**2. Karkheh River Basin characteristics**

*Multifunctionality and Impacts of Organic and Conventional Agriculture*

Challenge Program on Water and Food (CPWF<sup>1</sup>

migration rate [16].

of Iran.

(WANA) region.

project in KRB.

Francisco, Volta, and Karkheh River Basin.

In the upper KRB, the dryland agriculture prevails. The challenges for the rural households in such areas are similar to the ones in other dryland areas, i.e., agricultural options are limited, and wheat, barely, and pulses are dominant cropping patterns in the landscape. Agricultural outputs are usually low and unstable, due mainly to the resource degradation, drought spells, and climate change impacts [16]. Irregular rainfall on poorly vegetated hill slopes results in severe soil erosion, downstream flooding, and sedimentation. Consequently, the lifetime of the Karkheh Reservoir Dam in the downstream basin is dwindling rapidly. These environmental constraints combined with their economic problems make this southwest corner of Iran one of the poor areas of the country with a high out-

KRB had been selected as one of the nine benchmark basins of the CGIAR

projects focuses on interventions for the improvement of on-farm agricultural WP in KRB. This project was carried out jointly by the International Center for Agricultural Research in the Dry Areas (ICARDA) and Agricultural Research, Education and Extension Organization (AREEO) of Iran. The objectives of the project were to develop biophysical interventions to improve the farm and basin level of WP and sustainable management of the natural resources and to develop appropriate policies and institutions supporting the project interventions to help the poor communities for the improvement of their income and livelihoods. Moreover, the project aimed at strengthening and enhancing the capacity of the National Agricultural Research and Extension Systems (NARES)

KRB is becoming a water-scarce area, and droughts and climate change are becoming permanent features of this region. Because of water scarcity and degradation of land and water resources, livelihoods of rural communities are at stake. With the current rate of deterioration of natural resources if no remediation is taken, the situation will worsen in the near future. However, there are great potentials for the improvement of land and water productivities in the KRB. Therefore KRB was well adapted to be a pilot area for the development-oriented research activities to be implemented under Phase 1 of CGIAR Challenge Program on Water and Food (CPWF). KRB situation provided a unique opportunity for the CPWF to make an impact through improvements in land and water productivities, which in turn will improve the livelihoods of rural poor living in this basin. The issues of KRB have a great similarity with other basins located in the similar hydrological conditions, e.g., West Asia and North Africa

This chapter provides an overview of the soil and water potential of the L-KRB

<sup>1</sup> The Challenge Program on Water and Food (CPWF) is one of the pilot programs designed to reinvent the business model for the CGIAR. The CPWF was launched in 2002 as a reform initiative of the CGIAR, the Consultative Group on International Agricultural Research. CPWF aims to increase the resilience of social and ecological systems through better water management for food production (crops, fisheries, and livestock). CPWF does this through an innovative research and development approach that brings together a broad range of scientists, development specialists, policymakers, and communities to address the challenges of food security, poverty, and water scarcity. CPWF Phase 1 worked in nine river basins globally: Andean system of basins, Indo-Gangetic, Limpopo, Mekong, Nile River, Yellow River, Sao

and the salinity and waterlogging constraints to agricultural production and agricultural WP improvement under saline areas of L-KRB. The findings are mostly based on the research results conducted during the CPWF Phase 1 comprehensive

). One of the CPWF Phase 1

**178**

KRB is located in the west to southwest of Zagros ranges in Iran (**Figure 1**). It is located between 56°, 34′–58°, 30′ north latitude and 46°, 06′–49°, 10′ longitude. The area of the basin (inside Iran) is 50,764 square kilometers (km2 ). Out of which 27,645 km2 are mountains and 23,119 km2 are plains and hills. The mountainous areas of KRB are mostly in the eastern and central parts. The plains are mostly in the northern and southern parts and cover almost 45% of the basin area. Hypsometric studies indicate that 75% of the basin is located in altitudes of 1000–2000 and 0.6% of the basin is above 2500 m altitude.

The Karkheh River arises from the confluence of numerous large and small tributaries including the three large rivers, namely, Gamasiyab, Ghareh-So, and Kashkan. The Karkheh River has various names along its route and is locally best known as the Saymareh River at the point where the Gamasiyab and Ghareh-So Rivers combine, and later the point where the Kashkan River flows into the main waterway is known as the Karkheh River. When approaching to the Khuzestan province hypsometric and slope of the basin decrees and gently the river ultimately flows into the Hawr-al-Azim (HAA) wetland at the basin outlet. Therefore KRB could be classified as a closed basin.

Based on general hydrological classification of basins in Iran, the KRB is considered as one of the sub-basins of the Persian Gulf Great Basin.

