[[Image:AfricaDrought.jpg|thumb|right|250px|In Kenya where drought is challenging, communities are encouraged to wash their hands with ash, a local disinfectant that is free and easily accessible. <br>Photo: REUTERS. [http://marysanyuosire.blogspot.com/2012/01/saving-lives-during-worst-drought-in-60.html Health of East Africa blog.]]]
It is difficult to predict how and where climate change will have the greatest effects. Some studies show changes in the seasonality of river flows in areas where much of the winter rain falls as snow. Yet, every Every region in the world will not have reduced overall water availability – some areas will receive have more annual rainfall, while other areas will receive less. Even so, changes in rainfall patterns will increase, with more intense rainfall over shorter periods of time or no rainfall at all for longer periods, including more extreme events such as floods or droughts.
Water availability plays a critical role in people’s ability to handle a drought – especially during drought emergencies.<br>
[[Image:flood control India.jpg|thumb|right|250px|Flood irrigation in India. More efficient use of water for agriculture is key to protecting and conserving water supplies. [http://blogs.ei.columbia.edu/2012/03/22/water-water-everywhere-but-nary-a-drop-to-drink/ Water, Water Everywhere, But Nary a Drop to Drink.] Photo: Jeremy Hinsdale.]]
For example, in accessing groundwater and rainwater sources during a drought, more efficient capture and storage of rainwater / and groundwater is focused on, rather than expanding the use of groundwater itself. Introducing new techniques to an area is also important. Many rainwater harvesting techniques (e.g. floodwater harvesting and storage) are not only uncommon, but unknown and not used at all. Therefore , understanding the what technology adoption criteria works best for a region must include biophysical preconditions, socio-economic conditions, market issues, land tenure issues, and human capacity.
Collecting rainwater more efficiently includes both “blue flow” (water that recharges aquifers, lakes and rivers) as well as “green flow” (water that supports plant/crop production). It is the efficient use of “green flow” that has huge consequences for food security since an estimated 60% of the world’s staple food production relies on this water (and in Sub-Saharan Africa it is almost 100%).
==Definitions of drought==
[[Image:ClimateChangeDiagram.jpg|thumb|right|250px| Four Approaches to Drought. National Drought Mitigation Center (NDMC), University of Nebraska-Lincoln, USA.]]
[[Image:DroughtMap.jpg|thumb|right|250px|Regions of drought recorded between 1979 and 2008, where drought events are identified as three consecutive months with less than 50% of precipitation rainfall as compared with the average.]]
* Drought is defined as a diversion (may be temporary) from the average or expected rainfall pattern in an area.
Drought also adds stress to arid and semi-arid lands (ASALs), where dry conditions already exist, due to:
* Annual [http://en.wikipedia.org/wiki/Evapotranspiration evapotranspiration ] (PET) rates that are usually more than twice the annual rainfall. These occur due to a mix of high temperatures, greater amounts of sunshine, less cloud cover, high winds and low relative humidity.
* Greatly varied rainfall over geography and time – timing and location of rainfall events is never certain.
* High run-off volume (rather than infiltration). Very common in ASALs.