Impact of extreme climate events on water supply sustainability in Egypt: case studies in Alexandria region and Upper Egypt

Climate change could be considered to be the most severe environmental problem the world is facing today. The problem will not be eliminated but civilization will be forced to adapt to the new conditions. One of the key issues in the adaptation process is the sustainability of water resources. The water resources undergo stress as a result of many factors, such as water quality variation, urban development (domestic water consumption, industrialization, agriculture, and urbanization), and population growth.

For heavy rainfall and strong hydrologic conditions, runoff and solid material transportation are the main consequences. For countries in the temperate zone, climate change will decrease the number of rainy days but increase the average volume of each rainfall event (Brunetti et al. 2001; Bates et al. 2008). As a consequence, drought–rewetting cycles may impact water quality as they enhance decomposition and flushing of organic matter into streams (Evans et al. 2005). Many of the reported outbreaks were observed after heavy rainfall events, which suggests that such events could result in deterioration of the quality of drinking water (Tornevi 2015).

Heavy rainfall can provide challenges for drinking water producers and have consequences for drinking water supply. Extreme weather affects both surface water and ground water resources, but distribution systems and wastewater treatment plants are also, to varying degrees, not designed to cope with extreme weather. With excessive rainfall, runoff causes the water in many surface water sources to become too turbid to treat with a higher content of humus, but it may also contain more pathogens. Climate change is believed, therefore, to affect both groundwater and surface water sources, but surface water sources are particularly vulnerable to extreme weather events because surface water resources exhibit greater and quicker variations in quality than groundwater sources (Delpla et al. 2009).

Sustainable management of water resources requires the design of appropriate strategies, approaches, and measures to achieve an optimal distribution and use of water. Hence, preparations for these events in the future are necessary to develop such sustainable concepts.

Egypt is a part of the East Mediterranean region which is characterized by mild, wet winters and hot, dry summers (Said et al. 2012). Precipitation rates drop quickly as one moves away from the coast. Most of Egypt receives about 2 mm of precipitation per year. Thus, most of Egypt is a desert and can be classified as arid. The exception is the slightly wetter Mediterranean coast, which can be considered semiarid (MrGeogWagg 2015).

The Nile delta varies in extent under the impact of storm surges and heavy rains due to extreme climate events. The trend for these extreme climate events is to become longer term and longer lasting. The heavy rainfall across Egypt has caused rapid flooding affecting many regions of the country. This heavy rainfall swept away a great deal of dirt and dust from surrounding environments to the watercourses, which would have a great influence on the quality and quantity of the water.

This study concentrates on two significant events which had a severe influence on water supplies in two different regions at different times. The first event was a heavy rainfall event in the north-west of the Nile delta (Alexandria region, 2015) while the second one was a heavy rainfall event in the Red Sea Mountains (Sohag Governorate, Upper Egypt region, 2014). The floods were hydrodynamically directed towards the valleys and the rainwater drained to the River Nile.

This paper investigates two areas in Egypt that have undergone the effects of extreme events in recent years. The two areas are investigated in different ways (climatically, geographically, and in terms of water resources quality).

According to the Koppen Climate classification this area is considered as a semi-desert and characterized by two seasons only: a mild winter from November to April and a hot summer from May to October.

The north-west of the Nile delta is one of the wettest areas in Egypt, where the annual rainfall average is around 200 mm but can be as high as 417 mm (Tutiempo.net 2016). The rainfall decreases suddenly a few kilometers away from the coastal strip.

The main source of water for agriculture, domestic, and industrial purposes are two main canals, El-Mahmoudia and Nubaria. These two canals fluctuate in water quality which could be attributed to different reasons such as the water feeders for these canals, the types of discharge into the canals and finally the type of soils in which these canals are located.

AWC is an affiliated body to the Holding Company for Water and Wastewater (HCWW) and it provides its services through production of drinking water according to the Egyptian standard from nine water treatment plants (WTPs) with total design capacity of 3.5 Mm³/day. The actual producing capacity is 2.4 Mm³/day and this water quantity serves about 4 million inhabitants, increasing to 6 million inhabitants during summer vacations (Alexandria Water Company n.d.).

The second investigated area is the Upper Egypt area consisting of two different topographic features, the Sahara (Desert) with its hills and mountains (such as the Red Sea Mountains) and the plain of the Nile valley (such as Sohag Governorate) characterized by concentrated urbanization aspects such as residential settlements, cultivated lands, and industrialization.

While the population in Sahara (Desert) is sparse, the Sohag Governorate, which is located in the Nile valley, is densely populated with about 4.1 million inhabitants.

As in the rest of Egypt, the weather in Upper Egypt is characterized by desert weather. The year in these two areas (Red Sea Mountains and Sohag Governorate) is divided into two seasons in terms of climate conditions: winter – cold starting from November until April, and summer – very hot starting from May until October. There is a large difference in the annual amount of rainfall between the two areas and that is attributed to topographical factors such as the strong variation in ground surface levels. One mm is the average annual rainfall in Sohag Governorate, while it is 27 mm in the Red Sea Mountains.

Heavy rains occasionally occur (Warner 2004) owing to the sudden change of weather patterns that brings more extreme weather events, of which flash floods of the wadis (dry valleys) are the most devastating. Floods in the Sahara are often characterized by deep and fast flowing water; these floods are combined with the short time available to respond (Seene 2013). Based on these indicators, the WTPs which are located downstream of the Wadi Qena are directly affected.

