Drought results in shortfall in agricultural production and hence, may cause food shortages. However, due to reduced purchasing power of the poorer sections of the society and if timely help is not available from the community or government, the situation can lead to famine.
Reduced production of food is only one of several problems; secondary effects include reduced rural employment; which results in loss of income and reduction of purchasing power for buying food. Drought causes crop failure, but mismanagement of the drought mitigation measures can cause famines.
There are three different types of droughts namely meteorological, hydrological and agricultural.
Meteorological drought, describes a situation where there is a reduction in rainfall for a specified period (day, month, season or year) below a specified amount - usually defined as some proportion of the long term average for specified time period, Its definition involves only precipitation statistics.
Hydrological drought involves a reduction in water resources (stream flows, lake levels, ground water, underground aquifers) below a specified level for a given period of time. Its definition involves data on water availability and off take rates in relation to the normal requirements of the system (domestic, industrial, agricultural) being supplied. In case of rivers fed by snow-melt, irrigated areas downstream may experience reduced water availability as a result of reduced snow-melt caused by below normal temperatures during the summer months. Areas drawing water from underground aquifers through wells and bore-wells may experience hydrological drought as a result of geological changes which cut off parts of the aquifer. Overutilization of the aquifer may also result in its exhaustion.
Agricultural drought is the impact of meteorological and/or hydrological droughts on crop yields. Crops have particular temperature, moisture and nutrient requirements during their growth cycle in order to achieve optimum production. If moisture availability falls below the required amount during the growth cycle, crop growth will be impaired and yields reduced.
However, droughts have different impacts on different crops, e.g., sesame often thrives in dry (season) years. Because of the complexity of the relationships involved, agricultural drought is difficult to measure. A fall in yields may be due to insufficient moisture but it may also stem from, or have been aggravated by, such factors as the unavailability of fertilizers, lack of weeding, the presence of pests and crop diseases or the lack of labor at critical periods in the growth cycle. Also these factors can interact with each other and complicate the conditions.
Cause of Famines:
Famines are caused by either or both of the following reasons:
a) decline in the availability of food
b) reduction in people's access to, or their ability to acquire food.
It was generally believed that the only cause of famine is a decline in food availability due to a reduction in production resulting from adverse weather, disease/pest infestation or through a cutting off of sources of supply.
However, over the last century there has been a growing realization that famines can also occur in areas where overall food availability has not declined, but as a result of a reduction in the ability of certain disadvantaged or economically weak groups within the population to acquire food, for instance as a result of a loss in their income or a sudden rise in the price of food.
Decline in food availability may be caused by a range of "natural" and human-induced-factors.
Natural factors are:
i. Agricultural drought
iii. Unseasonal cold spells/frosts
iv. Crop disease
v. Pest infestation
Human induced factors are:
i. Conflict preventing farmers from planting, weeding, harvesting and selling or possibly, involving the physical destruction of standing crops.
ii. External economic shocks, e.g., sudden increases in the price of agricultural inputs (power, fertilizers, pesticides, good seeds) or appreciable fall in the sale price of agriculture produce.
iii. Unchecked hoarding
iv. Disruption in movement of food grains from one part of the country to the other either due to natural hazards or dislocation due to civil strife.
V. Internal macro economic conditions, e.g., poor agricultural pricing policies discouraging farmers from growing food crops (as against cash crops).