Evaluation of Impacts and Adaptation

Business as usual

The impact of climate change and associated other drivers without adaptation can be considered as the 'business as usual' adaptation strategy. Using the aforementioned drivers and indicators, the simulation models were applied to calculate indicator values. The status of the basin will be evaluated separately for the selected periods and climate change scenarios.

According to the present water allocation policies, domestic and industrial demands have first and second priority, respectively. The agricultural and environmental sectors are next, such that during the recent prolonged drought spells (1997-2001) water was completely cut for the Gaw Khuni swamp. According to new regulations, Esfahan Water Authorities has been committed to allocating 75-140 X 106 m3/year for the river and swamp ecosystems, depending on the year's wetness. These policies have been embedded in ZWAM to examine possible water deficits and their durations during future periods. So, whatever happens with the climate, the domestic and industrial water demands must be fulfilled first and what is left over can be used for agriculture and environment.

The agriculture sector is the main water consumer. While this sector absorbs 80% of the basin water resources in the baseline period (1960-1990), this has to go down in the future since urban and industry have higher priorities. Model results indicate that these agricultural extractions will go down to 75% and 68% of the current situation for the near future (2010-2039) and distant future (2070-2099), respectively. These numbers assume fixed agricultural demands and no new source of water from trans-basin transfer.

The reduction in water availability makes it essential to apply adaptation strategies. Three different possible adaptation measures have been analysed in this study:

• domestic and industrial; and

• balanced between food and domestic/industrial.

Food-focused adaptation

There is a clear need to produce more food in the future to feed the increased population. Two sub-types of adaptation measures have been evaluated to explore options for agriculture:

• change in the total cropped area in the basin; and

• change in the cropping pattern.

Available data on crop yields are not irrigation-system dependent, but are aggregated at the level of the regions that have been defined by the Esfahan Agriculture Organization (EAO). We have elected to concentrate the analysis on the Nekou Abad and Abshar irrigation systems that are located in the Esfahan region. Rice and potatoes have been analysed according to the Nekou Abad situation and wheat and barley according to that of Abshar. Cropped area for rice, potatoes, wheat and barley are estimated to be 11,260, 3480, 20,892 and 4273 ha, respectively. Optimum water supplies to these crops are estimated to be 17,000, 11,000, 9000 and 8000 m3/ha, respectively.

To perform our analyses on food adaptation strategies, the basin level and field level models were linked to indicate water quality and quantity at the irrigation systems and the response of crops to the allocated water for the climate change scenarios. During the 2070-2099 period, a negative impact on crop production (average as well as variation) can be expected and also that rice is more sensitive to the climate change than the other crops in the basin.

In order to compare adaptation strategies we will concentrate on water consumed by the crops and the caloric production as indicators. This caloric production was calculated assuming that 3600, 760, 4000 and 4000 are the kilocalories produced per kilogram of rice, potatoes, wheat and barley, respectively.

One of the possible food adaptation strategies is to reduce the total cropped area in order to maintain sufficient irrigation water. This strategy has been investigated and cropped areas have been reduced such that optimum water requirements can be met for the major crops. The results of this strategy are shown in Table 6.3, and indicate that reducing the cropped area in order to have sufficient water per hectare to irrigate crops with the optimum amount has only a positive impact on rice. For the other crops, providing somewhat less irrigation but keeping the area constant is more beneficial. This can be explained by the fact that deficit irrigation is damaging for rice, but is less harmful for the other crops.

Changing the cropping pattern is one of the other strategies that has been explored. Rice requires a substantial amount of water and caloric production is not as high as that for wheat. Moreover, the coefficient of variation of rice yields is higher than that of wheat: 0.14 to 0.29 for rice versus 0.59 to 1.21 for wheat. So, also from a food security point of view, rice production is a less reliable food source. Therefore, the models have been set up to explore what will happen if rice is replaced by wheat.

Table 6.3. Produced total energy (in kcalx109/year) for the two food scenarios: fixed area (=less irrigation per ha) and optimal irrigation (=reduce area).

