Distributed Hydrological Modelling

It is the task of the engineer, as of any other professional person, to do everything that is reasonably possible to analyse the difficulties with which his or her client is confronted, and on this basis to design solutions and implement these in practice. The distributed hydrological model is, correspondingly, the means for doing everything that is reasonably possible - of mobilising as much data and testing it with as much knowledge as is economically feasible - for the purpose of analysing problems and of designing and implementing remedial measures in the case of difficulties arising within the hydrological cycle. Thus the aim of distributed hydrologic modelling is to make the fullest use of cartographic data, of geological data, of satellite data, of stream discharge measurements, of borehole data, of observations of crops and other vegetation, of historical records of floods and droughts, and indeed of everything else that has ever been recorded or remembered, and then to apply to this everything that is known about meteorology, plant physiology, soil physics, hydrogeology, sediment transport and everything else that is relevant within this context. Of course, no matter how much data we have and no matter how much we know, it will never be enough to treat some problems and some situations, but still we can aim in this way to do the best that we possibly can.

During ten years serving with the USDA Soil Conservation Service (SCS), now known as the Natural Resources Conservation Service (NRCS), I became amazed at how millions of dollars in contract monies were spent based on simplistic hydrologic models. As project engineer in western Kansas, I was responsible for building flood control dams (authorized under Public Law 566) in the Wet Walnut River watershed. This watershed is within the Arkansas-Red River basin, as is the Illinois River basin referred to extensively in this book. After building nearly 18 of these structures, I became Assistant State Engineer in Michigan and, for a short time, State Engineer for NRCS. Again, we based our entire design and construction program on simplified relationships variously referred to as the SCS method. I recall announcing that I was going to pursue a doctoral degree and develop a new hydrologic model. One of my agency's chief engineers remarked, "Oh no, not another model!" Since then, I hope that I have not built just another model but have significantly advanced the state of hydrologic modeling for both researchers and practitioners. Using distributed hydrologic techniques described in this book, I also hope one day to forecast the response of the dams I built.

The current popularity of the rainfall-runoff model Topmodel is a direct result of the widespread availability of catchment GIS systems and particularly of digital terrain maps. Water flows downhill, therefore topography must be hydrologically significant, therefore how can the digital terrain data be used in hydrological modelling to improve the realism of the predictions? There are not many choices available: Topmodel is one of them but the concepts on which it is based will not be applicable everywhere (see some of the papers in this volume). Indeed, one of the most important aspects of the use of Topmodel is the possibility of mapping the simulations back into space so that the distributed predictions can be compared with field observations. The experiences reported here in applications from around the world represent an excellent summary of the success and limitations of the concepts in a wide variety of environments. Topmodel was never intended to be a fixed model structure but rather a set of concepts that could be modified if required. As such it is important that the experiences of other uses can be gathered together and passed on.

This volume is a collection of a selected number of articles based on presentations at the 2005 L’Aquila (Italy) Summer School on the topic of “Hydrologic Modeling and Water Cycle: Coupling of the Atmosphere and Hydrological Models”. The p- mary focus of this volume is on hydrologic modeling and their data requirements, especially precipitation. As the eld of hydrologic modeling is experiencing rapid development and transition to application of distributed models, many challenges including overcoming the requirements of compatible observations of inputs and outputs must be addressed. A number of papers address the recent advances in the State-of-the-art distributed precipitation estimation from satellites. A number of articles address the issues related to the data merging and use of geo-statistical techniques for addressing data limitations at spatial resolutions to capture the h- erogeneity of physical processes. The participants at the School came from diverse backgrounds and the level of - terest and active involvement in the discussions clearly demonstrated the importance the scienti c community places on challenges related to the coupling of atmospheric and hydrologic models. Along with my colleagues Dr. Erika Coppola and Dr. Kuolin Hsu, co-directors of the School, we greatly appreciate the invited lectures and all the participants. The members of the local organizing committee, Drs Barbara Tomassetti; Marco Verdecchia and Guido Visconti were instrumental in the success of the school and their contributions, both scienti cally and organizationally are much appreciated.

