C. Prakash Khedun

Water Deficit Duration and Severity Analysis Based on Runoff Derived from Noah Land Surface Model

AbstractThe identification and prediction of drought events depend on the integrity of the dataset employed. Streamflow is a good indicator of surface water availability and has dominated the literature on frequency analysis of hydrological droughts and water management. However, gauged measurements are impaired by climate and land use changes, especially in large, modified watersheds. Hence, their use in drought prediction is limited because they may violate the assumption of stationarity unless a naturalized observation series is obtained. In this paper, a land surface model is used to generate runoff in the Rio Grande/Rio Bravo del Norte basin. Land use land cover is kept constant so that changes are a result of climatological variations. The river threads across several climatic zones; therefore the basin is divided into different regions for analysis. Using statistical theory of runs, water deficit duration and severity and drought interarrival time are extracted from 3-month Standardized Runoff Inde...

Climate Change, Water, and Health: A Review of Regional Challenges

Climate change is a phenomenon affecting the whole planet; however, its impacts are mostly felt by those who are already deprived—low—income countries and regions prone to climate related disasters. The occurrence, intensity, and spatial extent of hydrological extremes are likely to change with global warming. This paper reviews current and future impacts of a changing climate on the hydrological cycle and how it affects floods; droughts and related impacts on agriculture and food availability; sea-level rise and its impacts on coastal communities; and waterborne, rodent-borne, and vector-borne diseases. The effect of climate on quality of life and risks of conflicts is also explored. Regions that are most likely to be impacted by each are highlighted. The disasters associated with climate change are very similar to those that the world has periodically witnessed due to climate variability patterns, such as the El Niño Southern Oscillation. However, their frequency and severity may be much higher and they may compromise efforts currently underway to solve existing problems.

World Water Supply and Use: Challenges for the Future

Water is the most precious natural resource on the earth. The amount of water available on the earth is limited and some regions are already heading toward water bankruptcy. Rising population, climate change, conversion of agricultural land for biofuel production, etc. further complicate the problem of adequate water allocation. The problem can be even more complex in transboundary river basins. This article presents the current state of water around the world and explores impending water challenges.

Review of Floods in a Changing Climate: Hydrologic Modeling by P. P. Mujumdar and D. Nagesh Kumar

