Papers by Sreedhar Acharya
International Journal of Remote Sensing, 2011
The objective of this study was to investigate the changes in cropland areas as a result of water... more The objective of this study was to investigate the changes in cropland areas as a result of water availability using Moderate Resolution Imaging Spectroradiometer (MODIS) 250 m time-series data and spectral matching techniques (SMTs). The study was conducted in the Krishna River basin in India, a very large river basin with an area of 265 752 km2 (26 575 200 ha), comparing a water-surplus year (2000–2001) and a water-deficit year (2002–2003). The MODIS 250 m time-series data and SMTs were found ideal for agricultural cropland change detection over large areas and provided fuzzy classification accuracies of 61–100% for various land‐use classes and 61–81% for the rain-fed and irrigated classes. The most mixing change occurred between rain-fed cropland areas and informally irrigated (e.g. groundwater and small reservoir) areas. Hence separation of these two classes was the most difficult. The MODIS 250 m-derived irrigated cropland areas for the districts were highly correlated with the Indian Bureau of Statistics data, with R 2-values between 0.82 and 0.86.The change in the net area irrigated was modest, with an irrigated area of 8 669 881 ha during the water-surplus year, as compared with 7 718 900 ha during the water-deficit year. However, this is quite misleading as most of the major changes occurred in cropping intensity, such as changing from higher intensity to lower intensity (e.g. from double crop to single crop). The changes in cropping intensity of the agricultural cropland areas that took place in the water-deficit year (2002–2003) when compared with the water-surplus year (2000–2001) in the Krishna basin were: (a) 1 078 564 ha changed from double crop to single crop, (b) 1 461 177 ha changed from continuous crop to single crop, (c) 704 172 ha changed from irrigated single crop to fallow and (d) 1 314 522 ha changed from minor irrigation (e.g. tanks, small reservoirs) to rain-fed. These are highly significant changes that will have strong impact on food security. Such changes may be expected all over the world in a changing climate.
IWMI's mission is to improve water and land resources management for food, livelihoods and nature... more IWMI's mission is to improve water and land resources management for food, livelihoods and nature. In serving this mission, IWMI concentrates on the integration of policies, technologies and management systems to achieve workable solutions to real problems-practical, relevant results in the field of irrigation and water and land resources.
... Priyanie Amerasinghe 1 , Philipp Weckenbrock 2 , Robert Simmons 3 , Sreedhar Acharya 1 , Axel... more ... Priyanie Amerasinghe 1 , Philipp Weckenbrock 2 , Robert Simmons 3 , Sreedhar Acharya 1 , Axel Drescher 2 and Michael Blummel 4 ... project. Special thanks to KB Suleman, Navanita Ragupathi, Judith Christiana, Venkatapuram Aparna and Mohammed Quadeer. ...
Irrigation and Drainage, 2012
The Upper Bhima River Basin is facing both episodic and chronic water shortages due to intensive ... more The Upper Bhima River Basin is facing both episodic and chronic water shortages due to intensive irrigation development. The main objective of this study was to characterize the hydrologic processes of the Upper Bhima River Basin and assess crop water productivity using the distributed hydrologic model, SWAT. Rainfall within the basin varies from 450 to 5000 mm in a period of 3-4 months. The basin has an average rainfall of 711 mm (32 400 Mm 3 (million cubic metres)) in a normal year, of which 12.8% (4150 Mm 3 ) and 21% (6800 Mm 3 ) are captured by the reservoirs and groundwater reserves, respectively, 7% (2260 Mm 3 ) exported as runoff out of the basin and the rest (63%) used in evapotranspiration. Agricultural water productivity for sugarcane, sorghum and millet were estimated as 2.90, 0.51 and 0.30 kg m¯3, respectively, which were significantly lower than the potential and global maximum in the basin and warrant further improvement. Various scenarios involving different cropping patterns were tested with the goal of increasing economic water productivity values in the Ujjani Irrigation Scheme. Analysis suggests that maximization of the area by provision of supplemental irrigation to rainfed areas as well as better on-farm water management practices can provide opportunities for