Impact of rainfall on agriculture in Himachal Pradesh :

Climate is one of the main determinants of agricultural production. Climate change projections made up to 2100 for India indicate an overall increase in temperature by 2-4 degree Celsius with no substantial change in precipitation quantity . Studies by IARI and others indicate greater expected loss in Rabi crop. Every 1o C rise in temperature reduces wheat production by 4-5 million tones. Variability in monsoon rainfall and temperature changes within a season. Global reports indicate a loss of 10-40% in crop production.

The effect of climate variations is also seen in Himachal Pradesh. The impact of rainfall on crop production can be related to its total seasonal amount or its intra-seasonal distribution. In the extreme case of droughts, with very low total seasonal amounts, crop production suffers the most. But more subtle intra-seasonal variations in rainfall distribution during crop growing periods, without a change in total seasonal amount, can also cause substantial reductions in yields. This means that the number of rainy days during the growing period is as important, if not more, as that of the seasonal total.

Impact on wheat :

There is positive correlation between the rainfall and the production as well as area sown under wheat crop which showed that rainfall is the major factor influencing the production as well as area sown under wheat in all districts. The area sown under the wheat was increasing or decreasing according to the occurrence of rainfall during the growing season of wheat. Maximum production was in the year 2003 when there was sufficient rainfall while minimum production was in the year 2004 in Kinnaur, 2008 in Lahaul & Spiti and 2009 in rest of the districts when there was less rainfall during the growing season of wheat. However the production was not increasing and the trend showed downfall in the year 2012 in almost all the districts due to irregular, less and untimely rainfall during the growing season.

Impact on barley crop :

Correlation between barley production and rainfall was similar as that of wheat i.e. positive. The decrease or increase in production was influenced directly by the amount of rainfall an area received during the growing season of barley. The maximum production was recorded in the year 2002 in Bilaspur and 2003 in rest of the districts while minimum was observed during 2001 in Hamirpur, Kangra, Kullu, Mandi and Una, during 2004 in Kinnaur, during 2008 in Lahaul & Spiti, during 2009 in Bilaspur, Chamba and Shimla and during 2012 in Sirmour, Shimla and Solan districts. The variation in production might be due to the irregular and insufficient rainfall during the growing season.

Impact of rainfall on Rice:

Geographical distribution of rice growing areas in the world over regions of heavy rainfall in the relatively short period of the cropping season indicates that water supply is probably the chief limiting factor to the growth and production of rice. The pattern of frequency and depth of precipitation in different month of growing season would seem to have important physiological bearing of rice plants particularly relating to yield. The rice production and area sown under rice is positively correlated with the amount of rainfall received during the growing season of rice. The maximum production was recorded during 2003 in Bilaspur, Chamba, Hamirpur, Kinnaur, Kullu, Mandi, Shimla, Sirmour, Solan and Una while in Lahaul & Spiti the maximum production was recorded during the year 2002. The minimum production was observed in during 2005 in Bilaspur. In Chamba minimum production was recorded in 2007 and 2009. In Hamirpur minimum production was recorded in the year 2001 and 2002. In Kangra, Sirmour, Mandi, Solan and Una minimum production was observed during the year 2002. In Kinnaur minimum production was recorded in 2004 and 2012. In Lahaul & Spiti minimum production was observed in 2004 and in Shimla during the year 2012. Decrease in production and area sown was might be due to low rainfall or untimely irregular rainfall during the growing season of rice.

Impact of rainfall on Maize:

Maize performs best in well well-drained, well aerated, deep, warm loamy and silt loamy soils containing adequate organic matter and well supplied with available nutrients. The reason for this is deduced from the observation made that the patterns of mean rain days generally follow the same pattern with mean rainfall amounts and that greater percentages of the rain days will be during the rainy season. Therefore, the concentration of rain days during rainy season is having a great influence on maize yield annually such that the higher and less evenly distributed the number of rain days the lower the maize yield. Maize requires a well distributed, considerable amount of rainfall over an appropriate numbers of days during its growing season for optimum yield.

The rainfall directly influenced the production as well as area sown under maize which showed positive correlation between them. When there was sufficient rainfall during the growing season of maize the production was high however during less rainfall, irregular and untimely rainfall there was decrease in production and area under the crop. The maximum production of maize was recorded during the year 2003 in Bilaspur, Chamba, Hamirpur, Kinnaur, Kangra, Kullu, Mandi, Shimla, Sirmour, Solan and Una while in Lahaul & Spiti during the year 2002. The minimum production was recorded during 2005 in Bilaspur, 2007 and 2009 in Chamba and Shimla, 2004 in Kinnaur and Lahaul & Spiti and during the year 2002 in rest of the districts.

Mitigation:

The options available for HP are mitigation measures to reduce the pace and magnitude of the changes in anthropogenic climate change activities or adaptation measures to reduce the adverse impacts on human-well being as a result of the climate change occurrences – enough mitigation to avoid the unmanageable, enough adaptation to manage the unavoidable. The possible mitigation agricultural strategies required to be implemented are to reduce GHG emissions, enhance carbon sinks and proper understanding of the effects of climate change helps scientists to guide farmers to make crop management decisions such as selection of crops, cultivars, sowing dates and irrigation scheduling to minimize the risks.  

• Switching to crop that can withstand higher temperature.
•   Decrease emission of green house gases.
•   Development of arid land crops and pest management as well as capacity building of extension workers and NGO’s to support better vulnerability reducing practices.  
• Programme to minimize the adverse effects of drought on production of crops and livestocks· and on productivity of land, water and human resources, so as to ultimately lead to drought proofing of affected areas.
•  Aim to promote overall economic development and improve the socioeconomic development condition of resource poor and disadvantaged section inhibiting the programme areas.
•  Improve methods to conserve soil and water.
• Non conventional methods for utilization of· water, including inter-basin transfers, artificial recharge of groundwater and desalination of brackish or sea water, as well as traditional water conservation practices like rainwater harvesting, including roof top rainwater harvesting should be practiced to increase utilizable water resources.  
• Development of drought and pest resistant crop varieties.
•   There should be stakeholder consultations, training workshops and demonstration exercises for farming communities for agro-climatic information sharing and dissemination.  
• Financial support to enable farmers to invest in and adopt relevant technologies to overcome· climate related stresses.