Abstract

Egypt's water resources are already limited. Moreover, climate change will put greater pressure on these resources. This research aims to assess the impact of climate change on the water demands for one of the most important Egyptian food crops which is the wheat crop. In addition, a number of adaptation strategies were tested to mitigate the negative impact of climate change on wheat productivity and its water relations. The current study was carried out in the Middle Egypt region. Two models were used, the first is the climate model (MAGICC/SCENGEN), which is used to simulate the impact of global greenhouse gas emissions on the rate of rise in temperature at the regional level. The second is the irrigation model (CROPWAT8.0), which is used to simulate the irrigation water requirements under current and likely climate change conditions. The results indicated that the increase in greenhouse gas emissions will cause the temperature to rise over the study area by about 2.12 °C in 2050 and 3.96 °C by 2100. As a result, the irrigation water needs for wheat crop are likely to increase by 6.2 and 11.8% in 2050 and 2100, respectively. In addition, wheat productivity will decline by 8.6 in 2050 and 11.1% in 2100.

HIGHLIGHTS

  • Simulate the impact of climate change on the irrigation water needs of wheat crops.

  • Impact of climate change on irrigation water requirements, cumulative yield reduction and crop water productivity for wheat crops.

  • Adaptation strategies will be examined to mitigate the adverse impact of climate change on the crop under study.

INTRODUCTION

Rapid population growth, as well as limited water resources and sometimes weather variability, is the main negative factor affecting the self-sufficiency of many major crops in Egypt. The issue of climate change is putting greater pressure directly and indirectly on achieving self-sufficiency, food security and safe food.

According to the World Meteorological Organization (WMO 2019), the tell-tale signs and impacts of climate change – such as sea-level rise, ice loss and extreme weather – increased during the period of 2015–2019, which is set to be the warmest five-year period on record. In addition, the WMO Secretary-General reported that climate change causes and impacts are increasing rather than slowing down. The challenges are immense. Besides the mitigation of climate change, there is a growing need to adapt. According to the recent Global Adaptation Commission report, the most powerful way to adapt is to invest in early warning services and pay special attention to impact-based forecasts.

Kaini et al. (2020a, 2020b, 2020c) studied the limitations of the previous studies on general circulation model (GCM) selection and how to provide new climate insights to the region. They added that the selection of GCMs with high capability to represent the past and likely future climate for a specific geographical location is a crucial step to assess impacts of climate change on different sectors. The results indicated that the average annual temperature is expected to increase, but with higher increases during winter than in the monsoon period.

Schwartz (2020) explained that in more than 40 years, scientists anticipated a range of possible temperature increases, between 1.5 and 4.5 °C, that will result from carbon dioxide levels doubling from preindustrial times. Now, a team of researchers has sharply narrowed the range of temperatures, tightening it to between 2.6 and 4.1 °C.

In water scarcity regions, climate change could increase the existing risks; meanwhile, in other areas new opportunities could be created. Agricultural water management needs to develop adaptation strategies that could benefit from recognizing these risks and adaptation strategies have been proposed (Iglesias & Garrote 2015).

Climate change may affect water resources as well as water demand. Agriculture relies on groundwater in many regions. These regions are mainly arid and semi-arid. Groundwater recharge is considered a by-product of irrigation return flow. Thus, aquifer storage could be significant due to climate change (Yu et al. 2010).

Egypt's water resources rely mainly on the Nile River. Therefore, any changes in its flow are significantly important. Khaled & Sherien (2017) explained that, along its 3,000 km course through arid northern Sudan and Egypt, the Nile River loses a huge amount of water due to evaporation. Thus, temperature and precipitation changes are of great importance to water supply. They concluded in their study that in the Egypt Nile valley and delta, the availability of groundwater may be reduced due to the impact of climate change on water demand and withdrawals of groundwater. In many areas, surface and groundwater supplies have been reduced due to precipitation and runoff changes combined with changes in consumption and withdrawal.

Interaction between climate change, water and agriculture may be strong. Water resources could be affected by climate change in many dimensions. These dimensions include changes in the amount and patterns of precipitation. Extreme events such as floods and droughts could also affect water resources. Droughts and drier soils may be expected in West Africa and the Amazon during the June–August season, and in the Asian monsoon region during the December–February season. The production of agriculture and food security could be seriously affected by these changes worldwide (OECD 2014).

There remains significant uncertainty regarding the anticipated impacts of climate change on Nile River flows, with some studies suggesting that increased evaporation rates due to rising temperatures could decrease water availability by up to 70%, while other studies suggest that increased rainfall in the Ethiopian highlands and Blue Nile Basin may increase flows by 15–25%. As the Nile River's sources are located outside Egypt, the country is highly vulnerable to changing climate conditions both within and outside the country's borders. Additionally, the majority of the population lives in close proximity to the Nile River, increasing potential exposure to flood events, with the urban poor particularly exposed and vulnerable (Climate Risk Profile: Egypt 2020).

Kaini et al. (2020a, 2020b, 2020c) assessed climate change impacts on the hydrological regime of a river basin and its implications for future irrigation water availability in the Koshi River basin using RCP4.5. The average annual flow in the Koshi River is expected to increase by 15–30% in all three periods. For the RCP8.5 scenario, the increases are even larger, ranging from 20 to 60%. Higher floods can be expected. A shift in peak flow toward August and September is expected.

Climate change could affect all food security dimensions (availability, accessibility, utilization and stability). Human life aspects could be impacted by climate change (health, livelihood assets, and food production and distribution channels). Purchasing power and market flows may also be affected (FAO 2008). In the same direction, increasing pests and diseases, and changes in the distribution of pollinators under climate change would negatively affect productivity as mentioned in IPCC Report (2019).

Middle East and North Africa (MENA) is highly vulnerable to climate change. People's food security will be affected due to more frequent, longer and more intense heat extremes and droughts. Beyond 2030, food security will be affected more and more with the long-term climate change (Jobbins & Henley 2015).

Irrigation is very important for food security and economic development in the Mediterranean. For the time being, water resources in the Mediterranean can be saved by 35% if more efficient irrigation and conveyance systems would be applied. Gross irrigation requirements may be increased between 4 and 18% if there is no improvement of the irrigation systems and conveyance in the Mediterranean due to climate change effects. Furthermore, these requirements may increase to 22–74% caused by population growth, especially in the southern and eastern Mediterranean. By improving irrigation technologies and conveyance systems in the eastern Mediterranean, these increases may be compensated to some extent (Fader et al. 2016).

In Egypt, the irrigation water source is mainly the Nile River (more than 90% of its total resources) which irrigates about 95% of the agricultural land. The Egyptian agriculture strategy aims to reclaim more land (horizontal expansion) and to optimize the use of water to increase agricultural production. It should be pointed out that Egypt has reached below the water poverty line. The decrease in water share per individual is 600 cubic meters per capita per year and is expected to decrease to less than 500 in 2030 (https://www.agri2day.com/2019/01/26/%D8%AF-).

