Does use of the blue/green/grey water concept improve or dumb-down water management? Charles Batchelor

Transcription

1 Does use of the blue/green/grey water concept improve or dumb-down water management? Charles Batchelor

2 Case Study 1

3 Case Study 1 Ramgarh Dam Constructed in 1903 Mean annual rainfall: 550 mm Gross storage capacity: 75 MCUM Catchment area: around 770 Sq Km Constructed for irrigation but, until recently, an important source of water supply for Jaipur City Study technical committee as a result of a High Court petition Report finalised in January 2013

4 Annual Inflow (MCFT) 2500 RAINFALL-ACTUAL INFLOW TREND DURING DIFFERENT TIME SEGMENT- RAMGARH DAM, JAIPUR Case Study cum = 35 cuft RAINFALL mm/year Source: SWRPD (2013)

5 Case Study 1 What s happening? Major public and private expenditure on in-field water harvesting, drainage line water harvesting, borewell construction, diversion weirs (anicuts), land-levelling, intensification of irrigated and rainfed farming systems Increase in consumptive water use in the catchment area in the form evaporation from rainfed and irrigated crops and from small water bodies at the expense of decreased inflow to the reservoir

6 Case Study 2 Krishna River at Vijayawada Source: IWMI Since the 1960s Krishna river flows have been decreasing as a result of: Major engineering works (including: inter-basin transfers, new irrigation schemes etc) Intensification of agricultural water use (including groundwater-based irrigation, intensive water harvesting, improved rainfed farming, dryland horticulture etc)

7 Gundlur Tank Catchment 1234 ha Tank capacity 27 ham Annual rainfall 500 mm Before openwells & 3 borewells, 4 nala bunds, 1 tank, 8 irrigator farmers ET irrigation : 26.4 ham ET structures : 1.5 ham Runoff: 60 ± 29 ham Spillage/releases: 25 ± 22 ham Losses: 9 ± 4 ham Case Study 3 Irrigation (surface water): 38.4 ham After openwells & 80 borewells 1 tank, 15 checkdams, 7 nala bunds & 1 pond 93 irrigator farmers ET irrigation : ham ET structures : 4.0 ham Runoff: 35 ± 23 ham Sluice leakage: 10 ± 12 ham Losses: 5 ± 3 ham Irrigation (ground water): 38.4 ham 1 ham = 10,000 cum

8 Case Study 3 Gundlur Tank summary Tank inflow reduced by 40%. Frequency of spill also reduced Big increase in irrigated area and the number of irrigator farmers Irrigator farmers in tank command area now use groundwater and water leaking from sluices instead of water released from the tank.since this study the tank has been rehabilitated (i.e. tank desilted, sluices repaired and more WH structures have been constructed)

9 Case Study 3 Gundlur Tank Catchment Area: Consumptive Water Use (ham) Surface flow Sub-surface flow ET irrigated ET water bodies ET rainfed Before Negligible After Negligible No tank spillage in 11 years preceding this study. Groundwater recession (GR) is difficult to estimate but is likely to be negligible. ET rainfed and ET water bodies vary with rainfall. ET irrigated much less dependent on rainfall From before 1990 to after 1990, green/blue consumptive water use ratio has changed from around 80:20 to around 70:30 or even 60:40 depending on how the irrigated crop water use is partitioned between green/blue consumptive use. (The fact that farmers over-irrigate complicates the green/blue water partitioning)

10 Key messages from these case studies Water scarcity (i.e. an imbalance between water supply and demand) is increasing Government and private expenditure on watershed development, rainfed and agricultural development, borewell construction is working (i.e. delivering benefits, improving livelihoods etc) but often at a cost to downstream water users Some states and agencies are now reacting to this problem. In others it is business as usual Reasons for ignoring exerternalities / tradeoffs are complex, inter-sectoral, political and contested. Im balances in supply and demand can and should be predicted and/or underlying causes can be identified by using water accounting and auditing

11 What is needed? The case for using water accounting and auditing in areas of increasing water scarcity is argued in FAO Water Reports 38. Water accounting is the systematic study of the current status and future trends in water supply, demand, accessibility and use within a given spatial domain. Water auditing places the outcomes from water accounting into a broader framework comprising of water governance, institutions finance, legislation, services delivery and the wider political economy Water auditing (water governance, finance, institutions legislation, services delivery and wider political economy) Water accounting (water supply, demand, accessibility and use) e/i3015e.pdf

12 What are the main attributes of water accounting and auditing? Sound scientific base: Within constraints of available resources, based on a solid upto-date understanding of bio-physical, environmental, social and political sciences. Interdisciplinary and inter-sectoral. Active involvement of stakeholders Adaptable and flexible: e.g. based on needs assessment Emphasis on information management: e.g. rigorous quality control, use of hard and soft information, use of mapping and spatial analysis etc

13 What are the benefits of using blue/green concepts & terminology? Highlights the relative importance of rainfed agriculture, forestry, rangeland etc in relation to irrigated agriculture in terms of water use. By association with the above, the importance of stream-flow reducing activities in rainfed areas is or should be highlighted (e.g. forestry, land levelling, contour planting, SWC, improved rainfed farming systems etc) But the above would have been possible without using blue/green concepts and terminology

14 Often the bigger challenge is to improve understanding of differences between consumptive and nonconsumptive water uses Consumptive water use is water removed from available supplies within a specified domain that does not return to a water resources system (e.g. evaporation from a crop) Non-consumptive water uses do not substantially deplete water supplies (e.g. the fraction of irrigation that drains to groundwater) Source: FAO Water Report 38

15 Example of an awareness campaign that could be improved by: Getting the water accounting right Recognising the sociocultural context Issued by a Water Resources Planning Department 111 Ways to conserve the water 93. Wash your pets outdoors in an area of your lawn that needs water 101. If you accidentally drop ice cubes when filling your glass from the freezer, don t throw them in the sink. Drop them in a house plant instead

16 Thank You