Last time the Caspian Sea is exposed to the anthropogenous influence connected with active economic development of a water area more and more. In these conditions it is necessary to know a sea hydrological regime and its changes substantially determining ecological conditions in region. However, the Caspian sea hydrological regime, especially its variability, is poorly studied. The role of the sea regime mathematical modeling increases by data deficiency, as allows to spend numerical experiments on the diagnosis and the forecast of hydrological conditions by anthropogenous influence without significant material expenditures. Such approach when the studying of level fluctuations on observed data is combined with the hydrodynamical modeling and numerical experiments, expands opportunities of the scientific analysis.
The research of Caspian Sea level fluctuations by means of the numerical hydrodynamical modeling enables to solve the following problems:
- To reveal a role of the various factors that cause the water level fluctuations in specific physic-geographical conditions;
- To develop the methods of calculation of the sea level and its extreme characteristics for practical l employment into hydraulic engineering, industrial and municipal designing and construction;
- The study of the water level fluctuations regime for areas, is not enough or completely not shined by observed data;
- To execute a probability estimation of the future water level regime for needs of various large economic actions (construction of dams, protective dams, withdrawals of a rivers runoff, etc.);
- To develop the forecast methods of the water level fluctuations.
The studying of the forming of wind effected phenomena on the Caspian Sea and definition of their greatest height was made by means of the Danish Hydrodynamic Model MIKE 21. The Hydrodynamic module MIKE 21 is a general numerical modeling system for the simulation of water levels and flows in estuaries, bays and coastal areas. MIKE 21 HD can calculate storm surges as a function of meteorological condition. The hydrodynamic module of MIKE 21 solves vertically integrated equations of continuity and conservation of momentum in two horizontal dimensions. The following effects are included in the equations: convective and cross momentum; wind shear stress at the surface; barometric pressure gradients; Coriolis forces; momentum dispersion ('eddy'); sources and sinks (both mass and impulse); evaporation. To solve the mentioned system of equations it is used the finite difference scheme with the second order of accuracy. It has allowed taking into account the influence of perturbations in a stratum of water on dynamic of underlying stratum, where they are changed quickly under influence of atmospheric processes.
Storm Surges Forecast for the Various Zones
of the Caspian Sea Kazakhstan’s Coast
Storm surges are short-term acyclic changes of a sea level under influence of a wind and atmospheric pressure. Under this influence in a superficial layer of the sea there is the progress of water that results in moving water weights that cause the sea level short-term fluctuations at coast. Extensive shallow lands, small slope of a bottom and a land, a configuration of coastal feature, the vigorous activity of a wind create favorable conditions for development in Northern Caspian Sea the significant storm surges. There are essential changes of hydrology-morphological, hydrochemical and ecological processes because of the storm surges at the coastal zone of Near-Caspian lowland.
During the modern period when the Caspian Sea high background level the storm surges are accompanied by flooding of greater areas, that were flood-free sites at one time on the Kazakhstan’s coast. It brings huge losses to economic objects, the population and ecology of the region. In the Northern Caspian Sea the water level falling can reach 2,5 m during negative storm surges. It will cause infringement of work of water-fences, the drying up of port water areas and navigable sea channels, reduction of the spawning and the areas valuable food fishes fattening, first of all - sturgeon, change of landscape structure of coastal territories, and desertification of coastal areas. In the open part of the sea more remote from coast at significant negative storm surges conditions for pass of courts worsen, and they go with underloading. Negative storm surges limit pass on Mangishlak’s a threshold.
The caused damage can be considerably lowered by the preliminary prevention storm surges.
The sea level forecast is made as a table two times a week (Tuesday and Friday) for two economic regions of Kazakhstan (Atyrau and Mangistau oblasts), adjoining to Caspian Sea. the numerical weather forecasts from the European Middle Weather Forecast Center (UK) are the basis of the sea level forecast. The sea level forecasts are made for eight stations chosen with the account morphometry conditions and specificity of the synoptic processes of this region. Step-type behaviour of a sea level calculation (forecast) is one hour, earliness - till 120 hours (5 days). The maximal, minimal and average levels for the period of the forecast also are presented In the table. The storm surges forecasts are specified every day at threat of occurrence dangerous. The estimation of accuracy of the forecast is carried out by comparison of the measured and observed sea level on the basis of the tables. The example forecast tables for Northern and Middle Caspian Sea is resulted below.
Developed in RSE «Kazhydromet» the system of the water level forecasting allows put out the forecast information for any point set by the consumer.
Weekly Caspian Sea Bulletin
The sea level forecast is made on the basis of the received results of hydrodynamical modeling. The bulletin is made in electronic and printed versions.
The Summer Weekly Caspian Sea Bulletin includes the review of on the sea level state for the previous week and the sea level forecast for 5 days forward in a graphic kind. In our bulletin are submitted a table with criteria of danger of the storm surges for the Caspian Sea northeast coast and a table with maximal, minimal and average values of the forecasted sea level for stations for the period of earliness.
During winter time there is the Winter Weekly Caspian Sea Bulletin. In this variant the condition of a Caspian Sea water table is displayed, the level forecast of a nonfreezing part of the sea is given. In the Winter Bulletin the review of ice conditions at the Kazakhstan stations is given and graphic of water temperature for marine stations, space pictures are submitted also.
Forecasting of the wave situation is of great importance for the regions of the Middle Caspian. To solve this problem, a wave forecasting method has been developed that has been successfully introduced into production and now Kazhydromet issues a bulletin and wave forecasts with a lead time of 5 days for 3 squares of the open water area of the Caspian Sea, as well as Bautino and Kuryk bays. In accordance with the agreements, a methodology has been developed and wave forecasts for oil production areas are being issued. The information received from the European Center for Medium-Range Weather Forecasts is also used as an input characteristic.
Caspian Sea Ice Monitoring
Caspian Sea ice reviews are issued weekly during the winter period. After the ice period finishing summary tables of the Caspian Sea ice basic characteristics made on the basis of materials of urgent supervision on each sea hydrometeorological station. Then the tables are published in the «Annual data about of a Caspian Sea waters regime. Kazakhstan’s coast»:
Basic Characteristics of the Caspian Sea Ice
Besides the review of Caspian Sea ice is published in the «Annual data about Caspian Sea waters regime. Kazakhstan’s coast».