**7. Emerging trends**

*Hydrology*

resources [9].

Today, new technologies such as microwave sensors (**Figure 8a**) and drones (**Figure 8b**) allow to monitor extreme events (e.g., floods, droughts, and hurricanes) and mitigate their damage on the environment, infrastructures, and critical

Weather models were developed at the end of 20th century and beginning of 21st century. The first real-time medium-range forecasting model was developed by the European Centre for Medium-Range Weather Forecasts (ECMWF) in 1979. The Intergovernmental Panel on Climate Change (IPCC) was founded in 1988 by the United Nation (UN) to monitor climate change, and its economic, social and environmental impacts across the world. In the 1990s, the Weather Research and Forecasting (WRF) model was developed by simulating the atmospheric processes. This model has been used in more than 150 countries around the world to simulate the atmosphere via real-time data [9]. In 2002, the Aviation Model (AVN) was developed by the National Centers for Environmental Prediction (NCEP) for shortrange weather forecasting. This model (called the Global Forecasting System, GFS) is the leading forecasting model in the US [69]. A review of history of hydrometeo-

*The image of the Gulf of St. Lawrence from the (left) TIROS-1 weather satellite (1970s) and (right) S-NPP* 

*(a) A monitoring site which is equipped with microwave sensors to provide real-time measurements of water level for forecasting storm surge [9], and (b) NASA's drone (Sierra) for remote sensing sampling in inaccessible* 

*regions such as polar regions, mountaintops, and open waters [70].*

rology is provided in Appendix A as supplementary materials.

**12**

**Figure 8.**

**Figure 7.**

*satellites (2013) [9].*

Recent advances in active and passive remote sensing systems have created new cost-effective opportunities for meteorological applications. The new generation of satellites (e.g., Soil Moisture Active Passive (SMAP), Meteosat Third Generation (MTG), Himawari-9, and FY-4B satellites) allows monitoring the earth and atmosphere with higher spatial and temporal resolution. Progresses in technology have also improved field instruments used to collect weather data. In addition, numerical models have become more advanced as new theories and concepts were incorporated into them, allowing them to simulate hydrometeorological processes more accurately. At present, three-dimensional coupled atmosphere–ocean models use remotely sensed and in-situ observations to forecast weather up to ten-days ahead [9].

Weather modification by cloud seeding and aerosols spreading is one of the emerging trends to decelerate the threats associated with global warming [73]. The main purpose of cloud seeding and aerosols spreading is to alter rainfall patterns [73]. However, these methods are expensive and have not yet reached a practically acceptable level. In addition, the amount of precipitation that reaches the land surface is often negligible. This happens because snowfalls and/or light drizzles generated by the stratiform clouds are evaporated prior to reaching the ground level. To overcome this issue, stratocumulus clouds should be created that can have a global impact [74]. On the other hand, a number of scientists hypothesize that the weather modification can cause climate change and may lead to extreme weather events such as drought and flood [73, 75]. Some hydrometeorologists believe that the chemicals used in cloud seeding are dangerous for human health because of their toxicity and damage the ozone layer [75]. Moreover, the increase of particulate matters in the weather modification process may change the color of the sky from blue to gray [75].

Applying the science of hydrometeorology to real-world problems is another emerging trend. It is called operational hydrometeorology and deals with the application of hydrometeorology to real-time operational systems. The major components in an operational prediction system are monitoring equipment, meteorological and hydrological forecasting models, demand (water supply) prediction models, and decision support tools [76, 77]. The difficulty of forecasting rainfall has become a main challenge in the development of operational hydrometeorology [76]. There have been some attempts to overcome this issue. For example, the Flood Forecasting Center (FFC) was established in England and Wales in 2009 to forecast rainfall. A number of scientists used inverse modeling to predict rainfall [78–81]. For example, they assimilated river discharge observations within an ensemble data assimilation framework to predict rainfall [82–84]. Similarly, several studies assimilated soil moisture observations into water balance models to improve rainfall predictions [85–91].

