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Article Climatology and Dynamical Evolution of Extreme Rainfall Events in the —

Marina Baldi 1,* , Doaa Amin 2, Sabry Al Zayed 3 and Giovannangelo Dalu 1,4

1 CNR-IBE, 00185 Rome, Italy; [email protected] 2 Water Resources Research Institute (WRRI), National Water Research Center (NWRC), 13621, Egypt; [email protected] 3 Technical Office, Headquarter, National Water Research Center (NWRC), Cairo 13411, Egypt; [email protected] 4 Accademia dei Georgofili, 50122 Firenze, Italy * Correspondence: [email protected]

 Received: 7 June 2020; Accepted: 28 July 2020; Published: 31 July 2020 

Abstract: The whole Mediterranean is suffering today because of changes, with projections of more severe impacts predicted for the coming decades. Egypt, on the southeastern flank of the , is facing many challenges for water and food security, further exacerbated by the arid climate conditions. The River represents the largest freshwater resource for the country, with a minor contribution coming from rainfall and from non-renewable groundwater aquifers. In more recent years, another important source is represented by non-conventional sources, such as treated wastewater reuse and desalination; these water resources are increasingly becoming valuable additional contributors to water availability. Moreover, although rainfall is scarce in Egypt, studies have shown that rainfall and flash floods can become an additional available source of water in the future. While presently rare, heavy rainfalls and flash floods are responsible for huge losses of lives and infrastructure especially in parts of the country, such as in the Sinai Peninsula. Despite the harsh climate, water from these events, when opportunely conveyed and treated, can represent a precious source of freshwater for small communities of . In this work, rainfall climatology and flash flood events are presented, together with a discussion about the dynamics of some selected episodes and indications about future climate scenarios. Results can be used to evaluate the water harvesting potential in a where water is scarce, also providing indications for improving the weather forecast. Basic information needed for identifying possible risks for population and infrastructures, when fed into hydrological models, could help to evaluate the flash flood water volumes at the outlets of the effective watershed(s). This valuable information will help policymakers and local governments to define strategies and measures for water harvesting and/or protection works.

Keywords: Sinai Peninsula; flash flood; climate change; CORDEX; water harvesting

1. Introduction In recent decades, as in past times, heavy rainfall resulting in flash floods has affected not only the Egyptian coastal areas along the Mediterranean Sea and the but also arid and semi-arid areas such as Upper Egypt (e.g., , , and Assiut) and the Sinai Peninsula [1–5]. Under changing climate conditions, the frequency of extreme rainfall episodes is also changing. These episodes, although rare, can be catastrophic in characterized by very low annual precipitation, with large impacts on lives, infrastructures, properties, and last but not least, to the great cultural heritage of Egypt [6]. Recent heavy rainfall events in the densely populated region of Cairo Governorate have forced authorities to close schools, offices, and highways connecting Cairo to

Sustainability 2020, 12, 6186; doi:10.3390/su12156186 www.mdpi.com/journal/sustainability Sustainability 2020, 12, 6186 2 of 20 other provinces, producing electricity disruption and floods in large areas of the town. These floods have also trapped people in their cars for several hours, as happened during the recent episodes that occurred in April 2018, October 2019, and March 2020 [7–10]. Scientific literature [11] has illustrated how the heavy rainfall and subsequent flash floods can be harmful in the Sinai Peninsula and how important the production of risk maps and implementing the flash flood protection works for the main watersheds of the Peninsula is, taking into consideration the complex morphological parameters [12,13]. Concerning the heavy rainfall episodes that have occurred in the Region and specifically in Egypt, many authors, e.g., [14–18], have focused their analysis on the evolution of extreme rainfall episodes and on the atmospheric pattern precursors of the evolution of these events. Due to the scale of the rare phenomenon, the forecast of a small or, at its largest, mesoscale severe thunderstorm, bringing heavy rainfall and causing flash flood, is not an easy task. Only the use of an appropriate tool like a mesoscale model can help to produce a timely and detailed forecast of the episode, which can be used as the major “ingredient”, together with data-driven weather-runoff forecast models, for an Early Warning System (EWS) to be adopted in order to avoid or, at least, minimize major impacts and save lives [19–21]. In addition, if, in this flood-prone region, it is important on one hand to minimize damages and avoid disastrous events deriving from severe thunderstorms, on the other hand, it is also important to favor the use of rainfall as a precious source of fresh water. For this purpose, it is essential that the development and use of EWS [19–21] present high performances. In order to decrease the uncertainties in the EWS, it is necessary to work on the improvement of Weather Prediction Tools (WPT) in parallel with the adoption of a sophisticated data-driven weather-runoff model; however, this improvement can come only through a thorough validation of the WPT. Due to their randomness, low frequency of occurrence, rapidity in evolution, and small mesoscale dimension, observations related to these thunderstorms are scarce in the Region and do not permit a robust validation of WPT and therefore of EWS. In this respect, the aim of the present study is to contribute to an increase of the knowledge about the present and future occurrence of extreme rainfall events in the Sinai Peninsula and on their dynamics. To this aim, the study starts with a general overview of the climatic trends in the Sinai Peninsula, followed by a discussion on the climatology of extreme rainfall events in Sinai and by the analysis of a selection of heavy rainfall episodes. The second part of the study presents a general overview of future climate scenarios that might affect the frequency and intensity of extreme events in this region. This part of the work not only gives some general information, but also results can represent a necessary basis for more detailed climate scenario studies, and it will possibly encourage the development of specific regional projections at a higher resolution. More detailed scenario analysis can be used for the implementation of more sophisticated risk maps for future decades and can foster the elaboration and adoption of adaptation plans for population, agriculture, and water resources management and, finally, might help the decision-makers to plan the construction of flood water harvesting structures and flash flood protection works.

2. Materials and Methods

2.1. Data and Methods The climatological analysis of the current climate and its changes in the last decades is based on the National Centers for Environmental Modeling/National Center for Atmospheric Research global analyses of atmospheric fields, NCEP/NCAR reanalysis, provided by National Oceanic and Atmospheric Administration (NOAA) [22] as well as the global atmospheric reanalysis ERA-Interim provided by the European Centre for Medium-Range Weather Forecasts (ECMWF) available at a spatial resolution of approximately 80 km [23]. The annual rainfall trend over Sinai Peninsula is analyzed using the Global Precipitation Climate Center data (GPCC) provided by the NOAA Physical Sciences Laboratory (PSL), Boulder, Colorado, USA (https://psl.noaa.gov/). The study of the spatio-temporal Sustainability 2020, 12, 6186 3 of 20 evolution of the selected episodes of heavy rainfall is based on the analysis of meteorological data from ground stations in Sinai and rainfall estimates derived by satellite images from Tropical Rainfall

