Tritium hydrology of the Mississippi River basin

In the early 1960s, the US Geological Survey began routinely analysing river water samples for tritium concentrations at locations within the Mississippi River basin. The sites included the main stem of the Mississippi River (at Luling Ferry, Louisiana), and three of its major tributaries, the Ohio River (at Markland Dam, Kentucky), the upper Missouri River (at Nebraska City, Nebraska) and the Arkansas River (near Van Buren, Arkansas). The measurements cover the period during the peak of the bomb‐produced tritium transient when tritium concentrations in precipitation rose above natural levels by two to three orders of magnitude. Using measurements of tritium concentrations in precipitation, a tritium input function was established for the river basins above the Ohio River, Missouri River and Arkansas River sampling locations. Owing to the extent of the basin above the Luling Ferry site, no input function was developed for that location. The input functions for the Ohio and Missouri Rivers were then used in a two‐component mixing model to estimate residence times of water within these two basins. (The Arkansas River was not modelled because of extremely large yearly variations in flow during the peak of the tritium transient.) The two components used were: (i) recent precipitation (prompt outflow) and (ii) waters derived from the long‐term groundwater reservoir of the basin. The tritium concentration of the second component is a function of the atmospheric input and the residence times of the groundwaters within the basin. Using yearly time periods, the parameters of the model were varied until a best fit was obtained between modelled and measured tritium data. The results from the model indicate that about 40% of the flow in the Ohio River was from prompt outflow, as compared with 10% for the Missouri River. Mean residence times of 10 years were calculated for the groundwater component of the Ohio River versus 4 years for the Missouri River. The mass flux of tritium through the Mississippi Basin and its tributaries was calculated during the years that tritium measurements were made. The cumulative fluxes, calculated in grams of ³H were: (i) 160 g for the Ohio (1961–1986), (ii) 98 g for the upper Missouri (1963–1997), (iii) 30 g for the Arkansas (1961–1997) and (iv) 780 g for the Mississippi (1961–1997). Copyright © 2004 John Wiley & Sons, Ltd.     

Tritium balance in macro‐scale river basins analysed through distributed hydrological modelling

The recession of bomb tritium in river discharge of large basins indicates a contribution of slowly moving water. For an appropriate interpretation it is necessary to consider different runoff components (e.g. direct runoff and ground water components) and varying residence times of tritium in these components. The spatially distributed catchment model (tracer aided catchment model, distributed; TAC^D) and a tritium balance model (TRIBIL) were combined to model process‐based tritium balances in a large German river basin (Weser 46 240 km²) and seven embedded sub‐basins. The hydrological model (monthly time step, 2 × 2 km²) estimated the three major runoff components: direct runoff, fast‐moving and slow‐moving ground water for the period of 1950 to 1999. The model incorporated topography, land use, geomorphology, geology and hydro‐meteorological data. The results for the different basins indicated a contribution of direct runoff of 30–50% and varying amounts for fast and slow ground water components. Combining these results with the TRIBIL model allowed us to estimate the residence time of the components. Mean residence times of 8 to 14 years were found for the fast ground water component, 21 to 93 years for the slow ground water component and 14 to 50 years for an overall mean residence time within these basins. Balance calculations for the Weser basin indicate an over‐estimation of loss of tritium through evapotranspiration (more than 60%) and decay (10%). About 28% were carried in stream‐flow where direct runoff contributed about 12% and ground water runoff 13% in relation to precipitation input over the studied 50‐year period. Neighbouring basins and nuclear power plants contributed about 1% each over this time period. Copyright © 2007 John Wiley & Sons, Ltd.     

Analysis of river runoff in the Poyang Lake Basin of China: long-term changes and influencing factors

An analysis of the variation characteristics and evolutionary trends in the runoff of five rivers in the Poyang Lake Basin was conducted using the MK trend test, Morlet wavelet transforms, correlation analyses, and other methods. For 1956–2011, the inflow runoff displays small, statistically insignificant trends. However, for 2000–2011, significant downward trends are present. River runoff in the basin is significantly correlated with precipitation, while water intake and use is less influential; the most significant impact on river runoff is climate variability. To analyse the effects of water conservancy project scheduling and operation, we also compare the inflow and outflow runoff processes of typical large reservoirs before and after peak reservoir construction. The scheduling and operation of large reservoirs in the five rivers is known to play a supplementary role in dry season inflow runoff. The recent reduction in inflow runoff was mainly caused by basin precipitation; reasonable scheduling of water conservancy projects in the five rivers plays a positive role in safeguarding the water required by the dry season ecosystem in Poyang Lake.     