The pattern of precipitation in KRB is affected by Mediterranean regime. It means that the dry season is coinciding with summer and rainy season match with cold months. The rainfall distribution in the basin is very scatter, but most of the rain falls in winter and autumn seasons. The annual precipitation of the basin is 219 mm in Hamidieh (in L-KRB) to 765 mm in the northern dryland farming areas (in upper KRB).

Based on climatic maps, the hottest areas of the basin are located in its southern parts (L-KRB) and are surrounded by the 25°C iso-temperature (isohyets) contours. The coldest areas of the basin are located in altitude higher than 3000 m and are mostly located in the north and northeast of the basin and are surrounded by the 5°C isohyets' contour map.

Evaporation in KRB varies between 1800 and 3600 mm depending on the altitude. For example, it is around 3561 mm in Abdul-Khan Station in an altitude of 40 m in L-KRB. Almost 79% of annual evaporation occurs from May to September.

**Figure 1.** *Geographical location and boundaries of KRB.*

In KRB both surface and groundwater resources are used. Based on data, in 1994, the share of total agricultural water uses from both resources was 3.92 BCM. The agricultural water consumption till completion of the ongoing water works could be increased to 7.43 BCM (90% increase).

The water resources of the basin in general have a good quality. However, the quality of groundwater in the Southern plains deteriorates to some extent. The potential of surface water resources of KRB is 7.4 BCM. In wet years it can be doubled, and in dry years, it can be reduced to half. Agricultural water withdrawn in KRB is 3.96 BCM (in year 1994). Out of which 36.8% is supplied from groundwater and 63.2% is supplied from surface water resources.

Plains of L-KRB are the highest consumer of surface water resources. Based on year 1994 statistics, out of different plains of KRB, Azadegan plain (Dasht-e Azadegan, DA) with 662 MCM water consumption is the greatest consumer of water in the basin. This plain also is the greatest consumer (660.2 MCM) of surface water in the basin.

Based on year 1994 statistics, out of 4157.4 MCM consumed water resources, 2504.6 MCM (60.2%) were from surface water, and 1653 MCM (39.8%) from groundwater resources. Out of the total consumption, share of rural, urban, industry and mining, and fishery consumptions was 1.23, 3.93, 0.32, and 0.35 BCM, respectively. The share of agricultural water uses this year was 94.2%. The share of agricultural water consumption in the basin is the highest. The sums of industrial and mining consumptions are very low and just consist 0.32% of total water consumptions. Therefore, from the aspects of water resources' uses, the KRB could be defined as an agricultural basin.

Two major agricultural production systems prevail in the KRB. The dryland system prevails in the upstream areas (upper KRB), while the fully irrigated areas are located in some part of upstream and mainly in downstream of the KRB (L-KRB). The dryland areas are well established and cover most of the basin agricultural lands, occupying 894,125 ha, whereas irrigated lands occupy 578,862 ha but are expected to expand up to 340,000 ha following the completion of irrigation and drainage networks under Karkheh reservoir Dam [16].

Owing to the different flowing rivers, abundant water resources, fertile lands, and sufficient extraterrestrial energy, Khuzestan province in the southwest Iran is one of the potentially most suitable regions for agricultural production. However, salinization of land and water resources has become a serious threat to the efficient use of agricultural lands. It is estimated that out of the total 6.7 Mha of the province, 1.2–1.5 Mha (18–22% of total area) are faced with the conjunctive problems of soil salinization and waterlogging [16].

The next agricultural production system in the KRB is irrigated agriculture. It is estimated that about 1 Mha of land are irrigable in KRB. Out of which about 380,000 ha are currently under cultivation [16]. About 340,000 ha of additional available arable lands will be brought under irrigation following the completion of irrigation and drainage networks under Karkheh Reservoir in L-KRB [16].

The drainage outlet of the KRB is the HAA wetland along with the Iran-Iraq border (**Figure 2**). At present, there are very limited modern irrigation and drainage networks under operation within the L-KRB. However, the networks are under completion, and irrigated agriculture is developing gradually [17]. The government has started construction of irrigation and drainage networks, especially on the tertiary canal level, with the goal of improving on-farm water management and modernization of traditional irrigation networks. The focuses of these activities are the arable lands under the Karkheh Reservoir and in pilot projects such as DA plains in the southern parts of the L-KRB (**Figure 2**).

**181**

improvement.

**Figure 2.**

area [16].

during flood periods.

efficiencies of irrigated lands in the area.

