*4.2.6 Bamboo based bio-engineering measures*

The bamboo based bio-engineering measures is found as an effective means for natural resource conservation in ravines [14, 15]. The soil erosion is found comparatively less in bamboo plantations (178 kg ha−1) compared with other forest plantation [16]. The significant stem flow and funneling ratio of bamboo plants provides better opportunity for rainfall absorption in degraded ravine lands [17]. Bamboo also acts as a vegetative barrier and filter for silt laden runoff flowing in gullies. The bamboo induces silt deposition and reduces the velocity of flowing water along bare river banks and deforested areas in ravines. *Dendrocalamus strictus* which occupies major area covered under bamboo plantation in India was found best for economic utilization of ravines. It is reported that annually about 4000 culms of bamboo per hectare can be harvested from ravine lands [18]. The benefit–cost ratio of 1.98 from bamboo plantation in ravines is profitable having an economic return of 19.3% over a period of 20 years [19]. The intangible benefits of carbon sequestration and prevention of soil erosion are supplementary. The ravine lands under the bamboo plantation increased the soil pH, organic carbon along with reduced runoff [20].

#### **4.3 Forestry and agroforestry measures for management of ravines**

The engineering measures are expensive and also needs technical acquaintance for proper designing and execution for management of ravines. The medium and deep gullies of ravine needs permanent vegetative cover having deep root system to bind the soil against strong forces of erosion in gullies during rainy season. The afforestation and agroforestry are relatively cheaper and affective in checking the soil erosion in medium and deep gullies. The performance of various afforestation and agroforestry system evaluated in ravine developed along the Mahi River in Western India is discussed below.

#### *4.3.1 Afforestation*

Afforestation is an important tool to mitigate land degradation due to soil erosion. Afforestation in ravine land provides ecosystem provisioning services i.e. fodder, timber, fuel, non-timber forest product, medicine and gum; regulating services i.e. nutrient cycling, controlling soil erosion, moderating climate,

**187**

*Ecological Engineering Measures for Ravine Slope Stabilization and Its Sustainable Productive…*

Agroforestry is perennial and annuals plants combination that enhances landscape productivity and conserve natural resources. Agroforestry measures particularly for soil conservation have shown great potential in enhancing productivity of ravine lands [5, 22]. *Prosopis cineraria*, *Acacia leucophloea* and other regional multipurpose trees (MPT's) grown on field boundaries in Gujarat state of Western India. Sometime negative effect on crops may also occur due to competition for light, moisture and nutrients between the trees and crops. The combinations of *Dendrocalamus strictus*+*Cenchrus ciliarus* was also found successful in ravine slopes. *Dendrocalamus strictus*+*Cenchrus ciliarus* the reduced sediment yield 10–20 times less, compared to area without plantation [19]. *Moringa oleifera* and *Embilca officinalis* based agri-horticultural systems were also found effective in enhancing land productivity, conserving natural resources and improving soil health. Soil and water conservation measures (SWCM) also helps to improve agroforestry trees survival and growth due to improved soil moisture and reduced soil erosion. in an agroforestry experiment observed that Cowpea + Castor cultivation in between

carbon sequestration; supporting service i.e. net primary production, soil formation and cultural services, recreation [3, 4]. The vegetation exploration in ravine shows the dominance of flora like *Azadirachta indica*, *Acacia nilotica* and *Prosopis cineraria*. In ravine gully head, there is predominance of *Prosopis cineraria*, *Acacia nilotica*, *Acacia senegal*, *Azadirachta indica*, *Holoptelia integrifolia*, *Feronia elephantum* and *Balanites roxbyrghii*. In ravine gully slope, there is equal distribution of *Acacia nilotica*, *Acacia senegal*, *Azadirachta indica* and *Prosopis cineraria*, followed by *Holoptelia integrifolia* and *Salmalia*. In bottom of ravine gully beds, there is predominance of *Holoptelia* species, *Acacia* species, *Azadirachta indica*, *Anogeissus latifolia* and *Balanites roxburghii*. Artificial regeneration results indicated the dominance of *Acacia nilotica* followed by the *Azadirachta indica*. The other dominant species were *Prosopis cineraria*, *Holoptelia integrifolia*, *Salmalia malabaricum* and *Anogiessus* species. *Acacia nilotica* attained diameter at breast height (DBH) between 19.6 cm and 28 cm in the Mahi ravines of Western India after 28 years. Semi-arid edaphically degraded soils in ravine lands are dominated by low value thorny trees and the plantation of well adapted and commercially important tree species is utmost important in such lands for obtaining higher ecological and economic benefits. In fact, the effective forest cover is less than 10%, causing shortage of fuel, fodder and timber wood in the area and further minimum 50% forest cover is required to prevent the land degradation. Therefore in such conditions maintenance of continuous canopy covers is extremely important to check soil erosion. *Eucalyptus tereticornis* and *Leuceana leucocephala* was found to be a fast growing tree species and is in much demand especially in the industries [10]. Plantation of bamboo (*Dendrocalamus strictus*) was found highly effective in enhancing vegetation cover, preventing soil erosion and stabilization of ravine slopes [21]. The uncontrolled grazing in ravines accelerates soil erosion which cannot be completely stopped. Therefore a system of restricted and rotational grazing may be helpful to some extent. In ravines, huge gap exists between the demand and supply for timber wood, and sustainable utilization of ravine land can reduce the demand–supply gap. Promotion of awareness and encouragement of tree planting on individual farm land can considerably improve the regional ecology and economy of the local people. These measures also help to improve soil carbon stock that may positively influences soil physical, chemical and biological property, improving the overall

