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Li H.-Y.,Hydrology Technical Group | Sivapalan M.,University of Illinois at Urbana - Champaign | Tian F.,State Key Laboratory of Hydroscience and Engineering
Water Resources Research | Year: 2014

Inspired by the Dunne diagram, the climatic and landscape controls on the partitioning of annual runoff into its various components (Hortonian and Dunne overland flow and subsurface stormflow) are assessed quantitatively, from a purely theoretical perspective. A simple distributed hydrologic model has been built sufficient to simulate the effects of different combinations of climate, soil, and topography on the runoff generation processes. The model is driven by a sequence of simple hypothetical precipitation events, for a large combination of climate and landscape properties, and hydrologic responses at the catchment scale are obtained through aggregation of grid-scale responses. It is found, first, that the water balance responses, including relative contributions of different runoff generation mechanisms, could be related to a small set of dimensionless similarity parameters. These capture the competition between the wetting, drying, storage, and drainage functions underlying the catchment responses, and in this way, provide a quantitative approximation of the conceptual Dunne diagram. Second, only a subset of all hypothetical catchment/climate combinations is found to be “behavioral,“ in terms of falling sufficiently close to the Budyko curve, describing mean annual runoff as a function of climate aridity. Furthermore, these behavioral combinations are mostly consistent with the qualitative picture presented in the Dunne diagram, indicating clearly the commonality between the Budyko curve and the Dunne diagram. These analyses also suggest clear interrelationships amongst the “behavioral“ climate, soil, and topography parameter combinations, implying these catchment properties may be constrained to be codependent in order to satisfy the Budyko curve. © 2014. American Geophysical Union. All Rights Reserved.

Li H.-Z.,Central Research Institute of Building and Construction | Hu L.-M.,Tsinghua University | Hu L.-M.,State Key Laboratory of Hydroscience and Engineering | Xin H.-B.,Central Research Institute of Building and Construction
Yantu Gongcheng Xuebao/Chinese Journal of Geotechnical Engineering | Year: 2015

The groundwater pollution by organic contaminants is becoming more and more severe, making groundwater remediation be imperative. The researches on the remediation technology are of theoretical and practical importance. Based on the review of in-situ groundwater remediation technology for organic contaminants and micro-nano bubble MNBs technology, MNB technology is proposed for groundwater remediation. The scheme using MNB for in-situ groundwater remediation is introduced. The contaminants can be removed by biodegradation enhanced by MNB. The numerical simulation results of in-situ application show a great enhancement on dissolved oxygen and a significant influence zone for contaminant removal. The MNB technology is effective, energy-efficient and environment-friendly to clean up contaminants, which has great potential in groundwater remediation. ©, 2015, Yantu Gongcheng Xuebao/Chinese Journal of Geotechnical Engineering. All right reserved.

Niu X.,State Key Laboratory of Hydroscience and Engineering | Yu X.,Tsinghua University
Wave Motion | Year: 2011

An analytical solution of the mild-slope wave equation is derived to describe long wave propagating over the idealized dredge excavation pit. The pit is assumed to be axisymmetrical and composed of a flat bottom and a convex slope. The convex slope is expressed by a simple power function. The problem is solved in the polar coordination system by the separation of variables. By the obtained solution, the characteristics of the wave refraction and reflection over the dredge excavation pit are discussed. The results show that wave amplitude is attenuated within and in the lee side of the pit and amplified at the rear flank of the pit due to wave refraction. The effects of the incident wave length and the shape of the pit on wave refraction are also discussed. © 2010 Elsevier B.V.

Zhou J.,State Key Laboratory of Hydroscience and Engineering | Zhang M.,State Key Laboratory of Hydroscience and Engineering | Lin B.,State Key Laboratory of Hydroscience and Engineering | Lu P.,Water Environment Monitoring Center for the Upper Reach of Yangtze River
Water Resources Research | Year: 2015

Dams affect ecosystems, but their physical link to the variations in fluvial fluxes and downstream ecological consequences are inadequately understood. After estimating the current effects of the Three Gorges project and other reservoirs upstream on the Yangtze River on the fluvial phosphorus (P) in the middle and lower Yangtze River, we further investigated the long-term effects of dams on the fluvial regimes of P and P-enriched sediment (PES). Simultaneously measured P distributions with sediment size (PDSS) from the Three Gorges Reservoir (TGR) proved that the areal density of particulate P (PP) bound on graded sediment can be measured using the surface area concentration of the total sediment. A PDSS relationship is obtained and the selective transport and long-term sedimentation of P are simulated using a nonuniform suspended sediment model, which incorporates the PDSS formula. The computations revealed that a reservoir would significantly lower the downstream availability of P in the dry season and promote high pulses of P in summer when the reservoir is flushed as sedimentation accumulates. As a result, the P buffering and replenishing mechanism in the pristine ecosystem from upstream supplies and local re-suspension are permanently eliminated when a regulating reservoir is built upstream. This change is irreversible if reservoir regulation continues. Changes could potentially aggravate the existing P-limitation, decrease the water's ability to adjust nutrient/pollutant fluctuations, accumulate a greater surplus of carbon and nitrogen, and even exacerbate blooms in favorable conditions. © 2015. American Geophysical Union. All Rights Reserved.

Han D.,Tsinghua University | Han D.,State Key Laboratory of Hydroscience and Engineering | Fang H.,Tsinghua University | Fang H.,State Key Laboratory of Hydroscience and Engineering | Chen M.,China Agricultural University
Shuili Fadian Xuebao/Journal of Hydroelectric Engineering | Year: 2012

Zero flow often occurs in river channel network in dry season. This paper presents an amended zero flow method for simulation of the impact of zero flow on flow splitting, siltation and erosion. This method combines the advantages of virtual flow area method and zero flow method, and it can correct coefficient matrix according to the zero flow conditions. The new method was applied to the Jingjiang-Dongting Lake region downstream the Three Gorges project to study the flow diversion features of the three lake outlets under the condition of zero flow discharge. The calculations of water level and flow discharge agree well with the measurements. The method avoids excessive estimation of split flow discharge by virtual flow area method and the singular coefficient matrix of zero flow method.

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