MeasuringSustainability Mission 2020, 12 (TRMM), x FOR PEER and REVIEW the Hydrologic Data and Information System (HyDIS). In3 addition,of 20 NCEP-NCAR reanalysis is used to highlight the atmospheric patterns before, during, and after the selectedmeteorological episodes data in from order ground to individuate stations in Sinai (i) the and main rainfall atmospheric estimates derived patterns by contributingsatellite images to the evolutionfrom Tropical of the events,Rainfall Measuring (ii) possible Mission driving (TRMM) mechanisms, and the Hydrologic and (iii) Data similarities and Information among System the events. Finally,(HyDIS). climate In scenariosaddition, NCEP at the-NCAR regional reanalysis scale were is used obtained to highlight from the the atmospheric outputs available patterns throughbefore, the during, and after the selected episodes in order to individuate (i) the main atmospheric patterns Coordinated Regional Downscaling Experiment (CORDEX). contributing to the evolution of the events, (ii) possible driving mechanisms, and (iii) similarities 2.2. Studyamong Area the events. Finally, climate scenarios at the regional scale were obtained from the outputs available through the Coordinated Regional Downscaling Experiment (CORDEX). Egypt is located on the northeastern side of , covering nearly 3% of the total area of the .2.2. Study This Area country is bordered to the north by the Mediterranean Sea and to the east by the Red Sea, by theEgypt Gulf is of located o andn the , northeastern to theside south of Africa, by the covering Republic nearly of Sudan,3% of the and total to thearea west of the by the Republiccontinent. of Libya. This country A few geographicalis bordered to the sub-regions north by the of Mediterranean the country can Sea beand identified: to the east theby the Nile Red valley and delta,Sea, by covering the Gulf aboutof Aqaba 4% and of thePalestine total, area;to the the south Eastern by the desert, Republic covering of Sudan, about and to 22%; the thewest Western by desert,the covering Republic aboutof Libya. 68%; A few and geographical the Sinai Peninsula, sub-regions covering of the country about can 6%. be identified: the Nile valley Hotand delta and dry, covering conditions about characterize4% of the total the are generala; the Eastern climate desert of Egypt, covering with about an average 22%; the annual Western rainfall over thedesert whole, covering country about of 68%; about and 10 the mm. Sinai Even Peninsula along, covering the narrow about northern 6%. strip of the Mediterranean Hot and dry conditions characterize the general with an average annual rainfall coastal land, where most of the rainfall occurs, the average annual rainfall is usually less than 200 mm, over the whole country of about 10 mm. Even along the narrow northern strip of the Mediterranean and thiscoastal amount land, verywhere rapidly most of decreases the rainfall proceeding occurs, the furtheraverage inland.annual rainfall The only is usually regular less supply than of200 water is frommm, the and Nile. this Thisamount river, very which rapidly has decreases its main proceeding source in fu therther highlands inland. The of Eastonly Africa,regular crossessupply of Egypt fromwater the south is from to the north Nile. end This with river, a which large has delta its inmain the source Mediterranean in the highlands Sea. of In East Egypt, Africa, the crosses Nile water is artificiallyEgypt from channeled the south on to bothnorth sides.end with The a large Nile supportsdelta in the the Mediterranean life along its Sea. length, In Egypt, and t allowedhe Nile the growthwater of ais greatartificially civilization channeled in on peace both andsides. stability The Nile [ 24supports]. The the importance life along its of length, the river and was allowed very clear sincethe ancient growth times; of a ingreat fact, civilization Herodotus in peace (484–425 and BC)stability stated [24]. that The “Egypt importance is the of Gift the ofriver the was Nile”. very Theclearstudy since ancient area of times the present; in fact, workHerodotus is Sinai, (484 a–425 triangular-shaped BC) stated that “Egypt peninsula is the withGift of an the area Nile”. of about 60,000 kmThe2; this study peninsula area of the is boundedpresent work by theis Sinai, Mediterranean a triangular- Seashaped to the peninsula north, with the Red an area Sea of to about the south, 60,000 km2; this peninsula is bounded by the Mediterranean Sea to the north, the Red Sea to the south, and by the Gulfs of and Aqaba to the west and to the east, respectively (Figure1). The territory of and by the Gulfs of Suez and Aqaba to the west and to the east, respectively (Figure 1). The territory the regionof the isregion quite is roughquite rough with awith complex a complex orography orography and and elevated elevated mountains, mountains, which which reachreach up to to and aboveand 2400 above m ASL 2400 (above m ASL sea(above level); sea Mountlevel); , Catherine, Egypt’s Egypt’s highest highest mountain, mountain, reaches reaches 2642 2642 m ASL. The centralm ASL. areaThe central of Sinai area consists of Sinai ofconsists two plateaus,of two plateaus, Al-Tih Al and-Tih and Al-Ajmah, Al-Ajmah, both both deeply deeply indentedindented and dippingand northward dipping northward towards towards El . Wadi El Towards Arish. theTowards Mediterranean the Mediterranean Sea, the region Sea, the is regioncharacterized is by a plateau,characterized by a by system a plateau, of a numberby a system of dome-shaped of a number of hills, dome and-shaped by a belthills, of and parallel by a belt dunes, of parallel which can be asdunes, high as which 100 m.can be as high as 100 m.

Figure 1. The location of the study area showing the Sinai Peninsula and its orography. Credits: ESRI Figure 1. The location of the study area showing the Sinai Peninsula and its orography. Credits: ESRI WorldWorld Imagery. Imagery. Sustainability 2020, 12, 6186 4 of 20 Sustainability 2020, 12, x FOR PEER REVIEW 4 of 20

The whole territory of the Peninsula is is characterized characterized by by the the presence presence of of numerous watersheds, watersheds, which discharge rainwater rainwater on on three three sides: sides: the the Mediterranean Mediterranean Sea Sea,, the the Gulf Gulf of ofAqaba Aqaba,, and and the the Gulf Gulf of Suezof Suez (Figure (Figure 2). 2Rivers). Rivers in these in these watersheds watersheds are short are short but fierce but fierce because because of the of combined the combined effect eofff ectsteep of slopessteep slopes and rare and episod rare episodeses of he ofavy heavy rainfall. rainfall. The The main main characteristics characteristics of ofthe the watersheds watersheds in in the the Sinai Sinai Peninsula are summarized in Table1 1,, as as inin [ 25[25].].

Figure 2. WatershedsWatersheds of study area (Source: Elsayed et al., 2013).

