4. Water-agriculture balance in spate irrigation

This anomalous behaviour of water opens new windows for searching water resources. We receive water either from rainfall or from floods. Both resources are the outcomes of recycling. When climate temperatures slightly rise, it causes glaciers to melt which changes the ice into water. But this change in climate is controlled and bearable. In summer when temperatures are expected to become the highest, it then dismays the environment and brings floods. On having such situations, it becomes necessary to channelize this flood into irrigation water that can be termed as water harvest. In spate areas the inhabitant or farmers receive these floods as blessing of God, and in urban area it is not more than a menace.

In spate-irrigated areas, poverty commands and people are very hard to live. They are dependent of agriculture profession as main and sole profession. Soil is hard and barren, and water table is very low and neither so link nor black top road to link between farms to market. Although the area is responsive to many crops like wheat, gram, millet, Sorghum, guar, melon, Brassica and onion, they prefer to grow wheat and gram as second choice. An irony is that farmer cannot decide, only flood decides which crop should be sown and when to sow that crop. In Pakistan, after 2010 floods, the climate sway has been observed by the scientific community. This flood was prominent for its severity; 2010 floods are notable for their severity [26]. Projections related to the impacts of climate change warn that developing countries will be the greatest victims of climate change. The Global Climate Risk Index has rated Pakistan as the seventh most vulnerable country to be affected by climate change [27]. Imbalance environment (climate change) and over- and underwatering have depicted the significant changes amongst the common strata/people. Unusual floods in terms of time and magnitude have greatly influenced the prevailing climate and also disturbed the seasonal monsoon route. Such alteration has also made upset the rainfall schedule due to which crops are being grown either early or delayed to their actual time. Thus it can be said that farmers'sowing trend has been shifted due to changed rainfall docket. An interesting thing which has been observed in locality amongst the farmer is adoption of the people according to changed climate as well as water mood/temper. That is why they apply indigenous knowledge which they have perceived from remote ancestors for the purpose of biological control, moisture conservation from the flood water, fencing the flood, diverting flood route, converting flood water into irrigation water and handling noxious weeds and baneful pests. This native cognition also covers the cultivation method, crop choice, quality seed grading, seed storage, livestock health and crop care and their safety from diseases, pest identification and eradication.

#### 4.1 Crops

The farmers in spate are growing different crops as source of fodder, fibre and food for earning their livelihood. The farmers in the spate-irrigated area are subsistent and wait throughout the year for harvesting water and growing crops. During the dry season, they have to migrate to the canal-irrigated area to earn their living.

the different factors influencing the spate irrigation in Ethiopia from the year 2005; they have studied the crop choice and the requirement of irrigation. They collected data using the logit model. It was found from the study that farmers having the low

Figure 3.

properly leveled

irrigated area

Source: [20].

Table 2.

106

the access to main market

The extensive system of spate irrigation of Dera Ismail Khan.

Due to continuous siltation, the land is not

The water distribution is uneven, and sometimes the head farmers may apply water more than once while the tail does not even receive a drop of it

Lack of technological development in the spate-

The crops grown in the spate-irrigated area lack

The organic food produced in the spate has not gain the attention of the market or promotion

The identified problems and their potential solution.

Identified problems Potential solution

Irrigation - Water Productivity and Operation, Sustainability and Climate Change

Unpredictability of the magnitude of the floods Farmers in the spate should be prepared for the

There is less attention from the stakeholders There is a need for the spate community to be

construction of check dam before time and should

The farmers should be facilitated through the government agencies in land leveling

The water user association functioning may help in even distribution of water between the

The linkage between the different stakeholders is

Access to market may be accomplished after the linkages are developed, and the mobility of the

have fields well ready for flood harvest

necessary for the development of area

aware to raise their voice and highlight the

The consumers are less aware about the importance of organic products. But it is gaining

importance as the health hazards and environmental problems are increasing

different streams

problems

people enhances

Mostly the cereal crops are grown on vast area [18]. These include rabi (winter) crops such as wheat, gram and kharif (summer) sorghum, millet and melon. The comparison of yield of both flood water and perennial water revealed that the yield is low in flood-irrigated area. These cereal crops are essential for the food security and survival of the spate farmers, but there is potential for certain cash crops as cotton, sesame, guar, etc. [28]. However, there is very little choice for the farmers, as it mainly depends on the amount and time of water being received. During the monsoon floods, if the water received is huge, then wheat is the option, but if it is less in magnitude, the farmers have to grow gram. The cotton crop vanished due to more insect pest and shortage of water, whereas mung bean has disappeared due to growing of other fodder crops such as millets and sorghum. The wheat and gram are the preferred crops of the area, and the farmers and the owner try hard to get enough water to cultivate gram and wheat.

