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931.
EDWIN T. ENGMAN 《水文科学杂志》2013,58(4):637-647
Abstract The case is made that the hydrological sciences are data limited and that future progress in understanding hydrological processes is hampered by the lack of adequate data. The future applications of remote sensing to hydrology should provide new types of data that enable hydrologists to address the previously unsolved questions. 相似文献
932.
This paper assesses the various factors contributing to climate change in the region of the Kashafroud G-WADI Basin in Iran; quantifies
the local impacts of climate change, especially local water scarcity; and simulates and discusses several proposed methods to
combat these impacts. Hydrologic and climatic data are statistically analyzed and VENSIM modeling is used for various simulations
of water resources in the basin. Results show that the natural climate changes affecting Kashafroud Basin include increased temperature,
less rainfall, more frequent droughts, and changes in rainfall patterns, all of which are local symptoms of climate change in recent
years. However, the most important challenge in the basin is the overexploitation of surface and groundwater resources to meet the
growing water demands, especially domestic needs. Changes in land use, reallocation of water uses, groundwater depletion, and degradation
of the quality of surface waters have all contributed to significant changes in the environmental features of this basin, and are
the main reason why water demands now exceed the renewal capacity of the basin. Proposed response measures include reallocation
of resources among different uses, inter-basin water transfers, drawing water from six small dams on the Kashafroud River, reducing
groundwater extraction, and replacing groundwater extraction for agriculture by reuse of urban wastewater. This study concludes that
although changes in global climatic parameters have altered environmental features in the basin, local factors, such as water utilization
beyond the renewable capacity of the basin, are more significant in worsening the impacts of climate change. 相似文献
933.
The normalized difference vegetation index (NDVI) is used extensively to describe vegetation cover and ecological environment
change. The purpose of this study was to contrast the response of different tree species growing in the same habitat to
climate change and retrieve past NDVI using tree-ring width data from tree cores collected from the transitional zone of Pinus
tabulaeformis and Picea crassifolia in the Luoshan Mountains in the middle arid region of Ningxia. Correlation analysis indicated
that radial growth of P. tabulaeformis is more sensitive to precipitation and temperature change than that of P. crassifolia.
Natural factors such as water availability and heat at this elevation are more suited to the growth of P. crassifolia, and are more
advantageous to its renewal and succession. P. crassifolia is probably the better of the two species for protecting the forest
ecosystem and conserving water in the Luoshan desertification area. Ring width of P. crassifolia correlates significantly with
average NDVI for April–May (r =0.641, p <0.01), and both of them are influenced positively by precipitation in April–May.
The reconstructed NDVI for 1923–2007 shows the relatively low vegetation cover occurred in the 1920s–1930s, the
1960s–1970s, and the early 21st century. The reconstructed NDVI better reflected the drought climate in the study area. 相似文献
934.
Abstract The reassessment of flood risk at York, UK, is pertinent in light of major flooding in November 2000, and heightened concerns of a perceived increase in flooding nationally. Systematic flood level readings from 1877 and a wealth of documentary records dating back as far as 1263 AD give the City of York a long and rich history of flood records. This extended flood record provides an opportunity to reassess estimates of flood frequency over a time scale not normally possible within flood frequency analysis. This paper re-evaluates flood frequency at York, considering the strengths and weaknesses in estimates resulting from four contrasting methods of analysis and their corresponding data: (a) single-site analysis of gauged annual maxima; (b) pooled analysis of multi-site gauged annual maxima; (c) combined analysis of systematic annual maxima augmented with historical peaks, and (d) analysis of only the very largest peaks using a Generalized Pareto Distribution. Use of the historical information was found to yield risk estimates which were lower and considered to be more credible than those achieved using gauged records alone. Citation Macdonald, N. & Black, A. R. (2010) Reassessment of flood frequency using historical information for the River Ouse at York, UK (1200–2000). Hydrol. Sci. J. 55(7), 1152–1162. 相似文献
935.
AbstractFloods, as extreme hydrological phenomena, can be described by more than one correlated characteristic, such as peak, volume and duration. These characteristics should be jointly considered since they are generally not independent. For an ungauged site, univariate regional flood frequency analysis (FA) provides a limited assessment of flood events. A recent study proposed a procedure for regional FA in a multivariate framework. This procedure represents a multivariate version of the index-flood model and is based on copulas and multivariate quantiles. The performance of the proposed procedure was evaluated by simulation. However, the model was not tested on a real-world case study data. In the present paper, practical aspects are investigated jointly for flood peak (Q) and volume (V) of a dataset from the Côte-Nord region in the province of Quebec, Canada. The application of the proposed procedure requires the identification of the appropriate marginal distribution, the estimation of the index flood and the selection of an appropriate copula. The results of the case study show that the regional bivariate FA procedure performed well. This performance depends strongly on the performance of the two univariate models and, more specifically, the univariate model of Q. The results show also the impact of the homogeneity of the region on the performance of the univariate and bivariate models.
Editor D. Koutsoyiannis 相似文献
936.