Table 1. The geomorphology characteristics of the watersheds of Sinai (Source: [25]). Sinai is economically important for Egypt because it represents one of its largest areas. This peninsula has also a great potentialBasin forBasin agriculture and industrialMax. development.Max. Although there Area Perimeter Mean Basib ID Basin Name Length Slope Stream Stream are some limitation: the(km region2) is prone to flash flood(m) events resulting from heavy, sudden,Elevation and (m)short (m) (m/m) Length (m) Slope (m/m) duration rainfall events, which represent a risk for the population, infrastructures, properties, and 1 Al Arish 23,784.9 238,040 0.0469 1,213,900 354,250 0.0037 499.23 economic2 Watiersectors like 3521industry and 76,110 agriculture 0.1446 itself. 483,620 118,450 0.0122 912 3On Al the Grafee other 2610 hand, flash 84,713 floods 0.0334 caused 412,010 by heavy 114,110 rainfall 0.0051 events in Sinai 640 and southern/southeastern4 Dhab 2070 Egypt represent 56,686 a 0.2217potential 353,930source of non 93,238-conventional 0.02 freshwater 1062.9 resources. 5 Al Awag 1941 55,070 0.1967 278,530 75,529 0.0082 549.1 In particular,6 Fieran the water, 1780 which 80,341usually drains 0.1949 into 420,050the Gulf of 132,660Suez and the 0.0177Gulf of Aqaba, 1015 if wisely harvested,7 Wardan could fulfill 1180 a non- 59,345negligible 0.1025 amount 273,720 of water demand 86,222 and/or 0.0113 recharge the 523 shallow groundw8 Ghrandalater aquifers, 1074.1 becoming 78,119 a precious 0.1536 fresh water 340,680 source 105,380for local people 0.0134 of the region 801.73 and their 9 Kied 1045.9 47,766 0.3465 258,500 679.14 0.0206 928.8 agriculture10 Sidry. 868.6 56,292 0.1438 243,580 82,224 0.0107 570.24 11 Paapaa 712.7 54,971 0.1386 232,620 71,005 0.0154 600.24 12 SidrTable 1. The 623.45 geomorphology 54,196 characteristics 0.0862 205,660 of the watersheds 79,078 of Sinai 0.0073(Source: [25]). 417 13 Al Rahaa 452 42,466 0.105 181,690 51,580 0.0134 488 Basin Area Basin Basin Slope Perimeter Max. Stream Max. Stream Mean Basib ID14 Om Adwy 367.6 35,744 0.2589 151,320 47,503 0.0282 659.75 15 NameTieba (km2) 333.9Length (m) 43,354 (m/m) 0.303 (m) 158,240 Length 51,471 (m) Slope 0.0311 (m/m) Elevation 999.5 (m) 1 16 Al ArishLehataa 23,784.9 276.44 238,040 31,331 0.0469 0.0571 1,213 114,790,900 354 43,528,250 0.01420.0037 214.64499.23 2 Watier 3521 76,110 0.1446 483,620 118,450 0.0122 912 3 Al Grafee 2610 84,713 0.0334 412,010 114,110 0.0051 640 4 Dhab 2070 56,686 0.2217 353,930 93,238 0.02 1062.9 5 SinaiAl Awag is economically1941 important55,070 for0.1967 Egypt because278,530 it represents75,529 one of0.0082 its largest mining549.1 areas. This6 peninsulaFieran has1780also a80 great,341 potential0.1949 for agriculture420,050 and132, industrial660 development.0.0177 Although1015 there7 areWardan some limitation:1180 59 the,345 region0.1025 is prone to273 flash,720 flood86 events,222 resulting0.0113 from heavy,523 sudden, 8 Ghrandal 1074.1 78,119 0.1536 340,680 105,380 0.0134 801.73 and9 shortKied duration 1045.9 rainfall events,47,766 which0.3465 represent 258 a, risk500 for the679.14 population, infrastructures,0.0206 properties,928.8 and10 economicSidry sectors868.6 like industry56,292 and0.1438 agriculture 243 itself.,580 82,224 0.0107 570.24 11 Paapaa 712.7 54,971 0.1386 232,620 71,005 0.0154 600.24 12 OnSidr the other623.45 hand, flash54, floods196 caused0.0862 by heavy205,660 rainfall events79,078 in Sinai and0.0073 southern /southeastern417 Egypt13 Al represent Rahaa a452 potential 42 source,466 of non-conventional0.105 181,690 freshwater51,580 resources.0.0134 In particular, the488 water, 14 Om Adwy 367.6 35,744 0.2589 151,320 47,503 0.0282 659.75 15 Tieba 333.9 43,354 0.303 158,240 51,471 0.0311 999.5 16 Lehataa 276.44 31,331 0.0571 114,790 43,528 0.0142 214.64 Sustainability 2020, 12, 6186 5 of 20 which usually drains into the and the , if wisely harvested, could fulfill a non-negligible amount of water demand and/or recharge the shallow groundwater aquifers, becoming a precious fresh water source for local people of the region and their agriculture.

3. Results

3.1. Climate Variability in the Sinai Peninsula The temperature and precipitation monthly mean over the country are shown in Figure3, evaluated using ECMWF ERA-Interim reanalysis for the period 1981–2010. In the northern part, the Sinai Peninsula is characterized by a Mediterranean climate, whilst in the southern part, the climate is semi-desert to desert. Thus, in most of the Peninsula the climate is hot to very hot. However, sub-regions along the Mediterranean coast in the North and over the mountains are more temperate. In winter, the temperatures are surely lower, with temperatures that can drop to 0 ◦C at night over the mountains (Figure3). Most of the precipitation occurs during the winter and then in spring and autumn, while during summer rainfall is almost totally absent over the Sinai (Figure3). Using ECMWF ERA-Interim reanalysis, an increase of about 1 ◦C in mean temperature has been evaluated over Sinai, as shown in Figure4. This figure shows the anomalies of air temperature at 850 hPa during the last decade over the African Continent at large compared to the baseline period (1979–2000). In addition, the analysis performed using ECMWF ERA-Interim reanalysis for the period 1979 to 2018 over the domain (27◦–32◦ N, 32◦–35◦ E) shows a clear tendency towards increasing average temperatures (Figure5) and decreasing total rainfall (Figure6). Sustainability 2020, 12, 6186 6 of 20 Sustainability 2020, 12, x FOR PEER REVIEW 6 of 20

Monthly Mean Precipitation

Monthly Mean Air Temperature at 2 m

Figure 3. Climatology of Egypt, including the Sinai Peninsula, evaluated over the period 1981–2010. Monthly mean precipitation (in mm) and air temperature (in Figure 3. Climatology of Egypt, including the Sinai Peninsula, evaluated over the period 1981–2010. Monthly mean precipitation (in mm) and air temperature (in ◦K) at°K) 2 m. at (Data2 m. (Data Source: Source: European European Centre Centre for Medium-Range for Medium-Range Weather Weather Forecasts Forecasts (ECMWF) (ECMWF) ERA-Interim ERA-Interim reanalysis). reanalysis). Sustainability 2020, 12, 6186 7 of 20

Sustainability 2020, 12, x FOR PEER REVIEW 7 of 20 Sustainability 2020, 12, x FOR PEER REVIEW 7 of 20

Figure 4. Mean air Temperature at 850 hPa: anomaly over the period 2010–2018 relative to the base FigureFigureperiod 4. Mean 1979 airair– Temperature2000Temperature (Data at at 850 Source: 850 hPa: hPa: anomaly ECMWF anomalyover over ERA the -the periodInterim period 2010–2018 reanalysis, 2010–2018 relative relative available to the to base the at: period base period1979–2000https://climatereanalyzer.org). 1979 (Data–2000 Source: (Data ECMWF Source: ERA-Interim ECMWF reanalysis, ERA available-Interim at: https: reanalysis,//climatereanalyzer.org available at:). https://climatereanalyzer.org).