The crop yield has been fluctuated by heavy rainfall or floods and limited in no rainfall or drought. Other fields responded to fodder growth with little moisture. Under spate irrigation yield of the crops like sorghum, oilseed and wheat have been reported as 745,510 and 915.5 kg ha<sup>1</sup> , respectively [18]. The spate-irrigated land has the potential to give better yield of crops (Table 3) if the floods are timely available and management practices, i.e. land preparation, weeds management, pest control etc., are used.

Wheat grown in area has unique quality due to which it has captured the main focus of the farmers. The peculiarities of the local landrace of wheat is that it has greater loaf volume and greater protein content, hence having a better baking quality than the improved varieties. This wheat variety is known as dual purpose wheat, i.e. both consumed by human beings and livestock, or in other words it is used for fodder during early-growing season and also as straw after harvest. The grain yield of this landrace is comparatively low but has the potential to improve if proper environmental conditions are provided. It is meritorious in many aspects, i.e. fodder, grain and even straw is utilized which is very high. The physiology of this wheat cultivar is also praiseworthy as the seed grown at a depth of 10 cm may germinate, which indicate that it has a longer coleoptile length. As most of the farming system is based on monocropping, the farmers strive for growing wheat as it is a source of food and also seed for the coming season. The landrace has the potential to grow in dry condition as well as in the absence of fertilizer. These are the main reason that wheat is the first choice subject to the availability of water or flood whatsoever.

included were date palm, grapes, mangoes, apples, ber, etc. But now most of the orchards have been turned into living places and houses; this is due to shortage and injudicious use of water and growth in population and land fragmentation. The major fruit trees found now are ber, date palm and melon. Ber is known in Pakistan as a 'Miracle Tree' as it has the potential to tolerate the severe drought condition. It is used as fruit and also a very good fodder tree; the shepherd in the spateirrigated area buys the tree for its twigs and leaves [29]. The height of these trees may reach up to 10 ft. But now the population of this tree has been reduced due to scarcity of water, and also as the trees are the commodities of the owner of the land, the tenant is mostly not allowed to use the branches for their livestock, so the

50 years ago Now Reason for change

Spate Irrigation: Impact of Climate Change with Specific Reference to Pakistan

Cotton Cotton was grown Not grown anymore Pest attack and people have

Very few ber trees except for the upstream perennial water receiving villages and at household

Tractors and bulldozers are used beside the bullocks used by limited

But now the trends of half and half share without sixth have

farmers

started

Not cultivated any more Mung bean requires more

water, and therefore most people turned towards gram

changed from Sorghum, and millets staple food to wheat, so by growing cotton land was not available for wheat

The Kuliyat and Riwajat in which the trees are the property of landowner, and therefore the tenants did not care much for the trees

mechanization in the 1972 onward by Agri. Engineering department and tractors became more common after provision through subsidies in

To cultivate land by hired labour or temporary tenancy, the tenants do not agree for the sixth share; this is also happening in few of the area in permanent tenancy

Introduction of

1989–1990

Different vegetables as bitter gourd, ladyfinger, tomato, onion, green chilies, etc. were grown in the upstream area and local market existed. Due to increasing population and easier access to the main markets, most of the vegetable gardens have been changed to living places. Conflicts of water usage to irrigate orchards have been also minimized. In the middle stream and downstream villages, they grow vegetables on the embankments for stabilization of the embankments with the crops for their own consumption. These vegetables include pumpkins and bitter

tenants do not look after them and even do not let them grow.

4.1.2 Vegetables

Farming practice

Mung bean cultivation

Tenancy pattern

Table 4.

Cultivated on few of the area which has received a lot of

DOI: http://dx.doi.org/10.5772/intechopen.85889

common fruit in all villages and date palm orchards in some of the villages as

plowing and earthen bund

The production was divided half and half with the sixth share of the owner

flood

Fruit trees Ber (Ziziphus sp.) is the

Chodhwan

Plowing Bullocks were used for

construction

Changes in spate agriculture over the 50 years.

gourd.

