2. Objects and methodology

132.6 km2

basin is 39,160 km<sup>2</sup>

flow is about 1032 m<sup>3</sup>

. According to the Agency of Hydrometeorology of the Republic of Tajikistan, there

have been significant changes of geometric dimensions and mass loss of Zeravshan glacier during the period 1927–1991. The glacier retreated 88–94 m/year for the period 1991–2001 and its area decreased by 700,000 m2 and it is expected to decrease by 30–35% by 2050 [6, 9]. The next

The problem of the water quality change and development of mechanisms of its control is still actual and concerns not only the separately taken country of Central Asia (CA) but also all the states of the region. Nowadays one of the most polluted rivers of Central Asia is Zeravshan River. The capacity of this water is changed under the influence of collector drainage water of irrigating basin zone and wastewater of Samarqand, Kattakurgan, Navoi, and Bukhara cities. Mineralization of water exceeds from origin to estuary: from 0.27–0.30 to 1.5–1.6 g/l. The most exceed of maximum permissible concentration (MPC) among heavy metals is observed in Cr and Zn. Moreover, in Zeravshan River high amounts of antimony was found and its phenol pollution composes 3–7.5 MPC [1]. The problem of water quality in transboundary river basins, in particular in the Zeravshan River Basin, is compounded by the fact that up to now there is no network sharing of information regarding the quality of the waterways between the neighboring states of Central Asia. Herewith, a uniform standard for assessing of the anthropogenic load degree on geoenvironmental systems (maximum permissible concentration) is not developed. The problem of water quality of the Zeravshan River is mostly associated with its pollution by wastewater of the Anzob mountain-concentrating combine—the mining enterprise for extraction and enrich-

The Vakhsh River is the main river of the Republic of Tajikistan and one of the tributaries of the Transboundary Amu Darya River in Central Asia. It has a length of 691 km and the area of the

merge at a height of 1151 m. The right inflow to the Vakhsh Rivers, the Surkhob River has a length of 81 km, and the basin covers an area of 1760 km<sup>2</sup> at an average altitude of 3140 m.

component of the Vakhsh, the Obikhingou River, is 196 km long by basin area of 6660 km<sup>2</sup> [6].

The Pyanj River is one of the tributaries of the Transboundary Amu Darya River in Central

It is quite natural that the formation of the basic characteristics and the water quality of the main river runoff is the result of the imprint of the properties and parameters of its tributaries with prehistory meteorological conditions and the condition of its feeding sources (ice, snowice, rain, etc.). Therefore, the monitoring of hydrological characteristics, the study of the chemical composition of the main rivers tributaries and thus the creation of a database on the river basin meteorological conditions, hydrological parameters and degree of contamination

This chapter presents the results of many years' studies of the hydrological parameters, hydrochemical and meteorological conditions of the basins of the Vakhsh, Zeravshan and

There are 246 glaciers in the Sorbog River Basin covering a total area of 105.6 km2

are the pledge for preparation of the reliable information about the main river.

. The Vakhsh River originates when the Surkhob and Obikhingou Rivers

/s. The total area of glaciation of the Pyanj River Basin is 3767 km<sup>2</sup> [19].

. The left

. The average value of the water

section provides an analysis of the Zeravshan River Basin meteorological condition.

152 Achievements and Challenges of Integrated River Basin Management

ment of mercury-antimony ores of the Dzidzikurut deposit [10–18].

Asia by a length of 921 km and a basin area of 114,000 km2

Pyanj rivers—the main tributaries of the Amu Darya.

The object of study is the Vakhsh River and its tributaries—Surkhob and Obikhingou—by use of water discharge data corresponding to rivers from Hydroposts: on the Surkhob-Garm Hydropost; Obikhingou river—Tavildara-Yozgand; on the Vakhsh river—Darband for the period 1960–2012. For estimation of the meteorological conditions of the Kyzilsu, Obikhingou and Vakhsh rivers Basin, the meteorological data of the Lyakhsh, Tavildara and Garm meteorological stations were used.

