Preface

The importance of the science of water, commonly called "the hydrologic science," is increasing day by day as the resources of water are depleting and becoming scarcer. The depletion problem is not that the amount of total water available on this planet is reducing with time, but that the amount of sweet water, potable water, arable water, usable water, and water suitable for human usage and consumption is depleting every day in contrast to the rapid population growth on this planet. This is happening because the resource is being polluted by humankind itself, rendered unsuitable due to negligence and mismanagement, or its quantity is fast diminishing due to exhaustive extraction and consumption.

With this state of affairs, in recent times, knowledge of the science of water has gained an importance many times its original scale; and with that, its acquisition, expansion, research, advancement, and dissemination have become equally or more important. With so many dimensions of hydrology, any contributory work on the science of water, now available for exploration, research, and technological advancement, is more than welcome. This book will play its part in furthering the knowledge of the science of water and will prove useful reading for various cross-sections of academia in training institutions, researchers in laboratories, and engineers working in the field.

This voluminous book is the outcome of the consistent work of authors, researchers, engineers, and scientists from various continents across the globe. It consists of seven chapters covering various dimensions of hydrology. The first chapter jointly authored by myself and Ms. Laila Khalid, "Hydrologic science—where we stand today?," presents the journey of progress of hydrology through the ages, culminating in the present-day state of knowledge, research, and application of hydrologic science. The next chapter titled "The hyporheic zone" by Vanessa J. Banks introduces the key concepts of the hyporheic zone with an emphasis on the importance of understanding streambed sediments and their architecture to assess hydraulic functioning and modeling of such a zone. The third chapter by Mikhail Burakov discusses the accuracy of hydrogeological calculations and forecasts, and presents a method to make assessments of flow parameters. The fourth chapter authored by Faye Cheikh tries to assess the impacts of climate change on the water resources of the Gambian River Basin. In Chapter 5 "Analysis of non-rainfall periods and their impacts on soil water regime," Milan Gombos investigates significant non-rainfall periods, their periodicity, and statistical characteristics in the region of the eastern Slovak lowlands. The sixth chapter written by Amin Shaban, "Striking challenges on water resources of Lebanon," investigates the existing physical and anthropogenic challenges faced by water resources in Lebanon, even though there is no visible shortage of water in the region. The seventh chapter by Nawa Raj Pradhan, "Process modeling of soil thermal and hydrological dynamics," explains the simulation of soil thermal state effects on hydrological response, soil thermal regime, frozen soils, and permafrost simulation capability of a model developed at a permafrost laboratory.

The entire concept of IntechOpen Access is simply laudable. Providing a platform for writers, researchers, scholars, scientists, engineers, users, and all stakeholders of "water" to give them an opportunity to document their valuable knowledge is a great scheme in itself. Also, providing an open and free access of this knowledge to the whole world is the greatest service possible for humanity. In the offices of IntechOpen the contributions of author service managers Ms. Manuela Gabrić and Mr. Josip Knapić need to be recognized because without their relentless reminders of the timelines, their cooperation, and their assistance this book would not have been completed within the specified time limits.

The contributions of my colleague Dr. Fariha Masood Siddiqui are also recognized as it was her knowledge and comments in the field of water quality that helped me complete the editing job in a befitting manner encompassing all needed aspects.

I dedicate this book to my grandson Ibrahim Waqar and all kids of his age. It is for his generation and all generations that come after him that we would want to leave this already scarce, life-sustaining resource called water in a fit, suitable, usable, and sustainable form. The dangers of global warming, drastic climate change, ozone layer depletion, and water and food scarcity are looming over the coming generations and need to be challenged and remedied, right now! May the future generations live in an environment much better than ours.

> **Dr. Muhammad Salik Javaid** Abasyn University, Islamabad, Pakistan

> > **1**

flows in urban areas.

**Chapter 1**

**1. A journey through ages**

Introductory Chapter: Hydrologic

Science - Where We Stand Today?

Much has been written in the scientific literature about this diverse field of hydrologic science. However, this chapter is aimed at introducing modern hydrology, highlighting its evolution from ancient times to the recent era of rationalization, theorization, and computerization. Though hydrology is a main branch of science, it has exhibited very slow but steady developmental strides as compared to some other branches of science showing quantum leaps. Discussing the historical development of hydrology, it can be divided into [1] six successive periods of time: (a) ancient hydrology (1000 BC–AD 500), (b) medieval water technology (500– 1500), (c) renaissance concepts and measurements (1500–1700), (d) the emergence of water science (1700–1800), (e) the era of empirical hydrology (1800–1930), and

Hydrology is the science of water came into being the day the first winds blew across the meadows, the day first cloud was formed in the sky, the day the first drop of rain fell on the surface of this earth, the day some sage tried to collect rainwater and diverted it to his farmlands, and the day mankind got an inkling of the immense value of water for the survival of life. Now once we look back, we see that starting from that very first day, the hydrology has come a long way, travelling through history and adopting many faces of knowledge. In the thematic framework, hydrology now has evolved to become a cross-cutting theme for civil engineering, agricultural engineering, earth science, environmental science, climatology, geography, geology, and watershed management. Hydrologic phenomena have proved to be the most intrigu-

During the eighteenth century, there was a huge advancement in the field of hydrology, when new hydraulic principles and experiments such as Bernoulli's equation and Chezy's formula, and improved instruments such as current meter and tipping bucket rain gauge, were developed. John Dalton derived the principle for evaporation using lysimeter, and Mulvaney proposed the rational method for determining peak flood flow. Darcy derived his equation and developed his law of porous media flow, while Chamier applied rational method to the design of culverts, and Kuichling applied rational method for the estimation of storm water

In the nineteenth century, to meet the estimation and design demands of hydraulic engineering projects, empirical approach was used. However, at the start of the twentieth century, the quantitative hydrology was still undeveloped. The year from 1930 to 2000 is the period in which modern hydrology evolved through stages and developed as a geoscience. In this period, Horton developed infiltration theory, and Richard developed the equation for unsaturated flow. In the early 1930s, the main focus was rationalization of empirical results which were derived earlier and used in practice. In the middle of the period, theoretical basis replaced empiricism,

(f) rationalization, theorization, and computerization (1930–2000).

ing among elements of our environment, that is, sun, soil, air, and water.

*Muhammad Salik Javaid and Laila Khalid*

#### **Chapter 1**