109

## 4.1.1 Fruits


As perennial water has been mostly available to the upstream villages, there were many orchards in the spate-irrigated areas (Table 4). The fruit orchards

#### Table 3.

Productivity of crops grown under non-perennial and perennial spate irrigation in D.I. Khan and tank districts of KPK (agriculture census, 2006).


Spate Irrigation: Impact of Climate Change with Specific Reference to Pakistan DOI: http://dx.doi.org/10.5772/intechopen.85889

#### Table 4.

Mostly the cereal crops are grown on vast area [18]. These include rabi (winter) crops such as wheat, gram and kharif (summer) sorghum, millet and melon. The comparison of yield of both flood water and perennial water revealed that the yield is low in flood-irrigated area. These cereal crops are essential for the food security and survival of the spate farmers, but there is potential for certain cash crops as cotton, sesame, guar, etc. [28]. However, there is very little choice for the farmers, as it mainly depends on the amount and time of water being received. During the monsoon floods, if the water received is huge, then wheat is the option, but if it is less in magnitude, the farmers have to grow gram. The cotton crop vanished due to more insect pest and shortage of water, whereas mung bean has disappeared due to growing of other fodder crops such as millets and sorghum. The wheat and gram are the preferred crops of the area, and the farmers and the owner try hard to get

Irrigation - Water Productivity and Operation, Sustainability and Climate Change

The crop yield has been fluctuated by heavy rainfall or floods and limited in no rainfall or drought. Other fields responded to fodder growth with little moisture. Under spate irrigation yield of the crops like sorghum, oilseed and wheat have been

Wheat grown in area has unique quality due to which it has captured the main focus of the farmers. The peculiarities of the local landrace of wheat is that it has greater loaf volume and greater protein content, hence having a better baking quality than the improved varieties. This wheat variety is known as dual purpose wheat, i.e. both consumed by human beings and livestock, or in other words it is used for fodder during early-growing season and also as straw after harvest. The grain yield of this landrace is comparatively low but has the potential to improve if proper environmental conditions are provided. It is meritorious in many aspects, i.e. fodder, grain and even straw is utilized which is very high. The physiology of this wheat cultivar is also praiseworthy as the seed grown at a depth of 10 cm may germinate, which indicate that it has a longer coleoptile length. As most of the farming system is based on monocropping, the farmers strive for growing wheat as it is a source of food and also seed for the coming season. The landrace has the potential to grow in dry condition as well as in the absence of fertilizer. These are the main reason that wheat is the first choice subject to the availability of water or

As perennial water has been mostly available to the upstream villages, there were many orchards in the spate-irrigated areas (Table 4). The fruit orchards

Productivity of crops grown under non-perennial and perennial spate irrigation in D.I. Khan and tank districts

Crop Yield (kg ha<sup>1</sup>

Wheat 905 1600 Gram 500 710 Millet and sorghum 610 1050 Melons 4080 5200

has the potential to give better yield of crops (Table 3) if the floods are timely available and management practices, i.e. land preparation, weeds management, pest

, respectively [18]. The spate-irrigated land

)

Flood irrigation Perennial irrigation

enough water to cultivate gram and wheat.

reported as 745,510 and 915.5 kg ha<sup>1</sup>

control etc., are used.

flood whatsoever.

4.1.1 Fruits

Table 3.

108

of KPK (agriculture census, 2006).

Changes in spate agriculture over the 50 years.

included were date palm, grapes, mangoes, apples, ber, etc. But now most of the orchards have been turned into living places and houses; this is due to shortage and injudicious use of water and growth in population and land fragmentation. The major fruit trees found now are ber, date palm and melon. Ber is known in Pakistan as a 'Miracle Tree' as it has the potential to tolerate the severe drought condition. It is used as fruit and also a very good fodder tree; the shepherd in the spateirrigated area buys the tree for its twigs and leaves [29]. The height of these trees may reach up to 10 ft. But now the population of this tree has been reduced due to scarcity of water, and also as the trees are the commodities of the owner of the land, the tenant is mostly not allowed to use the branches for their livestock, so the tenants do not look after them and even do not let them grow.