Eid et al. (2006) studied the impact of climate change on wheat evapotranspiration in Egypt. The results showed that climate change will cause the water consumption of wheat to increase by about 10.8, 11.4 and 10.3% in Kafr El-Sheikh, Giza and Sohag governorates, respectively, compared with wheat evapotranspiration under current conditions.

El-Marsafawy (2016) indicated that climate change could decrease the national production of many crops and cause an increase in irrigation requirements in the Nile Delta in Egypt. As a result of reduced crop production and increased water needs, the crop water productivity (CWP) will decline accordingly.

Asseng et al. (2018) indicated that Egypt produces half of the 20 million tons of wheat that it consumes with irrigation and imports the other half. The demand for wheat in Egypt will triple by the end of the century. At the same time, future wheat yield will decline mostly from climate change, despite some yield improvements from new technologies. Additionally, the demand for irrigation will increase from 6 to 20 billion m3 for the expanded wheat production, but even more, water is needed to account for irrigation efficiency and salt leaching (to a total of up to 29 billion m3). Supplying water for future irrigation and producing sufficient grain will remain challenges for Egypt.

This study aims to simulate the impact of climate change on the irrigation water needs of one of the most important crops on which the Egyptian people depend for their food. The study also includes the impact of weather variability on productivity and some water relations. In addition, a number of adaptation strategies will be examined to mitigate the adverse impact of climate change on the crop under study.

Wheat is one of the most important grain crops in Egypt. According to the 2016/17 Economic Affairs Sector (EAS), the planted wheat area was about 3.2 million acres (1.3 million ha) and about 8.4 million tons were produced. Egypt is one of the largest countries importing wheat. The imports from various markets in 2017 amounted to 12.061 million tons (Food Balance of the Arab Republic of Egypt 2017). The most important research objectives are summarized in the following points:

  1. Prediction of potential change in the annual mean temperature in Middle Egypt under climate change conditions during the middle and end of this century (2050 and 2100).

  2. Impact of climate change on irrigation water requirements (IWR) for wheat crops, cumulative yield reduction and economic return of the land and water units.

  3. Adaptation strategies to cope with the adverse impact of climate change on irrigation water needs and crop productivity for wheat crops.

MATERIALS AND METHODS

Study area

The current study is selected in the Middle Egypt region. It includes Giza, Bani-Sweif, Al-Fayoum and Minya governorates, as shown in Figure 1. The Nile Valley in Middle Egypt represents the old irrigated batch along the Nile and extends from Assuit Barrages to the Delta Barrages (Allam et al. 2005). This zone has the following characteristics:

  • 1.

    The irrigated area is about 1.1 million acres where a very small area is irrigated by pumping from the river (not more than 4%), located on the eastern side of the river.

  • 2.

    Lower temperature compared to Zone I (Upper Egypt), and the reference crop evapotranspiration (ETo) is about 10% less.

  • 3.

    Cotton and maize are the major dominant crops in the summer, while wheat and berseem are the major crops in the winter.

  • 4.

    Drainage water returns to the river by gravity.

In addition, the Fayoum area is a natural closed system in the desert where the water delivery system is different and characterized by a steep hydraulic gradient and water allocation is made on a continuous basis. It has the following conditions:

  • The irrigated area is about 0.4 million acres where a very small area is irrigated by pumping.

  • Lower temperature compared to Zone I, and the reference crop evapotranspiration (ETo) is about 10% less.

  • Cotton and maize are the major dominant crops in summer, while wheat and berseem are the major crops in winter.

  • Drainage water flows by gravity to Lake Qaroun and Wadi Elrayyan depression in the desert.

As a result of the lack of weather data for a long period, Giza governorate has been selected to represent the Middle Egypt region due to the availability of sufficient data.

Meteorological data

Monthly weather data for Giza governorate (latitude: 30.03°N; longitude: 31.13°E; elevation: 19 m) over 30 years (1985–2014) were obtained from the Egyptian Meteorological Authority (EMA). Average monthly minimum and maximum temperatures, relative humidity, wind speed and sunshine percent, in addition to total monthly rainfall, throughout the study period are presented in Table 1.

Table 1

Average monthly weather data for Giza governorate throughout 1985–2014

MonthTemp. (°C)
RF (mm)TmaxTminRH (%)WS (m/sec)SS (%)
January 2.1 20.1 8.9 67 1.6 68 
February 2.9 21.4 9.4 64 1.8 72 
March 2.3 24.0 12.0 60 2.0 73 
April 0.7 29.0 15.3 55 2.1 75 
May 0.0 32.7 18.7 52 2.2 80 
June 0.0 35.4 21.9 54 2.2 86 
July 0.0 35.9 23.6 61 1.8 85 
August 0.0 35.8 23.8 63 1.8 85 
September 0.0 34.3 22.1 62 1.8 85 
October 0.3 30.7 19.1 64 1.7 82 
November 1.3 25.8 14.6 68 1.4 78 
December 2.8 21.4 10.5 68 1.3 70 
Average 12.5 28.9 16.7 61.4 1.8 78 
MonthTemp. (°C)
RF (mm)TmaxTminRH (%)WS (m/sec)SS (%)
January 2.1 20.1 8.9 67 1.6 68 
February 2.9 21.4 9.4 64 1.8 72 
March 2.3 24.0 12.0 60 2.0 73 
April 0.7 29.0 15.3 55 2.1 75 
May 0.0 32.7 18.7 52 2.2 80 
June 0.0 35.4 21.9 54 2.2 86 
July 0.0 35.9 23.6 61 1.8 85 
August 0.0 35.8 23.8 63 1.8 85 
September 0.0 34.3 22.1 62 1.8 85 
October 0.3 30.7 19.1 64 1.7 82 
November 1.3 25.8 14.6 68 1.4 78 
December 2.8 21.4 10.5 68 1.3 70 
Average 12.5 28.9 16.7 61.4 1.8 78 

RF, rainfall (mm); Tmax and Tmin, maximum and minimum temperatures (°C); RH, relative humidity (%); WS, wind speed (m/sec); SS, sunshine (%).

Methodology

To assess the emissions of greenhouse gases induced by climate change, a regional climate model of MAGICC/SCENGEN (version 5.3, Wigley 2008) is used. MAGICC (Model for the Assessment of Greenhouse-gas Induced Climate Change) consists of a suite of coupled gas-cycle, climate and ice-melt models integrated into a single software package. The software allows the user to determine changes in greenhouse gas concentrations, global-mean surface air temperature and sea level resulting from anthropogenic emissions. SCENGEN (A Regional Climate SCENario GENerator) constructs a range of geographically explicit climate change projections for the globe using the results from MAGICC together with AOGCM climate change information from the CMIP3/AR4 archive (Climate Model Intercomparison Project – phase 3).

MAGICC has been one of the primary models used by IPCC since 1990 to produce projections of future global-mean temperature and sea-level rise. The climate model in MAGICC is an upwelling-diffusion, energy-balance model that produces global- and hemispheric-mean temperature output together with results for oceanic thermal expansion (operating details can be seen in Figure 2).

