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1.
Streamflow simulation is often challenging in mountainous watersheds because of incomplete hydrological models, irregular topography, immeasurable snowpack or glacier, and low data resolution. In this study, a semi-distributed conceptual hydrological model (SWAT-Soil Water Assessment Tool) coupled with a glacier melting algorithm was applied to investigate the sensitivity of streamflow to climatic and glacial changes in the upstream Heihe River Basin. The glacier mass balance was calculated at daily time-step using a distributed temperature-index melting and accumulation algorithm embedded in the SWAT model. Specifically, the model was calibrated and validated using daily streamflow data measured at Yingluoxia Hydrological Station and decadal ice volume changes derived from survey maps and remote sensing images between 1960 and 2010. This study highlights the effects of glacier melting on streamflow and their future changes in the mountainous watersheds. We simulate the contribution of glacier melting to streamflow change under different scenarios of climate changes in terms of temperature and precipitation dynamics. The rising temperature positively contributed to streamflow due to the increase of snowmelt and glacier melting. The rising precipitation directly contributes to streamflow and it contributed more to streamflow than the rising temperature. The results show that glacial meltwater has contributed about 3.25 billion m3 to streamflow during 1960–2010. However, the depth of runoff within the watershed increased by about 2.3 mm due to the release of water from glacial storage to supply the intensified evapotranspiration and infiltration. The simulation results indicate that the glacier made about 8.9% contribution to streamflow in 2010. The research approach used in this study is feasible to estimate the glacial contribution to streamflow in other similar mountainous watersheds elsewhere. 相似文献
2.
《Journal of Hydrology》2006,316(1-4):213-232
The Magdalena River, a major fluvial system draining most of the Colombian Andes, has the highest sediment yield of any medium-sized or large river in South America. We examined sediment yield and its response to control variables in the Magdalena drainage basin based on a multi-year dataset of sediment loads from 32 tributary catchments. Various morphometric, hydrologic, and climatic variables were estimated in order to understand and predict the variation in sediment yield. Sediment yield varies from 128 to 2200 t km−2 yr−1 for catchments ranging from 320 to 59,600 km2. The mean sediment yield for 32 sub-basins within the Magdalena basin is ∼690 t km−2 yr−1. Mean annual runoff is the dominant control and explains 51% of the observed variance in sediment yield. A multiple regression model, including two control variables, runoff and maximum water discharge, explains 58% of the variance. This model is efficient (ME=0.89) and is a valuable tool for predicting total sediment yield from tributary catchments in the Magdalena basin. Multiple correlations for those basins corresponding to the upper Magdalena, middle basin, Eastern Cordillera, and catchment areas greater than 2000 km2, explain 75, 77, 89, and 78% of the variance in sediment yield, respectively. Although more variance is explained when dataset are grouped into categories, the models are less efficient (ME<0.72). Within the spatially distributed models, six catchment variables predict sediment yield, including runoff, precipitation, precipitation peakedness, mean elevation, mean water discharge, and relief. These estimators are related to the relative importance of climate and weathering, hillslope erosion, and fluvial transport processes. Time series analysis indicates that significant increases in sediment load have occurred over 68% of the catchment area, while 31% have experienced a decreasing trend in sediment load and thus yield. Land use analysis and increasing sediment load trends indicate that erosion within the catchment has increased over the last 10–20 years. 相似文献
3.
Response of snow cover and runoff to climate change in high Alpine catchments of Eastern Switzerland
A model study on the impact of climate change on snow cover and runoff has been conducted for the Swiss Canton of Graubünden. The model Alpine3D has been forced with the data from 35 Automatic Weather Stations in order to investigate snow and runoff dynamics for the current climate. The data set has then been modified to reflect climate change as predicted for the 2021–2050 and 2070–2095 periods from an ensemble of regional climate models.The predicted changes in snow cover will be moderate for 2021–2050 and become drastic in the second half of the century. Towards the end of the century the snow cover changes will roughly be equivalent to an elevation shift of 800 m. Seasonal snow water equivalents will decrease by one to two thirds and snow seasons will be shortened by five to nine weeks in 2095.Small, higher elevation catchments will show more winter runoff, earlier spring melt peaks and reduced summer runoff. Where glacierized areas exist, the transitional increase in glacier melt will initially offset losses from snow melt. Larger catchments, which reach lower elevations will show much smaller changes since they are already dominated by summer precipitation. 相似文献
4.