## 4.1.2 Vegetables

Different vegetables as bitter gourd, ladyfinger, tomato, onion, green chilies, etc. were grown in the upstream area and local market existed. Due to increasing population and easier access to the main markets, most of the vegetable gardens have been changed to living places. Conflicts of water usage to irrigate orchards have been also minimized. In the middle stream and downstream villages, they grow vegetables on the embankments for stabilization of the embankments with the crops for their own consumption. These vegetables include pumpkins and bitter gourd.

#### 4.1.3 Trees

The native trees in spate-irrigated area are Acacia nilotica,Tamarix aphylla, Capparis decidua, Prosopis cineraria, etc. which are common but found standing alone in a huge field. In the early 1900s, Prosopis juliflora (mesquite) was introduced in by Mian Musa Alvi the servant of Dak bangle; he was provided the seed by the English officer for his barren land to control the land degradation. This tree has the ability to spread faster and has now occupied the whole spate area, and every day eight to ten lorries of the fuelwood obtained from this tree have been sent to urban area and therefore have proven to support the labourer class in their daily life. Due to the rapid spread of mesquite, other tree species have reduced.

runoff and reduction in the rate of infiltration into the soil. The crust formation reduces the germination of seedling and eventually results in the decline of crop yield. There are different solutions proposed for overcoming the problem of crust formation such as optimal tillage operations, application of manures, crop residue incorporation, mulching, seed sowing at appropriate depth, sowing on ridges, etc. Soil in this part of Pakistan is moderately to strongly calcareous with alkaline pH. Soils have sufficient potassium content and micronutrients but are mostly deficient in nitrogen and phosphorus. The fertility status of spate-irrigated soils of Dera Ismail Khan, Pakistan, in 87 soil samples collected from different locations and analyzed for various soil physico-chemical characteristics showed that 50% of the soil were of medium texture and 45.9% were clayey fine texture. There were very little soil with coarse texture (3.5%), and saturation percentage of the soil ranged between 16.2 and 67.0%; salinity and sodicity showed that 13.8% were saline, 5.8% were sodic and 74.7% were normal soils. The fertility status of the soils under investigation revealed that all the soils were deficient in nitrogen, while phosphorus was deficient in 89.4% soils, but potassium was found adequate in 70.6% of soil

Spate Irrigation: Impact of Climate Change with Specific Reference to Pakistan

Climate change is an important term that mentions the variation in climate over time; it may be due to changes in natural events or due to human activities [26]. The climate change has greatly influenced Pakistan by frequent spells of extreme events of weather, i.e. floods, glacial lake outbursts, droughts, heat waves, etc. These extreme events have made Pakistan more vulnerable to climate change and also have killed many lives. The impact of climate change on Pakistan agriculture, economy, property, etc. is well documented [34]. The heavy flood of 2010 has alone killed 1600 people, caused damage of approximately \$10 billion and flooded 38,600

The freshwater resources of Pakistan are very small. The primary source of water is rainfall and it provides major as monsoon rains [36]. Climate change will affect the arid and hyperarid areas of Pakistan due to uncertain and erratic rainfall pattern. The rate of evapotranspiration will increase which will also enhance the

Spate irrigation and climate change are deeply intertwined, as the system in spate is wholly solely dependent on the rainfall and floods. The time and the magnitude of rainfall also matter. Mostly the timely rainfall received in monsoon and spring seasons are crucial for the summer and winter floods which are made useful for growing agricultural crops. Also the selection of crops in spate irrigation is

influenced by the time and magnitude of floods received, as there are limited options for the farmers of spate regarding selection of agriculture crops. Due to untimely rainfall either early or late, the cropping season is badly affected and may lead to a fallow season or low crop yield. The yield of wheat crop may be significantly

decreased by receiving greater rainfall, but marginal enhancement in the rainfall will not be going to have any considerable results of wheat [28]. Also the livestock may be affected by the climate change in two main ways, one by the reduction of fodder

Other climatic constraints under spate irrigation may be increased atmospheric temperatures which may lead to higher evaporation and severe moisture stressed conditions. More extreme condition may be recorded if heavy floods are received which may wear away the big embanked field and standing crops and erode the fertile soil. In Pakistan the communities which are found to be the most vulnerable to climate change are the subsistence farmers having the small landholdings [39].

and forage and second directly by the temperature intensity [38].

samples analyzed [30].

square kilometres (km<sup>2</sup>

111

4.3 Climate change: pros and cons

DOI: http://dx.doi.org/10.5772/intechopen.85889

) [35].

water requirement of crops by 10–30% [37].