Shuang-Ye Wu 《水文科学杂志》2013,58(8):1251-1263
Abstract This study aims to assess the potential impact of climate change on flood risk for the city of Dayton, which lies at the outlet of the Upper Great Miami River Watershed, Ohio, USA. First the probability mapping method was used to downscale annual precipitation output from 14 global climate models (GCMs). We then built a statistical model based on regression and frequency analysis of random variables to simulate annual mean and peak streamflow from precipitation input. The model performed well in simulating quantile values for annual mean and peak streamflow for the 20th century. The correlation coefficients between simulated and observed quantile values for these variables exceed 0.99. Applying this model with the downscaled precipitation output from 14 GCMs, we project that the future 100-year flood for the study area is most likely to increase by 10–20%, with a mean increase of 13% from all 14 models. 79% of the models project increase in annual peak flow. Citation Wu, S.-Y. (2010) Potential impact of climate change on flooding in the Upper Great Miami River Watershed, Ohio, USA: a simulation-based approach. Hydrol. Sci. J. 55(8), 1251–1263. 相似文献
937.
Abdullah Gokhan Yilmaz 《水文科学杂志》2013,58(12):2148-2162
AbstractThere is increasing concern that flood risk will be exacerbated in Antalya, Turkey as a result of global-warming-induced, more frequent and intensive, heavy rainfalls. In this paper, first, trends in extreme rainfall indices in the Antalya region were analysed using daily rainfall data. All stations in the study area showed statistically significant increasing trends for at least one extreme rainfall index. Extreme rainfall datasets for current (1970–1989) and future periods (2080–2099) were then constructed for frequency analysis using the peaks-over-threshold method. Frequency analysis of extreme rainfall data was performed using generalized Pareto distribution for current and future periods in order to estimate rainfall intensities for various return periods. Rainfall intensities for the future period were found to increase by up to 23% more than the current period. This study contributed to better understanding of climate change effects on extreme rainfalls in Antalya, Turkey. 相似文献
938.
《水文科学杂志》2013,58(1):90-100
Abstract In the past 50 years, influenced by global climate change, the East Asian summer monsoon intensity (SMI) changed significantly, leading to a response by the water cycle of the Yellow River basin. The variation in SMI has three stages: (1) 1951–1963, SMI increased; (2) 1963–1965, SMI declined sharply, a feature that may be regarded as an abrupt change; and (3) 1965–2000, SMI remained at low levels and showed a tendency to decline slowly. The decreased SMI led to a reduction in water vapour transfer from the ocean to the Yellow River basin, and thus precipitation decreased and the natural river runoff of the Yellow River also decreased. Due to the increase in population and therefore in irrigated land area, the ratio of net water diversion to natural river runoff increased continuously. Comparison of the ratio of net water diversion to natural river runoff before and after the abrupt change in SMI indicates some discontinuity in the response of the man-induced lateral branch of the water cycle to the abrupt change in SMI. The frequently occurring flow desiccation in the lower Yellow River can be regarded as a response of the water cycle system to the decreasing summer monsoon intensity and increasing population. When the ratio of net water diversion exceeded the ratio of natural runoff of the low-flow season to the annual total natural runoff, flow desiccation in the lower Yellow River would occur. When the ratio of net water diversion is 0.3 larger than the ratio of the natural runoff of the low-flow season to the annual total natural runoff, an abrupt increase in the number of flow desiccation events is likely to occur. 相似文献
939.
《水文科学杂志》2013,58(6):1121-1136
Abstract One of the most significant anticipated consequences of global climate change is the change in frequency of hydrological extremes. Predictions of climate change impacts on the regime of hydrological extremes have traditionally been conducted by a top-down approach that involves a high degree of uncertainty associated with the temporal and spatial characteristics of general circulation model (GCM) outputs and the choice of downscaling technique. This study uses the inverse approach to model hydrological risk and vulnerability to changing climate conditions in the Seyhan River basin, Turkey. With close collaboration with the end users, the approach first identifies critical hydrological exposures that may lead to local failures in the Seyhan River basin. The Hydro-BEAM hydrological model is used to inversely transform the main hydrological exposures, such as floods and droughts, into corresponding meteorological conditions. The frequency of critical meteorological conditions is investigated under present and future climate scenarios by means of a weather generator based on the improved K-nearest neighbour algorithm. The weather generator, linked with the output of GCMs in the last step of the proposed methodology, allows for the creation of an ensemble of scenarios and easy updating when improved GCM outputs become available. Two main conclusions were drawn from the application of the inverse approach to the Seyhan River basin. First, floods of 100-, 200- and 300-year return periods under present conditions will have 102-, 293- and 1370-year return periods under the future conditions; that is, critical flood events will occur much less frequently under the changing climate conditions. Second, the drought return period will change from 5.3 years under present conditions to 2.0 years under the future conditions; that is, critical drought events will occur much more frequently under the changing climate conditions. 相似文献
940.
《水文科学杂志》2013,58(1):189-198
Abstract Concurrent reconstructions of October—April precipitation at Madaba and Rabba gauging sites in central Jordan back to the year 1777 using a multivariate regression model are presented. The reconstruction model was calibrated using concurrent precipitation and tree-ring data for the period 1953–1981 The regression equation is significant (p < 0.05), while reconstructions account for 53% and 48% (adjusted for lost degrees of freedom) of the total variability of the precipitation at the Madaba and Rabba sites, respectively. The validation statistic obtained indicates the existence of worthwhile information in the reconstructions. A threshold of 1 standard deviation below the mean is used to define extremely dry years. The concurrent analysis of the reconstructed precipitation at both sites indicates the occurrence of 24 regional extremely dry periods of between 1 and 2 years' duration. Dry periods of more than 2 years' duration rarely occur. This study indicates the occurrence of noticeable extremely dry individual years: 1800, 1827, 1895 and 1933. The estimated mean recurrence times of extreme droughts are 9.3 and 51.3 years for droughts of 1-year and 2-years duration, respectively. 相似文献