Using low-cost sensors for flash flood forecasting [78], and application of hydrometeorology in marine sciences [92] and urban environment [80, 81] are other emerging trends.

#### **8. Future issues and challenges**

About 90% of disasters in the world during 1995–2015 were related to weather [93]. During this period, more than 600,000 people died, and more than 4 billion others were evacuated or injured because of weather-related hazardous events. The annual cost of damages caused by weather and climate extremes at the global scale is about \$300 billion. Most disasters have been observed in the US, China, India, Philippines, and Indonesia [93].

Modern technologies such as advanced weather balloons, radars, satellites, and mathematical and numerical models have allowed to mitigate the impact of weather-related disasters on human beings and environment. In addition, innovative hydrometeorological devices and synoptic stations have provided concrete weather data to further lessen the effect of extreme weather events.

Despite these advances, the complexity of climate requires the development of more accurate models and instruments to manage the natural disasters more efficiently [9]. Overall, the future of the science of meteorology and hydrometeorology relies on new sophisticated instruments and prediction models, which enhance our ability to forecast weather and mitigate related hazards [9]. Having said that, the fourth industrial revolution (IR 4.0) may help the science of hydrometeorology by developing microchips, microcontrollers and more accurate sensors (i.e., multisensor meteorology) that can be utilized in weather sites [94–99].

Today, hydrometeorologists take advantage of satellite data at different spatial and temporal scales [100, 101]. Artificial intelligence (AI) and machine learning (ML) approaches can use long-term remotely sensed data from satellites to improve weather prediction and climate modeling capabilities [102–104]. Also, the advancement in Internet of Things (IoT) will make real-time data observations more precise [105–108].

#### **9. Conclusions**

This study provides a thorough review of the historical evolution of the science of hydrometeorology and its significant milestones from past civilizations to contemporary times. Hence, it can expand our knowledge of the advances in hydrometeorology through different centuries. In the past civilizations, the first steps were taken to understand weather changes. Today, the availability of robust numerical models, remote sensing data, and high computational capabilities have allowed humankind to predict meteorological and climatological events. Five major periods are considered in this study: 1) the prehistoric, 2) the archaic and medieval, 3) the early and mid-modern, 4) the modern, and finally 5) the contemporary periods. The key advancements and achievements in each period are presented.

The theocratic explanation of meteorology was dominant until the 7th century BC. In the prehistoric period, weather was unpredictable. Also, religion, folklore, tradition, culture, and beliefs were the main elements for studying hydrometeorology. In the late Archaic times, the Ionian philosophers explained hydrometeorological processes for the first time. Beginning in the historical period, Anaxagoras (*ca* 500–428 BC) used the ideas of the Ionian philosophers to develop rain gauge instruments in Athens. Also, in this period, the first evidence of measuring rainwater was seen in Greece and India. Later, Plato (*ca* 428–348 BC) developed the concept of the hydrological cycle in his academy in Athens. In the early Hellenistic times, Theophrastus of Eresos (*ca* 371–287 BC) wrote the book *Signs De Signis Tempestatum*, which was the first weather forecasting manual.

From 27 BC to 200 AD, Pomponius Mela, the Roman Emperor in Spain, worked on geographical maps and divided the earth into five climate zones. Investigating weather and atmospheric phenomena was almost stopped from the end of the Roman period to the Middle Ages of the Renaissance. However, there were considerable attempts from *ca* 1400 to 1900 AD to monitor hydrometeors and forecast weather by meteorological instruments, which were invented during this period.

