ON-GOING RESEARCH IN THE KRISHNA BENCHMARK BASIN
Theme 1: Basin Water Management
Introduction |
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The concept of Benchmark Basins (BMB) as an instrument to further the IWMI research agenda and other objectives was developed in the 2001-05 strategic plan and consolidated in the 2004-08 plan. This strategy envisioned strengthening IWMI's research agenda through long term research in varying agro-ecological zones, with continuity and synergy compared to the project based approach and the development of a deeper understanding and knowledge as the basin evolves over time. How do river basins change in response to socio-economic shifts, water scarcity or competition? It was also expected that BMB would enhance working relationships with partners and stakeholders; facilitating research work and data sharing, enabling interventions and impact monitoring, and also resulting in capacity building. The Krishna River Basin in peninsular India is one IWMI's Basin Mark Basin. IWMI's has launched several studies with the aim of improving water and productivity and alleviating poverty in the basin. This note provides overview of on-going research in the basin. |
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The Research Context |
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The Krishna Basin is India's fourth largest river basin and covers 258,948 km2 of southern India, traversing the states of Karnataka (113,271 km2), Andhra Pradesh (76,252 km2) and Maharashtra (69,425 km2). The basin is relatively flat, except for the Western Ghats and some forested hills in the center and northeast. It lies mostly on granites and basalts with limited groundwater potential, with some deep alluvium in the delta with high groundwater potential. The basin's climate largely semi-arid, but there a narrow north-south strip along the Western Ghats is humid, a dry-subhumid area in the Krishna Delta, to arid in the rain-shadow east of the Western Ghats. Annual rainfall averages ~800mm but ranges from below 300mm in the northwest, to ~1000mm in the delta, to a maximum of over 2000mm in the Western Ghats. About 90% of the rainfall is received during the monsoon months of May to October. Potential evapotranspiration varies spatially over the basin and is highest in the south and the east while lowest records are registered in the northwest. Evapotranspiration exceeds precipitation in all but three months of the year during the peak of the monsoon (July, August, and September) which make necessary irrigation during the other periods of the year and notably in the east and the northwest of the basin. IWMI studies have shown that, at the basin scale, the Krishna is in danger of approaching closure. Time-series analysis of discharge at the basin outlet (Vijayawada) shows that the Krishna basin began to close in the late 1960s. The basin-wide annual water balance has changed markedly over time: evapo-transpiration increased by 20% and runoff decreased by 42% from 1901-1960 to 1965-1970, and by about 60% by 1990-2000 (Figure 1), despite no statistically significant change in rainfall. The basin is home to some 74.2 millions inhabitants The population density of 287 inh/km² with concentration of the population in the irrigated areas and metropolitan urban centres. The lowest densities are recorded in the south west and centre of the basin in Karnataka state (Deccan plateau). Some 68% of the population live in rural areas and dependent on agriculture for their livelihood. Basin closure has also resulted in interstate conflict, as three states share the shrinking water resource. The downstream state, Andhra Pradesh, has experienced a state-wide decline in agriculture, while Karnataka and Maharashtra, which lie further upstream, have large dry regions and want to continue developing their water resources to maintain their agricultural growth and reduce poverty. |
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Agriculture |
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The basin supports an irrigated area of approximately 63,865 km2 (25% of total area) split nearly equally between surface water and groundwater. Some 177,250 km2 (68% of total area)the basin are mainly rainfed areas including some rangeland and wastelands. Nearly 15000 km2 are under forest cover, shrublands and grasslands. These figures illustrate the crucial importance of green water in the basin. The three cropping seasons are Kharif during the monsoon (June-November), Rabi during post-monsoon (December-March) and a short summer season (April-May).Crops in the irrigated areas include rice, sugarcane, cotton, and vegetables, and supplemental irrigation of fruit, oilseeds, pulses, and sorghum. Irrigated areas range from less than a hectare in isolated groundwater plots to hundreds of square kilometers in the Krishna Delta. Major rainfed crops include rice, coarse grains, oilseeds, pulses, cotton, chillies and a variety of fruit and vegetables. |
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Urban water demand and wastewater irrigation |
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Rapid urbanization in the basin also makes demands on water supplies. Hyderabad city, for example, now has 7 million people and consumes 380 million m3 of water annually. Much of the urban water supply returns to the local Musi River as wastewater and is used for irrigation, which has important consequences for human health, soil salinity and the environment. A new project called "Ensuring Health and Food Safety from Wastewater Irrigation in South Asia" by IWMI, ILRI [International Livestock Research Institute] and local partners in Hyderabad, India and Faisalabad, Pakistan, will focus on vegetable and fodder production to recommend concrete measures to mitigate the risks to farmers and consumers. |
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Water Scarcity and Poverty |
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Remote sensing shows that cropping patterns in some parts of the basin change quickly in response to water scarcity. In particular, large areas of downstream irrigated areas change from double cropped rice-rice to single cropped rice or no cropping at all during years of water stress. These changes have caused income shocks to farmers in the affected areas. Other parts of the basin have naturally low rainfall and high incidence of water stress, and potentially high poverty rates. In many water stressed basins in developing countries a large number of poor people do not have access to water of sufficient quality and quantity to satisfy basic needs let alone water for productive purposes. Although as basins close many processes come into play in perpetuating poverty, there is clear evidence that access to water and land are important for the poor to build sustainable livelihood systems. |
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Environmental impacts |
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The near total collapse of inflows to the Krishna Delta also has implications for environmental stability; salt water intrusion into aquifers already affects part of the Krishna Delta and may become worse as inflows decrease and groundwater extraction continues. The Delta also hosts some unique mangrove ecosystems, whose species composition depends crucially on the balance of salt and freshwater. Changing that balance will alter these ecosystems, perhaps irreversibly. The Krishna Basin closure occurs in the wider context of other basin closures in southern India. The Cauvery and Penneru basins have also experienced near total basin closure; nearly all of southern India, starting at the northern border of the Krishna Basin, is closing, with wide-ranging effects on agriculture, ecosystems and the regional and national economy. IWMI's work continues in the hope that by understanding how basins close, and by devising innovative, basin-wide strategies for managing water, economic development does not come at the cost of the environment. The sections below outline the details of on-going studies in the basin. |
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Project 1: WATER MANAGEMENT SCENARIOS TO IMPROVE WATER PRODUCTIVITY IN AGRICULTURE OF KRISHNA RIVER BASIN |
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Project 2: MAPPING INDICATORS OF WATER-LAND-POVERTY NEXUS IN THE LOWER KRISHNA BASIN |
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