*DOI: http://dx.doi.org/10.5772/intechopen.94136*

productivity of such ecosystem.

*4.3.2 Agroforestry*

*Ecological Engineering Measures for Ravine Slope Stabilization and Its Sustainable Productive… DOI: http://dx.doi.org/10.5772/intechopen.94136*

carbon sequestration; supporting service i.e. net primary production, soil formation and cultural services, recreation [3, 4]. The vegetation exploration in ravine shows the dominance of flora like *Azadirachta indica*, *Acacia nilotica* and *Prosopis cineraria*. In ravine gully head, there is predominance of *Prosopis cineraria*, *Acacia nilotica*, *Acacia senegal*, *Azadirachta indica*, *Holoptelia integrifolia*, *Feronia elephantum* and *Balanites roxbyrghii*. In ravine gully slope, there is equal distribution of *Acacia nilotica*, *Acacia senegal*, *Azadirachta indica* and *Prosopis cineraria*, followed by *Holoptelia integrifolia* and *Salmalia*. In bottom of ravine gully beds, there is predominance of *Holoptelia* species, *Acacia* species, *Azadirachta indica*, *Anogeissus latifolia* and *Balanites roxburghii*. Artificial regeneration results indicated the dominance of *Acacia nilotica* followed by the *Azadirachta indica*. The other dominant species were *Prosopis cineraria*, *Holoptelia integrifolia*, *Salmalia malabaricum* and *Anogiessus* species. *Acacia nilotica* attained diameter at breast height (DBH) between 19.6 cm and 28 cm in the Mahi ravines of Western India after 28 years. Semi-arid edaphically degraded soils in ravine lands are dominated by low value thorny trees and the plantation of well adapted and commercially important tree species is utmost important in such lands for obtaining higher ecological and economic benefits. In fact, the effective forest cover is less than 10%, causing shortage of fuel, fodder and timber wood in the area and further minimum 50% forest cover is required to prevent the land degradation. Therefore in such conditions maintenance of continuous canopy covers is extremely important to check soil erosion. *Eucalyptus tereticornis* and *Leuceana leucocephala* was found to be a fast growing tree species and is in much demand especially in the industries [10]. Plantation of bamboo (*Dendrocalamus strictus*) was found highly effective in enhancing vegetation cover, preventing soil erosion and stabilization of ravine slopes [21]. The uncontrolled grazing in ravines accelerates soil erosion which cannot be completely stopped. Therefore a system of restricted and rotational grazing may be helpful to some extent. In ravines, huge gap exists between the demand and supply for timber wood, and sustainable utilization of ravine land can reduce the demand–supply gap. Promotion of awareness and encouragement of tree planting on individual farm land can considerably improve the regional ecology and economy of the local people. These measures also help to improve soil carbon stock that may positively influences soil physical, chemical and biological property, improving the overall productivity of such ecosystem.

#### *4.3.2 Agroforestry*

*Slope Engineering*

*4.2.5 Trenching*

the deep ravine slopes [11].

Western India is discussed below.