Figure 5. Annual and seasonal mean (top panel) and anomalies (bottom panel) of air temperature at 2 m over the Sinai Peninsula for the period 1979–2018, evaluated in the domain (27◦–32◦ N, 32◦–35◦ E). Base period for anomalies (1979–2000). (Data Source: ECMWF ERA-Interim reanalysis, available at: https://ClimateReanalyzer.org).

Sustainability 2020, 12, x FOR PEER REVIEW 8 of 20

Figure 5. Annual and seasonal mean (top panel) and anomalies (bottom panel) of air temperature at 2 m over the Sinai Peninsula for the period 1979–2018, evaluated in the domain (27°–32° N, 32°–35° SustainabilityE).2020 Base, 12 period, 6186 for anomalies (1979–2000). (Data Source: ECMWF ERA-Interim reanalysis, available 8 of 20 at: https://ClimateReanalyzer.org). Sustainability 2020, 12, x FOR PEER REVIEW 8 of 20

Figure 5. Annual and seasonal mean (top panel) and anomalies (bottom panel) of air temperature at 2 m over the Sinai Peninsula for the period 1979–2018, evaluated in the domain (27°–32° N, 32°–35° E). Base period for anomalies (1979–2000). (Data Source: ECMWF ERA-Interim reanalysis, available at: https://ClimateReanalyzer.org).

FigureFigure 6. Annual 6. Annual Total Total Precipitation Precipitation over the the Sinai Sinai Peninsula Peninsula for the for period the period 1979– 1979–2018,2018, evaluated evaluated in in thethe domain domain (27 (27°◦–32–32°◦ N, N, 32 32°◦––3535°◦ E).E). (Data (Data Source: Source: ECMWF ECMWF ERA ERA-Interim-Interim reanalysis, reanalysis, available available at: at: https:https://ClimateReanalyzer.org).//ClimateReanalyzer.org).

The analysis of the GPCC historical data for the period 1901–2013, shows a tendency to decrease precipitation in different sub-regions of the Sinai Peninsula: in the North, at the border with the Mediterranean Sea, in the Centre, and in the South (Figure7). In general, the total rainfall distribution

is quite different along the Peninsula, and it decreases from the northeast towards the southwest, with a maximumFigure in6. Annual . TheTotal southern Precipitation part over of the the PeninsulaSinai Peninsula is characterized for the period by 1979 much–2018 lower, evaluated rainfall in totals in coastalthe domain areas, (27°along–32° the N, Gulfs 32°–35° of Suez E). (Data and Aqaba.Source: ECMWF ERA-Interim reanalysis, available at: https://ClimateReanalyzer.org).

Figure 7. Annual Total Precipitation in North, Middle, and South Sinai Peninsula with linear decreasing trend superimposed. (Data Source: Global Precipitation Climate Center data (GPCC) — https://www.esrl.noaa.gov/psd/data/gridded/data.gpcc.html).

3.2. Extreme Rainfall Events in Sinai The analysis of rainfall data is the most important element in hydrological studies because it can be used in the EWS development as input to determine the flood discharges. Timing, duration, and extent of rainfall episodes are especially important in Sinai because they represent the major potential source of renewable water. Unfortunately, these flash floods are very difficult to forecast; in addition,

their fresh water is difficult to collect because of the steepness of the slopes of the terrain in the Figurepeninsula.Figure 7. Ann Moreover,Annualual Total Total in this Precipitation Precipitation semiarid- to in in- arid North, North, region, Middle Middle, rainfall, and and is Southusually South Sinai Sinaicharacteriz Peninsula Peninsulaed by with with extremely linear linear decreasingdecreasing trend trend superimposed. superimposed. (Data (Data Source: Source: Global Global Precipitation Precipitation Climate Climate Center Center data data (GPCC) (GPCC) — —https://www.esrl.noaa.gov/psd/data/gridded/data.gpcc.html).https://www.esrl.noaa.gov/psd/data/gridded/data.gpcc.html ). 3.2. Extreme Rainfall Events in Sinai 3.2. Extreme Rainfall Events in Sinai The analysis of rainfall data is the most important element in hydrological studies because it The analysis of rainfall data is the most important element in hydrological studies because it can can be used in the EWS development as input to determine the flood discharges. Timing, duration, be used in the EWS development as input to determine the flood discharges. Timing, duration, and and extent of rainfall episodes are especially important in Sinai because they represent the major extent of rainfall episodes are especially important in Sinai because they represent the major potential potential source of renewable water. Unfortunately, these flash floods are very difficult to forecast; in source of renewable water. Unfortunately, these flash floods are very difficult to forecast; in addition, their fresh water is difficult to collect because of the steepness of the slopes of the terrain in the peninsula. Moreover, in this semiarid-to-arid region, rainfall is usually characterized by extremely Sustainability 2020, 12, 6186 9 of 20 addition, their fresh water is difficult to collect because of the steepness of the slopes of the terrain in the peninsula. Moreover, in this semiarid-to-arid region, rainfall is usually characterized by extremely high spatial and temporal variability [26], with intense episodes of very short duration, spatially scattered over the territory. These characteristics make the collection of this water very difficult without the construction of important infrastructures. An additional source of fresh water is the non-renewable groundwater, as in the case of the Nubian Aquifer. As already mentioned, in recent decades Sinai has been affected by significant changes in the climate, with drier and hottest conditions relative to the baseline period (Figures4–6), and with more intense storms with associated short, but intense rainfall events. This trend caused severe and long dry periods suddenly interrupted by sporadic intense rainfall with increased space-time variability; this has increased the forecast difficulties in recent years. If this tendency continues, the impacts on the natural environment and resources, including renewable water, as well as on population, infrastructure, and properties, will be severe. The major storms which affected North and South Sinai in the past years are listed in Table2 for South Sinai and in Table3 for North Sinai. The lists show how the number of events since the year 2000 is quite significant.

Table 2. List of heavy rainfall events in the South Sinai Peninsula at different locations.

