between the low-temperature hydrothermal systems and geophysical data of the area. The depth of the reservoir basement, which was derived from gravity data, gradually deepens toward the east; it includes some steep depth gradients in the Hakata hot springs area. High intensities of gamma-rays were detected around these gradients. In addition, higher hot spring temperatures and flow rates can be observed in this area. These results indicate that some part of the level of the basement where the hot springs are concentrated is a part of the Kego Fault and is similar to the fracture zone created by past activities of the fault. Moreover, these steep depth gradients act as a path for hot spring water from the deeper side of the granitic body to the surface.  相似文献   

18.
In this paper, a nonlinear stochastic seismic analysis program for buried pipeline systems is developed on the basis of a probability density evolution method (PDEM). A finite element model of buried pipeline systems subjected to seismic wave propagation is established. The pipelines in this model are simulated by 2D beam elements. The soil surrounding the pipelines is simulated by nonlinear distributed springs and linear distributed springs along the axial and horizontal directions, respectively. The joints between the segmented pipes are simulated by nonlinear concentrated springs. Thereafter, by considering the basic random variables of ground motion and soil, the PDEM is employed to capture the stochastic seismic responses of pipeline systems. Meanwhile, a physically based method is employed to simulate the random ground motion field for the area where the pipeline systems are located. Finally, a numerical example is investigated to validate the proposed program.  相似文献   

19.
Stable isotopes of water are known to provide information on mean altitudes of spring recharge areas, which is an important parameter for groundwater resources management especially in karstic environments. Very often, a lack of precipitation input data limits the possibility for an appropriate estimation of mean catchment altitudes. In the Jeita spring catchment, Lebanon, a characterization of precipitation input was possible with samples collected at six stations at varying altitudes (88 amount‐weighted monthly samples). A local meteoric water line for the Jeita spring catchment was characterized as δ2H = 6.04 * δ18O + 8.45 (R 2 = .92) for a 2‐year observation period between October 2012 and September 2014. Integral samples from the snow layer were collected at 22 sites at altitudes ranging from 1,000 to 2,300 m above sea level at the end of February 2012 and February 2013, when snow height reached a maximum of more than 6 m at the highest peak in the catchment. Water samples were continuously collected from six springs (Jeita, Kashkoush, Labbane, Assal, Afqa, and Rouaiss). Jeita spring water samples were collected additionally in daily time steps during the snowmelt season in 2012. Mean isotope values of the sampled springs range from ?6.8‰ to ?8.2‰, and from ?33‰ to ?44‰, for δ18O and δ2H, respectively. The stable isotope data show that input variability (space and time, snow cover, and rainfall) has direct impacts on mean altitude estimates of spring catchments. A more profound interpretation of spring response to rainfall for six local springs in the Lebanon Mountains was possible in comparison to four earlier described springs collected in the Anti‐Lebanon Mountains in Syria.  相似文献   

20.
Groundwater resources of the Republic of the Maldives are threatened by a variety of factors including variable future rainfall patterns, continued population growth and associated pumping demands, rising sea level, and contamination from the land surface. This study assesses changes in groundwater availability due to variable rainfall patterns and sea level rise (SLR) in the coming decades, a key component of water resources management for the country. Using a suite of two‐dimensional density‐dependent groundwater flow models, time‐dependent thickness of the freshwater lens is simulated for a range of island sizes (200 to 1,100 m) during the time period of 2011 to 2050, with recharge to the freshwater lens calculated using rainfall patterns provided by general circulation models for the three distinct geographic regions of the Maldives. The effect of SLR on the freshwater lens is quantified using estimates of shoreline recession and associated decreases in island width. If rainfall is solely considered, groundwater availability is projected to increase, as lens thickness during the 2031–2050 time periods is slightly greater (1–5%) than during the 2011–2030 time period. However, including the impact of SLR indicates an overall decrease in lens thickness, with drastic decreases (60% to 100%) projected for small islands (200 m) and moderate decreases (12% to 14%) expected for 400 m islands, which accommodate one third of the national population. Similar methodologies can be used for other atoll island nations, such as the Republic of Marshall Islands, Federated States of Micronesia, and the Republic of Kiribati. For the Maldives, results from this study can be used in conjunction with population growth estimates to determine the feasibility of including groundwater in water resources planning and management for the country.  相似文献   

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