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Integrating Environment, Climate-Change & Water
Ashvani K. Gosain Professor, Civil Engineering Department Indian Institute of Technology Delhi
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Water resource development
Shall always remain one of the preferred options to cater to Inherent Spatial and Temporal variability of this resource Climate change impacts as an additional factor Going to further enhance complexity Saturday, June 23, 2018Saturday, June 23, 2018
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Implications of Development
Water resource is finite (within natural variability) Any development big or small involves in moving the water around (more often upstream) Every development/intervention has associated impact Saturday, June 23, 2018Saturday, June 23, 2018
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Issues around water resources development
Many parallel programs with competing demands No mechanism for tradeoffs between competing demands Ignoring environmental demand Saturday, June 23, 2018Saturday, June 23, 2018
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Sustainability – Major concern
This brings us to the question of sustainability Which is about maintaining the hydrological and environmental health of the drainage basins IWRM philosophy has been the scientific option available but seldom used Watershed being the natural system where water balance can be resolved and thereby impacts of the manmade interferences quantified Hydrological modeling is the tool to be used
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Preferred Attributes of a Model
a model that can handle river basin as well as small watersheds can quantify the impact of land management practices can handle climate change implications
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SWAT Model Components
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Objectives of SWAT Predict the impact of man-made changes & management practices as well as water balance components water, sediment, nutrient and pesticide yields generate alternate scenarios
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Model Output Model outputs include all the water balance component at various levels ie basin, subbasin or watershed level and at intervals of daily, monthly or annual surface runoff evapotranspiration lateral flow recharge percolation sediment yield Nutrients
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Doddahalla (Bijapur, Karnataka) Watershed - Salient Features
Taluks: Indi, Bijapur (30 villages) Area: 30,000 ha (~61,000 ha from automatic delineation – entire watershed) Contour: 20 m interval digitized contours,1:50,000 Land use: 1:50,000 from satellite imagery Soil: 1:50,000 digitised Drainage: 1:50,000 digitised Weather station: one IMD station at Bijapur
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DEM & Drainage
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Automatically Delineated Watersheds with Weather Station Location
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Watersheds overlaid with Landuse
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Watersheds overlaid with Soil
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Water Yield Map
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Sediment Yield Map
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Average Annual Basin Values (All units are in mm)
Water Balance Components mm % of rainfall Rainfall Predicted Surface runoff Shallow Aquifer runoff Shallow-Deep Percolation Shallow Aquifer Recharge Predicted Water Yield ET PET Basin Sediment Yield T/Ha
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Prioritization - Criteria
Social Economic Economically weaker SC/ST population Uniform land holdings and many others Physical Head water Erodability, land degradatiom, water scarcity problem Rainfall less than 750 mm Net cultivated area is not more than 20 %. Proportion of irrigated area should not exceed the state average or 30 % Cropping pattern – no long duration crop or water intensive crops Villages fully falling in watershed
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Watershed prioritization layers
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Climate Change impact studies
India’s National Communications (NATCOM) to UNFCCC Coordinated by MoEF The first communication was made in 2004 and the Second in 2012 Work on quantification of climate change impacts on water Resources was entrusted to IIT Delhi
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River Basins Modeled – NATCOM II
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Modelling Outcomes Detailed outputs include all the water balance component at spatial and temporal scales which are analysed for Changes in magnitude and frequency of flood peaks Severity of droughts Changes in flow patterns Changes in groundwater recharge
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Change in Water Yield towards 2030s and 2080s
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Change in Evapo-transpiration towards 2030s and 2080s
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Change in Sediment Yield towards 2030s and 2080s
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Change in monsoon drought weeks towards 2030s & 2080s
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A shareable information base
To keep pace with the fast changing baseline To provide an integrated information Generate scenarios and provide information on implications thereof Saturday, June 23, 2018Saturday, June 23, 2018
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Conclusions Integrated Watershed Management plans are required to be formulated keeping the planning unit as River Basin Creation of sharable information is essential for sustainable use of water resources through engagement of stakeholders Implications of climate change needs to be integrated in the planning process Saturday, June 23, 2018Saturday, June 23, 2018
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Thank you
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