*Water Productivity Improvement Under Salinity Conditions: Case Study of the Saline Areas…*

In the L-KRB because of the differences in factors affecting agricultural WP in the northern and southern parts, two distinct regions can be identified. In the northern part, there are no serious limiting factors in regard to soil and water quality. In this part improving farmer's skills and use of appropriate farming systems can improve WP sufficiently. Shortfalls in water supply and excess irrigation water losses, mainly in earthen canals, cause low WPs of cultivated crops in this area. Extension of new farming systems, e.g., pressurized irrigation and land preparation methods (e.g., raised-bed and double-row cropping systems, etc.), could be some useful approaches for improving WP in the area. Overall in this part, successful introduction and implementation of new farming systems and technologies in accordance with other agricultural services could be effective ways for crop WP

*Karkheh River Basin (KRB) and Dasht-e-Azadegan (DA) region in the L-KRB.*

In the southern parts of L-KRB, heavy soil texture and subsurface water recharge from upstream areas cause natural condition for waterlogging. This situation is more induced by deep percolation losses resulting from low irrigation

The available soil data indicate that the majority of arable lands in L-KRB possess with various degrees of limitations. However, soil salinity, waterlogging, lack of soil organic matter, soil structural deterioration, intrinsic low permeability, and low infiltration rate caused by soil compaction are the main factors limiting economic and sustainable crop production of the irrigated lands in this

Waterlogging and soil salinity are the main causes of inefficiencies in achiev-

L-KRB. Major factors causing soil salinization in the L-KRB could be classified as follows [18–20]: shallow water table, existence of salt containing soil layers, inadequate natural drainage, inadequate artificial drainage networks, high evaporation demand of the climate, salt intrusions by wind, and salty sediment transport

In the southern parts of L-KRB, mainly DA plain, available data and surveys show that the problem of soil salinity is intensified because of deficiencies in farm-

In general, the main cause of soil salinity in the L-KRB is high water table which is often less than below 2.0 m from soil surface and usually varies between 1.2 and 3.0 m below the soil surface. If sufficient developments of drainage networks are not provided, the problem will be worsened considering the coming development

ing high WPs and are threats to sustainable agricultural production in the

ers' knowledge and skills and lack of new and improved farming practices.

plans with the aim of expansion of new irrigation networks.

*DOI: http://dx.doi.org/10.5772/intechopen.86891*

*Water Productivity Improvement Under Salinity Conditions: Case Study of the Saline Areas… DOI: http://dx.doi.org/10.5772/intechopen.86891*

**Figure 2.** *Karkheh River Basin (KRB) and Dasht-e-Azadegan (DA) region in the L-KRB.*

In the L-KRB because of the differences in factors affecting agricultural WP in the northern and southern parts, two distinct regions can be identified. In the northern part, there are no serious limiting factors in regard to soil and water quality. In this part improving farmer's skills and use of appropriate farming systems can improve WP sufficiently. Shortfalls in water supply and excess irrigation water losses, mainly in earthen canals, cause low WPs of cultivated crops in this area. Extension of new farming systems, e.g., pressurized irrigation and land preparation methods (e.g., raised-bed and double-row cropping systems, etc.), could be some useful approaches for improving WP in the area. Overall in this part, successful introduction and implementation of new farming systems and technologies in accordance with other agricultural services could be effective ways for crop WP improvement.

In the southern parts of L-KRB, heavy soil texture and subsurface water recharge from upstream areas cause natural condition for waterlogging. This situation is more induced by deep percolation losses resulting from low irrigation efficiencies of irrigated lands in the area.

The available soil data indicate that the majority of arable lands in L-KRB possess with various degrees of limitations. However, soil salinity, waterlogging, lack of soil organic matter, soil structural deterioration, intrinsic low permeability, and low infiltration rate caused by soil compaction are the main factors limiting economic and sustainable crop production of the irrigated lands in this area [16].

Waterlogging and soil salinity are the main causes of inefficiencies in achieving high WPs and are threats to sustainable agricultural production in the L-KRB. Major factors causing soil salinization in the L-KRB could be classified as follows [18–20]: shallow water table, existence of salt containing soil layers, inadequate natural drainage, inadequate artificial drainage networks, high evaporation demand of the climate, salt intrusions by wind, and salty sediment transport during flood periods.

In the southern parts of L-KRB, mainly DA plain, available data and surveys show that the problem of soil salinity is intensified because of deficiencies in farmers' knowledge and skills and lack of new and improved farming practices.

In general, the main cause of soil salinity in the L-KRB is high water table which is often less than below 2.0 m from soil surface and usually varies between 1.2 and 3.0 m below the soil surface. If sufficient developments of drainage networks are not provided, the problem will be worsened considering the coming development plans with the aim of expansion of new irrigation networks.

*Multifunctionality and Impacts of Organic and Conventional Agriculture*

works could be increased to 7.43 BCM (90% increase).

ter and 63.2% is supplied from surface water resources.

drainage networks under Karkheh reservoir Dam [16].

water in the basin.

be defined as an agricultural basin.

salinization and waterlogging [16].

in the southern parts of the L-KRB (**Figure 2**).