The Encyclopedia of GIS provides a comprehensive and authoritative guide, contributed by experts and peer-reviewed for accuracy, and alphabetically arranged for convenient access. The entries explain key software and processes used by geographers and computational scientists. Major overviews are provided for nearly 200 topics: Geoinformatics, Spatial Cognition, and Location-Based Services and more. Shorter entries define specific terms and concepts. The reference will be published as a print volume with abundant black and white art, and simultaneously as an XML online reference with hyperlinked citations, cross-references, four-color art, links to web-based maps, and other interactive features.

This book presents an overview of the hydrometeorological and hydrological studies and assists in tackling challenges posed by climate and land use land cover changes. The Ganga River is one of the major living streams on the planet earth and very important river system in India. This holy river is a lifeline for approximately five hundred million people. In the last few decades, River Ganges has been subjected to tremendous pressures with respect to both water quantity and water quality. This situation, already one of the alarming magnitudes, has been further provoked by hydrometeorological changes resulting in droughts, floods and reduced groundwater levels and river flows in addition to the poor river health. Thus, it is imperative to assess the various complexities and possible solutions for better management of River Ganges. This book is a valuable addition to the literature and contributes to research on River Ganges which will help better planning and management of Ganga river basin. The hydrological and hydrometeorological aspects covered in this book help practitioners, researchers, policymakers and other stakeholders.

This book explores a new realm in data-based modeling with applications to hydrology. Pursuing a case study approach, it presents a rigorous evaluation of state-of-the-art input selection methods on the basis of detailed and comprehensive experimentation and comparative studies that employ emerging hybrid techniques for modeling and analysis. Advanced computing offers a range of new options for hydrologic modeling with the help of mathematical and data-based approaches like wavelets, neural networks, fuzzy logic, and support vector machines. Recently machine learning/artificial intelligence techniques have come to be used for time series modeling. However, though initial studies have shown this approach to be effective, there are still concerns about their accuracy and ability to make predictions on a selected input space.

This book stemmed from a desire to provide a comprehensive account of some of the world's popular computer models of watershed hydrology. To achieve this objective, a variety of models that together spanned a range of characteristics were included. Some of those models represent a large class of models, some are comprehensive, some are applicable to not only civil works but also to agricultural, range and forest, and nonpoint source pollution fields; some are equipped with the GIS and remote sensing capability, and some represent a large cross-section of models from around the world. The subject matter of this book is divided into 29 chapters. Beginning with introductory remarks on watershed modeling in Chapter 1, model calibration and reliability estimation are presented in Chapters 2 and 3, respectively. The next ten chapters (4 to 13) present some of the popular models from around the world. These models are in the realm of civil engineering applications of watershed hydrology models. Some of the models are more comprehensive than others and some have the management capabilities. The next two models, presented in Chapters 14 and 15, are large-scale models and embody GIS and remote sensing technology. The models presented in Chapters 16 to 23 are more physically-based and distributed in nature, quite suited to nonpoint source pollution modeling, and to assess environmental impact of land use changes. The remaining 5 models presented in Chapters 24 to 29 are within the realm of agricultural and forestry applications. Nonpoint source pollution, erosion and impact on soil productivity, drainage design, etc., can be modeled by applying these models. Computer Models of Watershed Hydrology will be of interest to practicing hydrologists, especially to hydrologic modelers and the model users, as well as specialists in the fields of civil engineering, agricultural engineering, environmental science, forest and range science, earth science, climatology, and watershed sciences. Graduate students, teachers engaged in graduate instruction, and researchers will also find this book useful. Due to the popularity of this book and with innovations in printing, this was reprinted in 2012 with the original information. It is now part of WRP’s Classic Resource Edition.