Figure 2

Structure and flow of the MAGICC/SCENGEN software. Elliptical shapes are used to highlight user-defined model parameters (Fordham et al. 2012).

Figure 2

Structure and flow of the MAGICC/SCENGEN software. Elliptical shapes are used to highlight user-defined model parameters (Fordham et al. 2012).

In addition, to complete the research objectives, CropWat modeling software version 8.0 is used to calculate the IWR of wheat crops under current conditions and future climatic changes.

Irrigation water requirements

Three steps are carried out to determine IWR as follows.

Calculating the reference crop evapotranspiration (ETo)
The ETo is calculated by the FAO Penman–Monteith method, using the decision support software CROPWAT 8.0 developed by FAO, based on Allen et al. (1998). The equation used for calculating ETo is described as follows:
formula
(1)
where ETo is the reference crop evapotranspiration (mm day–1), Rn is the net radiation at the crop surface (MJ m–2 day–1), G is the soil heat flux density (MJ m–2 day–1), T is the mean daily air temperature at 2 m height (°C), u2 is the wind speed at 2 m height (m s–1), es is the saturation vapor pressure (kPa), ea is the actual vapor pressure (kPa), esea is the vapor pressure deficit (kPa), Δ is the slope of the pressure–temperature curve (kPa °C–1) and γ is the psychrometric constant (kPa °C–1).
Calculating the crop water use (crop evapotranspiration, ETc)
formula
(2)
where ETc is the crop evapotranspiration (mm day–1), Kc is the crop coefficient and ETo is the reference crop evapotranspiration (mm day–1).

The Kc values were obtained from FAO No. 56 (Allen et al. 1998) and adjusted according to the results of actual experiments in Egypt.

Calculating the IWR
formula
(3)
where IE is the irrigation efficiency. The irrigation efficiency values used in this study were 60% for the surface irrigation system (Jensen 1980) and 75% for the sprinkler irrigation system.

Water productivity

According to Wichelns (2014), water productivity (WP) is, most often, defined as the average amount of output per unit of water applied on a field (Equation (4)) or per unit of water evapotranspired (Equation (5)):
formula
(4)
formula
(5)

The output refers to the actual yield of wheat crops, which was obtained from the Agricultural Economic Research Institute Bulletins (AERI), to represent the current yield. It is worth mentioning that the change in wheat productivity under climate change conditions was obtained from the operation of the CropWat model using potential weather data under climatic change conditions (2050 and 2100).

Economics of the land and water units

Current data of the economics of the land unit (farm net return) were obtained from AERI. However, the economics under climatic change conditions were calculated according to the expected productivity under climatic change conditions.

Regarding the economics of water unit, the following equations were used for the amounts of water consumed (ETc) and applied (IWR):

Economic return of water consumption unit
formula
(6)
Economic return of IWR unit
formula
(7)

RESULTS

Prediction of potential change in the annual mean temperature in Middle Egypt under climate change conditions

Two scenarios of A1B-AIM and B2-MES were generated using the MAGICC model to predict the global emissions of GHGs. Then, the ScenGen model was operated using four models of CCSM-30, GFDLCM20, GFDLCM21 and GISS-EH to predict the possible temperature rise under future climate change conditions in 2050 and 2100.

The results of MAGICC/SCENGEN model are as recorded in Figures 3 and 4 which indicated that the potential increase in the annual mean temperature at the regional level of Middle Egypt at a latitude of 27.5–30.0°N and a longitude of 30.0–32.5°E by 2050 and 2100 registered 2.12 and 3.96 °C, respectively.

Figure 3

Change in annual mean temperature in 2050 at the regional level at a latitude of 27.5–30.0°N and a longitude of 30.0–32.5°E.

Figure 3

Change in annual mean temperature in 2050 at the regional level at a latitude of 27.5–30.0°N and a longitude of 30.0–32.5°E.

Figure 4

Change in annual mean temperature in 2100 at the regional level at a latitude of 27.5–30.0°N and a longitude of 30.0–32.5°E.

Figure 4

Change in annual mean temperature in 2100 at the regional level at a latitude of 27.5–30.0°N and a longitude of 30.0–32.5°E.

In addition, from the results of the model maps it is clear that Egypt, by virtue of its geographical location where it lies between the latitude of 22–32°N and the longitude of 24–37°E, it is possible by the mid of this century that the temperature will rise at rates ranging from 1.66 to 2.45 °C. However, by the end of this century (2100), the average temperature increase is likely to range from 3.10 to 4.56 °C. It is also noticeable that southern Egypt will see the greatest rise in temperature compared to northern Egypt.

Impact of climate change on the water relations of wheat crops

Irrigation water requirements

The results presented in Figure 5 indicate that there are fluctuations in IWR for wheat crops under current and climate change conditions due to weather variability. Values of IWR ranged from 5,462 to 8,177 m3/ha for current conditions, 5,773–8,712 m3/ha by 2050 and 6,063–9,240 m3/ha by 2100. Average IWR over 30 years (Figure 6) recorded 6,738, 7,155 and 7,535 m3/ha, for the current, 2050 and 2100, respectively. The change percent in IWR under climate change conditions of 2050 and 2100 compared to current conditions amounted to +6.2 and +11.8%, respectively (Figure 7). Such changes in IWR should be considered during the designing of new irrigation projects and rehabilitation of existing irrigation canal systems.

Figure 5

IWR for wheat crops under current and climate change conditions (during 2050 and 2100) in Middle Egypt.

Figure 5

IWR for wheat crops under current and climate change conditions (during 2050 and 2100) in Middle Egypt.

Figure 6

Average IWR for wheat crops under current and climate change conditions over 30 years.

Figure 6

Average IWR for wheat crops under current and climate change conditions over 30 years.

Figure 7

Change percent in IWR for wheat crops under climate change conditions compared to current conditions.

Figure 7

Change percent in IWR for wheat crops under climate change conditions compared to current conditions.

Kaini et al. (2011) analyzed seepage underneath the headwork of Chanda Mohana Irrigation Scheme, Sunsari, Nepal. They mentioned that Nepal could not achieve optimal production in the agriculture sector because of the failure of irrigation structures, mainly headwork. Regarding the importance of water resources, the irrigation systems should be upgraded to meet the increasing food demand.

Cumulative yield reduction (%)

The results in Figure 8 show the cumulative wheat yield reduction under climate change conditions. The highest reduction in wheat productivity (more than 10%) under climate change conditions during 2050 and 2100 compared to current production is shown in Table 2.