The rates of tritium input to the world oceans

Mean annual rates of tritium input into the ocean averaged over 5° latitude bands are presented for the major oceans, for the period 1952–1975. The rates are obtained by converting tritium concentrations in marine precipitation into net oceanic tritium input, by means of a hydrological model. The tropospheric tritium pattern is specified on the basis of available observations, and climatological means from the literature are used for the rates of evaporation and precipitation and for the relative humidity in ship's height, that enter the model. Tritium input by water vapor exchange exceeds that by precipitation about three-fold. Tritium input by river runoff and by net tropospheric tritium outflow from the continents is also accounted for. This contribution is small except for the northern Indian Ocean and the North Atlantic.The inputs have hemispheric maxima near 50° latitude. The northern hemisphere inputs were strongly peaked in 1963–1964, whereas temporal changes in the southern hemisphere were much more gradual. By 1972, about 75% of the total oceanic input had been received by the northern ocean. For the Pacific, the computed total input agrees with the actual tritium inventory within the limits of uncertainty (about ±20%). The global tritium inventory is estimated at 1.9 GCi in 1972, which corresponds to an average tritium yield of 0.9 kg tritium per megaton TNT equivalent of nuclear fusion.     

Periodicity of sediment load and runoff in the Yangtze River basin and possible impacts of climatic changes and human activities / Périodicité de la charge sédimentaire et de l'écoulement dans le bassin du Fleuve Yangtze et impacts possibles des changements climatiques et des activités humaines

Abstract

Periodicity of the runoff and the sediment load, and possible impacts from human activities and climatic changes, in the Yangtze River basin during 1963–2004 are discussed based on the monthly sediment and runoff data, and using the wavelet approach. Research results indicated that: (a) Sediment load changes are severely impacted by the different types of human activity (e.g. construction of water reservoirs, deforestation/afforestation); and the runoff variability is the direct result of climatic changes, e.g. the precipitation changes. (b) The impacts of human activity and climatic changes on the sediment load and runoff changes are greater in smaller river basins (e.g. the Jialingjiang River basin) than in larger river basins. The response of sediment load and runoff changes to the impacts of human activities and climatic changes are prompt and prominent in the Jialingjiang River basin relative to those in the mainstem of the Yangtze River basin. (c) Construction of the Three Gorges Dam has already had obvious impacts on the sediment transport process in the middle and lower Yangtze River basin, but shows no obvious influence on the runoff changes. Construction of the Three Gorges Dam will result in further re-adjustment of the scouring/filling process within the river channel in the middle and lower Yangtze River basin, and have corresponding effects on the altered sediment load because of the Dam's operation for the river channel, ecology, sustainable social economy and even the development of the Yangtze Delta. This will be of concern to local governments and policy makers.     

用氚讨论中国西部新疆干旱区的水循环率

Tritium concentrations are used to trace water circulation in the Urumqi and Turfan basins in the Xinjiang, western China. Tritium analyses were made for 77 water samples of river waters, groundwaters, spring waters, lake waters and glacier ice collected in summers in 1992 and 1994. The tritium concentrations in the waters are in a wide range from 0 to 125 TU, most of which are considerably high compared with those of most waters in Japan, because tritium levels in precipitation in the area are over ten times as high as those in Japan. River waters originating in glacier regions contain melt glacier, the proportion of which is over 0.5 to river water. The mean resi-dence time of circulating meteoric water in the mountain regions is estimated to be about 15 years. Most groundwaters and spring waters in the flat regions are mainly derived from river waters originating in glacier regions. The groundwater of greatest tritium concentrations in wells in Urumqi City is derived from Urumqi River about 25 years ago. It takes several ten years for river water to pass the underground to many springs. Some groundwaters and spring waters have taken a long time more than 40 years to travel under the ground. Enrichment of tritium in lake water by evaporation is considered to estimate the contribution of groundwater flow to the recharge of lake. Various contributions of groundwater to lakes are inferred for the various type of salinity in closed or semi-closed lakes. The inflow rates of groundwater to salt lakes are small as against fresh water lakes.     