A2 B2

Table 6.3. Produced total energy (in kcalx109/year) for the two food scenarios: fixed area (=less irrigation per ha) and optimal irrigation (=reduce area).

A2 B2

2010-2039

2070-2099

2010-2039

2070

-2099

Reference

Fixed

Optimal

Fixed

Optimal

Fixed

Optimal

Fixed

Optimal

1990-2000

area

irrigation

area

irrigation

area

irrigation

area

irrigation

Rice

196

121

133

53

56

113

114

56

79

Potatoes

69

91

85

66

62

78

71

74

67

Wheat

385

407

367

306

225

380

344

322

242

Barley

76

81

74

60

54

76

71

63

58

Total

726

700

658

485

397

647

600

515

446

Table 6.4. Produced total energy (in kcalx109/year) by changing crop pattern and substitution of rice by wheat.

2010-2039

2070-2099

2010-2039

2070-2099

Wheat (substituted) 390

Potatoes 91

Wheat 407

Barley 81

Total 969

287 66 306 60 719

330 78 380 76 864

309 74 322 63 768

Table 6.4 shows that this is indeed an adaptation strategy that will increase the total amount of food, expressed in calories.

However, rice is more profitable for farmers in terms of revenues in comparison to the other crops. The domestic price of rice in the basin is much higher than current world market prices. If the government wants to minimize rice production in the basin they will have to take measures to make growing crops like wheat more appealing. Such a strategy can result in an increase of 33-48% in the total produced calories in the basin and can reduce agricultural water demands by up to 10%. Since it is not expected that consumers are willing to replace rice for wheat, rice should be imported to the region and the additional amount of wheat produced should be exported. A full economic analysis is required to evaluate the impact of such a measure.

Environment-focused adaptation

The Esfahan Environment Organization is proposing to define a minimum flow requirement of 75 X 106 m3/year to the Gaw Khuny swamp to preserve the river and the swamp ecosystems in dry years. The impacts of these measures have shown that the pollution rates decreased in 2000, whereas in the same year the basin experienced a severe drought. The recent regulations have committed the industrial sector to increase their wastewater treatment efficiency, seen the installation of new waste-water treatment facilities and a number of factories have been relocated to other places. The painting units of the textile factories committed to shift to locations that are far from the river.

In spite of these environmentally friendly measures, results of the modelling framework show that for all of the future periods, BOD beyond the return flow of Esfahan water treatment will deteriorate. Even for May when discharges are highest, BOD is still higher than 10 mg/l. Another point that came out of the results of ZWAM is that even if no fixed amount of water was allocated to the swamp, at least 75 X 106 m3/year reached the swamp. This amount is obtained from return flows of the upstream demand sites. This was checked with historic records of inflows to the Gaw Khuny swamp, showing that inflow to the swamp ranged from 30 to 639 X 106 m3 over the last years. Yet in recent years (1997-2000) annual inflows have usually been down to 30 X 106 m3 as a result of the severe drought. The difference between this 30 X 106 m3 and the minimum flow requirement of 75 X 106 m3 should come from future additional inflows of Lenjan Tunnel and Tunnel No. 3 to the dam that will be exploited after 2010. So, even if no water is allocated for the swamp, it will still get a volume close to 75 X 106 m3.

Domestic- and industry-focused adaptation

The total amount of water presently allocated to the industrial sector is relatively small at about 100 X 106 m3, since there is not much industrial development in the basin that relies on water.

The only hydropower unit in the basin is the Chadegan Dam. The total electricity consumption in the basin has been estimated at about 3000 GWh. The Chadegan Dam produces only 5% of this amount. The main source of power in the basin is natural gas. Climate change can be considered as irrelevant for total power production.

The major measure that can be taken to reduce domestic demand is modification of the drinking water networks to reduce the present losses (25%, i.e. a reduction of 80 m3/year per capita to 60 m3/year per capita).

