Stochastic hydrology: the development of main ideas in Russia

The aim of the work is to assess the current state of scientific research and the main results in the field of stochastic hydrology. Various problems of scientific and applied hydrology are solved on the basis of different types of stochastic models. On the basis of these models, methods are being developed for obtaining secure engineering runoff characteristics, or reliable hydrological forecasts of various lead times. Most of the water management, construction, environmental and other problems are solved today within the framework of probabilistic models and statistical methods. The main tasks of stochastic hydrology can be divided into several groups. Despite the discussion in hydrology on the applicability of the theory of probability and random processes to the analysis of fluctuations of hydrometeorological series, the problem of choosing a research methodology remains one of the most important, and is often discussed in connection with anomalous manifestations of hydrological phenomena (extreme floods, prolonged droughts). An important applied and theoretical problem in hydrology is the choice of a one-dimensional probability distribution. In this part, discussions are important both on the problem of the type of new distributions and on methods for estimating parameters. Ideas and hypotheses are considered that can significantly increase the reliability of statistical characteristics. Climatic changes in many cases cause disturbances in the stationarity of time series of hydrological characteristics. Progress in the development of new approaches to probabilistic modeling is associated both with the well-known problem of the sufficiency of the Markov hypothesis and with the need to introduce new, more complex models and Bayesian estimation methods. The article is devoted to the discussion of the current state of these problems in the form of a scientific review.

Stochastic Hydrology: Is Scientific Understanding Growing?

Among many problems of stochastic hydrology, several major problems may be singled out. (1) The methodology problem – may fluctuation of hydro-meteorological values be considered within the framework of probabilities and random processes? Was this topic discussed after 1953? (2) One-dimensional probability distributions – is there progress? Are there new models? (3) Random Processes: Is Markovian property sufficient or more complex models with memory are needed? (4) Lack of stability resulting from climate changes: Is there progress in understanding the approaches to probabilistic forecasts?

Nicholas Constantinos Matalas (1930–2019)

A modest giant in the field of stochastic hydrology.

Evolution of hydrological sciences from dimensions of object, discipline and methodology

The evolution routes and development stages in hydrological sciences are summarised from the following three dimensions: research object, discipline and methodology, by means of the descriptive-explanatory-humanistic ideology. Modern technical breakthroughs and socioeconomic developments have promoted hydrology from geographical hydrology, engineering or applied hydrology to water resources hydrology in terms of the focus of research objectives or problems. It has been observed from the point of view of methodology that hydrological sciences go through deterministic hydrology, stochastic hydrology, isotope hydrology, digital hydrology, etc. Hydrological sciences in the context of discipline dimensions can be divided into three main categories: physical hydrology, chemical/environmental hydrology, biological hydrology including eco-hydrology and socio-hydrology, although there are overlaps between these due to the complex and intertwined water-related challenges facing the hydrological community and other geosciences. Humans have played a significant role in changing land uses throughout the world and therefore, socio-hydrology is an increasingly significant branch of the hydrological sciences. It can be seen from analyses that biological hydrology is a new approach to cope with global change issues, and a new frontier direction in the field of hydrological sciences. It can also be seen from dialectical analysis of the different stages in the evolution of hydrology, that new frontiers or directions requiring investigation, scientific recognition and technical innovation will continue to be generated in the field of hydrology. The 3-dimensional diagram of evolution routes of hydrological sciences may provide some ideas for Panta Rhei, the new IAHS Science Initiative 2013–2022 for hydrological research under changing human and environmental systems in the real world.