A specific characteristic of karst systems is the occurrence of time variant recharge areas. In our study we present a new type of hydrological karst model and a new calibration approach both considering this specific characteristic. The new model type considers the spatial variability of karst system properties by distribution functions, and is compared to a simple reservoir model. Both models are applied to a karst system in Southern Spain where objective functions applied on hydrodynamic and hydrochemical information helped to determine model parameters playing a role for hydrodynamic response. Thereafter, the recharge area is determined separately for individual hydrological years and for the entire time series by calibrating the model to match the water balance. We show that hydrochemical information is crucial to find a reasonable set of parameters for both models. Considering different hydrological years, we find that the recharge area is changing significantly (from 28 to 53 km2). The newly developed model is able to reproduce this variation and provide acceptable simulation results for the entire time series of available data. The classic reservoir model shows inferior performance concerning hydrodynamics and fails to reproduce the water balance because it does not consider variations of recharge area. Our calibration approach allows identifying a variable recharge area and our new model is able to reproduce its variability. Hence we obtain a more realistic system representation, which can be of high significance when models are used for prediction, i.e. beyond the conditions they were calibrated, e.g. for land-use or climate change scenarios. 相似文献
5.
Estimation of catchment yield and associated uncertainties due to climate change in a mountainous catchment in Australia 
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下载免费PDF全文 This paper examines the impacts of climate change on future water yield with associated uncertainties in a mountainous catchment in Australia using a multi‐model approach based on four global climate models (GCMs), 200 realisations (50 realisations from each GCM) of downscaled rainfalls, 2 hydrological models and 6 sets of model parameters. The ensemble projections by the GCMs showed that the mean annual rainfall is likely to reduce in the future decades by 2–5% in comparison with the current climate (1987–2012). The results of ensemble runoff projections indicated that the mean annual runoff would reduce in future decades by 35%. However, considerable uncertainty in the runoff estimates was found as the ensemble results project changes of the 5th (dry scenario) and 95th (wet scenario) percentiles by ?73% to +27%, ?73% to +12%, ?77% to +21% and ?80% to +24% in the decades of 2021–2030, 2031–2040, 2061–2070 and 2071–2080, respectively. Results of uncertainty estimation demonstrated that the choice of GCMs dominates overall uncertainty. Realisation uncertainty (arising from repetitive simulations for a given time step during downscaling of the GCM data to catchment scale) of the downscaled rainfall data was also found to be remarkably high. Uncertainty linked to the choice of hydrological models was found to be quite small in comparison with the GCM and realisation uncertainty. The hydrological model parameter uncertainty was found to be lowest among the sources of uncertainties considered in this study. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
6.
Model calibration is important for streamflow simulations using distributed hydrological models, especially in highland and cold areas of northwest China with scarce data. Quantitative analysis of water balance based on the accurate simulation is also essential for reasonably planning and managing water resources in these river basins facing a severe water shortage. In this study, a comprehensive method was proposed to calibrate the Soil and Water Assessment Tool (SWAT) model in the Yingluoxia watershed, upstream area of the Heihe River basin; it was based on multi-temporal, multi-variable and multi-site integrated drainage characteristics. Meanwhile a fresh approach of the parameter transferability and model validation was used by applying the set of calibrated parameters in its tributary to other area of the watershed. The results indicated that the method was effective and feasible; the values of Nash–Sutcliffe Efficiency (NSE) and Coefficient of Determination (r2) were greater than 0.81 and as high as 0.94 and the absolute values of the Percent Bias (PBIAS) were less than 2. Based the output of model the water balance in the Yingluoxia watershed was analyzed, that the mean annual precipitation, evapotranspiration, and discharge of the watershed from 1990 to 2000 were 491.8 mm, 334 mm, and 157.8 mm, respectively. The comprehensive calibration method based on multi-temporal, multi-variable and multi-site integrated drainage characteristics can better portray the hydrological processes of watershed and improve the model simulation; and the output of the model then provide a reliable reference for assessing and managing water resource of the watershed. 相似文献
7.