Combined adaptations

Period 2010-2039

If we consider the total demands for the period 2010-2039, we can see arise from 2376 X 106 m3 in year 2010 to 2522 X 106 m3 in 2039. As was pointed out earlier, two tunnels (Tunnel No. 3 and Lenjan Tunnel) are presently under construction and will be operational before 2010. This water diversion has been added to the present amount of available water. It is assumed that 425 X 106 m3 is the maximum capacity of these tunnels. Results show that when comparing A2 and B2 scenarios for this period, the basin will face more severe and longer water deficits in the future under climate change.

The strategies have been compared with the present water distribution and cropping patterns (Table 6.5). Applying the environment-focused adaptation strategy to

Table 6.5. Effect of the different adaptation strategies on the indicators.

Table 6.5. Effect of the different adaptation strategies on the indicators.

BAU

Env

Agr

Dom

BAU

Env

Agr

Dom

Food

Total produced

2489

2384

2968

3123

2373

2268

2824

2979

calories (109 kcal/year)

Max. shortage (X106 m3)

600

670

487

592

835

865

682

592

No. dry years

15

20

10

6

15

15

14

14

Max. continuous dry

7

7

3

2

15

15

14

14

years

Environment

Inflow <75x106 m3/year

12

0

0

0

15

0

0

0

75<inflow<140x106 m3/year

18

12

12

12

15

15

15

15

Inflow>140x106 m3/year

0

18

18

18

0

15

15

15

BAU, business as usual; Env, environment-focused adaptation; Agr, food adaptation (rice replaced by wheat); Dom, urban and industrial adaptation.

save the swamp causes a near 5% reduction in food production and higher water shortages. Applying the food adaptation strategy eliminates the previous negative impacts, increases food production up to 20% and reduces water shortage. For the next step, applying the domestic/industry adaptation, agricultural production may increase up to 25% compared to BAU and lower water shortage. It is evident that reduction in agricultural demands has a significant impact in reducing the vulnerability of the basin to water deficits.

Period 2070-2099

For the period 2070-2099, competition between domestic and agricultural demands will be more serious. While the present domestic demands are about 10% of available water resources, it rises to 25% at the end of this century.

The present water resources cannot meet the basin's agricultural and industrial water demands. In addition, an increase in domestic demand can be expected due to population growth. For this period, the basin will face more water shortage and scarcity. Similar to the previous periods, adaptation strategies have been examined for this period (Table 6.6).

As already pointed out, the Behesht Abad trans-basin project is one of the projects that is proposed by the Esfahan Water Authority to transfer water from the neighbouring basin (Karoon Basin). This project requires huge investments and may have some negative impacts on hydropower infrastructures in the Karoon Basin. More investigation is needed to assess the positive and negative aspects of this tunnel. The transfer capacity of the project is between 700 and 1000 X 106 m3, but for the present analysis 700 X 106 m3 has been assumed. Including this volume of water in the total amount of available water does not only reveal water shortage, but also generates new capacity to improve agricultural lands and produce more food. Such an improvement is definitely required, when the basin should accommodate and feed 7-9 million

Table 6.6. Similar to Table 6.5, but for the period 2070-2099. Tun is constructing the new Behesht Abad tunnel, which will transfer 700X106 m from the neighbouring Karoon Basin.

A2 B2

BAU Env Agr Tun BAU Env Agr Tun

Food

Total produced 2245

calories (109 kcal/year)

Max. shortage (X106 m3) 778

No. dry years 19

Max. continuous dry 11 years

Environment

Inflow <75x106 m3/year 14

75<inflow<140x106 m3/year 16

Inflow>140x106 m3/year 0

2140

2665

4557

2272

2167

2698

4590

848

665

0

1201

1271

1088

0

19

18

0

17

20

16

0

11

11

0

3

4

3

0

0

0

0

11

0

0

0

14

14

14

18

11

11

11

16

16

16

1

18

18

18

people. While present resources of the basin are enough to produce 3460 kcal/day per capita, it will reduce to almost 810 kcal/day per capita in year 2099. Including the new tunnel, this will increase to 1400 kcal/day per capita. Thus, even after constructing the tunnel, the basin will still need to import a substantial amount of food.

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