Tritium in ground water of the georgia piedmont: Implications for recharge and flow paths

Environmental tritium was measured in 33 natural water samples representative of precipitation, stream runoff, and groundwater (derived principally from production wells) within the Georgia Piedmont Province. Major ion analyses were used to assist in the interpretation of the tritium results. Tritium concentrations were significantly greater within shallow groundwater derived from the regolith (28–34 TU) and stream runoff (25–30 TU) than within recent rainfall (4–17 TU). Based upon the decay-corrected tritium input function, this probably indicates that at least some of the shallow water is stored within the regolith for a period of approximately 25 years. A ‘post-bomb’ component of recharge was present in all groundwater derived from production wells in the study area. Groundwater sampled from the bedrock aquifers was commonly less tritiated than either stream runoff or shallow water stored in the regolith. the lower tritium concentrations May, have resulted from the mixing of ‘pre-bomb’ water stored within the fractures or the transitional zone directly above the bedrock and modern water stored in the shallow regolith. the preponderance of modern water provides evidence that groundwater flow paths are areally restricted within this setting, probably confined to local surface water drainage basins. the residence time of groundwater in the Piedmont is limited by the lack of deep, gravity-driven regional flow and the localized vertical flow induced by pumping. the results of this study indicate that relatively small tritium concentration variations (10-20 TU) May, have regional hydrological significance in the southeastern Piedmont Province and similar settings.     

太湖北岸湖滨带观测场水生植物群落特征及其影响因素分析

研究了鄱阳湖流域在1955-2002年间的径流系数的变化,重点分析了它与水循环的两个基本要素:降水量和蒸发量的关系,同时对其原因进行了初步的探讨.经分析,在鄱阳湖流域中,径流系数较大的是饶河流域和信江流域,较小的是抚河流域;在年内变化上,4-6月为五河流域径流系数比较大的月份,这与鄱阳湖流域降水集中期相对应.在空间上,4-6月仍然以饶河流域和信江流域相对较大,而抚河流域较小,特别是8月份的径流系数远小于其他四河;年代际变化上,1990s径流系数增加较为显著.尽管鄱阳湖流域的径流系数除了受气候因子的影响外,还受到水土流失和地形等因素的影响,但是降水量的增加,特别是暴雨频率的增加仍然是其主要影响因素,蒸发量的减小对径流系数的增加也有一定程度的影响.径流系数与气温并无明显的线性相关关系.     

Utilization of decadal tritium variation for assessing the residence time of base flow

An iterative algorithm is presented that allows the user to model the subsurface residence time of shallow ground water comprising stream base flow based on decadal scale variation of tritium concentrations. The algorithm accounts for the effects of radioactive decay, the shallow subsurface mixing of ground water with precipitation, and ground water flux. The inverse of the best-fitting modeled flux through the saturated zone is equivalent to the residence time. The data required for this model include at least two measurements of tritium in base flow for a given stream location made at least a decade apart and the long-term tritium input in precipitation for the region of interest. The model is sensitive to relatively small changes in tritium concentrations and is limited by analytic uncertainties to an accuracy of approximately +/-5 years. The algorithm was applied to stream base flow for several basins in the Piedmont Province of Georgia in which tritium concentrations were measured during the early 1990s and again in the 2000s. The model results produced highly concordant residence times for three hydrogeologically similar basins in the Upper Ocmulgee Basin in North Central Georgia. The best estimate of the average residence time for ground water comprising base flow in this Piedmont basin using this new method is between approximately 14 and 18 years. These results are generally consistent with calculations made in previous studies, and these relatively long residence times can be attributed to the storage of water in the clay soils that dominate Piedmont Province watersheds.     

Changes of flow regimes and precipitation in Huai River Basin in the last half century

Huai River Basin, as the sixth largest river basin in China, has a high‐regulated river system and has been facing severe water problems. In this article, the changing patterns of runoff and precipitation at 10 hydrological stations from 1956 to 2000 on the highly regulated river (Shaying River) and less‐regulated river (Huai River) in the basin are evaluated at the monthly, seasonal and annual scales using the Mann–Kendall test and simple linear regression model. The results showed that: (1) No statistically significant trends of precipitation in the upper and middle Huai River Basins were detected at the annual scale, but the trend of annual runoff at Baiguishan, Zhoukou and Fuyang stations in Shaying River decreased significantly, whereas the others were not. Moreover, the decreasing trends of runoff for most months were significant in Shaying River, although the trend of monthly precipitation decreased significantly only in April in the whole research area and the number of months in the dry season having significantly decreasing trends in runoff was more than that in the wet season. (2) The rainfall–runoff relationship was significant in both highly regulated river and less‐regulated river. In regulated river, the reservoirs have larger regulation capacity than the floodgates and thus have the smaller correlation coefficient and t‐value. In Huai River, the correlation coefficients decreased from upper stream to downstream. (3) The regulation of dams and floodgates for flood control and water supply was the principal reason for the decreasing runoff in Huai River Basin, although the decreasing precipitation in April in this basin was statistically significant. The findings are useful for recognizing hydrology variation and will provide scientific foundation to integrated water resources management in Huai River Basin. Copyright © 2010 John Wiley & Sons, Ltd.     