Surface soil moisture is an important parameter in hydrology and climate investigations. Current and future satellite missions with L-band passive microwave radiometers can provide valuable information for monitoring the global soil moisture. A factor that can play a significant role in the modeling and inversion of microwave emission from land surfaces is the surface roughness. In this study, an L-band parametric emission model for exponentially correlated surfaces was developed and implemented in a soil moisture retrieval algorithm. The approach was based on the parameterization of an effective roughness parameter of Hp in relation with the geometric roughness variables (root mean square height s and correlation length l) and incidence angle. The parameterization was developed based on a large set of simulations using an analytical approach incorporated in the advanced integral equation model (AIEM) over a wide range of geophysical properties. It was found that the effective roughness parameter decreases as surface roughness increases, but increases as incidence angle increases. In contrast to previous research, Hp was found to be expressed as a function of a defined slope parameter m = s2/l, and coefficients of the function could be well described by a quadratic equation. The parametric model was then tested with L-band satellite data in soil moisture retrieval algorithm over the Little Washita watershed, which resulted in an unbiased root mean square error of about 0.03 m3/m3 and 0.04 m3/m3 for ascending and descending orbits, respectively. 相似文献
8.
《Continental Shelf Research》2008,28(18):2594-2600
We analyzed the temporal and vertical distribution of biogenic (BSi) and lithogenic (LSi) silica, and diatom abundance in the upwelling center off Concepción, Chile, from April 2004 to May 2005. Measurements were performed at the FONDAP COPAS Time Series Station 18 (36°30.8′S, 73°07.7′W; 88 m water depth), and were combined with primary production estimates and river runoff data to assess the relationships between water column BSi and primary production, and between LSi and river runoff. Throughout the sampling period, water-column-integrated (0–80 m) BSi averaged 252±287 mmol m−2, and was about six times higher than average LSi (44±30 mmol m−2). The highest water column BSi observed during the upwelling season (786±281 mmol m−2) coincided with increments in total diatom abundance, and high integrated chlorophyll a concentration and primary production. In contrast, LSi was nearly two times higher in winter (85±43 mmol m−2) than the annual average, in agreement with the period of substantial discharges from the Itata and Bio-Bio rivers. The observed temporal patterns in BSi and LSi are coincident with primary production-related factors and riverine outflow, respectively, suggesting that the BSi and LSi pools are separate. With respect to the vertical distribution in the water column, most of the BSi and diatoms were found in surface waters (0–30 m depth), whereas LSi was most abundant at depth. Our study attempts to make an inventory of both BSi and LSi in the water column off Concepción, and gives the present-day background information necessary to assess potential future changes in the hydrological cycle that, in turn, may induce modifications in the Si path from the watersheds to the ocean. 相似文献
9.
Quantitatively evaluating the effects of adjusting cropping systems on the utilization efficiency of climatic resources under climate change is an important task for assessing food security in China. To understand these effects, we used daily climate variables obtained from the regional climate model RegCM3 from 1981 to 2100 under the A1B scenario and crop observations from 53 agro-meteorological experimental stations from 1981 to 2010 in Northeast China. Three one-grade zones of cropping systems were divided by heat, water, topography and crop-type, including the semi-arid areas of the northeast and northwest (III), the one crop area of warm–cool plants in semi-humid plain or hilly regions of the northeast (IV), and the two crop area in irrigated farmland in the Huanghuaihai Plain (VI). An agro-ecological zone model was used to calculate climatic potential productivities. The effects of adjusting cropping systems on climate resource utilization in Northeast China under the A1B scenario were assessed. The results indicated that from 1981 to 2100 in the III, IV and VI areas, the planting boundaries of different cropping systems in Northeast China obviously shifted toward the north and the east based on comprehensively considering the heat and precipitation resources. However, due to high temperature stress, the climatic potential productivity of spring maize was reduced in the future. Therefore, adjusting the cropping system is an effective way to improve the climatic potential productivity and climate resource utilization. Replacing the one crop in one year model (spring maize) by the two crops in one year model (winter wheat and summer maize) significantly increased the total climatic potential productivity and average utilization efficiencies. During the periods of 2011–2040, 2041–2070 and 2071–2100, the average total climatic potential productivities of winter wheat and summer maize increased by 9.36%, 11.88% and 12.13% compared to that of spring maize, respectively. Additionally, compared with spring maize, the average utilization efficiencies of thermal resources of winter wheat and summer maize dramatically increased by 9.2%, 12.1% and 12.0%, respectively. The increases in the average utilization efficiencies of precipitation resources of winter wheat and summer maize were 1.78 kg hm−2 mm−1, 2.07 kg hm−2 mm−1 and 1.92 kg hm−2 mm−1 during 2011–2040, 2041–2070 and 2071–2100, respectively. Our findings highlight that adjusting cropping systems can dominantly contribute to utilization efficiency increases of agricultural climatic resources in Northeast China in the future. 相似文献
10.