improving water productivity. RÉSUMÉ Le bassin versant du Haut-Bhima est confronté aux pénuries d'eau épisodiques et chroniques à cause de développement de l'irrigation intensive. L'objectif principal de cette étude est de caractériser les processus hydrologiques de ce bassin versant du Haut-Bhima et d'évaluer la productivité en eau des cultures en utilisant SWAT, le modèle hydrologique distribué. Les précipitations dans le bassin versant varient de 450 mm/an à 5000 mm/an et sont réparties inégalement dans le temps et dans l'espace. Le bassin a une pluviométrie moyenne de 711 mm (32 400 Mm 3 ) dans une année normale, dont 12.8% (4150 Mm 3 ) et 21% (6800 Mm 3 ) remplissent ou rechargent les réservoirs ou les nappes phréatiques, 7% (2260 Mm 3 ) ruissellent, et le reste (63%) est prélevé pour l'évapotranspiration. La productivité de l'eau agricole dans le bassin pour la canne à sucre, le sorgho et le mil ont été estimés à 2.90, 0.51 et 0.30 kg m¯3, ce qui est significativement plus faible que le potentiel maximal habituellement rencontré dans le monde.
Journal of Irrigation and Drainage Engineering-asce, 2010
In closing river basins where nearly all available water is committed to existing uses, downstrea... more In closing river basins where nearly all available water is committed to existing uses, downstream irrigation projects are expected to experience water shortages more frequently. Understanding the scope for resilience and adaptation of large surface irrigation systems is vital to the development of management strategies designed to mitigate the impact of river basin closure on food production and the livelihoods of farmers. A multilevel analysis ͑farm-level surveys and regional assessment through remote-sensing techniques and statistics͒ of the dynamics of irrigation and land use in the Nagarjuna Sagar project ͑South India͒ in times of changing water availability ͑2000-2006͒ highlights that during low-flow years, there is large-scale adoption of rainfed or supplementary irrigated crops that have lower land productivity but higher water productivity, and that a large fraction of land is fallowed. Cropping pattern changes during the drought reveal short-term coping strategies rather than long-term evolutions: after the shock, farmers reverted to their usual cropping patterns during years with adequate canal supplies. For the sequence of water supply fluctuations observed from 2000 to 2006, the Nagarjuna Sagar irrigation system shows a high level of sensitivity to short-term perturbations, but long-term resilience if flows recover. Management strategies accounting for local-level adaptability will be necessary to mitigate the impacts of low-flow years but there is scope for improvement of the performance of the system.
Agricultural Water Management, 2012
The basaltic aquifers of the Upper Bhima River Basin in India are highly utilized for irrigation ... more The basaltic aquifers of the Upper Bhima River Basin in India are highly utilized for irrigation but the sustainability of groundwater withdrawals and the agricultural production systems they support is largely unknown. Here we used hydrogeological data, supported by secondary data, to assess the effects of water scarcity over a decade-long period (1998)(1999)(2000)(2001)(2002)(2003)(2004)(2005)(2006)(2007) on the groundwater resources at the regional basin scale. This reveals no evidence of systematic declines in total groundwater availability over the period; only shorter-term losses/gains in storage associated with successive dry/wet years. The clearest indicator of stress comes from the more widespread drying out of wells following lower rainfall years throughout the basin and especially in upland areas where aquifers are least developed and most easily drained. Groundwater in the basin offers an adaptive mechanism to climate variability to some degree, but the buffering capacity is constrained by low aquifer storativity and average residence times of just a few years. Around 40% of the basin is currently at a level of development that is of concern, and the number of irrigation wells is growing rapidly. However recent evidence of conversion from high to low water use crops indicates the adaptive capacity of farmers to water-related stresses. Surplus surface water flows may provide opportunities to enhance groundwater recharge but requires careful trade-off analysis of the downstream impacts.
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Papers by Sreedhar Acharya