Flash Flood Events in South Sinai 1 1990–2015

Ras Sedr (32◦43000” E, (Elmelha) Saint Katherin (33◦56058” E, Newabaa (34◦41013” E, 29◦35000” N) (32◦59054” E, 29◦44023” N) 28◦33043” N) 28◦58057” N) 02/03/1997 07/12/2000 22/03/1991 17/01/2010 07/02/1999 04/12/2001 17/10/1993 27/01/2013 07/12/2000 06/01/2003 20/10/1993 09/03/2014 10/01/2002 14/12/2003 01/01/1994 08/05/2014 16/12/2003 22/01/2004 18/01/2010 12/09/2015 14/01/2004 05/02/2004 08/01/2013 26/10/2015 04/02/2004 04/04/2011 25/01/2013 18/01/2010 31/12/2013 27/01/2013 25/02/2010 09/03/2014 09/03/2014 09/01/2013 08/05/2014 01/02/2013 12/09/2015 09/03/2014 25/10/2015 07/05/2014 1 Other events occurred in South Sinai more recently, including a 27–29 October 2016 episode when the storm also affected the Red Sea, Ismailia, , , Assiut, and Suhag provinces (https://reliefweb.int/disaster/fl-2016- 000114-egy).

Table 3. List of heavy rainfall events in the North Sinai Peninsula at different locations.

Flash Flood Events in North Sinai 1990–2015

Godirat (34◦ 24035” E, 30◦ 38028” N) Maghara (34◦ 320 E, 30◦ 230 N) 22/03/1991 27/10/2005 05/01/2001 21/10/2007 29/01/2004 18/01/2010 17/04/2006 09/01/2013 10/12/2009 09/05/2014 17/01/2010 29/10/2015 09/03/2014 09/05/2014 25/10/2015 29/10/2015

Among all the events that occurred in the period 2000–2015, the following episodes that affected the whole Peninsula, although with different intensity, have been selected and analyzed: 8 January Sustainability 2020, 12, 6186 10 of 20 Sustainability 2020, 12, x FOR PEER REVIEW 10 of 20

2013on January and 9 March 7th. On 2014. January The 8th 2013, the event storm started conti onnued January only along 6th with the light north rainfall coast of and North reached Sinai a, peakcover oning January mainly 7th.the north On January Sinai and 8th, parts the storm of south continued Sinai, and only the along maximum the north daily coast rainfall of North (29.8 Sinai,mm) coveringwas observed mainly at Rafah the north station. Sinai The and 2014 parts event of south lasted Sinai, over andEgypt the for maximum three days daily from rainfall March (29.8 7th until mm) wasMarch observed 9th. This at event Rafah affected station. all The Sinai 2014 with event a maximum lasted over daily Egypt rainfall for three of 30 days mm from measured March at 7th until Marchstation. 9th. Table This 4 summarizes event affected the all total Sinai amount with a of maximum precipitation daily that rainfall occurred of 30 in mm Upper measured Egypt, at the Dahab Red station.Sea, and Table Sinai4 summarizes Peninsula during the total the amount storm (7 of–9 precipitation March 2014), that while occurred on the in Upper10th it Egypt, moved the rapidly Red Sea,towards and East. Sinai The Peninsula evolution during of the the 2014 storm storm (7–9 as March captured 2014), by whileTRMM on satellite the 10th images it moved is shown rapidly in towardsFigure 8, East.where The it is evolution clear how of the 2014storm, storm which as started captured to byform TRMM in Upper satellite Egypt images on the is shown7th, then in Figurerapidly8, moved where ittoward is clear the how North the storm,-East whichand strongly started toaffected form inSinai Upper Peninsula Egypt on in the the 7th, following then rapidly days moved(8th and toward 9th of theMarch). North-East and strongly affected Sinai Peninsula in the following days (8th and 9th of March).

Figure 8. Figure 8. Episode 7–107–10 MarchMarch 2014.2014. Storm evolution over Sinai and surrounding surrounding region. region. (Source: TRMM satellite data). TRMM satellite data). Results of the analysis of the large-scale configuration during these episodes show some similarities, Results of the analysis of the large-scale configuration during these episodes show some with heavy rainfall usually resulting from mesoscale convective systems embedded in synoptic-scale similarities, with heavy rainfall usually resulting from mesoscale convective systems embedded in disturbances interacting with the complex terrain of the Peninsula. The evolution of the storm synoptic-scale disturbances interacting with the complex terrain of the Peninsula. The evolution of (not shown) is similar in the selected cases (as an example, Figure9 shows the spatial distribution the storm (not shown) is similar in the selected cases (as an example, Figure 9 shows the spatial of the geopotential at 700 hPa during the selected episodes with a low pressure system over the distribution of the geopotential at 700 hPa during the selected episodes with a low pressure system Eastern Mediterranean bringing a disturbance to the region of interest, which then moves eastward), over the Eastern Mediterranean bringing a disturbance to the region of interest, which then moves and a correlation is also noticed with the atmospheric circulation over the Peninsula and with eastward), and a correlation is also noticed with the atmospheric circulation over the Arabic low-pressure systems over the Eastern Mediterranean. In addition, the distribution of the rainfall Peninsula and with low-pressure systems over the Eastern Mediterranean. In addition, the between the Northern and Southern parts of the Peninsula is strongly affected by the complexity of the distribution of the rainfall between the Northern and Southern parts of the Peninsula is strongly terrain and by the position of the mountain ranges, which is strongly influencing the areas where the affected by the complexity of the terrain and by the position of the mountain ranges, which is strongly majority of rain is observed. influencing the areas where the majority of rain is observed. Sustainability 2020, 12, 6186 11 of 20

Table 4. Total rainfall in Upper Egypt, the Red Sea, and the Sinai Peninsula during the 7–9 March 2014 event.

Amount of Precipitation Observed in the Upper Egypt, the Red Sea, and Sinai Peninsula during the 7–9 March 2014 Event Station Precipitation mm Aswan 29 UPPER EGYPT Luxor 29 9 RED SEA Hurgada 21 Sharm El-Sheikh 27 Dahab 30 Saint Cathrene 29 SINAI El Tor 17 Sustainability 2020, 12, x FOR PEER REVIEW Nuwaibaa 8 11 of 20 5