The River Nile and the irrigation canals represent the main water resources in Sohag Governorate; these represent about 70% of the drinking water production in the governorate and the remaining 30% is abstracted from groundwater. Sohag Water and Wastewater Company (SWWC) (an affiliated company of the HCWW) is responsible for drinking water production and distribution to all the inhabitants. SWWC has many utilities for water treatment and purification. Nowadays, the water supply approach in the region is changing from many small surface water and groundwater treatment plants (GWTP) to large centralized treatment plants. Now SWWC has at least eight conventional surface water treatment plants (SWTP), 31 compact SWTP, and 206 GWTP with a total production capacity of 0.7 Mm³/day.

In this study, Microsoft Excel was used to calculate the trend lines and statistical values of linear regression analysis.

For the other subject of analysis, water quality data was collected from intakes of WTPs highlighting turbidity because it has a significant influence on WTP operation. This approach was helpful in studying the potential impact of the extreme climate events on the water supply sustainability.

Historical data concerning the precipitation rate and the rainy days were compiled and covered the period 1980–2015. These data are analyzed and illustrated graphically to demonstrate the trend of climate pattern during the study period.

In contrast, the number of rainy days has tended to decrease even with a high precipitation rate. So the gap between the precipitation rate and the number of rainy days has become wider. This means that a large amount of rainfall occurs in fewer days, which seems unusual. This may indicate a change in the climate towards more extreme events, at least during the study period.

From 2000 onwards, the precipitation rate tends to increase according to the regression line. However, the number of rainy days remains almost constant; thereby, a relatively high precipitation amount has fallen in a few days. This could explain the flash floods which happened in Upper Egypt, in addition to other factors related to biodiversity, hydrological and run-off properties of the soil.

On a yearly basis and returning to the historical data, the heavy rain events change from month to month (Table 1); this makes early prediction difficult. At the same time, prediction of the effect of these events on the Nile River seems inapplicable; this is because the severity of these events depends on the direction and the pattern of rain-bearing clouds.

Regarding the significant amount of precipitation that occurs in only a few hours, leading to severe flooding, Table 1 details the main extreme events that have happened in the Red Sea Mountains region.

The combination of precipitation rate and the monthly average of raw water turbidity are very helpful in understanding the impact of extreme climate events on the water resources and water supply sustainability.

Table 2 shows that these unprecedented levels of turbidity exceeded the tolerance capacity of drinking water plants to deal with this high turbidity. That has led to a shutdown of all the surface drinking water plants, both conventional and compact, for some time. The downtime duration reached 72 hours in some conventional WTPs and 100 hours in compact WTPs. This illustrates the difference in tolerance ability among different types of WTPs to treat highly turbid water.

The plant shutdown would make a lot of people prone to use unsafe water source for drinking and domestic uses; for example, household water containers and hand water pumps. These non-routine sources could be contaminated. For example, a literature review found 11 observational studies in developing countries showing that mean coliform levels (an indicator of contamination) were considerably higher in household water containers than in the original source waters (VanDerslice & Briscoe 1993).

In terms of water safety plans, this kind of usage of alternative unsafe water sources is classified as a high potential risk to public health (WHO 2005). Especially when it is known that the sanitation service coverage in Egypt does not exceed 50% (HCWW 2016).

Extreme climate events as a result of climate variability have an impact on both water supply and sanitation systems efficiency; so the water utilities and also the sanitation systems become more stressed, which would increase the probability of cutting water supplies, reducing hygienic behavior, which would have a potential impact on public health.

Despite the fact that flash floods in arid areas are generally rare and infrequent (Reid et al. 1994), observations of heavy rain events in recent years indicate that they have become noticeably more frequent.

The rainfall could be predicted by meteorological measurements, but the amount, frequency, severity and even the timing (sometimes) of the heavy rain is variable and unpredictable over the years studied.

Therefore, water suppliers have to seek approaches and adaptation measures to deal with the sudden extreme climate events or other incidents that may affect the water supplies to ensure the sustainability of supplies in the framework of the sustainable water management concept.

Climate change and its related events are presenting more and more new challenges to traditional water supply management.

Within the water management framework, the climate features are relatively beyond the scope of water managers and experts. Also, the water suppliers' bodies have limited knowledge of climate change vulnerabilities.

Among the water management bodies, a great deal of adaptation measures, policies, and strategies could be developed to mitigate the impacts and the potential risks as well. However, to integrate all of these efforts there must first be a minimum requirement of consensus, understanding, and sense of responsibility among the stakeholders.

Concerning water supply bodies, this study seeks to determine a potential action plan in order to develop adaptation measures as a response to extreme climate events.

For existing adaptation measures and plans, multidimensional concepts and approaches are taken into consideration in the framework of integrated water management and public health-based targets. These measures must involve the main steps including: warming-up, planning, actions, and evaluation/feedback shown in Table 3.

The research team appreciates the support they received from Mr Fadel and Mr Mohammed Ali (Geographical Information System (GIS) department, HCWW) for this study. The team is also grateful to the quality departments in both Alexandria and Sohag water companies. Finally, the authors thank colleagues in the general department of Quality and Environmental Affairs (HCWW) for their effort in the data collecting. Finally, I express my deep gratitude to Dr Jauad El Kharraz for his help and support.