Table 2

Percentage change of more than 10% reduction in wheat productivity under climatic changes compared to production under current weather conditions

2050
2100
YearChange %YearChange %YearChange %
1987/88 –20.6 1987/88 –25.8 2001/02 –14.8 
1988/89 –19.8 1988/89 –24.2 2002/03 –10.1 
1989/90 –13.5 1989/90 –18.1 2007/08 –14.5 
1995/96 –11.5 1992/93 –11.9 2010/11 –12.6 
1997/98 –16.6 1995/96 –16.5 2012/13 –18.8 
1998/99 –11.3 1997/98 –21.3 2013/14 –11.4 
2000/01 –17.3 1998/99 –16.0   
2007/08 –10.1 1999/00 –10.3   
2013/13 –15.3 2000/01 –22.1   
2050
2100
YearChange %YearChange %YearChange %
1987/88 –20.6 1987/88 –25.8 2001/02 –14.8 
1988/89 –19.8 1988/89 –24.2 2002/03 –10.1 
1989/90 –13.5 1989/90 –18.1 2007/08 –14.5 
1995/96 –11.5 1992/93 –11.9 2010/11 –12.6 
1997/98 –16.6 1995/96 –16.5 2012/13 –18.8 
1998/99 –11.3 1997/98 –21.3 2013/14 –11.4 
2000/01 –17.3 1998/99 –16.0   
2007/08 –10.1 1999/00 –10.3   
2013/13 –15.3 2000/01 –22.1   
Figure 8

Cumulative yield reduction (%) for wheat crops in Middle Egypt under climate change conditions.

Figure 8

Cumulative yield reduction (%) for wheat crops in Middle Egypt under climate change conditions.

Crop water productivity

Values of CWP in kg per m3 of water consumption unit (ETc) for wheat crops ranged from 0.97 to 1.98 kg/m3 ETc under current conditions; 0.89 to 1.87 kg/m3 ETc in 2050; 0.80 to 1.77 kg/m3 ETc in 2100 (Figure 9). Average values of CWP over 30 years recorded 1.54, 1.36 and 1.25 kg/m3 ETc during current, 2050 and 2100, respectively (Figure 10). The change percent in CWP under climate change conditions compared to current conditions (Figure 11) registered −11.6% in 2050 and −19.1% in 2100.

Figure 9

CWP (kg/m3 ETc) for wheat crops under current and climate change conditions in Middle Egypt.

Figure 9

CWP (kg/m3 ETc) for wheat crops under current and climate change conditions in Middle Egypt.

Figure 10

Average CWP (kg/m3 ETc) for wheat crops during 30 years under current and climate change conditions in Middle Egypt.

Figure 10

Average CWP (kg/m3 ETc) for wheat crops during 30 years under current and climate change conditions in Middle Egypt.

Figure 11

Change percent in CWP under climate change conditions compared to current conditions.

Figure 11

Change percent in CWP under climate change conditions compared to current conditions.

From the previous results, it is clear that warming caused by climate change will cause a lack of productivity and increase water needs. This is because the high temperature will cause the crop growing season to fall short because the growing degree days needed for wheat during the entire growing season will be achieved in fewer days and therefore the period of the growing season will decrease, resulting in lower productivity. On the other hand, high temperature may lead to weakening of grains and consequently reduced weight of grains. Moreover, high temperatures may cause a decrease in the number of plant branches and thus a decrease in production.

Meanwhile, high temperature will cause increased evapotranspiration of the crop, so the amount of irrigation water the plant takes under current weather conditions will not be sufficient under climate change conditions. If the plant is given the same amount of water used currently, there will be a lack of productivity.

It is noteworthy that the decrease in the number of days of wheat growing season did not lead to a decrease in the water needs of the crop due to the fact that the impact of high temperature on crop evapotranspiration is greater than the decline of the growing season.

Valizadeh et al. (2014) found that the wheat-growing season period in all scenarios of climate change was reduced compared to the current situation. Possible reasons were the increase in temperature rate and the accelerated growth stages of wheat. Sabella et al. (2020) indicated that the plant life cycle was clearly shorter under climate change due to the physiological strategy of the plant to escape the high summer temperatures through the early ripening of the kernels. In addition, Liu et al. (2021) revealed that the impacts of future climate change on crop yield and CWP of wheat, barley and canola would all be negative.

In Egypt, climate change studies predict a reduction in the productivity of two major crops, wheat and maize, by 15 and 19%, respectively, by 2050. Projected future temperature rises are likely to increase crop water requirements thereby directly decreasing crop water use efficiency and increasing the irrigation demands of the agriculture sector. Crop water requirements of the important strategic crops in Egypt are expected to increase in the range of 6–16% by 2100 (https://www.iucn.org/sites/dev/files/import/downloads/egypt.pdf).

Regarding the values of CWP in kg per m3 of IWR unit, the results as shown in Figure 12 indicate that the highest and lowest values were 1.19 and 0.58 kg/m3 IWR under current conditions, 1.12 and 0.53 kg/m3 IWR in 2050 and 1.06 and 0.48 kg/m3 IWR in 2100. The average values over 30 years were 0.93, 0.82 and 0.75 kg/m3 IWR during current, 2050 and 2100, respectively (Figure 13).

Figure 12

CWP (kg/m3 IWR) for wheat crops under current and climate change conditions in Middle Egypt.

Figure 12

CWP (kg/m3 IWR) for wheat crops under current and climate change conditions in Middle Egypt.

Figure 13

Average CWP (kg/m3 IWR) for wheat crops over 30 years under current and climate change conditions in Middle Egypt.

Figure 13

Average CWP (kg/m3 IWR) for wheat crops over 30 years under current and climate change conditions in Middle Egypt.

Economics of the land and water units

Economics of the land unit (LE/ha)

The results as presented in Figure 14 clarify the farm net return for wheat crops under current and climate change conditions. It is clear that the economic return of the land unit (farm net return) under current conditions fluctuated between 545 LE/ha at the minimum value and 12,283 LE/ha as the highest value over 30 years. However, the economic return under climate change ranged from 525 to 11,043 LE/ha in 2050 and 500 to 10,502 LE/ha in 2100.

Figure 14

Farm net return for wheat over 30 years in Middle Egypt under current and climate change conditions. Currency equivalents (as of November 2019): US $1.00 = 16.14 LE. Data of current farm net return were obtained from AERI (volumes 1985–2014).

Figure 14

Farm net return for wheat over 30 years in Middle Egypt under current and climate change conditions. Currency equivalents (as of November 2019): US $1.00 = 16.14 LE. Data of current farm net return were obtained from AERI (volumes 1985–2014).

The large disparity in net income is likely due to weather fluctuations and their impact on the amount of production. Other factors may be related to selling prices, land, cultivated area, supply and demand for this crop.

Income from per unit farmland also depends on the socioeconomic settings of farmers, irrigation water availability, cooperation among stakeholders and land-use tenancy agreements.

Kaini et al. (2020a, 2020b, 2020c) developed a framework to assess socioeconomic factors impacting on the cropping intensity of an irrigation scheme in developing countries. It was applied in the Tarawali irrigation scheme in the western region of Nepal. It was concluded that cropping intensity was affected by farmers' socioeconomic status and their socio-cultural practices, mechanization in agricultural practices, coordination between irrigation and agricultural district offices with farmers, market facilities for agricultural inputs and agricultural products, and land tenancy agreements.