A simplified approach to analysing historical and recent tritium data in surface waters

Tritium concentrations in river and stream waters from different locations can be compared by normalizing them using the ratio of tritium concentrations in precipitation and surface water (C_p/C_s) in the study area. This study uses these ratios in a hydrological residence time context to make regional‐ and global‐scale comparisons about river basin dynamics. Prior to the advent of nuclear weapons testing, the C_p/C_s ratio was greater than or equal to 1 everywhere because of the decay of tritium in the watershed after it was deposited by precipitation. After an initial increase in the ratios during the bomb peak, the ratio dropped to less than 1 for most surface waters in the following years. This post‐bomb change in the ratio is due to the retention of the bomb‐pulse water in watersheds on timescales that are long relative to the residence time of tritium in the atmosphere. Ratios were calculated for over 6500 measurements of tritium in river and stream waters compiled by the International Atomic Energy Agency. These measurements span the post‐nuclear era (1940s to present) and include many long‐term datasets, which make it possible to examine residence times of waters in watersheds on a global basis. Plotting C_p/C_s versus time shows that ratios tended to reach a minimum in approximately one to two decades after the bomb peak for most locations. This result suggests that changes affecting quantity and quality of river flows need to be assessed on a multi‐decadal timescale. These long lag times have significant implications for assessing climate or land‐use change impacts on a large number of river systems around the world. The continuing value of tritium in studying surface water systems for both the Southern and Northern Hemisphere is also demonstrated. Published 2014. This article is a U.S. Government work and is in the public domain in the USA.     

Delineation of reservoirs using remote sensing and their storage estimate: an example of the Yellow River basin,China

Reservoirs are an integral component of water resources planning and management. Periodic and accurate assessment of the water storage change in reservoirs is an extraordinarily important aspect for better watershed management and water resources development. In view of the shortcomings of conventional approaches in locating reservoirs' spatial location and quantifying their storage, the remote sensing technique has several advantages, either for a single reservoir or for a group of reservoirs. The satellite‐based remote sensing data, encompassing spatial, spectral and temporal attributes, can provide high‐resolution synoptic and repetitive information with short time intervals on a large scale. Using remote sensing images in conjunction with Google Earth and field check of representative reservoirs, the spatial distribution of constructed reservoirs in the Yellow River basin was delineated, and their storage volume and the residence time of the stored water were estimated. The results showed that 2816 reservoirs were extracted from the images, accounting for 89·5% of the registered total. All large‐ and medium‐sized reservoirs were extracted while small reservoirs may not be extracted due to coarse resolution and cloud‐cover shadows. An empirical relationship between the extracted water surface area and the compiled storage capacity of representative reservoirs was developed. The water storage capacity was estimated to be 66·71 km³, about 92·7% of the total storage capacity reported by the authority. Furthermore, the basin was divided into 10 sub‐basins upon which the water's residence time was analysed. The water discharge in the basin has been greatly regulated. The residence time has surged to 3·97 years in recent years, ranking the Yellow River in the top three of the list in terms of residence time and flow regulation among large river systems in the world. It is expected that it will be further extended in future owing to decreasing water discharge and increasing reservoir storage capacity. Copyright © 2011 John Wiley & Sons, Ltd.     

The hydrological regime of large river basins in Northern Eurasia in the XX–XXI centuries

The ability of present-day climate models to reproduce the mean annual regime of river runoff and its within-year distribution is evaluated for major Eurasian basins, including the basins of the Volga and Amur and the major Siberian rivers: the Ob, Yenisei, and Lena. Estimates are made for possible variations in seasonal runoff and characteristics of daily precipitation (the amount, rate, and probability) in drainage areas for the late XXI century. The analysis involved the use of the results of calculations by climatic general circulation models carried out under international Coupled Model Intercomparison Project.     