In his foreword, Professor R. L. Wilby starts with a question: How much higher does the flood wall need to be built and how much larger does the reservoir spillway need to be? This is a pertinent and practical question that needs to addressed for flood management, but its answer gets complicated by the impacts of climate change on the hydrological cycle, reflected by the changes in the rainfall and streamflow regimes as well as in the watershed physiography itself. This book attempts to present methodologies for hydrologic modeling with particular focus on impacts of climate change on flood characteristics that will help answer this question. The book comprises six chapters. Chapter 1 is introductory, providing the background of and a brief introduction to the topics covered in the book, including hydrologic models; remote sensing, geographic information systems (GIS), and digital elevation model (DEM) for hydrologic modeling; and assessment of climate change impacts. The chapter concludes with a short discussion of the organization of the book. This is a well-written chapter. Chapter 2 deals with hydrologic modeling for floods from the perspective of planning and operations related to floods. It covers lumped models, such as the unit hydrograph method, the SCS method, the rational method, empirical intelligent models, flow routing models, and commonly used watershed models. Given the limitations of space, the chapter is a good synopsis. It could have been stronger with the inclusion of some well and useful models and techniques. Since the impact of climate change is most noticeable in the cryosphere, it would have been desirable to include snowmelt models. Climate change and its impact are receiving a lot of attention these days. Chapter 3 presents methodologies for assessing hydrologic impacts due to climate change. Beginning with a discussion of emission scenarios, it goes on to discuss the projection of hydrologic impacts, dynamical downscaling approaches, statistical downscaling, disaggregation models including deterministic and stochastic techniques, macroscale hydrologic models, hypothetical scenarios for hydrologic modeling, modeling of floods under climate change, and uncertainty analysis. This is a very good chapter and contains a wealth of information. Remote sensing for hydrologic modeling constitutes the subject matter of Chapter 4. Introducing basic concepts of remote sensing that are necessary to understand and analyze images obtained by remote sensing, such as spectral reflectance for vegetation, soil, and water remote sensing platforms, it goes on to discuss digital images, including color composites and image characteristics, image rectification, image enhancement, image information extraction, land use/land cover information, utility of remote sensing for hydrologic modeling, and demonstration of image processing using MATLAB. The chapter is written in an easyto-understand manner and is a good introduction for those not well versed in remote sensing. Chapter 5 deals with GIS for hydrologic modeling. Introducing the GIS technology, the chapter discusses representation of spatial objects in GIS, proximity analysis, DEM, representation of digital data, application of digital elevation models, other sources of DEM, integration of spatial, nonspatial and ancillary data into a distributed hydrologic model, GIS and remote sensing for flood zone mapping, and web-based GIS. This is a very useful chapter and the narrative is lucid. Case studies and future perspectives constitute the subject matter of Chapter 6, the concluding chapter. Case studies include the Malaprabha reservoir catchment, India; Mahanadi River basin, India; and future perspectives. The two case studies are very illustrative. For example, the Malaprabha case study discusses streamflow projection methods, soil and water assessment tool (SWAT) and ArcView SWATmodels, study region and data used, calibration and validation of SWAT, downscaling, disaggregation, streamflow generation with SWAT, and prediction of future streamflows for changed climates. In this manner, what is discussed in the preceding chapters is brought together to bear on dealing with the case study. The Mahanadi River basin study focuses on future flood peaks and water availability and uncertainty modeling. The chapter concludes with a discussion of future perspectives. The Mujumdar and Kumar book is well written and reflects the authors’ extensive experience in hydrologic and water resources systems modeling. It will be a good addition to the library of water resources engineers, hydrologists, watershed managers, and policy makers who are concerned with the impacts of climate change. The end-of-chapter exercises, albeit few, are good. The authors state in the preface that the book synthesizes various existing methodologies that can help with planning and operational decision making under the specter of climate change. We believe the authors have largely succeeded in accomplishing this synthesis and ought to be complimented for preparing a well-written treatise on a most interesting topic—the hydrologic modeling of floods in a changing climate.

Climate Change and Its Impact on Water Resources

Recent years have witnessed an increase in global average air temperatures as well as ocean temperatures, as documented by the Intergovernmental Panel on Climate Change (IPCC). The rise in temperature is considered irrefutable evidence of climate change, and this has already started to have serious consequences for water resources and will have even more dire consequences in the future. Compounding these consequences are population growth, land-use changes and urbanization, increasing demands for water and energy, rising standards of living, changing dietary habits, changing agricultural practices, increasing industrial activities, increased pollution, and changing economic activities. All these will likely have adverse effects on water resources. This article briefly discusses climate change and its causes and impacts on water resources.

Review of Floods in a Changing Climate: Extreme Precipitation by Ramesh S. V. Teegavarapu

In July 2010, Pakistan suffered the worst flooding, in its Indus River basin, it ever experienced. More than a fifth of the country’s land area was inundated, between 15 and 20 million people were displaced, and about 2,000 people perished. Economic damage resulting from this event is estimated at approximately US

Review of The Lower Damodar River, India: Understanding the Human Role in Changing Fluvial Environment by Kumkum Bhattacharyya

8–10 billion (World Bank 2010). The Indus basin has been frequently hit by floods during the monsoon season. In August 2013, another flash flood resulted in the death of 180 people. Between July and mid-August, unusually heavy rainfall in the transboundary Amur River watershed resulted in massive flooding in both China and Russia. More than 60,000 people were affected in China and over 787,000 ha of farm land were submerged. In Russia, the flooding is considered to be the worst in 120 years. In the United States, catastrophic flooding in Colorado in early September affected 17 counties; and 430 mm resulted in economic damages estimated at over US

Review of River Basin Trajectories: Societies, Environments and Development by François Molle and Philippus Wester

1 billion; and 430 mm of rain (close to its annual precipitation of 525 mm) fell over Boulder County in just 7 days. Earlier during the year, on June 20, 2013, heavy rainfall in Alberta, Canada, caused some of the worst flooding in the province’s history. More than 100,000 people were displaced and economic damage is estimated to exceed Can

