General

hydrology

The word hydrology (hydro – water and logos – science). It indicates studying of water especially of its physical characteristics and its appearance in the nature.

Classification of hydrology

The hydrology is divided into hydrometeorology, surface hydrology and hydrogeology.

Water that falls from the atmosphere in the form of rain, snow , as well as water that evaporates from the soil surface, rivers and lakes are studied and monitored by hydrometeorology.

Water of the soil surface, streams, rivers and lakes is studied and monitored by the surface hydrology. Hydrography and limnology find great application this field.

Water that is under the soil surface is studied and monitored by hydrogeology.

History

far past

In the pre-history primitive man learned that he can not survive without water. It was handed down by generation which water he could use for drinking, in which water he could fish in order to feed himself.

Basic records on knowing the laws on water and their use were found 7000 B.C. , in Mesopotamia ( today known as Iraq), along the Tigris and Euphrates rivers, where systems were built for irrigation of fields planted with plants for feeding of population.

Hydrology and civilizations

In the old Egypt (4000 B.C.) when Pharaohs ruled the enigma on pyramids is inexplicable until now, it is known that in that time the crops which were planted along the Nil coast were increased. Ancient Greeks with the great number of philosophies among which is Great Archimedes succeeded to pass the laws on water close to the people. Romans using the ancient and primeval rules and laws on water, succeeded to build magnificent hydro-technical constructions, perfect construction in every respect, the constructions that we admired until now. In the Ancient and Middle ages the most famous were empires and kingdoms where the science on water (hydrology) was the most studied. Leonardo da Vinchi is one of the most famous hydrologists. In that time he used wheelbarrow that represented a type of hydrometric instrument in order to measure the flow velocity of some water currents. The floods and droughts were enemies of all, but that one who understood hydrology could coped with them. Nowadays the situation is the same.

Cycle

Hydrological cycle

Movement of water in the nature represents a continuous circling.This water cycle(Water Cycle, is known as hydrological cycle.

Process of movement

Sun by its rays heats the Earth. Because of this sun heating, the water in liquid and ice state evaporates as vapor in the atmosphere and causes it to condense into clouds. The most evaporations occur from the oceans. The great cloud masses from the oceans move toward the land, where cooler temperatures in the atmosphere cause condensation of water vapor. Water from the atmosphere by gravitation falls on the land as rain, snow, hail etc. After falling on the land it continues to move as surface flow or ground sinking and flow. By river empty into the lakes, seas and oceans and through evaporation the water return again in the clouds. This hydrological cycle represents the life cycle.

Stations

Monitoring process

Hydrology is multidisciplinary science and in order to understand the hydrology necessary backgrounds of physics, meteorology, geology, geography, biology, chemistry are required. The hydrology monitors the hydrological cycle and it is a process of long duration. First of all precipitation stations are required, precipitation quantities which fall from the atmosphere are determined at these stations.

Hydrological station network

When waters from the atmosphere fall on the land they are monitored by hydrological stations. Therefore each country forms its state – hydrological station network. This network is usually divided into surface water network and ground water network.

These surface water stations are observed by free lancers-observers whose task is to record the water level of the river (H cm). The observations of ground waters are performed at 5-10-15-20-25 and the last day of the month. These information is sent to the Hydrometeorological Service once a month.

In the Hydrological Department there is a network of hydrological stations and stations of groundwaters and springs. On the territory of RM there is a network of 110 hydrological stations (68 active) and over 100 stations which are a part of additional investigative station network. There are 115 groundwater stations of which 38 are active. Hydrometric measurements are performed at the hydrological stations.

Hydrometry

measurement of discharge

Hydrometry is a science and practice of water measurement. It includes all aspects of water cycle, quantity and quality of surface water, groundwater, rainfalls, other forms of precipitation, evaporation, soil humidity and transport of sediment. Measurement of discharge is a part of hydrometry where the volume of water discharge is measured through cross-section of water current in unit of time.

way of measurement

These measurements are with aim to establish dependence between water level and discharges. As on the territory of RM there are mountain rivers which carry sediment and make deepening and dikes at river beds, the necessity of frequent hydrometric measurements is a condition for reliable and accurate hydrological data. Therefore 6 to 12 hydrometric measurements a year are necessary. Measurement of water velocity at determined number of verticals depending on depth and width of water current. after determination of average water velocity (V m/s) at a given cross-section and its average surface (A m2) the value of discharge quantities of water are obtained – V x A = Q (m3/s). For this way of measurement current meters are used, and measurements are performed by wading through water current with boat or from the bridge.
Recently the newest instruments and methods for water quantity measurements are used. One of them is a method by acoustic doppler instrument.(ADCP).

Tasks

• Directly measurements of hydrological parameters

• Systematic monitoring of the level of surface and ground waters

• Monitoring of sediment in rivers and lakes

• Monitoring of water temperatures in rivers and lakes

• Data control and their updating and archiving in the hydrological database

• public informing and warning on development and appearing of harmful and disastrous hydrological phenomena

• Preparation of hydrological reports, information, forecasts and other professional publications at the level of the whole country