#### 4.2 Soils

The soil of spate-irrigated area is usually rich soil with native soil fertility, and the sediments brought about through the floods replenish the fertility status. The texture of soil ranges between silty clay and silty clay loam, and these have greater water holding capacity due to fine size and may retain the moisture for a longer period of time [30]. It has been observed that most of the floods received during the monsoon season (July–August) are being allowed to infiltrate in the soil layers for 2–3 months, and the surface is mulched with the soil during the late summer when the temperature is still high, but the water is strongly held that it does not evaporate. The same moisture is used for cultivation in late October, and if no supplementary rains are received, the moisture is enough for the whole crop season till harvest. Changing climatic pattern will have great influence on the water resources and will also affect the soil resources [31]. Climatic model showed that the direct impact of climate change on soil properties may be the losses of soil carbon which will also affect other soil characteristics like poor soil structure, soil strength, water holding capacity, nutrient cycling and increase in soil erosion due to less soil cover [32]. The soil structure is an important soil property in the spate-irrigated area as it affects the movement of water and nutrients, growth of plants, exchange of gases and activities of soil fauna. The soil structure of spate soil is usually improved by the addition of organic matter with receiving of floods. As the temperature of soil increases the rate of organic matter, decomposition will also increase, and it will destroy the structure of soil. The water holding capacity of soil is also linked with the soil structure; the soil having good soil structure has greater water holding capacity. The water holding capacity of soil in dryland areas like spate irrigated is very important as the moisture is mostly stored in soil and the plants can efficiently use the moisture. The productive soil has the capacity to provide nutrients to the plants, but the nutrients' mobility is mainly concerned with the organic matter decomposition and availability of moisture. The soil of spate has native fertility, and it replenished with each flood, but under extreme drought the soil surface becomes scarce in vegetative cover, and the following floods may result in greater soil erosion. As there is open grazing, the threats towards the erosion both due to water and wind increase. The local farmers usually grow vegetable on the embankment to stabilize the structures. As the dry spell and temperature increase, the rate of evaporation exceeds the rainfall which may lead to salinity and sodicity. Sodicity is the excess amount of exchangeable sodium accumulated on the surface of the soil. Crust formation on the surface of the soil is a problem faced by different soils around the world [33]. The crust formation is also very common in the spateirrigated areas due to depositional and formational structure; this is due to the fact that the area of spate has the climate conducive to crust formation. The crust formation in spate-irrigated area may adversely affect the increase in the surface

Spate Irrigation: Impact of Climate Change with Specific Reference to Pakistan DOI: http://dx.doi.org/10.5772/intechopen.85889

runoff and reduction in the rate of infiltration into the soil. The crust formation reduces the germination of seedling and eventually results in the decline of crop yield. There are different solutions proposed for overcoming the problem of crust formation such as optimal tillage operations, application of manures, crop residue incorporation, mulching, seed sowing at appropriate depth, sowing on ridges, etc. Soil in this part of Pakistan is moderately to strongly calcareous with alkaline pH. Soils have sufficient potassium content and micronutrients but are mostly deficient in nitrogen and phosphorus. The fertility status of spate-irrigated soils of Dera Ismail Khan, Pakistan, in 87 soil samples collected from different locations and analyzed for various soil physico-chemical characteristics showed that 50% of the soil were of medium texture and 45.9% were clayey fine texture. There were very little soil with coarse texture (3.5%), and saturation percentage of the soil ranged between 16.2 and 67.0%; salinity and sodicity showed that 13.8% were saline, 5.8% were sodic and 74.7% were normal soils. The fertility status of the soils under investigation revealed that all the soils were deficient in nitrogen, while phosphorus was deficient in 89.4% soils, but potassium was found adequate in 70.6% of soil samples analyzed [30].

