Climate change impacts on water resources and supplies. Disruption of water supplies has socio-economic consequences that might take many years to recover. By the year 2025 more than 50% of the world population will suffer from freshwater supplies. Therefore, awareness, international agreements, and national strategies are built up worldwide to wisely manage and restore water resources on both local and regional scales. Technological advancement (e.g. water desalination, cloud seeding, dew and fog water harvesting) has been utilized whenever it is affordable to produce fresh water.
Jordan is an Eastern Mediterranean country (29°–34° North and 34°–40° East, (~89,000 km2, population ~11 million in 2021) with limited water sources and diverse habitats, ecosystems, biota. Geographically, Jordan comprises a wide variety of topography that defines its climate spatial variation:
(1) semi-arid climate in the Jordan Valley with a hot dry summer, warm winter, and precipitation less than 200 mm/yr;
(2) arid climate in the Eastern Desert (also known as Badia) characterized by a sharp change in temperature between day and night and between summer and winter; and
(3) Mediterranean climate on the Mountains Heights Plateau (including highlands above the Jordan Valley, mountains of the Dead Sea, Wadi Araba, and Ras Al-Naqab) with a hot-dry summer and cool-wet winter and two short transitional seasons. The Mountains Heights Plateau receives Jordan's highest amounts of precipitation (more than 300 mm/year), which falls during October–May with the peak usually during winter (December–February).
Jordan is one of the fifth countries in the world suffering from freshwater shortage. The available water per capita has declined considerably during the past century; it was about 3600 m3 in 1946 and it is expected to be as low as 100 m3 in 2025. Jordan's water demand estimated to be about 940 MCM (63% agriculture, 32% domestic, and 5% industry) in 2007 and it increased to be about 1600 MCM in 2010. The main sources of water include safe abstraction of groundwater, recycling wastewater, surface runoff water, and desalination. The annual mean water amount received in the form of rainfall is about 8300 million cubic meters (MCM).
In Jordan, the attention about dew formation should be given to the amount harvested and the quality of harvested water (e.g., potable water or utilized in for other applications). The EARL conducted extensive research on the potential of dew water harvesting based on long-term analysis of weather and climate analysis in Jordan (Atashi et al., 2020; Atashi and Hussein, 2022). The quality of dew water harvesting was also investigated at an urban site in Amman (Odeh et al., 2017). The link between dust loading in the atmosphere and dew formation was also investigated (Hussein et al., 2018).
Part I: Dew Water Harvesting at an Urban site in Amman
The quality and chemical composition of urban dew collections with dust precipitates without pre- cleaning of the collecting surface WSF (White Standard Foil) were investigated for 20 collected samples (Odeh et al., 2017). The harvested volumes ranged from 22 ml to 230 ml. The collection period was from March to July 2015 at an urban area, Jubaiha, which was located in the northern part of the capital city Amman.
Dew and fog formation a very complex phenomenon that involves water vapor condensation on a substrate (e.g., environmental surfaces) or on an airborne particle (e.g., forming fog). It has been understood as a two-step process: (1) formation of droplets on obstacles (particle, surface, etc.) via nucleation of water vapor and (2) droplet growth due to condensation of water vapor. Thermodynamically, dew is a phase transition from the vapor phase into the liquid/solid phase on a substrate held at a lower temperature than that of the gas.
The chemical analysis revealed that there was predominance of Ca2+ and SO42- ions (ratio 2.2:1) that originated from Saharan soil dust; where the collected samples were alkaline (mean pH= 7.35) with high mineralization (429.22 mg/L) exceeding the previously reported dew values in Amman-Jordan. A relocation of NaCl and to a less extent Mg2+ from sea to land by Saharan wind is indicated by the percent sea-salt fraction calculations (over 100 and 52 respectively).
The collected samples exhibited high total organic carbon (TOC) values ranging from 11.86 to 74.60 mg/L, presence of particulate settled material with turbidity ranging from 20.10 to 520.00 NTU, and presence of undesired elements like boron (mean = 1.48 mg/L) that made it different in properties from other dew water collections at clean surfaces.
These values exceeded the standard limits for drinking water for these parameters set by Jordanian Drinking Water standards (JS286/1997)/WHO standard. The quality of this water is more close to that for raw or agricultural water but if it is meant to be used as potable source of water at least sand and activated charcoal filters are needed to purify it.
Part II: Relationship between dust loading and dew formation in the Eastern Mediterranean
In this part of the research, we investigated the number concentrations of accumulation mode (0.3–1 µm) and coarse mode (1–10 µm) particles in the eastern Mediterranean urban environment with and without precipitation and dew formation (Hussein et al., 2018).
Figure 1. Statistical plot for the number concentration of (a) accumulation mode particles and (b) coarse mode particles with respect to the precipitation conditions during the wintertime (November, December, January, and February); days with 24-hour precipitation > 10 mm are indicated as “Rain" and those without 24-hour precipitation are indicated as “no Rain." (Hussein et al., 2018).