Economics of the water unit (LE/m3)

Concerning the economics of the consumed water unit (ETc) for wheat crops, the results in Figure 15 show that the lowest and highest values were 0.14–2.92 LE/m3 ETc under current weather conditions, 0.13–2.64 LE/m3 ETc in 2050 and 0.11–2.46 LE/m3 ETc in 2100.

Figure 15

Economic return of water unit (LE/m3 ETc) for wheat crops over 30 years in Middle Egypt under current and climate change conditions.

Figure 15

Economic return of water unit (LE/m3 ETc) for wheat crops over 30 years in Middle Egypt under current and climate change conditions.

With regard to the economics of the IWR unit for wheat crops in the old lands (under the conditions of flood irrigation), the results in Figure 16 indicate that the lowest and highest net income were 0.08 and 1.75 LE/m3 IWR under current weather conditions, 0.07 and 1.58 LE/m3 IWR in 2050 and 0.06 and 1.48 LE/m3 IWR in 2100.

Figure 16

Economic return of water unit (LE/m3 IWR) for wheat crops over 30 years in old lands under current and climate change conditions.

Figure 16

Economic return of water unit (LE/m3 IWR) for wheat crops over 30 years in old lands under current and climate change conditions.

With respect to the economics of the IWR unit in the new lands (under the modern irrigation system), the results in Figure 17 indicate that the values ranged between 0.10 and 2.19 LE/m3 IWR under current conditions, 0.09 and 1.98 LE/m3 IWR in 2050 and 0.08 and 1.84 LE/m3 IWR in 2100.

Figure 17

Economic return of water unit (LE/m3 IWR) for wheat crops over 30 years in new lands under current and climate change conditions.

Figure 17

Economic return of water unit (LE/m3 IWR) for wheat crops over 30 years in new lands under current and climate change conditions.

Berhane (2018) provided comprehensive review studies on the impacts of climate change on crop and water productivity, soil water balance and food security. Climate predictions indicate a warmer world within the next 50 years, with maximum and minimum temperatures increasing causing a substantial yield decrease in low latitude areas, whereas projected rainfall has no distinct variability pattern. By 2080, arid and semi-arid lands in Africa will increase by 5–8%. Identifying and assessing suitable adaptation and mitigation practices have paramount importance and contributions to improve crop productivity and reduce the negative impacts of climate change on water availability and productivity. Global and regional climate models have been used as decision support tools for climate change impact assessment, and hence, the application of such models to generate present and future climate data outputs for crop modeling and climate change impact assessment on crop production, water balance and food security is very essential.

ADAPTATION SCENARIOS TO CLIMATE CHANGE

Changing sowing date

The results as shown in Table 3 indicate the cumulative yield reduction for wheat crops under climate change conditions in the mid and end of this century without and with changing sowing dates as an adaption option. The results revealed that an early sowing date would reduce the negative impact of climate change on wheat productivity, while delays would result in an increased negative impact. The average cumulative yield reduction 30 years later in 2050 was 3.1, 8.6 and 17.9% for 1st November, 15th November and 1st December, respectively. However, averages in 2100 were 5.5, 11.1 and 22.2% for the respective sowing dates.

Table 3

Cumulative yield reduction for wheat crops under different sowing dates as adaptation strategy under climate change conditions

YearCumulative yield reduction in 2050Cumulative yield reduction in 2050 with adaptation strategies
Cumulative yield reduction in 2100Cumulative yield reduction in 2100 with adaptation strategies
Without adaptation (15 Nov.)1st sowing date (1 Nov.)2nd sowing date (1 Dec.)Without adaptation (15 Nov.)1st sowing date (1 Nov.)2nd sowing date (1 Dec.)
1985 3.6 0.0 16.5 8.3 0.1 21.3 
1986 2.4 0.0 16.3 6.9 0.0 20.8 
1987 1.2 0.1 12.2 5.6 0.7 17.2 
1988 20.6 10.8 32.9 25.8 16.4 37 
1989 19.8 8.4 34.5 24.2 13.9 38.4 
1990 13.5 1.6 27.5 18.1 5.2 31.8 
1991 0.2 0.0 12.2 3.4 0.0 16.6 
1992 4.8 0.0 19.1 9.9 1.4 23.7 
1993 7.1 1.5 15.4 11.9 5.7 19.6 
1994 0.0 0.0 5.8 0.0 0.0 9.8 
1995 0.0 0.0 1.8 0.0 0.0 5.4 
1996 11.5 1.0 26.1 16.5 5.3 30.3 
1997 1.8 0.0 14.6 6.2 0.5 19.2 
1998 16.6 4.8 30.1 21.3 9.8 34.1 
1999 11.3 1.7 24.2 16.0 6.1 28.4 
2000 5.4 0.2 18.7 10.3 2.0 23.3 
2001 17.3 6.6 29.9 22.1 11.7 33.9 
2002 9.7 3.0 21.9 14.8 7.6 26.4 
2003 5.3 0.8 16.9 10.1 3.0 21.4 
2004 0.0 0.0 6.6 0.6 0.0 10.6 
2005 0.0 0.0 10.2 0.0 14.4 
2006 0.0 0.0 5.9 0.1 0.0 10.1 
2007 1.6 0.0 14.3 5.7 0.0 18.4 
2008 10.1 1.0 21.6 14.5 4.8 25.5 
2009 0.0 0.0 7.8 1.4 0.0 11.8 
2010 4.5 0.0 15.8 8.7 0.8 19.8 
2011 8.1 0.9 18.7 12.6 4.4 22.9 
2012 0.0 0.0 11.3 2.5 0.0 15.3 
2013 15.3 4.2 27.6 18.8 7.6 30.9 
2014 6.8 0.0 20.6 11.4 2.4 24.5 
Average 8.6 3.1 17.9 11.1 5.5 22.1 
YearCumulative yield reduction in 2050Cumulative yield reduction in 2050 with adaptation strategies
Cumulative yield reduction in 2100Cumulative yield reduction in 2100 with adaptation strategies
Without adaptation (15 Nov.)1st sowing date (1 Nov.)2nd sowing date (1 Dec.)Without adaptation (15 Nov.)1st sowing date (1 Nov.)2nd sowing date (1 Dec.)
1985 3.6 0.0 16.5 8.3 0.1 21.3 
1986 2.4 0.0 16.3 6.9 0.0 20.8 
1987 1.2 0.1 12.2 5.6 0.7 17.2 
1988 20.6 10.8 32.9 25.8 16.4 37 
1989 19.8 8.4 34.5 24.2 13.9 38.4 
1990 13.5 1.6 27.5 18.1 5.2 31.8 
1991 0.2 0.0 12.2 3.4 0.0 16.6 
1992 4.8 0.0 19.1 9.9 1.4 23.7 
1993 7.1 1.5 15.4 11.9 5.7 19.6 
1994 0.0 0.0 5.8 0.0 0.0 9.8 
1995 0.0 0.0 1.8 0.0 0.0 5.4 
1996 11.5 1.0 26.1 16.5 5.3 30.3 
1997 1.8 0.0 14.6 6.2 0.5 19.2 
1998 16.6 4.8 30.1 21.3 9.8 34.1 
1999 11.3 1.7 24.2 16.0 6.1 28.4 
2000 5.4 0.2 18.7 10.3 2.0 23.3 
2001 17.3 6.6 29.9 22.1 11.7 33.9 
2002 9.7 3.0 21.9 14.8 7.6 26.4 
2003 5.3 0.8 16.9 10.1 3.0 21.4 
2004 0.0 0.0 6.6 0.6 0.0 10.6 
2005 0.0 0.0 10.2 0.0 14.4 
2006 0.0 0.0 5.9 0.1 0.0 10.1 
2007 1.6 0.0 14.3 5.7 0.0 18.4 
2008 10.1 1.0 21.6 14.5 4.8 25.5 
2009 0.0 0.0 7.8 1.4 0.0 11.8 
2010 4.5 0.0 15.8 8.7 0.8 19.8 
2011 8.1 0.9 18.7 12.6 4.4 22.9 
2012 0.0 0.0 11.3 2.5 0.0 15.3 
2013 15.3 4.2 27.6 18.8 7.6 30.9 
2014 6.8 0.0 20.6 11.4 2.4 24.5 
Average 8.6 3.1 17.9 11.1 5.5 22.1 