Figure 9. Geopotential height at 700 hPa for the selected episodes: 8 January 2013 and 9 March 2014. Figure(Source: 9. NCEP-NCARGeopotential reanalysis).height at 700 hPa for the selected episodes: 8 January 2013 and 9 March 2014. (Source: NCEP-NCAR reanalysis). The mechanism leading to storms with torrential rainfall, thunder, and lightning has been studied by someTable authors 4. Total [rainfall21] and in referencesUpper Egypt, therein the Red [18 Sea,27, 28and]; inthe these Sinai works,Peninsula it during is emphasized the 7–9 March that they are phenomena2014 event. of very limited spatial and time extent. Although this part of the study is not yet fully completed, some general remarks are outlined here. Climatically the whole is under the influenceAmount ofof thePrecipitation westerly Observed winds, i.e., in onthe average, Upper Egypt, the winds the Red blow Sea, fromand Sinai the west Peninsula towards during the the east 7– and9 March 2014 Event their intensity increases with altitude, and the weather is usually characterized by the presence of a Station Precipitation mm Red Sea Through (RST), i.e., a low-level pressure extending from the African Monsoon over Equatorial Aswan 29 Africa, northward over the Red Sea region toward the Eastern Mediterranean (EM). The RST, generated UPPER EGYPT Luxor 29 and supported by thermal forcing and supportedAsyut by the presence of the local complex9 topography, strongly influencesRED SEA the weather in the wholeHurgada Levant, usually bringing dry and hot21 conditions. The size of storms moving in the easternSharm El part-Sheikh of the is27 of the order of a few km, and their lifetime is only few days.Dahab Many storms in the East Mediterranean30 originate in the region around Cyprus; these storms travelSaint Cathrene eastwards. Therefore, they do not29 usually hit Egypt. SINAI However, if the conditions are favorable in theEl Tor Red Sea, they are diverted southeastwards,17 reaching North Egypt; if their lifetime is sufficiently long,Nuwaibaa they can hit Central Egypt. These8 storms are usually associated with the presence of an Active RedNekhel Sea Trough. While a (non-active) Red5 Sea Trough (RST) is a low-level trough extending northward from East Africa over the Red Sea region towards the LevantThe that mechanism brings dry, leading hot weather, to storms an Active with Red torrential Sea Trough rainfall, (ARST) thunder, is an and RST accompaniedlightning has by been an studiedupper trough by some which authors brings [21 severe] and weather,references heavy therein precipitation, [18,27,28]; andin these possible works flash, it floodsis emphasized as in the casethat theystudies are analyzed. phenomena of very limited spatial and time extent. Although this part of the study is not yet fully Incompleted, a very simplified some general scheme, remarks several are outlined factors here. can contributeClimatically to the transform whole Levant an RST is under into the influenceactive Red of Seathe storm;westerly the wind presences, i.e., on of average, these factors the winds enhances blow the from tropospheric the west towards instability the east and and the theirsynoptic-scale intensity increases forcing and with inducing altitude, ascendingand the weather motions is usually with the characterized formation of by an the ARST. presence Usually, of a Red Sea Through (RST), i.e., a low-level pressure extending from the African Monsoon over Equatorial Africa, northward over the Red Sea region toward the Eastern Mediterranean (EM). The RST, generated and supported by thermal forcing and supported by the presence of the local complex topography, strongly influences the weather in the whole Levant, usually bringing dry and hot conditions. The size of storms moving in the eastern part of the Mediterranean basin is of the order of a few km, and their lifetime is only few days. Many storms in the East Mediterranean originate in the region around Cyprus; these storms travel eastwards. Therefore, they do not usually hit Egypt. However, if the conditions are favorable in the Red Sea, they are diverted southeastwards, reaching North Egypt; if their lifetime is sufficiently long, they can hit Central Egypt. These storms are usually associated with the presence of an Active Red Sea Trough. While a (non-active) Red Sea Trough (RST) is a low- level trough extending northward from East Africa over the Red Sea region towards the Levant that brings dry, hot weather, an Active Red Sea Trough (ARST) is an RST accompanied by an upper Sustainability 2020, 12, 6186 12 of 20 the ARST configurations are more active in autumn, when there are two coinciding favorable elements: the position of the African Monsoon and Subtropical Jet Stream (STJ). These elements are absent in winter and spring, when the Middle East (ME) can be affected by extreme rainfall resulting from tropical-extratropical interactions. In the beginning, the systems, which started over Egypt, presented characteristics very similar to a Mesoscale Convective System (MCS), with rainfall particularly intense during its first stage when the convection was dominant. After this first phase, the intensity of rain, as well the role of convection, diminished considerably while the storms move eastwards. The kind storms weather affects not only Egypt but also the Middle East.

3.3. Expected Future Climate Changes Considering the fact that regional climate information is needed for decision-making on societal issues such as vulnerability and adaptation to a changing climate with weather/water extremes, the Coordinated Regional Climate Downscaling Experiment (CORDEX: https://cordex.org/) has been developed. CORDEX is a World Climate Research Project (WCRP) framework to evaluate regional climate model performance through a set of experiments aimed to the production of regional climate projections [29]. The CORDEX vision is to advance and coordinate the science and application of regional climate downscaling through global partnerships, and its main goals can be summarized as follows:

To better understand relevant regional/local climate phenomena, their variability, and changes, • through downscaling. To evaluate and improve regional climate downscaling models and techniques. • To produce coordinated sets of regional downscaled projections worldwide. • To foster communication and knowledge exchange with users of regional climate information. • Thanks to CORDEX, a set of experiments are available for different domains, including the Middle East- (MENA) domain, which contains the region of interest of the present study [30,31], and few selected results are briefly discussed here. Figures 10 and 11 show, respectively, the expected changes in temperature and precipitation over a domain including Egypt and the for the control period 1971–2000 and for three future time periods: 2011–2040, 2041–2070, and 2071–2100 for an intermediate stabilization Representative Concentration Pathway (RCP4.5). These figures show the result of an ensemble of nine different Global Circulation Models (GCMs), in which a general increase in the mean temperature for the mid-to-end of the century is evident. This will occur all over the country except for a narrow region along the Mediterranean Sea, and there will be a decrease in the mean annual precipitation for the same periods; this pattern is more evident in the Eastern Desert and Sinai Peninsula. Focusing on the Sinai Peninsula, several studies [32–34] showed that several parameters affected the occurrence of the flash floods over the Sinai Peninsula, namely urban expansion and extreme rainfall events. Three ensembles from three Global Circulation Models (GCMs)—CNRM-CM5, EC-EARTH and MPI-ESM-LR—downscaled by the Regional Climate Model (RCM) were used to present the future change in temperature and rainfall over Sinai through the mid (2041–2070) and the end of the century (2071–2100), where both periods are compared with the baseline period (1971–2000). All three ensembles are obtained from CORDEX data, with two ensembles (CNRM-CM5, EC-EARTH) from MENA Domain (created by RICCAR Project: https://riccar.org/) and one ensemble (MPI-ESM-LR) from Africa Domain. The ensembles analyzed are for one emission scenario (RCP4.5) with resolution 50 km 50 km. Figures 12 and 13 show the future change in temperature over Sinai during the periods of × 2050s and 2080s, respectively, while Figures 14 and 15 show the future change in precipitation over Sinai during the same periods. The results show increase in temperature for all three ensembles, while the change of temperature will increase highly during the end of the century (2071–2100). In addition, winter will become warmer, especially in mid and south Sinai, with increases in temperature between (0.2 ◦C to 3 ◦C) for both future periods, 2050s and 2080s. It is not clear from the results which model Sustainability 2020, 12, 6186 13 of 20 give the worst result, but all of them agree with the increase in temperature. The precipitation will be affected: Where the results show that the rainfall will be shifted to the summer, sudden storms will be expected to occur in summer during the mid and end periods (2041–2100). The results show increases in amount of the precipitation may reach to 300% in some local areas. There is no change expected during winter and autumn; however, south Sinai will suffer by decreasing rainfall during autumn. The expected distribution of the rainfall shows the localization, which indicates increases in damage (see Figures 14 and 15). Sustainability 2020, 12, x FOR PEER REVIEW 13 of 20 Sustainability 2020, 12, x FOR PEER REVIEW 13 of 20