In KRB both surface and groundwater resources are used. Based on data, in 1994, the share of total agricultural water uses from both resources was 3.92 BCM. The agricultural water consumption till completion of the ongoing water

The water resources of the basin in general have a good quality. However, the quality of groundwater in the Southern plains deteriorates to some extent. The potential of surface water resources of KRB is 7.4 BCM. In wet years it can be doubled, and in dry years, it can be reduced to half. Agricultural water withdrawn in KRB is 3.96 BCM (in year 1994). Out of which 36.8% is supplied from groundwa-

Plains of L-KRB are the highest consumer of surface water resources. Based on year 1994 statistics, out of different plains of KRB, Azadegan plain (Dasht-e Azadegan, DA) with 662 MCM water consumption is the greatest consumer of water in the basin. This plain also is the greatest consumer (660.2 MCM) of surface

Based on year 1994 statistics, out of 4157.4 MCM consumed water resources, 2504.6 MCM (60.2%) were from surface water, and 1653 MCM (39.8%) from groundwater resources. Out of the total consumption, share of rural, urban,

industry and mining, and fishery consumptions was 1.23, 3.93, 0.32, and 0.35 BCM, respectively. The share of agricultural water uses this year was 94.2%. The share of agricultural water consumption in the basin is the highest. The sums of industrial and mining consumptions are very low and just consist 0.32% of total water consumptions. Therefore, from the aspects of water resources' uses, the KRB could

Two major agricultural production systems prevail in the KRB. The dryland system prevails in the upstream areas (upper KRB), while the fully irrigated areas are located in some part of upstream and mainly in downstream of the KRB (L-KRB). The dryland areas are well established and cover most of the basin agricultural lands, occupying 894,125 ha, whereas irrigated lands occupy 578,862 ha but are expected to expand up to 340,000 ha following the completion of irrigation and

Owing to the different flowing rivers, abundant water resources, fertile lands, and sufficient extraterrestrial energy, Khuzestan province in the southwest Iran is one of the potentially most suitable regions for agricultural production. However, salinization of land and water resources has become a serious threat to the efficient use of agricultural lands. It is estimated that out of the total 6.7 Mha of the province, 1.2–1.5 Mha (18–22% of total area) are faced with the conjunctive problems of soil

The next agricultural production system in the KRB is irrigated agriculture.

The drainage outlet of the KRB is the HAA wetland along with the Iran-Iraq border (**Figure 2**). At present, there are very limited modern irrigation and drainage networks under operation within the L-KRB. However, the networks are under completion, and irrigated agriculture is developing gradually [17]. The government has started construction of irrigation and drainage networks, especially on the tertiary canal level, with the goal of improving on-farm water management and modernization of traditional irrigation networks. The focuses of these activities are the arable lands under the Karkheh Reservoir and in pilot projects such as DA plains

It is estimated that about 1 Mha of land are irrigable in KRB. Out of which about 380,000 ha are currently under cultivation [16]. About 340,000 ha of additional available arable lands will be brought under irrigation following the completion of irrigation and drainage networks under Karkheh Reservoir in

**180**

L-KRB [16].

The total rainfall in Susangerd and Bostan towns' climatological stations are 180 and 200 millimeter, respectively. The agricultural service centers also are equipped with rain gauges.

Current crops in Azadegan Plain in southern L-KRB include cereals (such as wheat, barely, rice), vegetables (such as melon, watermelon, tomato, cucumber, eggplant, okra, lettuce, cabbage, carrot, radish, onion, etc.), grains such as beans, and fodder crops (such as alfalfa, barely, maize, and sorghum). More than 78% of agricultural production in Azadegan Plain is dominated by grains, mainly wheat and barley [16, 21]. This is because of soil salinity and sodicity with high toxic elements which makes serious limitation for cultivation of other crops. Currently water supply limitations, agriculture economy (guaranteed purchase of with by the government), and security problems in the region (wheat need less labor, less irrigation, and in overall less need for the stay of farmer in his land) are some other reasons for the farmers' higher interests on wheat cultivation.

The main challenge of agriculture in this region is waterlogging and soil salinity. Waterlogging and secondary soil salinization occur in a certain period of the year. For example, early November is planting date of wheat cultivation system in DA. Late November is the first irrigation for land preparation, and the harvest time is in late May. Deep percolation losses of irrigation during this period cause rises in water table. The peak of water table rise is in February. The salinity [Electrical conductivity (EC)] of shallow groundwater and EC of irrigation water in this area are about 6–9 and 3 dS/m, respectively. The highest depth of water table depth is between 0 and 1.2 m. Operation of main drains has started in recent decade (in 2003), and their outlet is HAA Wetland in the border of Iran-Iraq [16].