Hua Chen Tiantian Xiang Xing Zhou Chong-Yu Xu 《Stochastic Environmental Research and Risk Assessment (SERRA)》2012,26(6):847-858
Qingjiang River, the second largest tributary of the Yangtze River in Hubei Province, has taken on the important tasks for power generation and flood control in Hubei Province. The Qingjiang River watershed has a subtropical monsoon climate and, as a result, has dramatic diversity in its water resources. Recently, global warming and climate change have seriously affected the Qingjiang watershed’s integrated water resources management. In this article, general circulation model (GCM) and watershed hydrological models were applied to analyze the impacts of climate change on future runoff of Qingjiang Watershed. To couple the scale difference between GCM and watershed hydrological models, a statistical downscaling method based on the smooth support vector machine was used to downscale the GCM’s large-scale output. With the downscaled precipitation and evaporation, the Xin-anjiang hydrological model and HBV model were applied to predict the future runoff of Qingjiang Watershed under A2 and B2 scenarios. The preformance of the one-way coupling approach in simulating the hydrological impact of climate change in the Qingjiang watershed is evaluated, and the change trend of the future runoff of Qingjiang Watershed under the impacts of climate change is presented and discussed. 相似文献
11.
Richarde Marques da Silva Celso Augusto Guimares Santos José Yure Gomes dos Santos 《国际泥沙研究》2018,33(2):117-125
This paper quantifies the runoff and sediment yield for four different land covers in a semiarid region of Brazil. The WESP model, a distributed, event-oriented runoff-erosion model, was applied and its physical parameters, Ns and KR, were adjusted based on observed runoff and sediment yield data using simulated rainfall with an average intensity of 53 mm h-1. The sediment yield obtained was 53.02 kg ha-1 (caatinga vegetation), 231.96 kg ha-1 (bare soil), 309.75 kg ha-1 (beans), and 847.38 kg ha-1(corn). The results showed that caatinga cover yields the lowest erosion and runoff when compared to the other treatments. The results also show that the sediment yield and runoff values simulated with Ns, KI, and KR parameters were well calibrated, within acceptable deviations. The caatinga vegetation was more effective in protecting the soil, when compared to the other types of coverage. The beans and corn covers had the highest values of runoff and sediment yield, even higher than those observed for bare soil. 相似文献
12.
The glacier is an important and stable water supply in Central Asia. Monitoring the change of glacier and understanding the impacts of glacier change on river discharge are critical to predict the downstream water availability change in future. Glacier changes were discussed and their impacts on river discharge were evaluated by hydrological modeling with a distributed hydrological model SWAT under two land use and land cover scenarios (1970 and 2007) in Tekes watershed, the most important source of water discharge to the Ili River. Compared to the glacier area of 1511 km2 in 1970s it decreased by 332 km2 in 2007, which resulted in the contribution the discharge from precipitation in the glacier area to the average annual discharge of the watershed changing from 9.8% in the period 1966–1975 to 7.8% in the period 2000–2008. In the month scale, with the decrease of glacier area, the distribution of the contribution of monthly discharge from precipitation in the glacier area to the total of the watershed changed from bimodal pattern to unimodal pattern. By linking a hydrological model to remote sensing image analysis and Chinese glacier inventories to determine glacier area change our approach in quantifying the impacts of glacier changes on hydrology at different scales, will provide quantitative information for stakeholders in making decisions for water resource management. 相似文献
13.