### 4.3 Climate change: pros and cons

4.1.3 Trees

4.2 Soils

110

The native trees in spate-irrigated area are Acacia nilotica,Tamarix aphylla, Capparis decidua, Prosopis cineraria, etc. which are common but found standing alone in a huge field. In the early 1900s, Prosopis juliflora (mesquite) was introduced in by Mian Musa Alvi the servant of Dak bangle; he was provided the seed by the English officer for his barren land to control the land degradation. This tree has the ability to spread faster and has now occupied the whole spate area, and every day eight to ten lorries of the fuelwood obtained from this tree have been sent to urban area and therefore have proven to support the labourer class in their daily life. Due

Irrigation - Water Productivity and Operation, Sustainability and Climate Change

The soil of spate-irrigated area is usually rich soil with native soil fertility, and the sediments brought about through the floods replenish the fertility status. The texture of soil ranges between silty clay and silty clay loam, and these have greater water holding capacity due to fine size and may retain the moisture for a longer period of time [30]. It has been observed that most of the floods received during the monsoon season (July–August) are being allowed to infiltrate in the soil layers for 2–3 months, and the surface is mulched with the soil during the late summer when the temperature is still high, but the water is strongly held that it does not evaporate. The same moisture is used for cultivation in late October, and if no supplementary rains are received, the moisture is enough for the whole crop season till harvest. Changing climatic pattern will have great influence on the water resources and will also affect the soil resources [31]. Climatic model showed that the direct impact of climate change on soil properties may be the losses of soil carbon which will also affect other soil characteristics like poor soil structure, soil strength, water holding capacity, nutrient cycling and increase in soil erosion due to less soil cover [32]. The soil structure is an important soil property in the spate-irrigated area as it affects the movement of water and nutrients, growth of plants, exchange of gases and activities of soil fauna. The soil structure of spate soil is usually improved by the addition of organic matter with receiving of floods. As the temperature of soil increases the rate of organic matter, decomposition will also increase, and it will destroy the structure of soil. The water holding capacity of soil is also linked with the soil structure; the soil having good soil structure has greater water holding capacity. The water holding capacity of soil in dryland areas like spate irrigated is very important as the moisture is mostly stored in soil and the plants can efficiently use the moisture. The productive soil has the capacity to provide nutrients to the plants, but the nutrients' mobility is mainly concerned with the organic matter decomposition and availability of moisture. The soil of spate has native fertility, and it replenished with each flood, but under extreme drought the soil surface becomes scarce in vegetative cover, and the following floods may result in greater soil erosion. As there is open grazing, the threats towards the erosion both due to water and wind increase. The local farmers usually grow vegetable on the embankment to stabilize the structures. As the dry spell and temperature increase, the rate of evaporation exceeds the rainfall which may lead to salinity and sodicity. Sodicity is the excess amount of exchangeable sodium accumulated on the surface of the soil. Crust formation on the surface of the soil is a problem faced by different soils around the world [33]. The crust formation is also very common in the spateirrigated areas due to depositional and formational structure; this is due to the fact that the area of spate has the climate conducive to crust formation. The crust formation in spate-irrigated area may adversely affect the increase in the surface

to the rapid spread of mesquite, other tree species have reduced.

Climate change is an important term that mentions the variation in climate over time; it may be due to changes in natural events or due to human activities [26]. The climate change has greatly influenced Pakistan by frequent spells of extreme events of weather, i.e. floods, glacial lake outbursts, droughts, heat waves, etc. These extreme events have made Pakistan more vulnerable to climate change and also have killed many lives. The impact of climate change on Pakistan agriculture, economy, property, etc. is well documented [34]. The heavy flood of 2010 has alone killed 1600 people, caused damage of approximately \$10 billion and flooded 38,600 square kilometres (km<sup>2</sup> ) [35].

The freshwater resources of Pakistan are very small. The primary source of water is rainfall and it provides major as monsoon rains [36]. Climate change will affect the arid and hyperarid areas of Pakistan due to uncertain and erratic rainfall pattern. The rate of evapotranspiration will increase which will also enhance the water requirement of crops by 10–30% [37].

Spate irrigation and climate change are deeply intertwined, as the system in spate is wholly solely dependent on the rainfall and floods. The time and the magnitude of rainfall also matter. Mostly the timely rainfall received in monsoon and spring seasons are crucial for the summer and winter floods which are made useful for growing agricultural crops. Also the selection of crops in spate irrigation is influenced by the time and magnitude of floods received, as there are limited options for the farmers of spate regarding selection of agriculture crops. Due to untimely rainfall either early or late, the cropping season is badly affected and may lead to a fallow season or low crop yield. The yield of wheat crop may be significantly decreased by receiving greater rainfall, but marginal enhancement in the rainfall will not be going to have any considerable results of wheat [28]. Also the livestock may be affected by the climate change in two main ways, one by the reduction of fodder and forage and second directly by the temperature intensity [38].

