Climate Exchange

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Improved livelihoods and building resilience

in the semi-arid tropics: science-led,

knowledge-based watershed management

Suhas P Wani, Assistant Research Program Director and Principal Scientist (Watersheds),

Resilient Dryland Systems (RDS);William D. Dar, Director General; Dileep K Guntuku, Global Leader,

Knowledge Sharing and Innovation; Kaushal K Garg, Scientist, RDS and AVR Kesava Rao, Scientist, RDS,

International Crops Research Institute for the Semi-Arid Tropics, India

ainfed agriculture (1.25 billion hectares out of 1.55 billion

hectares arable area) plays an important role globally in

improving livelihoods and food security as it covers 63

per cent of total agriculture in Asia and 97 per cent in Africa.

These areas are not only the hotspots of poverty but are also

food insecure, hotspots of malnutrition, water scarcity, prone to

severe land degradation and more vulnerable to the impacts of

climate change.

With increasing demand for food production

to meet the needs of the growing population (9 billion by 2050),

growing incomes and changing food habits, water scarcity will

also intensify. The per-capita availability of water has declined

considerably; for example, in India water availability was 1,820

cubic metres per person in 2001 compared to 5,177 cubic metres

in 1951, and it is expected to decrease further to 1,341 cubic

metres by 2025 and 1140 cubic metres by 2050.

Water is a finite natural resource and agriculture is a major user,

with 70 per cent of water withdrawal globally for food produc-

tion. Green water (such as rainwater stored in the soil profile) is

a valuable resource and often neglected when considering water

management for food production, which constitutes 85 per cent

of total freshwater use in crop plants and 98 per cent in grassland

across the world.

With competing demand from other sectors like

domestic, industry and ecosystem management, the pressure for

efficient water use by agriculture will grow. Water is the primary

limiting factor in dryland the water scarcity scenario in developing

countries. Rainfed agriculture has a vast untapped potential, as the

current farmers’ yields are lower by two to five times that of achiev-

able crop yields in Asia and Africa.

Now, however, there is a new paradigm to unlock the potential of

rainfed agriculture and build resilience against the impacts of climate

change through knowledge-based interventions at watershed scale.

Impacts of climate change

With the growing evidence of global warming and its associated impacts

on climate change, the existing water scarcity scenario is getting further

exacerbated by the increased variability of rainfall events during the

season. Although impacts of climate change at macro level are estab-

lished, a large knowledge gap exists at local level about the impacts

of climate change. Further, millions of smallholders and development

workers in Asia and Africa are not aware of the local

impacts of climate change in their regions. For example,

analysis at the International Crops Research Institute for

the Semi-Arid Tropics (ICRISAT) has revealed that at

Patancheru in India, a paradox of decreasing evapotran-

spiration under increasing temperature regime has been

observed over the last 35 years, with a reduction of 200

mm y-

in potential evapotranspiration from 1,850 mm to

1,650mm largely due to decreasing wind speed.

Similarly,

at Nemmikal watershed in the Nalgonda district of Andhra

Pradesh, India, the length of the growing period (LGP) has

decreased by about 15 days since 1978 and the climate has

shifted to more aridity from semi-arid. The shift in LGP, if

not understood by the farmers, generally results in more

crop failures due to late season drought.

Another study using long-term gridded weather data

sets in India revealed that 5.1 million hectares have

become drier and 5.6 million hectares have become

wetter during the periods 1971-1990 and 1991-2004.

For example, Rajasthan (1.5 million hectares) and

Gujarat (0.99 million hectares) became drier as some

of the semi-arid tropic areas were converted into arid

areas, with the largest shift in Madhya Pradesh where

an additional 3.82 million hectares became semi-arid.

New paradigm

Considering the existing yield gaps and lack of knowl-

edge for small and marginal farmers, ICRISAT and its

partners have developed farmer-centric knowledge

intensive soil, water, nutrient and crop manage-

ment options at watershed scale through community

participation.

Based on the participatory assessment

of the constraints and potential as well as yield gap

analysis using crop simulation models in consultation

with community members, the potential interventions

for rainwater harvesting, soil moisture conservation,

soil fertility management, use of drought tolerant

high-yielding cultivars, land and water management

practices and integrated pest management options

were introduced in partnership with the community.

griculture