Techniques of Water Conservation and rainwater harvesting for drought management

Abstract

South Asia is home to one of the oldest civilizations of the world. The sub-region includes the countries with Afghanistan, Bangladesh, Bhutan, India, Maldives, Nepal, Pakistan, and Sri Lanka. It has a 1.5 billion strong population growing at the rate of 1.8% per annum but has only 4.8 per cent of the world’s total land area. South Asia’s topography includes an amazing variety of mountains, plateaus, dry regions, intervening structural basins and beaches. It varies from world’s highest point, Mount Everest to the world’s lowest, the sea beach. The entire coastline runs to about 10, 000 km from Pakistan to Bangladesh, with wetlands occupying an area of 1,34,161 sq km. The region is characterized by a tropical monsoon climate. Two monsoon systems operate in the region: the southwest or summer monsoon (June-September) and the northeast or winter monsoon (December-April). This region also features large year-to-year variations in the rainfall frequently causing severe floods/droughts over large areas. Some of the world’s largest river systems are in the South Asia. The River Indus originates in China and flows to Pakistan. The Ganga-Brahmaputtra river systems originate partly in Bhutan, China and Nepal and flow to Bangladesh and India. The Indus is one of the world’s greatest river systems, measuring 3,180 km, from its source to the sea. The Ganga stretches for about 2,525 km and the Brahmaputtra – the third great Himalayan River, stretches for about 2,900 km flowing through Tibet, India and Bangladesh. Soil and water are the principlal natural resources of South Asian region and ultimate source of people’s livelihood. However, sustainability of these resources is a major concern due to land degradation in general and soil erosion in particular. Irrespective of slopes, the soils are used intensively, and severe erosion is common on hill slopes cultivated for upland crops. The soil erosion and landslides are considered as the most critical environmental hazards in the region.