The mass-induced sea level variability and the net mass transport between Mediterranean Sea and Black Sea are derived for the interval between August 2002 and July 2008 from satellite-based observations and from model data. We construct in each basin two time series representing the basin mean mass signal in terms of equivalent water height. The first series is obtained from steric-corrected altimetry while the other is deduced from GRACE data corrected for the contamination by continental hydrology. The series show a good agreement in terms of annual and inter-annual signals, which is in line with earlier works, although different model corrections influence the consistency in terms of seasonal signal and trend.In the Mediterranean Sea, we obtain the best agreement using a steric correction from the regional oceanographic model MFSTEP and a continental hydrological leakage correction derived from the global continental hydrological model WaterGAP2. The inter-annual time series show a correlation of 0.85 and a root mean square (RMS) difference of 15 mm. The two estimates have similar accuracy and their annual amplitude and phase agree within 3 mm and 23 days respectively. The GRACE-derived mass-induced sea level variability yields an annual amplitude of 27 ± 5 mm peaking in December and a trend of 5.3 ± 1.9 mm/yr, which deviates within 3 mm/yr from the altimetry-derived estimate.In the Black Sea, the series are less consistent, with lower accuracy of the GRACE-derived estimate, but still show a promising agreement considering the smaller size of the basin. The best agreement is realized choosing the corrections from WaterGAP2 and from the regional oceanographic model NEMO. The inter-annual time series have a correlation and RMS differences of 0.68 and 55 mm, their annual amplitude and phase agree within 4 mm and 6 days respectively. The GRACE-derived seawater mass signal has an annual amplitude of 32 ± 4 mm peaking in April. On inter-annual time scales, the mass-induced sea level variability is stronger than in the Mediterranean Sea, with an increase from 2003 to 2005 followed by a decrease from 2006 to 2008.Based on mass conservation, the mass-induced sea level variations, river runoff and precipitation minus evaporation are combined to derive the strait flows between the basins and with the Atlantic Ocean. At the Gibraltar strait, the net inflow varies annually with an amplitude of 52 ± 10 × 10−3 Sv peaking end of September (1 Sv = 106 m3 s−1). The inflow through the Bosphorus strait displays an annual amplitude of 13 ± 3 ×10−3 Sv peaking in the middle of March. Additionally, an increase of the Gibraltar net inflow (3.4 ± 0.8 × 10−3 Sv/yr) is detected. 相似文献
14.
Denis Lacelle Alfonso F. Davila Wayne H. Pollard Dale Andersen Jennifer Heldmann Margarita Marinova Christopher P. McKay 《Earth and Planetary Science Letters》2011,301(1-2):403-411
To date, studies of the stability of subsurface ice in the McMurdo Dry Valleys of Antarctica have been mainly based on climate-based vapor diffusion models. In University Valley (1800 m), a small glacier is found at the base of the head of the valley, and adjacent to the glacier, a buried body of massive ice was uncovered beneath 20–40 cm of loose cryotic sediments and sandstone boulders. This study assesses the origin and stability of the buried body of massive ice by measuring the geochemistry and stable O–H isotope composition of the ice and applies a sublimation and molecular diffusion model that accounts for the observed trends. The results indicate that the buried massive ice body represents an extension of the adjacent glacier that was buried by a rock avalanche during a cold climate period. The contrasting δ18O profiles and regression slope values between the uppermost 6 cm of the buried massive ice (upward convex δ18O profile and SD-18O = 5.1) and that below it (progressive increase in δ18O and SD-18O = 6.4) suggest independent post-depositional processes affected the isotope composition of the ice. The upward convex δ18O profile in the uppermost 6 cm is consistent with the ice undergoing sublimation. Using a sublimation and molecular diffusion model, and assuming that diffusion occurred through solid ice, the sublimation rate needed to fit the measured δ18O profile is 0.2 ? 10? 3 mm yr? 1, a value that is more similar to net ice removal rates derived from 3He data from cobbles in Beacon Valley till (7.0 ? 10? 3 mm yr? 1) than sublimation rates computed based on current climate (0.1–0.2 mm yr?1). We suggest that the climate-based sublimation rates are offset due to potential ice recharge mechanisms or to missing parameters, particularly the nature and thermo-physical properties of the overlying sediments (i.e., temperature, humidity, pore structure and ice content, grain size). 相似文献
15.