From the previous results, it is clear that the optimum sowing date for wheat crops in Middle Egypt under climate change conditions in 2050 or 2100 is 1st November.

Increasing the amount of irrigation water added

The results in Table 4 indicate that the cumulative yield reduction for wheat crops under climate change conditions can be reduced by increasing the amount of irrigation water applied. This is because the high temperature will lead to the loss of a large amount of evapotranspiration, so it is necessary to compensate the plant with an additional amount of water to overcome some of the negative effects of high temperature on the physiological processes of the plant.

Table 4

Cumulative yield reduction for wheat crops with increasing irrigation water amounts as adaptation strategy under climate change conditions

YearCumulative yieldCumulative yield reduction in 2050 with adaptation strategies
Cumulative yieldCumulative yield reduction in 2100 with adaptation strategies
reduction in 2050Without adaptationCurrent IWR +10%Current IWR +20%reduction in 2100Without adaptationCurrent IWR +10%Current IWR +20%
1985 3.6 0.1 0.0 8.3 3.3 0.5 
1986 2.4 0.7 0.2 6.9 2.8 1.1 
1987 1.2 0.0 0.0 5.6 1.1 0.0 
1988 20.6 15.4 10.5 25.8 20.8 15.8 
1989 19.8 15.1 10.5 24.2 19.8 15.4 
1990 13.5 8.6 4.3 18.1 13.4 8.8 
1991 0.2 0.0 0.0 3.4 0.6 0.3 
1992 4.8 0.7 0.2 9.9 4.5 1.2 
1993 7.1 2.2 0.4 11.9 6.5 2.1 
1994 0.0 0.0 0.0 0.0 0.0 0.0 
1995 0.0 0.0 0.0 0.0 0.0 0.0 
1996 11.5 5.9 1.8 16.5 10.9 5.9 
1997 1.8 0.0 0.0 6.2 1.3 0.0 
1998 16.6 10.9 5.6 21.3 15.9 10.5 
1999 11.3 5.7 2.3 16 10.5 5.3 
2000 5.4 0.7 0.0 10.3 4.8 0.9 
2001 17.3 11.7 6.4 22.1 16.7 11.4 
2002 9.7 4.3 0.4 14.8 9.2 4.1 
2003 5.3 0.8 0.0 10.1 4.7 0.7 
2004 0.0 0.0 0.0 0.6 0.0 0.0 
2005 0.0 0.0 0.0 2.0 0.0 0.0 
2006 0.0 0.0 0.0 0.1 0.0 0.0 
2007 1.6 0.0 0.0 5.7 0.9 0.2 
2008 10.1 4.7 2.0 14.5 9.0 4.0 
2009 0.0 0.0 0.0 1.4 0.0 0.0 
2010 4.5 1.1 0.3 8.7 3.6 1.3 
2011 8.1 2.9 0.2 12.6 7.1 2.3 
2012 0.0 0.0 0.0 2.5 0.0 0.0 
2013 15.3 9.7 5.7 18.8 13.4 8.3 
2014 6.8 1.9 0.5 11.4 5.9 1.6 
Average 8.6 5.4 3.2 11.1 8.1 4.8 
YearCumulative yieldCumulative yield reduction in 2050 with adaptation strategies
Cumulative yieldCumulative yield reduction in 2100 with adaptation strategies
reduction in 2050Without adaptationCurrent IWR +10%Current IWR +20%reduction in 2100Without adaptationCurrent IWR +10%Current IWR +20%
1985 3.6 0.1 0.0 8.3 3.3 0.5 
1986 2.4 0.7 0.2 6.9 2.8 1.1 
1987 1.2 0.0 0.0 5.6 1.1 0.0 
1988 20.6 15.4 10.5 25.8 20.8 15.8 
1989 19.8 15.1 10.5 24.2 19.8 15.4 
1990 13.5 8.6 4.3 18.1 13.4 8.8 
1991 0.2 0.0 0.0 3.4 0.6 0.3 
1992 4.8 0.7 0.2 9.9 4.5 1.2 
1993 7.1 2.2 0.4 11.9 6.5 2.1 
1994 0.0 0.0 0.0 0.0 0.0 0.0 
1995 0.0 0.0 0.0 0.0 0.0 0.0 
1996 11.5 5.9 1.8 16.5 10.9 5.9 
1997 1.8 0.0 0.0 6.2 1.3 0.0 
1998 16.6 10.9 5.6 21.3 15.9 10.5 
1999 11.3 5.7 2.3 16 10.5 5.3 
2000 5.4 0.7 0.0 10.3 4.8 0.9 
2001 17.3 11.7 6.4 22.1 16.7 11.4 
2002 9.7 4.3 0.4 14.8 9.2 4.1 
2003 5.3 0.8 0.0 10.1 4.7 0.7 
2004 0.0 0.0 0.0 0.6 0.0 0.0 
2005 0.0 0.0 0.0 2.0 0.0 0.0 
2006 0.0 0.0 0.0 0.1 0.0 0.0 
2007 1.6 0.0 0.0 5.7 0.9 0.2 
2008 10.1 4.7 2.0 14.5 9.0 4.0 
2009 0.0 0.0 0.0 1.4 0.0 0.0 
2010 4.5 1.1 0.3 8.7 3.6 1.3 
2011 8.1 2.9 0.2 12.6 7.1 2.3 
2012 0.0 0.0 0.0 2.5 0.0 0.0 
2013 15.3 9.7 5.7 18.8 13.4 8.3 
2014 6.8 1.9 0.5 11.4 5.9 1.6 
Average 8.6 5.4 3.2 11.1 8.1 4.8 

The results in 2050 showed that the increase in the amount of irrigation water added by 10% resulted in a reduction in the negative impact of climate change on wheat productivity from 8.6% (for base irrigation water amount) to 5.4%, but if the amount of irrigation water was increased by 20%, it will result in a reduction from 8.6% to 3.2%. The results added that in 2100, increasing the amount of irrigation water added by 10 or 20% will help reduce the negative impact of climate change on wheat productivity from 11.1% (with the base amount) to 8.1 and 4.8%, respectively.

