Major Crops and Water Scarcity in Egypt

This chapter described methodology to calculate evapotranspiration (ET) values similar to the values calculated with Penman–Monteith equation (P–M), using ET values calculated by Hargreaves–Samani equation (H–S) under current and climate change. The BISm model was used to calculate monthly values of ET using P–M and H–S equations using weather data averaged over 10 years, from 2004 to 2013 for each of the 17 studied governorates and the values were compared. The comparison showed that there were deviations between monthly ET values calculated for each equation in each governorate. Thus, a linear regression equation was established with ET values resulted from P–M plotted as the dependent variable and ET values from H–S equation plotted as the independent variable. The quality of the fit between the two methodologies was presented in terms of the coefficient of determination (R²) and root mean square error per observation (RMSE/obs). ECHAM5 climate change model was used to develop A1B climate change scenario for each governorate for the years 2020, 2030 and 2040, where ET values were calculated. The results indicated that R² was between close to one and RMSE/obs values were close to zero. The results also indicated that the calibration coefficients were capable to account for the effect of relative humidity, wind speed and potential sunshine hours, which were not included in the H–S equation. Furthermore, under A1B climate change scenario, the values of ET were increased. The above methodology could solve a large problem that faces researchers and extension workers in irrigation scheduling in Egypt and in other developing countries under current climate and in calculation of water requirements under climate change.

The objective of this chapter was to calculate water requirements for four crops: wheat, maize, rice and sugarcane grown in 17 governorates in Egypt under current climate and under the A1B climate change scenario in 2040. The BISm model was used to calculate crop coefficient water depletion from root zone. Water requirements under A1B climate change were calculated using the model. The results indicated that water requirements for wheat will increase by 2–19% depending on governorate location. The effect of climate change was more pronounced on maize as a summer crop, where the applied irrigation amount is expected to increase in all governorates under climate change in 2040 by 10–19%. Regarding rice, water requirements were increased by 10–14%. With respect to sugarcane, which is a unique case because of its long growing season (365 days), its water requirements under climate change conditions increased by 11–19%.

In this chapter, we investigated options to reduce the applied water for wheat, such as cultivation on raised beds and using sprinkler system for irrigation. We also investigated the effect of these two options on wheat national production under climate change in 2040. The effect of relay intercropping cotton on wheat on national production was also explored under current climate and under climate change. We also examined the effect of these options on water productivity under current climate and in 2040. The results indicated that under current situation of wheat production, which is grown under surface irrigation, production represents only 62 % of total consumption. Cultivating wheat on raised beds or using sprinkler system for irrigation increased total production compared to its counterpart under surface irrigation, which resulted in reduction of the applied water, increase in productivity and using the saved water in new land irrigation. Under climate change, wheat production will be reduced under surface irrigation. However, cultivation on raised beds or using sprinkler system for irrigation under climate change compensated a part of these losses. The results also indicated that the potential available water to irrigate new lands after changing water management practice can be reduced under climate change, compared to its values under current climate. As a result, the potential new cultivated areas will also be reduced. In relay intercropping cotton on wheat, the total cultivated area of wheat will consist of wheat area, cotton area and the added area as a result of water availability from raised bed cultivation WHICH will increase wheat total production under current and in 2040. The results also indicate that water productivity was the lowest under surface irrigation and was the highest when sprinkler system was used under both current and climate change.

In this chapter we investigated the effect of cultivating maize on raised beds and irrigation with drip system on increasing national maize production through increasing productivity, reducing the applied irrigation water and use it to irrigate more land with maize. Under climate change, maize vulnerability can be reduced by the above practices. We also calculated the contribution of each option in reducing maize production-consumption gap under current climate and under climate change in 2040. The effect of these practices on water and land productivity under preset time and under climate change in 2040 was also examined. The results revealed that production-consumption gap in maize are about 45 %. The results also indicate that cultivating maize on raised beds or using drip system for irrigation reduced production-consumption gap under current climate and in 2040, where the percentage of imported maize will reduce to 23 and 12 % under both systems, respectively, under current climate and will reduce yield losses under climate change. The results also indicate that water productivity was the lowest under surface irrigation and was the highest when drip system was used under both current and climate change.