The differential integral curves of average annual discharge are used to identify periods with high and low water run-off. The differential integral curve takes into account the fluctuations of the flow over relatively short periods. It is defined by summing the deviations of modular coefficients from the middle, that is, the ordinates are calculated as Σ (K1). Thus, the ordinates of the curve at the end the cumulative sum of the annual modular coefficients gives the deviations from the long-term average (K = 1). The use of differential integral curves gives a vision of cyclical fluctuations without the effect of the boundaries displacement between the phases of the low and high duration cycles [6].

The Dehavz station meteorological data for the period 1931–2011 were used as it is close to the Zeravshan glacier and Iskanderkul in the Yagnob River Basin. Water flow of the Zeravshan

Figure 1. Amu Darya River Basin [32].

River was measured at the Dupuly Hydropost, which is the only operating station on the Zeravshan River. To determine the mean annual value of the water flow of the Zeravshan and Yagnob Rivers for the period 1931–2011, the data of the Agency for Hydrometeorology of the Republic of Tajikistan were used. Sampling of water from the Zeravshan and Vakhsh rivers and its tributaries were used by the scheme (Figures 14 and 19) developed in [11, 20] accordingly. The complex chemical water analyses were carried out by methods described in [9]. Sampling of water for isotopic analysis was carried out according to the methodology developed at the University of Colorado at Boulder (USA). Isotopic analysis of water was performed on Wavelength-Scanned Cavity Ringdown Spectroscopy (WS-CRDS). The individuality of each river from the point of view of chemical composition of water is compiled by sampling of the tributaries to the confluence with the main river and with other tributaries [20] (Figure 1).

3.1. Vakhsh River Basin

The location of hydrological stations of the Vakhsh River Basin shown in Figure 2.

increase in the region and changing precipitation patterns [6].

same basin, Skogach, retreats at a rate of 11 m annually.

The increase in the volume of river flows of the Vakhsh River and its tributaries, Surkhob and Obikhingou rivers (Figure 3), shows that currently there is a reduction of the Tajikistan glaciations areas resulting in increased snow melt, probably due to the overall temperature

Monitoring of Meteorological, Hydrological Conditions and Water Quality of the Main Tributaries…

http://dx.doi.org/10.5772/intechopen.74958

155

In the Surkhob River Basin, there are intensively melting small glaciers of the Northern slopes in the Western part of a ridge of Peter the Great. On the southern slopes of the Alay Ridge, glaciation decreases slowly as there are larger glaciers. In the Obikhingou River Basin, the largest glacier Garmo is intensively melting. During the twentieth century, it became shorter by almost 7 km, having lost more than 6.0 km<sup>2</sup> in area. It is currently retreating at an average speed of 9 m/year and the surface settles up to 4 m/year due to melting. Another glacier in the

Another important aspect of the hydrology of the rivers, the cyclical nature of the water flow, should also be considered. Assessing the long-term fluctuations of annual runoff and their periodicity is important. On the other hand, there are attempts to link fluctuations in water availability with various geophysical processes. The lack of a clear periodicity in long-term fluctuation of flow does not rule out the tendency to have continuously alternating high water years, called cyclical fluctuations of water flow. The length of these cycles, their sequence and

Figure 2. Vakhsh River Basin with location of hydrological stations: 1-Tiger Beam (R. Vakhsh), 2-Darband (R. Vakhsh), 3-

Garm (R. Surkhob), 4-Tavildara (R. Obikhingou), 5-Dombrachi (Kizilsu), 6-Davsear (Muksu) [6].

The analysis of the meteorological conditions of the Pyanj River Basin and the dynamic change in temperature and precipitation were carried out using the date of the Agency of Hydrometeorology of the Republic of Tajikistan from the next meteorological station of the basin: Darvaz, Khorog, Dzavshangoz, Murgab and Gorbunov.
