Relationship between water availability and global distribution of (a) Vegetation ecosystems and (b) Agricultural system

Transcription

1 Relationship between water availability and global distribution of (a) Vegetation ecosystems and (b) Agricultural system Plant water Relationship 1 (CS-5102) Assessment-01 Name -R. P. S. P. Kumara Reg no

2 Vegetation ecosystem is plants and their interactions with both biotic and abiotic components of the ecosystem. The biotic components are interacted with forests, aboveground - belowground feedbacks. Below Fig -01 shows global distribution of vegetation ecosystems. Fig 01 Global distribution of vegetation ecosystems.

3 Agricultural System is an interaction between agricultural and other land use systems, and between agricultural systems and their natural and social environments Fig 02 Global distribution of land cover These vegetation ecosystems and agricultural system are critically related with water availability. Water controlled ecosystems are complex, evolving structures whose characteristics and dynamic properties depend on many interrelated links between climate, soil, and vegetation. Vegetation exerts important control on the entire water balance and is responsible for many feedbacks to the atmosphere. Soil moisture is the key variable which synthesizes the action of climate, soil, and vegetation on the water balance and the dynamic impact of the water balance on plants. Many ecosystems of tropical and sub tropical latitudes suffer water stress. In many of the world ecosystems soil moisture is the most important resource affecting vegetation structure and organization.

4 Fig- 03 Soil moisture regimes When consider about agricultural system vary based on different moisture regimes. Soils with an aridic moisture regime require irrigation to be used for crops. Soils with an ustic moisture regime can grow rain-fed crops, but moisture will be limited during some of the growing season. Soils with an udic moisture regime have sufficient moisture for crops. Crops may be grown in the udic moisture regime without irrigation, but irrigation is needed for crops in most years in an ustic moisture regime. Soils with an aquic (perudic) moisture regime need artificial drainage for most cropping practices.

5 Fig 04 water withdrawal and consumption The agricultural sector is by far the biggest user of freshwater. In the United States, agriculture accounts for some 49% of total freshwater use, with 80% of this volume being used for irrigation (Shiklomanov, 1999). In Africa and Asia, an estimated 85-90% of all freshwater used is for agriculture (Shiklomanov, 1999). Asia took place about 57% of the water withdrawal and 70% it is water consumption in 2000, where the world major irrigated lands are located. Because of this area practice more agricultural systems to produce more foods. According to estimates for the year 2000, agriculture accounted for 67% of the world s total freshwater withdrawal, and 86% of its consumption (UNESCO, 2000).

6 The world s irrigation areas totalled approximately 253 million hectares in By 2010, they are expected to reach about 290 million hectares, and by 2025 about 330 million hectares (Shiklomanov, 1999). By the year 2000, an estimated 15% of the world s cultivated lands had been irrigated for food crops, accounting for almost half the value of global crop production (UNESCO, 1999). Maps (fig 05 and fig 06) show agricultural water consumption. Fig 05 Trend in global water use by sector

7 Fig 06 Freshwater uses by sector

8 Sources https//passel.uml.edu.pages/informationmodule.php UNESCO, Summary of the Monograph World Water Resources at the beginning of the 21st Century, prepared in the framework of IHP UNESCO, Viewed at Shiklomanov I. A., World Water Resources: Modern Assessment and Outlook for the 21st Century, (Summary of World Water Resources at the Beginning of the 21st Century, prepared in the framework of the IHP UNESCO). Federal Service of Russia for Hydrometeorology & Environment Monitoring, State Hydrological Institute, St. Petersburg.