Yellow River Conservancy Commission

About: Yellow River Conservancy Commission is a based out in . It is known for research contribution in the topics: Sediment & Surface runoff. The organization has 381 authors who have published 336 publications receiving 3984 citations.

M5 Model Trees and Neural Networks: Application to Flood Forecasting in the Upper Reach of the Huai River in China

Abstract: The applicability and performance of the so-called M5 model tree machine learning technique is investigated in a flood forecasting problem for the upper reach of the Huai River in China. In one of configurations this technique is compared to multilayer perceptron artificial neural network (ANN). It is shown that model trees, being analogous to piecewise linear functions, have certain advantages compared to ANNs—they are more transparent and hence acceptable by decision makers, are very fast in training and always converge. The accuracy of M5 trees is similar to that of ANNs. The improved accuracy in predicting high floods was achieved by building a modular model (mixture of models); in it the flood samples with special hydrological characteristics are split into groups for which separate M5 and ANN models are built. The hybrid model combining model tree and ANN gives the best prediction result.

A spatial assessment of hydrologic alteration caused by dam construction in the middle and lower Yellow River, China

Abstract: The ‘range of variability approach’ (RVA) and mapping technique are used to investigate the spatial variability of hydrologic alterations (HA) due to dam construction along the middle and lower Yellow River, China, over the past five decades. The impacts of climate variability on hydrological process have been removed during wet and dry periods and the focus is on the impacts of human activities, such as dam construction, on hydrological processes. Results indicate the following: (1) The impacts of the Sanmenxia reservoir on the hydrologic alteration are relatively slight with a mean HA value of 0·48, ranking in the last place among the four large reservoirs. (2) Xiaolangdi reservoir has significantly changed the natural flow regime downstream with mean HA value of 0·56, ranking it in first place among the large reservoirs. (3) The results of ranked median degrees of 33 hydrologic alteration indicators for 10 stations in the Yellow River show that the hydrologic alteration of Huayuankou ranks the highest among 10 stream gauges. (4) Impacts of reservoirs on hydrological processes downstream of the dams are closely associated with the regulating activities of the reservoirs. At the same time, alterations of streamflow regimes resulting from climatic changes (e.g. precipitation variability) make the situation more complicated and more hydrological observations will be necessary for further analysis. The results of the current study will be greatly beneficial to the regional water resources management and restoration of eco-environmental systems in the middle and lower Yellow River characterized by intensified dam construction under a changing environment. Copyright © 2008 John Wiley & Sons, Ltd.

Paving the Way for Public – Private Partnerships in Infrastructure Development

Abstract: Infrastructure privatization has multidimensional impacts with long-term uncertainties and wide risk portfolios. A wide range of barriers to public-private partnerships (PPPs) in infrastructure development have been identified through a questionnaire survey, which are broadly classified into six aspects: (1) social, political, and legal risk; (2) unfavorable economic and commercial conditions; (3) inefficient public procurement framework; (4) lack of mature financial engineering techniques; (5) problems related to the public sector; and (6) problems related to the private sector. To explore measures for removing these barriers, a systematic research approach (literature review, case studies and interviews/correspondences with experts and experienced practitioners) has been taken to draw experience, learn lessons, and benchmark the best practices in international PPPs. An improved PPP protocol for infrastructure projects in general has been developed, addressing key issues in nine areas: (1) appropriate roles of governmental authorities; (2) best value for money approach; (3) effective management of adviser services; (4) formulation of appropriate PPP schemes; (5) use of relational contracts; (6) improvement of the procurement framework; (7) payment structure; (8) contract monitoring, termination, and step-in rights; and (9) transfer management. Effective measures for successful PPPs are identified in each of the nine areas.