Flood hydrograph attenuation induced by a reservoir system: analysis with a distributed rainfall‐runoff model

Spatially distributed hydrologic models can be effectively utilized for flood event simulation over basins where a complex system of reservoirs affecting the natural flow regime is present. Flood peak attenuation through mountain reservoirs can, in fact, mitigate the impact of major floods in flood‐prone areas of the lower river valley. Assessment of this effect for a complex reservoir system is performed with a spatially distributed hydrologic model where the surface runoff formation and the hydraulic routing through each reservoir and the river system are performed at a fine spatial and time resolution. The Toce River basin is presented as a case study, because of the presence of 14 active hydroelectric dams that affect the natural flow regime. A recent extreme flood event is simulated using a multi‐realization kriging method for modelling the spatial distribution of rainfall. A sensitivity analysis of the key elements of the distributed hydrologic model is also performed. The flood hydrograph attenuation is assessed. Several possible reservoir storage conditions are used to characterize the initial condition of each reservoir. The results demonstrate how a distributed hydrologic model can contribute to defining strategies for reservoir management in flood mitigation. Copyright © 2004 John Wiley & Sons, Ltd.     

Research on runoff forecast approaches to the Aksu River basin

The Aksu River (the international river between China and Kirghiz) has become the main water source for the Tarim River. It significantly influences the Tarim River’s formation, development and evolution. Along with the western region development strategy and the Tarim River basin comprehensive development and implementation, the research is now focused on the Aksu River basin hydrologic characteristic and hydrologic forecast. Moreover, the Aksu River is representative of rivers supplied with glacier and snow melt in middle-high altitude arid district. As a result, the research on predicting the river flow of the Aksu River basin has theoretical and practical significance. In this paper, considering the limited hydrometeorological data for the Aksu River basin, we have constructed four hydrologic forecast approaches using the daily scale to simulate and forecast daily runoff of two big branches of the Aksu River basin. The four approaches are the upper air temperature and the daily runoff correlation method, AR(p) runoff forecast model, temperature and precipitation revised AR(p) model and the NAM rainfall-runoff model. After comparatively analyzing the simulation results of the four approaches, we discovered that the temperature and precipitation revised AR(p) model, which needs less hydrological and meteorological data and is more predictive, is suitable for the short-term runoff forecast of the Aksu River basin. This research not only offers a foundation for the Aksu River and Tarim Rivers’ hydrologic forecast, flood prevention, control and the entire basin water collocation, but also provides the hydrologic forecast reference approach for other arid ungauged basins.     

Water quantity and quality simulation by improved SWAT in highly regulated Huai River Basin of China

High regulation of dams or sluices disturbs flow regimes and pollutant transformation process significantly in most basins over the world. The water quality and quantity simulation in highly regulated river basins is always a very complicated task. The Huai River Basin is a typical area in China with the highest density of water projects and serious pollution problems simultaneously. In this paper, a procedure based on Soil and Water Assessment Tool (SWAT) was proposed to carry out the water quantity and quality simulation of Huai River Basin by incorporating the operation rules of dams or sluices into the reservoir regulation module. The water quality module in SWAT is extended to suit the actual situation of river basin in China. The results show that: for runoff simulation, 28 of all the 38 stations (73.7%) have the acceptable performance, with the average correlation coefficient and efficiency coefficient of 0.83 and 0.66, respectively in the calibration period. In the validation period, 17 of all the 34 stations (50%) have the acceptable performance, with the average correlation coefficient and efficiency coefficient of 0.77 and 0.54, respectively. The model performs the worst for reservoirs, little better for sluices and the best for unregulated stations. Comparing to the low flow and high flow simulation of original SWAT model, the low flow simulation of reservoirs and the high flow simulation of sluices are much better because of their different main purposes. For water quality simulation, the standard reaching rates of NH₃–N and COD_Mn are 55.9% (19/34) and 67.6% (23/34) respectively for all the stations, and the average relation coefficients are 0.46 and 0.48 respectively. Comparing with the results of original SWAT model, the improved model better reproduces the long-term water quantity and quality processes in the Huai River Basin of China. This study provides a new approach and reference to understand the variation of water quantity and quality in highly regulated river basin, and is expected as technical support for the environment restoration and integrated management in the basins, especially in China.     