《Journal of Hydrology》2006,316(1-4):13-27
A linearized approach to quantifying predictive uncertainty in a 2-D model of shallow water flow in response to uncertainty in friction parameterization is presented. The resulting uncertain finite volume (UFV) method is tested against Monte Carlo simulations for uncertain models over channel only, floodplain only and channel and floodplain meshes. The results show that the UFV model performs well in predicting mean and standard deviations of water depths, for problems with two independent Manning's n values, with standard deviations of up to 0.02 m1/3 s−1 with a mean value of 0.03 m1/3 s−1. For depth averaged velocities, mean values are well represented, but standard deviations are poorly predicted by UFV. UFV also performs well when modelling flow over an uneven fractal topography and for a distributed (11 degrees of freedom) parameterization. A computation time advantage of >50 when compared to the Monte Carlo method is observed. 相似文献
16.
Marques AN Monna F da Silva Filho EV Fernex FE Fernando Lamego Simões Filho F 《Marine pollution bulletin》2006,52(5):532-539
Zn and Cd concentrations, stable lead isotopes and 210Pb-derived chronology were determined in a sediment core sampled at Sepetiba Bay (South-eastern Brazil). During the last decades, the bay’s watershed has been modified by the increase of industrial activities and human interventions. In particular, Zn and Cd ore treatment plants were built near the coast in 1960 and 1970, respectively, and water has been diverted from the adjacent Paraíba do Sul River watershed since 1950. The core collected at shallow depth near the industrial area exhibits four successive events: (i) at 50 cm depth, a change in the 206Pb/207Pb ratio from about 1.162 to more than 1.18 might be the result of the São Francisco Channel opening and water diversion from Paraíba do Sul river; (ii) at 40 cm depth, Zn concentration starts to increase (up to 0.8 mg g−1) (iii) above 30 cm depth, relatively high Cd concentrations (up to 1.6 μg g−1) are observed and (iv) at 16 cm depth, change in unsupported 210Pb slope is probably related to a waste dam built to prevent strong metal contamination in the bay. Sediment accumulation rates evaluated by Zn and Cd profiles used as time-markers are higher than those calculated from 210Pb-based chronology models. Using the constant initial concentration (CIC) model both events are supposed to date back to about 1884 and 1902, respectively, while using the constant rate of supply (CRS) model it shifts to about 1925 and 1935. Such discrepancies are probably assigned to the fact that these models do not take into account site-specific local sedimentation dynamics. In the study area, particles deposition seems to be controlled by enrichment with unsupported 210Pb transported by runoff from a mangrove flat bank. Chronology derived from a model that assumes an exponential increase of the initial 210Pb activity fits well with the estimated rates obtained from historical events. 相似文献
17.
《水文科学杂志》2013,58(1):100-111
Abstract The runoff of Iceland has been evaluated for the period 1961–1990, and changes in runoff from then to the period 2071–2100 predicted according to a future projection of climate change. The hydrological model WASIM-ETH was used, with meteorological data from the PSU/NCAR MM5 numerical weather model. The evaluation of the effects of climate change on water resources was based on a future climate simulation from the HIRHAM regional climate model with boundary conditions from the HadAM3H global climate model using A2 and B2 emissions scenarios. Future runoff was shown to become much higher in 2071–2100 compared to 1961–1990, predominantly due to increased glacial melt caused by increased temperature. Furthermore, changes in runoff seasonality would be substantial. Thus, according to this projection there could be great changes in hydropower production potential associated with climate change in Iceland. 相似文献
18.