*4.3.1 Afforestation*

*4.2.6 Bamboo based bio-engineering measures*

The impact of trenching in deep ravines was evaluated ravines developed along the Mahi River in Western India. The staggered contour trenches were designed based on maximum daily rainfall. The trenching density on the ravine slopes was kept to retain 30, 50 and 80% of runoff generated from the ravine catchment. A substantial reduction in runoff was observed for treatments with higher trench densities (50% and 80%) as compared to 30%. The sediment yield in different trench densities also followed the similar trend. The soil moisture was more or less similar in different trench densities just followed by the monsoon. However, soil moisture in the 80% trench density was highest and also remains for a longer period in the lower reaches of the ravine slopes. The survival of Neem (*Azadirachta indica*) saplings planted at a spacing of 6 m × 6 m was also recorded and was also found highest in 80% trench density. In another study, the trenching of size 2 m × 0.5 m × 0.5 m at 14% uniform slope with Sapota plantation resulted in decrease in runoff by 16% and soil loss by 15% along with enhanced tree growth, biomass and carbon stock in

The bamboo based bio-engineering measures is found as an effective means for natural resource conservation in ravines [14, 15]. The soil erosion is found comparatively less in bamboo plantations (178 kg ha−1) compared with other forest plantation [16]. The significant stem flow and funneling ratio of bamboo plants provides better opportunity for rainfall absorption in degraded ravine lands [17]. Bamboo also acts as a vegetative barrier and filter for silt laden runoff flowing in gullies. The bamboo induces silt deposition and reduces the velocity of flowing water along bare river banks and deforested areas in ravines. *Dendrocalamus strictus* which occupies major area covered under bamboo plantation in India was found best for economic utilization of ravines. It is reported that annually about 4000 culms of bamboo per hectare can be harvested from ravine lands [18]. The benefit–cost ratio of 1.98 from bamboo plantation in ravines is profitable having an economic return of 19.3% over a period of 20 years [19]. The intangible benefits of carbon sequestration and prevention of soil erosion are supplementary. The ravine lands under the bamboo plantation increased the soil pH, organic carbon along with reduced runoff [20].

**4.3 Forestry and agroforestry measures for management of ravines**

The engineering measures are expensive and also needs technical acquaintance for proper designing and execution for management of ravines. The medium and deep gullies of ravine needs permanent vegetative cover having deep root system to bind the soil against strong forces of erosion in gullies during rainy season. The afforestation and agroforestry are relatively cheaper and affective in checking the soil erosion in medium and deep gullies. The performance of various afforestation and agroforestry system evaluated in ravine developed along the Mahi River in

Afforestation is an important tool to mitigate land degradation due to soil erosion. Afforestation in ravine land provides ecosystem provisioning services i.e. fodder, timber, fuel, non-timber forest product, medicine and gum; regulating services i.e. nutrient cycling, controlling soil erosion, moderating climate,

**186**

Agroforestry is perennial and annuals plants combination that enhances landscape productivity and conserve natural resources. Agroforestry measures particularly for soil conservation have shown great potential in enhancing productivity of ravine lands [5, 22]. *Prosopis cineraria*, *Acacia leucophloea* and other regional multipurpose trees (MPT's) grown on field boundaries in Gujarat state of Western India. Sometime negative effect on crops may also occur due to competition for light, moisture and nutrients between the trees and crops. The combinations of *Dendrocalamus strictus*+*Cenchrus ciliarus* was also found successful in ravine slopes. *Dendrocalamus strictus*+*Cenchrus ciliarus* the reduced sediment yield 10–20 times less, compared to area without plantation [19]. *Moringa oleifera* and *Embilca officinalis* based agri-horticultural systems were also found effective in enhancing land productivity, conserving natural resources and improving soil health. Soil and water conservation measures (SWCM) also helps to improve agroforestry trees survival and growth due to improved soil moisture and reduced soil erosion. in an agroforestry experiment observed that Cowpea + Castor cultivation in between

Sapota trees may induce soil loss on ravine slope [3]. Supporting native or improved perennial grasses instead of crops may be a better option to reduce the soil erosion. Most researchers have concluded that incorporating trees in agriculture landscape conserve soil and water resources in ravine lands. In these conditions, extreme weather condition also affects plant growth and productivity and hence crop failure is a big problem. Tree-crop combinations system can be win-win situation in these climatically and edaphically venerable degraded agro-ecosystem. Tree and grass systems are also considered to be more resilient compared to crops during extreme weather conditions. Incorporating trees agriculture system also results in higher carbon stock and sequesters maximum carbon, compared to sole cropping systems. The CO2 mitigation in agroforestry is approximately 11–41% higher compared to sole cropping systems. The farmers in ravine should shift from annual crops to perennial plantations to conserve soil resources, avoid risk of crop failure and mitigate climate change. Moreover, a properly managed agroforestry systems can moderate/improve climatic conditions, conserve soil and water resources, improve ecosystems services and absorb atmospheric GHG's in ravine lands. This suggested agroforestry based farming systems should be preferred globally in degraded ravine agro-ecosystems.