From 1950 until present, theoretical approaches and mathematical analyses have been extensively used in the science of hydrometeorology. Sophisticated instruments have been developed to measure hydrometeorological variables. Computers

**15**

*Hydrometeorology: Review of Past, Present and Future Observation Methods*

have been utilized to solve complex mathematical equations and run numerical models to understand meteorological phenomena in the light of the application of meteorological theories (e. g., the application of heat and mass transfer theories to

The development of research and education in the field of hydrometeorology began after the Second World War, and accelerated with the formation of the World Meteorological Organization (WMO) in 1951. Scientists in the modern era have provided foundations for hydrometeorological investigations and instrumentations in a universal scale. Their efforts have improved humans' understanding of atmo-

The perspectives in the field of hydrometeorology are promising. This is mainly due to the advances in sensors and instrumentation, computational capabilities, remote sensing systems, data mining techniques, information and communication technologies (ICTs), decision support systems (DSS), and deep learning approaches. Although the science of hydrometeorology has significantly improved recently, there is still lack of adequate knowledge to accurately forecast extreme

*Ca* 3500 BC "Astrometeorology" emerged in Babylon. The sensitivity of humans to

*Ca* 1750 BC Water codes of King Hammurabi (*ca* 1792–1750 BC), which consisted of 282

*Ca* 740 BC Nabu-nasir (*ca* 747–734 BC) regularly recorded movement and location of the

*Ca* 600 BC The Thales of Miletus (*ca* 624–546), the founder of Ionian Stoa (School),

*Ca* 570 BC Anaximander (*ca* 610–546 BC) explained the relationship between rainfall

End of *ca* 5th BC Xenophanes (*ca* 570–475 BC) expressed the concept of hydrological cycle and

*Ca* 465 BC Anaxagoras (*ca* 500–428 BC) transferred the ideas of the Ionian philosophers

*Ca* 387 BC The Platonic Academy was founded by Plato (*ca* 428–348 BC). The concept of hydrological cycle was developed in that academy

*Ca* 400 BC Hippocrates of Cos (*ca* 460–370 BC) studied the effects of climate and

to the Athenians. He also explained the formation of hailstorms.

environment on human health in his treatise on *Airs, Waters, and Places*

*Ca* 550 BC Anaximenes (585–528 BC) explained the formation of winds, clouds,

moon. He also noted the times of sunrises, sunsets, and eclipses

is considered to be the father of natural philosophy and water science. He introduced the hydrologic cycle. He also presented a physical exegesis for the Nile flooding during summer time when rainfall in Egypt was minimal.

and evaporation in his book entitled "*On Nature*". The first known work on the

*Ca* 3500 BC Early Egyptians established sky-religion and rainmaking rituals *Ca* 3000 BC Nilometers were used to record water levels in the Nile River *Ca* 1800 BC Nilometers were developed at the second cataract of the Nile River

regulations

natural philosophy.

rainfalls, and hails

the role of sea in it. *Ca* 500 BC First attempts to measure rainfall in Greece

*Ca* 400 BC The first measurements of rain fall in India

**Historical to medieval times (***ca* **750 BC-1400 AD)**

weather increased because they no longer migrated

*DOI: http://dx.doi.org/10.5772/intechopen.94939*

analyze evaporation).

spheric phenomena.

**Appendix**

hydrometeorological events.

**Prehistoric times (***ca* **3500–750 BC)**

#### *Hydrometeorology: Review of Past, Present and Future Observation Methods DOI: http://dx.doi.org/10.5772/intechopen.94939*

have been utilized to solve complex mathematical equations and run numerical models to understand meteorological phenomena in the light of the application of meteorological theories (e. g., the application of heat and mass transfer theories to analyze evaporation).

The development of research and education in the field of hydrometeorology began after the Second World War, and accelerated with the formation of the World Meteorological Organization (WMO) in 1951. Scientists in the modern era have provided foundations for hydrometeorological investigations and instrumentations in a universal scale. Their efforts have improved humans' understanding of atmospheric phenomena.

The perspectives in the field of hydrometeorology are promising. This is mainly due to the advances in sensors and instrumentation, computational capabilities, remote sensing systems, data mining techniques, information and communication technologies (ICTs), decision support systems (DSS), and deep learning approaches. Although the science of hydrometeorology has significantly improved recently, there is still lack of adequate knowledge to accurately forecast extreme hydrometeorological events.