Figure 10. Temperature. Results from an ensemble of nine GCM, for RCP4.5 scenario. Ensemble mean Figure 10. Temperature.Temperature. Results Results from an ensemble of nine GCM, for RCP4.5 scenario. Ensemble Ensemble mean (mm/day) for the control period (1971–2000) (upper left panel-color scale on the upper left). Change (mm/day)(mm/day) forfor thethe controlcontrol periodperiod (1971–2000) (1971–2000) (upper (upper left left panel-color panel-color scale scale on on the the upper upper left). left). Change Change in in Ensemble mean (%-color scale at the bottom), for 2011–2040 (upper right), 2041–2070 (bottom left) inEnsemble Ensemble mean mean (%-color (%-color scale scale at theat the bottom), bottom), for for 2011–2040 2011–2040 (upper (upper right), right), 2041–2070 2041–2070 (bottom (bottom left) left) and and 2071–2100 (bottom right) compared with 1971–2000. (Source: https://cordex.org/). and2071–2100 2071–2100 (bottom (bottom right) right) compared compared with with 1971–2000. 1971–2000. (Source: (Source: https: https://cordex.org/).//cordex.org/).

Figure 11. Precipitation. Results from an ensemble of nine Global Circulation Models (GCMs), for Figure 11. Precipitation. Results from an ensemble of nine Global Circulation Models (GCMs), for FigureRCP4.5 11.scenario.Precipitation. Ensemble mean Results (mm/day) from an for ensemble the control of nineperiod Global (1971– Circulation2000) (upper Models left panel (GCMs),-color RCP4.5 scenario. Ensemble mean (mm/day) for the control period (1971–2000) (upper left panel-color forscale RCP4.5 on the scenario. upper left). Ensemble Change mean in Ensemble (mm/day) mean for the (% control-color scale period at (1971–2000)the bottom), (upper for 2011 left–2040 panel-color (upper scale on the upper left). Change in Ensemble mean (%-color scale at the bottom), for 2011–2040 (upper scaleright), on 2041 the– upper2070 (bottomleft). Change left) in and Ensemble 2071–2100 mean (bott (%-colorom right) scale compared at the bottom), with for 1971 2011–2040–2000. (Source: (upper right), 2041–2070 (bottom left) and 2071–2100 (bottom right) compared with 1971–2000. (Source: right),https://cordex.org/). 2041–2070 (bottom left) and 2071–2100 (bottom right) compared with 1971–2000. (Source: https://cordex.org/).https://cordex.org/). Focusing on the Sinai Peninsula, several studies [32–34] showed that several parameters affected Focusing on the Sinai Peninsula, several studies [32–34] showed that several parameters affected the occurrence of the flash floods over the Sinai Peninsula, namely urban expansion and extreme the occurrence of the flash floods over the Sinai Peninsula, namely urban expansion and extreme rainfall events. Three ensembles from three Global Circulation Models (GCMs)—CNRM-CM5, EC- rainfall events. Three ensembles from three Global Circulation Models (GCMs)—CNRM-CM5, EC- EARTH and MPI-ESM-LR—downscaled by the Regional Climate Model (RCM) were used to EARTH and MPI-ESM-LR—downscaled by the Regional Climate Model (RCM) were used to present the future change in temperature and rainfall over Sinai through the mid (2041–2070) and present the future change in temperature and rainfall over Sinai through the mid (2041–2070) and the end of the century (2071–2100), where both periods are compared with the baseline period the end of the century (2071–2100), where both periods are compared with the baseline period (1971–2000). All three ensembles are obtained from CORDEX data, with two ensembles (CNRM- (1971–2000). All three ensembles are obtained from CORDEX data, with two ensembles (CNRM- CM5, EC-EARTH) from MENA Domain (created by RICCAR Project: https://riccar.org/) and one CM5, EC-EARTH) from MENA Domain (created by RICCAR Project: https://riccar.org/) and one ensemble (MPI-ESM-LR) from Africa Domain. The ensembles analyzed are for one emission ensemble (MPI-ESM-LR) from Africa Domain. The ensembles analyzed are for one emission scenario (RCP4.5) with resolution 50 km × 50 km. Figures 12 and 13 show the future change in scenario (RCP4.5) with resolution 50 km × 50 km. Figures 12 and 13 show the future change in Sustainability 2020, 12, x FOR PEER REVIEW 14 of 20 temperature over Sinai during the periods of 2050s and 2080s, respectively, while Figures 14 and 15 show the future change in precipitation over Sinai during the same periods. The results show increase in temperature for all three ensembles, while the change of temperature will increase highly during the end of the century (2071–2100). In addition, winter will become warmer, especially in mid and south Sinai, with increases in temperature between (0.2 °C to 3 °C) for both future periods, 2050s and 2080s. It is not clear from the results which model give the worst result, but all of them agree with the increase in temperature. The precipitation will be affected: Where the results show that the rainfall will be shifted to the summer, sudden storms will be expected to occur in summer during the mid and end periods (2041–2100). The results show increases in amount of the precipitation may reach to 300% in some local areas. There is no change expected during winter Sustainability 2020, 12, 6186 14 of 20 and autumn; however, south Sinai will suffer by decreasing rainfall during autumn. The expected distribution of the rainfall shows the localization, which indicates increases in damage (see Figures

14 and 15). Figure 12. Temperature. Results from an ensemble of three GCMs for RCP4.5 scenario. Change in FigureEnsemble 12. Temperature. mean monthly Results (C) from for the an future ensemble period of 2041–2070three GCM (2050s)s for comparedRCP4.5 scenario. with 1971–2000. Change in January, EnsembleApril, mean July, andmonthly October (C) are for examples the future presenting period 2041 winter,–2070 spring, (2050s) summer, compared and autumn, with 1971 respectively.–2000. Sustainability 2020, 12, x FOR PEER REVIEW 15 of 20

SustainabilityJanuary,2020 April,, 12, 6186 July, and October are examples presenting winter, spring, summer, and autumn15, of 20 respectively.

