Hydrological monitoring
Hydrological monitoring: what it is, objectives and principles
Hydrological monitoring is an integrated activity aimed at systematically studying various aspects of the state of water systems, including rivers, lakes, reservoirs and groundwater. At the centre of such monitoring is the assessment of the impact of environmental factors and human activities on water resources and the identification of potentially dangerous trends, such as deterioration of quality due to industrial pollution or natural processes such as soil erosion.
The main objective of monitoring is the early detection and prediction of negative changes that may affect water quality and condition. This allows timely development and implementation of measures to prevent or minimise possible damage.
One of the key objectives of hydrological monitoring is to provide relevant and accurate information for making informed management decisions that relate to resource use and protection.
Effective monitoring also helps in establishing a regulatory framework for regulating activities that affect hydrological bodies, setting scientifically based water quality standards and measures to maintain them.
Monitoring of water bodies
Hydrological observations include a set of measures to monitor various water resource sites, using specific equipment and techniques.
Water level measurement
Water level and water level changes are monitored to assess water level fluctuations in rivers and reservoirs. These measurements are made using level and pressure gauges installed on rivers, lakes and reservoirs. These data are important for flood forecasting and prevention, as well as for regulating the use of water resources, e.g. in agriculture and hydropower.
Water temperature monitoring
Temperature affects many biological processes and the state of the aquatic ecosystem. Temperature measurements are made using temperature sensors to help assess the impact of climate change on aquatic ecosystems and influence species distribution, including invasive species, which is important for biodiversity conservation and fisheries management.
Precipitation monitoring
The precipitation regime is a characteristic of its temporal distribution and intensity that plays a critical role in analysing runoff.
Observation of precipitation amount and regime is a key aspect of hydrological monitoring because precipitation directly affects surface and groundwater runoff. Precipitation measurements using pluviometers and other meteorological instruments provide an estimate of how much water is delivered to a given area by rain or snow. These data are important for understanding changes in the region's water balance, including soil saturation and groundwater levels.
Water flow measurement
Water flow, which is measured at a particular section of a watercourse, plays an important role in water resources management.
Hydrometric fluviographs and ultrasonic Doppler devices are used for this purpose as they provide accurate and continuous measurement. Hydrometric fluviographs record fluctuations in level, while ultrasonic Doppler devices measure flow velocity, which allows the calculation of the volumetric flow rate in a river.
Such data are needed not only to calculate available resources, but also to determine when hydropower projects can be developed, dams regulated and water levels maintained to preserve biodiversity and prevent environmental disasters.
Measurement of snow cover height and density
Information on snow cover is essential for predicting spring floods, especially in mountainous and subarctic regions, and for calculating the freshwater resources available throughout the year.
Using snow gauges and snow density measuring devices, hydrologists can estimate the total amount of water contained in snow cover.
Monitoring of evaporation from the water surface
Understanding evapotranspiration is critical to accurately calculating water balances, especially in agrarian and arid regions where such resources are limited. This data helps in optimising the management of reservoirs and irrigation systems, ensuring that water use is maximised and losses minimised, which is a key aspect in maintaining sustainable water supply and agriculture.
Various instruments such as evaporimeters and atmometers are used to estimate evaporation from the surface of reservoirs. These devices measure the amount of water that evaporates from the surface of a water body over a certain period of time.
How hydrological monitoring is carried out
Hydrological monitoring is a complex procedure aimed at assessing the condition of water resources and includes several stages.
- During the planning phase, the objectives of hydrological monitoring are defined, key locations for observations are selected, and the periods when measurements will be taken are established. Decisions on the choice of measurement locations and times depend on the specific hydrological conditions and data needs. Particular attention is paid to areas where changes in water body regimes are expected or already observed, or where environmental problems have the potential to develop.
- Data collection: hydrological stations with the necessary equipment measure all necessary parameters, including water level, temperature, water chemistry, flow velocity and other important indicators. Depending on the monitoring tasks, data can be collected manually by experts or automatically using sensors and transducers.
- The collected data is transferred to databases where it is analysed to assess the current status of sites. The analyses help to determine the dynamics of changes in the aquatic environment and identify possible trends or anomalies. The results of the analysis are used to make management decisions aimed at the protection and rational use of water resources.
Effective monitoring and timely response to changes help ensure sustainable use of water resources and prevent environmental and social problems associated with water scarcity.