text: Paleohydrological study usually starts in the field with observations, measurements and the collection of samples; it continues with analysing the samples in the laboratory, recording the data, collating it, modelling systems, time-system analyses and eventually making inferences. A major step is the dating of the material. Methods here include using radioactive isotopes, considering the geological development of the area, the presence or absence of certain organisms and the identification of fossil pollen. Paleohydrology makes use of indirect methods that give an indication of the climatological conditions prevailing at the time.
  Paleo hydrology uses methods that include using direct and indirect climatic data; these can be used to assess the variability in the hydrological cycle. Direct data encompasses measured and historical information, including streamflow records, flood occurrences, and drought events. In certain regions such as Egypt and China, direct data can extend back thousands of years, offering a rich historical perspective, while globally, it commonly spans approximately two centuries. Complementing direct data, indirect data—often referred to as proxy data—serves to extend climatic and hydrological insights. For instance, the analysis of tree rings allows for the reconstruction of past precipitation and temperature patterns, while deep-sea sediment cores contribute to predictions of long-term global temperatures. Proxy data is instrumental in providing evidence for prehistoric floods, with its traces commonly preserved in sedimentological deposits within streambeds and botanical evidence. This collective data is crucial for forecasting the frequency and magnitude of floods and droughts in specific geographic areas.