CNRM-CM5 EC-EARTH MPI-ESM-LR

January

April

July

October

Figure 13. Temperature. Results from an ensemble of three GCMs for RCP4.5 scenario. Change in Figure 13. Temperature. Results from an ensemble of three GCMs for RCP4.5 scenario. Change in Ensemble mean monthly (C) for the future period 2071–2100 (2080s) compared with 1971–2000. Ensemble mean monthly (C) for the future period 2071–2100 (2080s) compared with 1971–2000. January, January, April, July, and October are examples presenting winter, spring, summer, and autumn, April, July, and October are examples presenting winter, spring, summer, and autumn, respectively. respectively. Sustainability 2020, 12, 6186 16 of 20 Sustainability 2020, 12, x FOR PEER REVIEW 16 of 20

CNRM-CM5 EC-EARTH MPI-ESM-LR

January

April

July

October

Figure 14. Precipitation. Results from an ensemble of three GCMs for RCP4.5 scenario. Change in Figure 14. Precipitation. Results from an ensemble of three GCMs for RCP4.5 scenario. Change in ensemble mean monthly (no sign where the change is produced by dividing future by baseline) for ensemble mean monthly (no sign where the change is produced by dividing future by baseline) for the future period 2041–2070 (2050s) compared with baseline period 1971–2000. January, April, July, the future period 2041–2070 (2050s) compared with baseline period 1971–2000. January, April, July, and October are examples present winter, spring, summer, and autumn, respectively. (White color and October are examples present winter, spring, summer, and autumn, respectively. (White color indicates that baseline value equals zero). indicates that baseline value equals zero). Sustainability 2020, 12, 6186 17 of 20 Sustainability 2020, 12, x FOR PEER REVIEW 17 of 20

CNRM-CM5 EC-EARTH MPI-ESM-LR

January

April

July

October

Figure 15. Precipitation. Results from an ensemble of three GCMs for RCP4.5 scenario. Change in Figure 15. Precipitation. Results from an ensemble of three GCMs for RCP4.5 scenario. Change in ensemble mean monthly (no sign where the change is produced by dividing future by baseline) for ensemble mean monthly (no sign where the change is produced by dividing future by baseline) for the future period 2071–2100 (2080s) compared with baseline period 1971–2000. January, April, July, the future period 2071–2100 (2080s) compared with baseline period 1971–2000. January, April, July, and October are examples present winter, spring, summer, and autumn, respectively. (White color and October are examples present winter, spring, summer, and autumn, respectively. (White color indicates that baseline value equals zero). indicates that baseline value equals zero).

4. Conclusions Conclusions The Sinai Sinai Peninsula Peninsula is is a a region region characterized characterized by by severe severe data data limitations limitations and and by bythe the occurrence occurrence of thofunderstorms thunderstorms very very limited limited in intime time and and space space;; therefore therefore,, the the improvement improvement of of Weather Weather Prediction Systems feeding feeding Early Early Warning Warning Systems Systems is isdifficult. difficult. The Thelack lackof reliable of reliable WPS WPSand appropriate and appropriate EWS impairEWS impair not only not only the design the design and and adoption adoption of of adaptation adaptation and and mitigati mitigationon measures measures but but also also the development of emergency plans to save lives as well as the the harvesting harvesting of of water water precious precious for the the local local BedouiBedouinn Communities, which is otherwise lost. The scientific problem addressed in the paper is to assemble information about severe thunderstorms leading to flash flood in the two sub-regions, North and South Sinai, and to present a first attempt to describe, for the same region, the expected evolution of climate in the future. The Sustainability 2020, 12, 6186 18 of 20

The scientific problem addressed in the paper is to assemble information about severe thunderstorms leading to flash flood in the two sub-regions, North and South Sinai, and to present a first attempt to describe, for the same region, the expected evolution of climate in the future. The study presented here is a step forward in order to respond to the need of a deeper knowledge of extreme rainfall in Sinai Peninsula that is driving flash floods affecting population and infrastructure with damage and elevated costs. The results presented are derived from the Academy of Scientific Research and Technology of Egypt (ASRT) and the National Research Council of Italy (CNR) joint project and show, in particular, the intensity of the current climate change in terms of increase in temperature, decrease in precipitation, and increase (in number and intensity) of heavy rainfall episodes in the interested region. Some results were also discussed showing an increase in the severity of the changes in temperature and precipitation under future climate scenario for an intermediate stabilization Representative Concentration Pathway, RCP4.5. Further analysis of the heavy rainfall episodes generating flash floods in both the North and South part of the Peninsula is not only needed but also particularly useful to increase the knowledge about the generation and evolution of these short-lived and patchy storms, focusing, in particular, on the atmospheric factors driving their formation. A deeper knowledge of the mechanism could also provide some indication for improving the weather forecast systems over the region, while results will contribute to the development of regional climate scenarios at higher resolution to be used for the implementation of more sophisticated risk maps for future decades. Results can also encourage and sustain the elaboration of adaptation plans for population, agriculture, and water resources management and help decision-makers to plan the construction of water harvesting structures [35]. In conclusion, the knowledge of extreme rain events in Sinai is presently scarce; thus, this study intends to give a contribution to the improvement of their understanding. A possible future study to address this could be a comparative analysis of episodes occurring in the Sinai Peninsula and in neighboring countries, because thunderstorms affecting the Peninsula then move eastward and largely impact the whole Levant. Further specific studies on the Sinai’s present and future climate that can help to understand better if there will be an evolution of heavy rainfall episodes driving flash floods are needed. Sophisticated risk maps for future decades are also needed, together with adoption of adaptation plans for population, agriculture, and water resources management. Finally, results from this and future studies will be largely used by decision-makers in their design and planning of the construction of water harvesting structures in the near future for the good of the Sinai people.

Author Contributions: Individual contributions to the research is as follows: Conceptualization, M.B. and D.A.; methodology, M.B. and D.A.; formal analysis and investigation, M.B., D.A., I.S.A.Z., and G.D.; writing—original draft preparation and review and editing, M.B.; writing—review and editing, D.A., I.S.A.Z., and G.D. All authors have read and agreed to the published version of the manuscript. Funding: This research was funded by ARST and CNR in the framework of the Agreement on Scientific Cooperation between the Academy of Scientific Research and Technology of Egypt (ASRT) and the National Research Council of Italy (CNR), who provided support for scientists’ mobility. Acknowledgments: The study has been funded in the framework of the Agreement on Scientific Cooperation between the Academy of Scientific Research and Technology of Egypt (ASRT) and the National Research Council of Italy (CNR). The two Institutes participating to the project were, respectively: the Water Resources Research Institute (WRRI) of the National Water Research Center (NWRC), and the Institute of Biometeorology (CNR-Ibimet, now CNR-IBE). M.B and G.D. are grateful to the research group at the WRRI-NWRC for their kind hospitality and useful discussions and to the Italian Scientific Attaché Office in Cairo for support. D.A. and I.S.A. are also thankful to the research staff of the CNR-IBE for supporting the research stay in Italy that enabled the completion of this work. Conflicts of Interest: The authors declare no conflict of interest. The funders had no role in the design of the study; in the collection, analyses, or interpretation of data; in the writing of the manuscript, or in the decision to publish the results. Sustainability 2020, 12, 6186 19 of 20

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