Hydrochemical research of the condition of surface waters is conducted by the Centre of Hydrometeorological Service of the Republic of Uzbekistan (Uzhydromet) in 59 water bodies, 86 water points, 108 sections by 43 ingredients. Annually more than 1000 water samples are collected and analyzed at the monitoring points, their chemical analysis is conducted in order to define the following components:
- Ion composition: salinity level, water hardness, calcium, magnesium, sodium, potassium, chlorides, sulphate, etc.;
- Biogenic components: nitrogen compounds (ammonium, nitrite, nitrate), phosphates, silicon, etc.;
- Heavy metals: copper, zinc, cadmium, ferrum, mercury, chromium (III) and chromium (IV), arsenic;
- Organic compounds: pesticides, phenols, petrochemicals and other specific pollutants.
During the samples collection, the first day is dedicated to the identification of common indicators: temperature, oxygen content, CO2, transparency, etc.
Samples collection at the monitoring points is conducted every month or during the basic hydrological phases according to their categories. For example, at the observation stations of 3rd category dedicated to the plain area of intense consumption of land drainage, where water is moderately polluted, samples are taken per month.
At the observation stations of 4th category, dedicated to the mountanious and foothill areas of generating land drainage (clean or slightly polluted water), samples are taken during the basic hydrological phases. At the stations of 2nd category in the areas of intense consumption of land drainage, where water is dirty and very dirty, samples are taken during every decade.
Detected concentrations of natural components and pollutants in surface waters of government sections and monitoring points are compared with the water quality standards - maximum admissable concentration (MAC). The Uzhydromet system for the assessment of surface water quality uses one of the most stringent environmental criteria that is Fishery MAC. For the assessment of the general level of water pollution in sections and observation stations the standard water quality indicator is used, it is calculated according to the results of hydrochemical analysis - Index of Water Pollution (IWP), rates of the IWP are used to determine the degree of water quality in accordance with the table.
Criteria of water pollution based on the Index of Water Pollution and criteria for improvement (deterioration) of water quality
|
Degree of water quality |
Textual description |
Level of the IWP |
Information on the possible use of water |
|
I |
Very clean |
less than 0.3 |
Baseline ecological condition. Water can be used for all types of water use. |
|
II |
Clean |
from 0.3 to 1.0 |
Significant impact on human, good ecological condition is preserved. Water can be used for all types of water use. |
|
III |
Moderately polluted |
from 1.0 to 2.5 |
Satisfactory ecological condition. Water from these water bodies can be used for most forms of water use including drinking and household, after completing the standard procedure of water purification. |
|
IV |
Polluted |
from 2.5 to 4.0 |
Polluted watercourses - transition/unsustainable ecological condition so-called condition of ecological tension. The use of water from these water bodies for different purposes is limited and requires specific purification and treatment. |
|
V |
Dirty |
from 4.0 to 6.0
|
Poor ecological condition. This includes water bodies and watercourses of collector and drainage systems in the farmland area of the new irrigation zone, specifically - collectors and irrigation waste lakes as well as the lakes located in urbanized areas, vulnerable to the pollution by the complex industrial and household waste effluents. The use of water is limited for most water uses. |
|
VI |
Very dirty |
from 6.0 to 10.0 |
Poor or inadmissable ecological condition. This type of water bodies are usually common for densely populated industrial areas. Water is environmentally hazardous - unsafe for any kind of use. |
|
VII |
Extremely dirty |
from 10.0 and high |
Monitoring points for the quality of surface waters
Observations in the basin of Amu Darya are carried out on the: Amu Darya river in 5 sections, Surkhandarya river (in 2 sections), estuary section of the rivers Obizarang, Karatag, Sangardak, Khalkajar (1 section), Sherabad river (1 section), Kashkadarya river (in 3 sections), Akdarya river (2 sections), Takhizidarya river (1 section), on the left-bank of the Chimkurgan reservoir channel (1 section).
In the Zerafshan river basin (geographically related to the Amu Darya basin), observations are carried out on the: Zerafshan river (in 10 sections), Amankutan river (1 section), the Siab collector (1 section), discharge and internal supply channels of the Kattakurgan reservoir (1 section), South Bukhara canal (2 sections).
In the basin of Syr Darya river observations are carried out on the: Syr Darya river (in 6 sections), Naryn river (1 section in the estuarine area), the Great Fergana canal (1 section), in the South Ferghana canal (1 section), in the North Fergana canal (1 section), Kara Darya river (3 sections), Isfayramsay river (2 sections), Margilansay river (3 sections), Kokandsay river (2 sections), in the Middle Kiziltepa reservoir (2 sections), in the Derivation channel of the Farkhad Hydroelectric Power Station (1 section), Gedzhigen river (1 section), Zaaminsu river (1 section); In the Akhangaran river basin (right tributary of the Syr Darya river) observations are carried out on the: Akhangaran river itself (in 6 sections), estuaries of the Akhangaran tributaries - in the rivers Kizilcha, Dukantsay, Abjazsay, Karasu left-bank (1 section), the right-bank channel of Tuyabuguz reservoir (1 section);
In the basin of the river Chirchik (right tributary of the Syr Darya river) observations are carried out: on the Chirchik river (in 9 sections), in the Chirchik tributaries - in the rivers Pskov, Chimgansay, Ugam, Aktashsay (1 section), in the Salar channels (4 sections), Karasu right-bank (2 sections), Bozsu (4 sections), in the channel named after Kirov (1 section).
On reservoirs observations are carried out on the: reservoirs of the Tyuyamuyun hydro-electric site on the Amu Darya - Tyuyamuyun (1 section), Sultanzhar (1 section), Kaparas (1 section), South Surkhan reservoir of the Surkhandarya river (1 section), Chimkurgan reservoir of the Kashkadarya river (1 section), Kattakurgan reservoir of the Zerafshan river (1 reservoir), Andijan reservoir of the Karadarya river (1 section), Tuyabuguz reservoir in the Akhangaran river (2 sections), Charvak reservoir of the Chirchik river (1 section).
On collectors, observations are carried out on the: Shuruzyak collector (1 section), the Main right-bank collector (1 section).
Observations on the Aidar-Arnasay lake system are carried out on the: Western Arnasay lake (1 section), Aidar lake (1 section).