Hydrology
Introduction
Hydrology (from Greek: ὕδωρ, "hýdōr" "water" and λόγος, "lógos" "study") is a branch of Earth sciences that studies water, its occurrence, distribution, circulation, and physical, chemical and mechanical properties in the oceans, atmosphere and Earth's surface. This includes precipitation, runoff, soil moisture, evapotranspiration, and glacial mass balance. On the other hand, the study of groundwater corresponds to hydrogeology.
On the contrary, hydrography is called the study of all the masses of water on Earth and, in a stricter sense, the measurement, compilation and representation of data related to the ocean floor, coasts, tides and currents, so that they can be captured on a hydrographic chart. "Notwithstanding this difference, the terms will be used almost synonymously, since the part of hydrography that is of interest here is that which creates relief, therefore, that which is in contact with the Earth's surface, and therefore the same thing that is the object of a hydrological analysis.
The circulation of water masses on the planet is responsible for the modeling of the Earth's crust, as evident in the geographic cycle. This influence is manifested as a function of the distribution of the masses of coherent and crumbly rocks, and the deformations that have affected them, and are fundamental in the definition of the different reliefs.
Let us remember that a river is a stream of water that flows through a channel from highlands to lowlands and empties into the sea or into an endorheic region (collector river) or into another river (tributary). Rivers are organized in networks. "A hydrographic basin is the total area that discharges its runoff waters into a single river, waters that depend on the characteristics of the feed"). A drainage basin is the part of the Earth's surface that is drained by a unitary river system. Its perimeter is delimited by the dividing line or interfluve.
The layouts of the hydrographic elements are characterized by adaptation or non-adaptation to lithological and tectonic structures, but the geological structure also acts in the domain of hydrographic networks, determining their structure and evolution.
The hydrological study begins with the morphometric analysis of the basin, which includes: the delimitation of the basin, measurement of the area and length, maximum and minimum height, compactness index, shape factor, hypsometric curve, average slope, characterization of the drainage network and the altimetric profile of the main channel, among others.