Simulation of Combined Best Management Practices and Low Impact Development for Sustainable Stormwater Management

5 billion. On the other side of the Atlantic, in central Europe, heavy rains caused massive flooding, with damages estimated at approximately US

A copula‐based precipitation forecasting model: Investigating the interdecadal modulation of ENSO's impacts on monthly precipitation

3.9 billion. On March 30, 2013, 152 mm of rain (equivalent to 70% of March’s average precipitation) fell on Port Louis, the capital of Mauritius, in less than 2 h. Within minutes, roads were transformed into rivers, causing a huge traffic jam and paralyzing the economic center of the island. Residents were not warned of the possibility of heavy rainfall on that day; the flooding claimed the lives of 11 people. Devastating flash floods seem to be happening very frequently and on every continent. Is it really the case, or does it seem that they are becoming more and more frequent as a result of efficient reporting by the media? Are these extreme precipitation events a result of climate change? Regardless, the latter is the first to bear the brunt. From a scientific standpoint, rising atmospheric temperature owing to global warming will result in higher evaporation and an increase in the water-holding capacity of the atmosphere. This may lead to an intensification of the hydrologic cycle resulting in a change in the frequency, intensity, spatial extent, duration, and timing of extreme precipitation events, evapotranspiration, tropospheric water content, and runoff (National Research Council 2011). Changes in precipitation extremes can be in the following three ways: (1) a shift in the mean, resulting in less low magnitude events and more high magnitude events; (2) an increase in variability, i.e., more low and high magnitude events; and (3) a change in the shape of the distribution, i.e., near-constant low-magnitude events but an increase in high-magnitude events [Intergovernmental Panel on Climate Change (IPCC) 2012]. Because it is known with a high degree of confidence that a rise in the concentration of greenhouse gases in the atmosphere influences the climate and subsequently the hydrological cycle, frequent occurrences of flash floods are probably the effect of climate change. Although this hypothesis is valid, it is still hard to pin any one particular event and state with certainty that it is a result of climate change, or had the climate not been changing, that particular event would not have happened. Research in this area is extremely important and may help to unravel the reason behind the seeming increase in the number of flood events. Marvel and Bonfils (2013), for example, demonstrated that changes in land and ocean precipitation predicted by the global warming theory are indeed occurring, even though they are hard to detect in observational records. Internal variability in the atmospheric system accounts for only part of the changes detected. The other factor responsible for this change is external and probably anthropogenic. Teegavarapu’s Floods in a Changing Climate: Extreme Precipitation is therefore extremely timely. The 269-page book is divided into nine chapters covering almost everything from the basics of precipitation and climate change to modeling and future direction in this area. Chapter 1 of the book gives an overview of climate change and variability, the precipitation process and how it can lead to floods, and the influence of climate change and climate variability. It also describes the main issues pertaining to extreme precipitation in the context of a changing climate. Chapter 2 covers precipitation measurement techniques. Ground-, radar-, and satellite-based measurements are discussed. Both chapters are well-written and provide a good introduction of the topic and how it is relevant in the context of climate change. On a temporal scale, a flood is one event that has a duration, frequency, and return-period. On the ground, however, the event is spatial in nature, covering anything from a few km to counties and can even be transboundary. Therefore, spatial analysis of precipitation is important. This topic is covered in Chapter 3— the longest chapter in the book. Teegavarapu presents a summary of almost every technique available. The techniques include both classical approaches and emerging techniques, and some are illustrated with pertinent examples. This chapter is extremely detailed and can be a valuable reference guide. Analysis of extreme precipitation and floods is presented in Chapter 4. This chapter discusses the hydrometeorological aspects of precipitation and floods. Flood mechanisms and the role and effect of shallow groundwater and soil moisture are explained. Cyclone-related flooding, which some argue is becoming more frequent as a result of climate change, is also presented. General circulation models (GCMs) and hydrological models often run at different temporal and spatial scales. To perform hydrological forecasts based on climate projections, climate model outputs have to be downscaled and reconciled with hydrological