From the previous results, it can be concluded that increasing the amount of irrigation water added by 10% in 2050 and 20% in 2100 will help improve wheat productivity. The cumulative yield reduction will be around 5% instead of 8.6% in 2050 and 11.1% in 2100.

Use of modern irrigation systems

The application of the modern irrigation system instead of the old irrigation system (flood irrigation) will result in saving irrigation water without a shortage of wheat productivity. The results (average 30 years) in Table 5 show that the average IWR when applying the flood irrigation system and the sprinkler irrigation system, respectively, was 6,738 and 5,390 m3/ha under current weather conditions; 7,155 and 5,724 m3/ha in 2050; and 7,535 and 6,028 m3/ha in 2100.

Table 5

Current and future IWR for wheat crops under flood and modern irrigation system (sprinkler)

YearIWR under current conditions
Change amount in IWR (current)IWR in 2050
Change amount in IWR (2050)IWR in 2100
Change amount in IWR (2100)
Floodsprinklerm3/haFloodsprinklerm3/haFloodsprinklerm3/ha
1985 6,537 5,229 –1,307 6,970 5,576 –1,394 7,372 5,897 –1,474 
1986 6,780 5,424 –1,356 7,217 5,773 –1,443 7,625 6,100 –1,525 
1987 6,403 5,123 –1,281 6,833 5,467 –1,367 7,233 5,787 –1,447 
1988 8,177 6,541 –1,635 8,712 6,969 –1,742 9,240 7,392 –1,848 
1989 8,060 6,448 –1,612 8,557 6845 –1,711 9,055 7,244 –1,811 
1990 7,365 5,892 –1,473 7,858 6,287 –1,572 8,313 6,651 –1,663 
1991 6,673 5,339 –1,335 7,103 5,683 –1,421 7,503 6,003 –1,501 
1992 6,767 5,413 –1,353 7,218 5,775 –1,444 7,637 6,109 –1,527 
1993 6,682 5,345 –1,336 7,102 5,681 –1,420 7,488 5,991 –1,498 
1994 5,792 4,633 –1,158 6,110 4,888 –1,222 6,418 5,135 –1,284 
1995 5,462 4,369 –1,092 5,773 4,619 –1,155 6,063 4,851 –1,213 
1996 7,052 5,641 –1,410 7,507 6,005 –1,501 7,928 6,343 –1,586 
1997 6,417 5,133 –1,283 6,820 5,456 –1,364 7,193 5,755 –1,439 
1998 7,455 5,964 –1,491 7,922 6,337 –1,584 8,353 6,683 –1,671 
1999 7,128 5,703 –1,426 7,565 6,052 –1,513 7,968 6,375 –1,594 
2000 6,565 5,252 –1,313 6,982 5,585 –1,396 7,372 5,897 –1,474 
2001 7,543 6,035 –1,509 8,002 6,401 –1,600 8,440 6,752 –1,688 
2002 6,888 5,511 –1,378 7,323 5,859 –1,465 7,738 6,191 –1,548 
2003 6,573 5,259 –1,315 7,020 5,616 –1,404 7,403 5,923 –1,481 
2004 5,963 4,771 –1,193 6,312 5,049 –1,262 6,627 5,301 –1,325 
2005 6,233 4,987 –1,247 6,565 5,252 –1,313 6,900 5,520 –1,380 
2006 5,940 4,752 –1,188 6,300 5,040 –1,260 6,608 5,287 –1,322 
2007 6,440 5,152 –1,288 6,835 5,468 –1,367 7,185 5,748 –1,437 
2008 7,017 5,613 –1,403 7,435 5,948 –1,487 7,798 6,239 –1,560 
2009 5,943 4,755 –1,189 6,285 5,028 –1,257 6,573 5,259 –1,315 
2010 6,897 5,517 –1,379 7,305 5,844 –1,461 7,655 6,124 –1,531 
2011 6,835 5,468 –1,367 7,245 5,796 –1,449 7,608 6,087 –1,522 
2012 6,195 4,956 –1,239 6,553 5,243 –1,311 6,857 5,485 –1,371 
2013 7,435 5,948 –1,487 7,878 6,303 –1,576 8,197 6,557 –1,639 
2014 6,912 5,529 –1,382 7,337 5,869 –1,467 7,707 6,165 –1,541 
Average 6,738 5,390 –1,348 7,155 5,724 –1,431 7,535 6,028 –1,507 
YearIWR under current conditions
Change amount in IWR (current)IWR in 2050
Change amount in IWR (2050)IWR in 2100
Change amount in IWR (2100)
Floodsprinklerm3/haFloodsprinklerm3/haFloodsprinklerm3/ha
1985 6,537 5,229 –1,307 6,970 5,576 –1,394 7,372 5,897 –1,474 
1986 6,780 5,424 –1,356 7,217 5,773 –1,443 7,625 6,100 –1,525 
1987 6,403 5,123 –1,281 6,833 5,467 –1,367 7,233 5,787 –1,447 
1988 8,177 6,541 –1,635 8,712 6,969 –1,742 9,240 7,392 –1,848 
1989 8,060 6,448 –1,612 8,557 6845 –1,711 9,055 7,244 –1,811 
1990 7,365 5,892 –1,473 7,858 6,287 –1,572 8,313 6,651 –1,663 
1991 6,673 5,339 –1,335 7,103 5,683 –1,421 7,503 6,003 –1,501 
1992 6,767 5,413 –1,353 7,218 5,775 –1,444 7,637 6,109 –1,527 
1993 6,682 5,345 –1,336 7,102 5,681 –1,420 7,488 5,991 –1,498 
1994 5,792 4,633 –1,158 6,110 4,888 –1,222 6,418 5,135 –1,284 
1995 5,462 4,369 –1,092 5,773 4,619 –1,155 6,063 4,851 –1,213 
1996 7,052 5,641 –1,410 7,507 6,005 –1,501 7,928 6,343 –1,586 
1997 6,417 5,133 –1,283 6,820 5,456 –1,364 7,193 5,755 –1,439 
1998 7,455 5,964 –1,491 7,922 6,337 –1,584 8,353 6,683 –1,671 
1999 7,128 5,703 –1,426 7,565 6,052 –1,513 7,968 6,375 –1,594 
2000 6,565 5,252 –1,313 6,982 5,585 –1,396 7,372 5,897 –1,474 
2001 7,543 6,035 –1,509 8,002 6,401 –1,600 8,440 6,752 –1,688 
2002 6,888 5,511 –1,378 7,323 5,859 –1,465 7,738 6,191 –1,548 
2003 6,573 5,259 –1,315 7,020 5,616 –1,404 7,403 5,923 –1,481 
2004 5,963 4,771 –1,193 6,312 5,049 –1,262 6,627 5,301 –1,325 
2005 6,233 4,987 –1,247 6,565 5,252 –1,313 6,900 5,520 –1,380 
2006 5,940 4,752 –1,188 6,300 5,040 –1,260 6,608 5,287 –1,322 
2007 6,440 5,152 –1,288 6,835 5,468 –1,367 7,185 5,748 –1,437 
2008 7,017 5,613 –1,403 7,435 5,948 –1,487 7,798 6,239 –1,560 
2009 5,943 4,755 –1,189 6,285 5,028 –1,257 6,573 5,259 –1,315 
2010 6,897 5,517 –1,379 7,305 5,844 –1,461 7,655 6,124 –1,531 
2011 6,835 5,468 –1,367 7,245 5,796 –1,449 7,608 6,087 –1,522 
2012 6,195 4,956 –1,239 6,553 5,243 –1,311 6,857 5,485 –1,371 
2013 7,435 5,948 –1,487 7,878 6,303 –1,576 8,197 6,557 –1,639 
2014 6,912 5,529 –1,382 7,337 5,869 –1,467 7,707 6,165 –1,541 
Average 6,738 5,390 –1,348 7,155 5,724 –1,431 7,535 6,028 –1,507 

