Hydrology is a scientific discipline, as it adopts the scientific method in its study. Hydrological studies involve the application of scientific knowledge and mathematical principles to solve water related problems.
The focus of this unit is the introductory aspect of hydrology. Sub-topics such as: what is hydrology? Scope and major branches of hydrology will be highlighted.
What is Hydrology?
Hydrology is the science dealing with the waters of the earth, their occurrence, distribution and circulation, their chemical and physical properties and their interaction with the environment (Ward and Robinson, 2000).
Similarly, Universities Council on Water Resources (UCWR, 2011) defines hydrology as the science that encompasses the occurrence, distribution, movement and properties of the waters of the earth and their relationship with the environment within each phase of the hydrologic cycle.
From the above definitions of hydrology, it can simply be summarized that hydrology is the detailed scientific study of water.
Scope of Hydrology
The study of hydrology is multi-disciplinary. That is, it incorporates professionals from various disciplines such as geography, chemistry, physics, biology, geology and engineering.
The hydrologic cycle is the central theme of the study of hydrology; hence all of the physical, chemical and biological processes involving water as it travel its various paths in the atmosphere, over and beneath the earth’s surface are of interest to the hydrologist (person that studied hydrology).
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Although hydrology is concerned with the study of water, especially atmospheric and terrestrial fresh water, its emphases have changed from time to time and vary from one practitioner to another.
Some have discerned in such changes identifiable historical patterns or ‘eras’ of hydrology, with a progression, for example, from physical hydrology, through engineering hydrology, to water resources hydrology (Ward and Robinson, 2000).
In spite of the changing emphases however, hydrological studies involve the application of scientific knowledge and mathematical principles to solve water related problems such as quantity, quality and availability in society. Hydrologists may be concerned with finding water supplies for cities or irrigated farms, or controlling river flooding or soil erosion.
The study of hydrology involves both laboratory analysis and direct field measurements of hydrological processes: rainfall, erosion, runoff, soil moisture etc.
Measurement is fundamental for assessing water resources and understanding the processes involved in the hydrologic cycle. Because the hydrologic cycle is so diverse, hydrological measurement methods equally span many disciplines including soil, oceanography, atmospheric science, geology, geophysics amongst others.
The data obtained through measurements of hydrological processes are analyzed and interpreted by the hydrologist for the purpose of predicting or solving water resources problems. Generally, each hydrologic problem is unique in that it deals with a distinct set of physical conditions within a specific river basin.
Hence, quantitative conclusions of one analysis are often not directly transferable to another problem. However, the general solution for most problems can be developed from application of a few relatively basic concepts (Linsley, et al, 1982).
It should be noted at this point that the modern day hydrologist relies on computers for organizing, summarizing and analyzing masses of data, and for modeling studies.