Other climatic constraints under spate irrigation may be increased atmospheric temperatures which may lead to higher evaporation and severe moisture stressed conditions. More extreme condition may be recorded if heavy floods are received which may wear away the big embanked field and standing crops and erode the fertile soil. In Pakistan the communities which are found to be the most vulnerable to climate change are the subsistence farmers having the small landholdings [39].

Growth of crop is highly affected by the amount of water and changes in temperature; according to an estimate, the increase in temperature by 0.5–2.5°C the agriculture productivity of the crop will decline by 8–10%, and this is estimated to be the case by year 2040 [40]. The crop growth simulation model showed that the length of growing season of major crops, i.e. wheat and rice, will decrease which will result in the decrease in yield of crop. Also the climate change projection provided by the Intergovernmental Panel on Climate Change (IPCC) states that the productivity of agriculture crop in Asia is bound to decline due to heat stress and the floods and drought tend to increase.

information of all the villages, labour and also the land. Also an official was responsible for the execution of these rules, urging the farmers to rebuild the embankments and plug the eroded gullies. As according to the flood water distribution rules in Pakistan in the main riverine, the concrete structure is not allowed. Only the earthen structure is allowed; the Department of Agriculture Engineering used to provide the machinery as bulldozers, etc. for the construction of large structure which were strong enough to face the strong flood, but after the closing of agriculture engineering department, the farmers construct the structure on their own through contribution. The place for construction of structure is already demarcated; they are constructed each year on the same place. As floods are unpredictable, often the structure in the upstream is not built at proper time, so the floods make their way to the mid-stream and tail. Also the surplus water is allowed to flow to the tail after breaching of the structures. The amount or depth of irrigation to be applied is not confined; usually the farmer shows voracity in water storage, which leads to breaking of bunds, and sometimes the farmer has to remove the excess water so that

Spate Irrigation: Impact of Climate Change with Specific Reference to Pakistan

DOI: http://dx.doi.org/10.5772/intechopen.85889

the soil may come to field capacity on time for sowing of crops. In the spate irrigation rules, the farmer is allowed to irrigate for the second time if all the other fields in the area have been irrigated. But factually it is not practiced, because the influential irrigate sometimes more than two times while the tail area does not receive a drop of water. Also the number of irrigation depends on the amount of water being received after the flood. As the climatic pattern is changing, the floodbased system is also changing with severe floods in some of the years and drought in other years. The conflicts may become even worse due to water distributions with

Perennial water is another source of water in the spate irrigation. This water is locally called as Kala Pani; it is received throughout the year in the riverine through the streams. Like the land there is ownership for irrigation water. At watershed level the water is distributed amongst the different tribes living there. If we consider the example of Chodhwan Zam (watershed), the largest watershed in Dera Ismail Khan District, the perennial water is distributed between the Babar and Mina Khel tribes as 7:5. These are distributed through a unit locally called Boli. There are 10.5 Boli in the share of Babar tribes, which is again distributed as 1 for orchards, 1.5 for drinking and 8 for raising crops. Each boli is divided amongst the Babar subtribe or sub-cast. These casts are Musazai, Mardanzai, Badanzai, Shakarzai, Ahmad Khel, Ibrahimzai, Safarzai and Mangalzai. Each has single Boli. Each Boli is again divided into 18–20 wails, and in each wail there are 16 churukas. To make it understandable, 1 churuka means irrigation for 45 minutes depending on the amount of water. The water rights for the perennial water are different than flood water. The water in perennial system flows throughout the year. There are a number of crops that can be grown on perennial water. The perennial water may be used for irrigation on any land depending on its availability. Usually they are grown in the areas where they do not have the flood water rights. The tenure system in the perennial irrigating

land is usually 7:5 for the land and water owner and the tenant.

Climatic sway has greatly influenced the perennial water as there is less rain during some of the years which may result in less water for recharging of streams and less water for perennial. Also during the flood season, the perennial water which mixes into the flood water as the riverine for both the flood and perennial water is the same. Also the farmers in spate are turning towards digging of tube wells, and some of them have been artesian well. Due to the extensive use of these

change in rainfall and flood patterns.

4.4.2 Perennial water

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