Overall, the results showed that the application of the sprinkler irrigation system instead of the flood irrigation system will save the amount of irrigation water by around 1,348 m3/ha under current weather conditions, 1,431 m3/ha in 2050 and 1,507 m3/ha in 2100.

In future, the possibility of multiple uses of irrigation water should be explored for the sustainable use of irrigation systems.

Kaini (2016) stated that using irrigation water for both irrigation and micro-hydro purposes may help ensure food security and energy security. Irrigation water can also be used for domestic water, water for cattle, power generation, fishery, transportation, industry and business, and recreation.

DISCUSSION

The issue of climate change is one of the most complex environmental problems facing the development process, especially in arid and semi-arid regions due to limited water resources.

The wheat crop is one of the most important strategic crops, as it is used for food in most of the world. There is a lack of water needs for wheat crops under Egyptian weather conditions, as it is grown in the winter season and the amount of rain falling on the northern part of Egypt contributes to reducing the amount of water needed for this crop. Despite all this, the large area allocated to it is more than any other crop in Egypt, so it gets a large percentage of the total water budget for agricultural crops in Egypt. Accordingly, many measures and procedures must be taken to provide a suitable amount of water to cover an appropriate amount of food needs for the rapid population increase in Egypt and also to overcome some of the negative effects of rising temperatures and increasing demand for water under climatic change conditions.

Through this research, the negative impact of climate change on wheat crop productivity and some water relations was studied, and a number of adaptation strategies were considered to reduce the adverse impact of climate change on this crop.

The adaptation strategies proposed in this research are aimed at reducing productivity shortages and rationalizing water use without causing a significant shortage of crop productivity as well as improving the productivity of the land and water units.

The results of the adaptation strategies indicated that the delay in the sowing date of wheat crops under climate change conditions in Egypt causes a significant decrease in the crop productivity due to the fact that the delay of sowing date is accompanied by the exposure of plants to high temperatures before the end of the growing season. This can help the plant to take its needs from the heat (growing degree days) to move from one stage to another in a short period, which results in a reduction in productivity.

In addition, it is possible that in the milk or wax stages of the grains, the plant may be exposed to a high temperature during the months of February, March or April. This may cause weakening of the grains and their small size and accelerates the transition from one stage to another until the end of the growing season in a short period of time, and all this leads to a decrease in productivity.

Increasing the amount of irrigation water under climate change conditions could be an important way to reduce the negative impact of climate change on wheat production. The results showed that increasing the amount of irrigation water by 10% in the mid of this century or 20% by the end of this century could reduce productivity shortfalls to only about 5% instead of 8.6 or 11.1% in 2050 and 2100, respectively. This is due to the fact that the high temperature is accompanied by increased evapotranspiration, which requires compensating the plant by adding more water, and the absorption of nutrients occurs through irrigation water.

Meanwhile, the results of the research showed that the use of modern irrigation systems (sprinkler irrigation) will save water without a shortage of productivity. The amount of irrigation water that can be saved from the application of this system amounted to approximately 1,348, 1,431 and 1,507 m3 ha under current weather conditions, 2050 and 2100, respectively. This is because the irrigation efficiency of the flood irrigation system is about 60%, while the efficiency of the sprinkler irrigation system is about 75%, which means that about 15% of the irrigation water can be saved without any shortage of crop water consumption.

CONCLUSIONS

Due to the limited water resources in Egypt under the current conditions, the situation will become more serious under the circumstances of future climate change, so this study aims to assess the impact of climate change on irrigation water needs and crop productivity for one of the most important strategic crops that the world needs (wheat crop). In addition, a number of adaptation strategies were examined to mitigate the negative impact of climate change on crop productivity and its water relations.

Two models were used, one for climate and the other for irrigation. The climate model of MAGICC/SCENGEN was used to simulate the impact of global greenhouse gas emissions on the rate of rise in temperature at the regional level of the study area in Egypt. The irrigation model of CropWat8.0 was used to simulate the effect of temperature rise on wheat yield reduction and some water relations. Middle Egypt was selected to carry out the current study.

The results of the study showed that the increase in global greenhouse gas emissions is likely to cause an increase in the average temperature of the area under study of about 2.12 °C in 2050 and 3.96 °C in 2100.

Climate change, especially the increase in temperature, is expected to reduce wheat productivity. The average yield reduction in 2050 and 2100 compared to the current situation is 8.6 and 11.1%, respectively. Water consumption of wheat under climate change conditions will increase from about 6% in 2050 to nearly 12% in 2100. CWP will decrease as a result of low productivity and increased water consumption, and the results recorded a decline of 11.6 and 19.1% in 2050 and 2100, respectively.

The results of adaptation studies have shown that early wheat cultivation can reduce the negative impact of climate change on crop productivity. The optimum sowing date for wheat under climate change conditions in 2050 or 2100 is 1st November.

Increasing the amount of irrigation water added by +10% in 2050 and +20% in 2100 will help improve wheat productivity. The cumulative yield reduction will be 5.4% instead of 8.6% in 2050, and 4.8% instead of 11.1% in 2100.

The application of a sprinkler irrigation system instead of a flood irrigation system will save amounts of irrigation water by around 1,348 m3/ha under current conditions, 1,431 m3/ha in 2050 and 1,507 m3/ha in 2100.

DATA AVAILABILITY STATEMENT

All relevant data are included in the paper or its Supplementary Information.

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