In this chapter, we calculated the applied water amount for rice in 2013 growing season and investigated the effect of improved cultivation method on rice national production. Moreover, we graphed maximum temperature in 2040 with cutoff temperature to investigate suitability of growing rice in its current growing areas. Under climate change, with the assumption that potential rice production will be reduce by 11 %, its production was assessed in 2020, 2030 and 2040 under traditional and improved cultivation method. The effect of the reduction in the cultivated rice area under climate change was quantified, as well as using potential saved water to cultivate additional area with maize. The results indicated that changing cultivation method from traditional method to cultivation on wide furrows saved a large amount of irrigation water. The saved irrigation amounts were invested to cultivate 309,911 hectare of maize on raised beds, or 371,893 hectare under drip system, which will increase maize production. The results also showed that in 2020, 2030 and 2040 water requirements for rice under traditional planting will increase and consequently its cultivated area will be reduced. The results also showed that during the growing season of rice in both Alexandria and Demiatte, maximum temperature raised above cutoff temperature for a few days during the growing season. Thus, it is implied that Alexandria and Demiatte will be suitable to grow rice in 2040, with probably low yield losses. However, the effect of maximum temperature above cutoff temperature will be more pronounced in the rest of the studied governorates, which might restrict its cultivation in the future. In 2020, 2030 and 2040, water requirements for rice under wide furrows will increase, compared to its values under current climate. Thus, the amount of saved irrigation water, rice productivity and total production will decrease, compared to its counterpart under wide furrows and current climate. Furthermore, the saved water assigned to be use in maize production will be reduced. Water productivity values for rice grown on wide furrows were higher than its value under traditional method in all governorates, either under current climate or climate change.

In this chapter, we quantified the effect of the increase in water requirements under climate change on cultivated areas of spring sugarcane. Furthermore, we compared between prevailing temperature during growing season under current climate and cutoff temperature to assess the suitability of these governorates for sugarcane cultivation in 2040. We also investigated the effect using gated pipes to reduce the applied irrigation water to sugarcane. Furthermore, the effect of intercropping summer crops with sugarcane was also investigated to make use of sugarcane applied water and increase water and land productivity. The results indicate that sugarcane production was increased when gated pipes was used for irrigation instead of surface irrigation under both current climate and in 2040. Furthermore, an amount of saved water was attained and could be used in cultivating new land with sugar beet to reduce sugar production-consumption gap in two governorates and in cultivating wheat in the other two governorates. The results also indicate that water requirements for sugarcane will increase by 17 % as an average over all governorates in 2040, which will reduce the cultivated area of sugarcane. Furthermore, comparing measured temperature with predicted temperature in 2040 revealed that it will higher than cutoff temperature from May to September. However, it will be still suitable to grow sugarcane. Intercropping summer oil crops with sugarcane can reduce production-consumption gap in edible oil in Egypt, which will take its water requirements from the applied water to sugarcane. The results also revealed that water and land productivity will increase when gated pipes were used under current and climate change.

In this chapter we presented an example of prevailing crop rotation in the four soil types exist in Egypt, i.e. old clay, calcareous, sandy and salt affected soils. We also proposed one rotation in each site to replace the prevailing rotation to save on the applied irrigation water. We calculated water requirements for each rotation and determined the amount of saved water per hectare under current climate and in 2040. We also presented the prevailing sugarcane rotation and proposed other rotations to increase water and land productivity. In the proposed rotations, changing cultivation methods from flat or on rows to raised beds saved on the applied water. Furthermore, using intercropping instead of monoculture saved on the applied water under both current climate and in 2040. In the old land, the saved water amounts were 1095, 1331 and 1546 m3/ha in Nile Delta, Middle and Upper Egypt, respectively, under current climate. Under climate change, 610, 996 and 1278 m3/ha in Nile Delta, Middle and Upper Egypt, respectively was saved. In the new reclaimed land, the proposed rotation could save 3160 and 2908 m3/ha under current climate and climate change, respectively. Regarding sandy soil, the proposed rotation saved low amount of water, i.e. 53, 67 and 152 m3/ha in Lower, Middle and Upper Egypt, respectively under current climate. Under climate change, the saved amounts were 58, 66 and 131 m3/ha in Lower, Middle and Upper Egypt, respectively. In the salt-affected soils, the proposed rotation will save 3426 and 2828 m3/ha under current climate and in 2040, respectively. Regarding sugarcane rotations, the amount of saved irrigation water using the proposed rotations was 3,596 and 7,609 m3/ha for spring and autumn rotation, respectively.

This chapter provides insights to policy makers in Egypt on how to deal with water scarcity under current climate and in 2040 under climate change.