Research on runoff forecast approaches to the Aksu River basin

The Aksu River (the international river between China and Kirghiz) has become the main water source for the Tarim River. It significantly influences the Tarim River's formation, development and evolution. Along with the western region development strategy and the Tarim River basin comprehensive devel-opment and implementation, the research is now focused on the Aksu River basin hydrologic charac-teristic and hydrologic forecast. Moreover, the Aksu River is representative of rivers supplied with gla-cier and snow melt in middle-high altitude arid district. As a result, the research on predicting the river flow of the Aksu River basin has theoretical and practical significance. In this paper, considering the limited hydrometeorological data for the Aksu River basin, we have constructed four hydrologic forecast approaches using the daily scale to simulate and forecast daily runoff of two big branches of the Aksu River basin. The four approaches are the upper air temperature and the daily runoff correlation method, AR(p) runoff forecast model, temperature and precipitation revised AR(p) model and the NAM rainfall-runoff model. After comparatively analyzing the simulation results of the four approaches, we discovered that the temperature and precipitation revised AR(p) model, which needs less hydrological and meteorological data and is more predictive, is suitable for the short-term runoff forecast of the Aksu River basin. This research not only offers a foundation for the Aksu River and Tarim Rivers' hydrologic forecast, flood prevention, control and the entire basin water collocation, but also provides the hydrologic forecast reference approach for other arid ungauged basins.     

Cross-spectral analysis of rainfall and runoff for Raritan and Mullica river basins in New Jersey

Cross-correlation and cross-spectral analysis were employed in the analysis of rainfall and runoff in two river basins: the Raritan and Mullica River basins in New Jersey. Cross-covariance and coherence were studied in the correlograms for the following correlation cases: (a) rainfall-runoff for each one basin separately; (b) rainfall-rainfall analysis for two main meteorological stations in each one of the basins; (c) runoff-runoff for two main gaging stations in each one of the basins. From the estimates of the coherence at various frequencies the cross-spectral analysis shows a highly nonlinear relationship between rainfall and runoff in Raritan and Mullica River basins. A poor coherence observed at the annual cycles for each basin makes it difficult to predict the annual oscillations of runoff from those of rain-fall by a linear regression model. The high coherence between rainfall (or runoff) at the first station and rainfall (or runoff) at the second station within the same basin at almost all frequencies establishes an accurate prediction on a linear basis.     

Impact of warming climate on water management for the Ariège River basin (France)

Abstract

The French national project IMAGINE2030 aims to assess future water availability in the Garonne River basin (southwest France) by taking account of changes in both climate and water management in the 2030s. Within this project, two mountainous drainage basins located in the Pyrenees were examined to assess the specific impact of climate change on reservoir management. The Salat River basin at Roquefort, is considered as a proxy (representative of a natural basin), whereas the Ariège River at Foix is influenced by hydropower production in winter and by water releases to sustain low flows in summer. The Cequeau rainfall–runoff model, combined with a simplified model of reservoir management operations, was calibrated on present-day conditions and forced with climate projections derived from the IPCC AR4 report. The results show that a warming climate over the basins induces a decrease in mean annual runoff, a shift to earlier snow melting in mountainous areas and more severe low-flow conditions. The simulations show a decrease in electricity generation. Under two water management scenarios (one “business-as-usual” and the other incorporating an increased downstream water demand in compliance with requirements for increased minimum flow), simulations for the Ariège River basin suggest an earlier filling of the reservoir is necessary in winter to anticipate the increased release from reservoirs in summer to support minimum flow farther downstream.

Editor Z.W. Kundzewicz; Associate editor D. Hughes

Citation Hendrickx, F. and Sauquet, E., 2013. Impact of warming climate on water management for the Ariège River basin (France). Hydrological Sciences Journal, 58 (5), 976–993.     

Basinwide flood control system by combining prediction and reservoir operation

Japan has traditionally performed flood prevention through the construction and use of dikes, storage reservoirs, and basins which are costly and time consuming options. Another non-structural option is to operate the flood control system appropriately with a view to reducing flood damage. In this paper, a flood control system combining the runoff prediction model in the whole river basin with the reservoir operation is discussed. Different models of the runoff process are introduced in order to compare their accuracies and the computational time for the flood forecasting system. The reservoir operational rule is formulated in terms of fuzzy inference theory. Historical data are applied in a case study for verification of the proposed theories.