Emerging Technologies to Benefit Farmers in Sub-Saharan Africa and South Asia (2009) / Chapter Skim
Currently Skimming:
4 Water Resource Availability
4 Water Resource Availability
Pages 123-144
The Chapter Skim interface presents what we've algorithmically identified as the most significant single chunk of text within every page in the chapter.
Select key terms on the right to highlight them within pages of the chapter.
From page 123... ...
In arid regions, groundwater resources are not connected with surface rivers, so groundwater recharge (by rain) is more important than in humid areas.
|
From page 124... ...
The climate in southern Africa is diverse, from subtropical humid to arid. The Zambezi, Limpopo, and Orange Rivers serve the region, but the water resources are modest, and some groundwater reserves are not renewable (FAO, 2003)
|
From page 125... ...
. In contrast, the arid regions of northwestern and western AFGHANISTAN IRAN NEPAL PAKISTAN BHUTAN DRY ZONE HUMID ZONE INDIA BANGLADESH 90 Limit of 90-day LGP Boundary between dry and humid zones SRI LANKA FIGURE 4-2 The South Asia region showing the approximate boundary line at 4-2.eps which rainfall or soil moisture is adequate to support a 90-day-long growing period for crops.
|
From page 126... ...
The total renewable water resource per capita in South Asia is about 1,591 m3/year. Given population growth and other demands, renewable per capita freshwater resources in SA are likely to be severely constrained in the future, especially in Afghanistan, India, and Pakistan.
|
From page 127... ...
Of the 47 countries of SSA, six (Comoros, Eritrea, Lesotho, Malawi, Somalia, and Zambia) experience a moderate deficit of renewable water resources of about 1,500 m3/year per capita, and six others (Burkina Faso, Cape Verde, Djibouti, Kenya, TABLE 4-1 Total Water Withdrawal by Volume and as Percentage of Renewable Water Water Withdrawal Water Withdrawal (km3)
|
From page 128... ...
. Water Resources and Climate Change Climate change models predict scenarios for SSA and SA that may drastically affect the availability of water in parts of these regions.
|
From page 129... ...
On-farm water management includes techniques for water capture, storage, pumping, transfer, field application, and drainage technologies. On the scale of the small farmer in Africa or India, water capture has typically involved small dams to pool and store surface water.
|
From page 130... ...
. Studies comparing drip irrigation to conventional surface irrigation in a variety of cropping systems revealed water productivity gains ranging from 91 to 149 percent (Molden, 2007)
|
From page 131... ...
In the last 4 decades, systems have evolved to store water underground in aquifers, and a recent study by the National Research Council found that, given the "generally successful track record of managed underground storage [MUS] in a variety of forms and environments, MUS should be seriously considered as a tool in a water manager's arsenal" (NRC, 2008)
|
From page 132... ...
Such research could yield substantial benefits to farmers, assuming that efficient systems for bringing stored water back to the surface and distributing it for use in agriculture can be devised. Wastewater Reclamation Because of its ability to improve water quality, MUS might be used in conjunction with treatment of urban storm-water runoff and municipal wastewater.
|
From page 133... ...
Because profit margins on clean water production by desalination are small, commercial interest in the technology is weak. Most desalination projects are heavily subsidized with public funding, and research focuses on reducing costs by expanding economies of scale and optimizing operational efficiency.
|
From page 134... ...
In some applications, the concentrate is disposed of at sea, where dilution theoretically minimizes adverse effects. In an inland situation, an alternative is to deposit the salty brine in a solar-energy pond, where the lower dense layers of salty water reach high temperatures.
|
From page 135... ...
A National Research Council report (NRC, 2003) described a framework of basic research needs on weather modification and recommended steps to validate cloud-seeding operations that include statistical evaluations of their effects, tracking of introduced seeding agents and their effects in cloud cells, and physical measurement of rainfall.
|
From page 136... ...
. Increasing the efficiency of rainfall by 10 percent -- a figure that the American Meteorological Society considers to be the conservative potential of the technology -- could significantly affect water availability.
|
From page 137... ...
Until recently, however, predictive weather and climate models have relied on global averages of climate data and have focused on upper atmospheric processes even though it is known that such landscape features as soil moisture, terrain, and type of vegetation affect regional and local climate and weather. That information was not consistently available for a given swath of land, and the algorithms to integrate it into current models did not exist.
|
From page 138... ...
MODIS generates global maps of several land surface characteristics: surface reflectance, land surface temperature, and vegetation indexes, such as the density of vegetation. MODIS can distinguish urban areas from nonurban areas and distinguish among 11 categories of vegetation (deciduous forests, coniferous forest, crops, grassland, and so on)
|
From page 139... ...
It consists of a satellitebased precipitation radar (the only one of its type in space) that can provide three-dimensional images of clouds; a microwave instrument that provides quantitative estimates of rainfall, water vapor, cloud water content, and sea surface temperature; a visible and infrared spectrum scanner; and a lightning detector.
|
From page 140... ...
The NOAH Land Surface Model (LSM) was developed in 1999 by a partnership of the National Centers for Environmental Prediction, Oregon State University, the U.S.
|
From page 141... ...
2006. Effect of seasonal dynamics of vegeta tion cover on land surface models: A case study of NOAH LSM over a savanna farm land in eastern Burkina Faso, West Africa.
|
From page 142... ...
2003. Hydrological enhancements to the community Noah Land Surface Model: Technical description.
|
From page 143... ...
2008. Effect of explicit urban land surface representation on the simulation of the 26 July 2005 heavy rain event over Mumbai, India.
|
From page 144... ...
2006. Ethiopia: Managing Water Resources to Maximize Sustainable Growth.
|
Key Terms
This material may be derived from roughly machine-read images, and so is provided only to facilitate research.
More
information on Chapter Skim is available.