C. Rasmussen S. Brantley D. deB. Richter A. Blum J. Dixon A.F. White 《Earth and Planetary Science Letters》2011,301(3-4):521-530
Investigations to understand linkages among climate, erosion and weathering are central to quantifying landscape evolution. We approach these linkages through synthesis of regolith data for granitic terrain compiled with respect to climate, geochemistry, and denudation rates for low sloping upland profiles. Focusing on Na as a proxy for plagioclase weathering, we quantified regolith Na depletion, Na mass loss, and the relative partitioning of denudation to physical and chemical contributions. The depth and magnitude of regolith Na depletion increased continuously with increasing water availability, except for locations with mean annual temperature < 5 °C that exhibited little Na depletion, and locations with physical erosion rates < 20 g m? 2 yr? 1 that exhibited deep and complete regolith Na depletion. Surface Na depletion also tended to decrease with increasing physical erosion. Depth-integrated Na mass loss and regolith depth were both three orders of magnitude greater in the fully depleted, low erosion rate sites relative to other locations. These locations exhibited strong erosion-limitation of Na chemical weathering rates based on correlation of Na chemical weathering rate to total Na denudation. Sodium weathering rates in cool locations with positive annual water balance were strongly correlated to total Na denudation and precipitation, and exhibited an average apparent activation energy (Ea) of 69 kJ mol? 1 Na. The remaining water-limited locations exhibited kinetic limitation of Na weathering rates with an Ea of 136 kJ mol? 1 Na, roughly equivalent to the sum of laboratory measures of Ea and dissolution reaction enthalpy for albite. Water availability is suggested as the dominant factor limiting rate kinetics in the water-limited systems. Together, these data demonstrate marked transitions and nonlinearity in how climate and tectonics correlate to plagioclase chemical weathering and Na mass loss. 相似文献
19.
Climate change impacts on surface water resources in the Rheraya catchment (High Atlas,Morocco) 总被引：2，自引：2，他引：0
This study aimed to quantify possible climate change impacts on runoff for the Rheraya catchment (225 km2) located in the High Atlas Mountains of Morocco, south of Marrakech city. Two monthly water balance models, including a snow module, were considered to reproduce the monthly surface runoff for the period 1989?2009. Additionally, an ensemble of five regional climate models from the Med-CORDEX initiative was considered to evaluate future changes in precipitation and temperature, according to the two emissions scenarios RCP4.5 and RCP8.5. The future projections for the period 2049?2065 under the two scenarios indicate higher temperatures (+1.4°C to +2.6°C) and a decrease in total precipitation (?22% to ?31%). The hydrological projections under these climate scenarios indicate a significant decrease in surface runoff (?19% to ?63%, depending on the scenario and hydrological model) mainly caused by a significant decline in snow amounts, related to reduced precipitation and increased temperature. Changes in potential evapotranspiration were not considered here, since its estimation over long periods remains a challenge in such data-sparse mountainous catchments. Further work is required to compare the results obtained with different downscaling methods and different hydrological model structures, to better reproduce the hydro-climatic behaviour of the catchment.
EDITOR M.C. AcremanASSOCIATE EDITOR R. Hirsch 相似文献
20.
This paper documents our development and evaluation of a numerical solver for systems of sparsely linked ordinary differential equations in which the connectivity between equations is determined by a directed tree. These types of systems arise in distributed hydrological models. The numerical solver is based on dense output Runge–Kutta methods that allow for asynchronous integration. A partition of the system is used to distribute the workload among different processes, enabling a parallel implementation that capitalizes on a distributed memory system. Communication between processes is performed asynchronously. We illustrate the solver capabilities by integrating flow transport equations for a ∼17,000 km2 river basin subdivided into 305,000 sub-watersheds that are interconnected by the river network. Numerical experiments for a few models are performed and the runtimes and scalability on our parallel computer are presented. Efficient numerical integrators such as the one demonstrated here bring closer to reality the goal of implementing fully distributed real-time flood forecasting systems supported by physics based hydrological models and high-quality/high-resolution rainfall products. 相似文献