The number concentrations of both the accumulation mode and coarse mode particles decreased (with ratios of ~0.7 and ~0.36, respectively) during precipitation (Figure 1).
We assumed that dew formation occurred in Amman during nighttime when the relative humidity (RH) was higher than 80% and the difference between the temperature and dew point temperature (i.e., T – DP) was less than 2.5°C. In general, the accumulation mode particle number concentration increased with relative humidity and doubled, on average, during dew formation. On the other hand, the coarse mode particle number concentration was 30% lower during conditions with dew formation than without. The increased number concentration of the accumulation mode particles during dew formation conditions is most likely due to enhanced water vapor condensation on existing ultrafine aerosols (diameter < 0.1 µm), enabling particles to grow to detectable sizes, including the accumulation mode. The decreased number concentration of the coarse mode particles during dew formation conditions may be due to enhanced wet deposition.
Part III: Characterization of Dew Formation Zones in Jordan
In this part of the research, gridded model simulations (Figure 2) were performed to estimate the dew formation yield during 1979–2018 aiming at distinguishing the potential dew formation zones in Jordan (Atashi et al., 2020; Atashi and Hussein, 2022). The model simulations were made by adapting a global model, which was developed by (Vuollekoski et al., 2015), to accommodate the environmental conditions in different environments in Jordan. Detailed analysis was performed for ten locations representing the different dew formation zones in Jordan.
Figure 2: A map of Jordan illustrating the geographical topography and the domain of the grid points used in the model simulation (Atashi and Hussein, 2022).
Jordan has three dew formation zones (Figure 3). The 25th and 75th percentiles of the dew yields are illustrated in Figure 4. Eventually, distribution of the dew formation zones in Jordan are clearly aligned with topography, sources of moisture, and climate zones. These dew formation zones are: Dew zone A (eastern desert), Dew zone B (Jordan Valley), and Dew zone C (central heights Plateau). Zone A receives the least dew formation potential, which mainly occurs during the winter, and Zone C receives the highest dew formation potential, which occurs throughout the year. Based on our model simulation results to estimate the potential of dew formation in Jordan, the average dew yield was in the range of 0.05- 0.15 L/m2/ day.
The outcomes of this part of research is ought to be useful for managing and planning local feasibility studies for dew harvesting and better understand for the feedback processes between the water cycle and climate change in Jordan.
Figure 3: Dew formation zones in Jordan based on the cluster analysis of the daily cumulative dew yield during 1979–2018 (Atashi and Hussein, 2022).
Figure 4: long-term mean seasonal variation of the cumulative daily dew yield over 40 years (1079-2018). Note that color coding on this figure is the same and corresponds to the dew formation zones on Figure 3: (yellow) dew zone A (arid and semi-arid region), (blue) Zone B (coastal region), and (red) Zone C (central heights Plateau).The shaded parts around the lines represent the 25th and 75th percentile of daily dew yields for each cluster, and colors are the same as clusters.
Briefing about the EARL
The Environmental and Atmospheric Research Laboratory (EARL) was established by Prof. Tareq Hussein under the Department of Physics, School of Science of the University of Jordan. The EARL conducts multidisciplinary research activities on topics related to the atmosphere, water, and soil. The EARL is a part of a large international collaboration network spanning over four cotenants (Europe, Asia, North America, and Oceania). The Institute for Atmospheric and Earth System Research (INAR) at the University of Helsinki is the main collaborator.
References
Atashi, N., Hussein, T. (2022). Temporal–Spatial Dew Formation Potential in Jordan – Identification of Dew Formation Zones. Jordan Journal of Earth and Environmental Sciences 13, 146–157.
Atashi, N., Rahimi, D., Al Kuisi, M., Jiries, A., Vuollekoski, H., Kulmala, M., Vesala, T., Hussein, T. (2020). Modeling long-term temporal variation of dew formation in Jordan and its link to climate change. Water (Switzerland) 12. https://doi.org/10.3390/w12082186
Hussein, T., Sogacheva, L., Petäjä, T. (2018). Accumulation and coarse modes particle concentrations during dew formation and precipitation. Aerosol Air Qual Res 18, 2929–2938. https://doi.org/10.4209/aaqr.2017.10.0362
Odeh, I., Arar, S., Al-Hunaiti, A., Sa'aydeh, H., Hammad, G., Duplissy, J., Vuollekoski, H., Korpela, A., Petäjä, T., Kulmala, M., Kulmala, M., Hussein, T. (2017). Chemical investigation and quality of urban dew collections with dust precipitates. Environmental Science and Pollution Research 24, 12312–12318. https://doi.org/10.1007/s11356-017-8870-3
Vuollekoski, H., Vogt, M., Sinclair, V.A., Duplissy, J., Järvinen, H., Kyrö, E.-M., Makkonen, R., Petäjä, T., Prisle, N.L., Räisänen, P., Ylhäisi, J., Kulmala, M. (2015). Estimates of global dew collection potential on artificial surfaces. Hydrol Earth Syst Sci 19, 601–613. https://doi.org/10.5194/hess-19-601-2015