INDIA WATER WEEK-2013 S7- WATER AUDITING FOR IRRIGATION PROJECTS
GUIDELINES FOR WATER AUDITING V. K. CHAWLA Chief Engineer (POMIO) CWC & V. MOHAN MURALI Deputy Director (IPO) CWC
INTRODUCTION Overall water availability is almost fixed. In India, water demand from all the sectors is on rise. Challenge is to meet water demand with limited availability. Irrigation sector uses more than 80% of developed water resources. With competing demand from various sectors, water availability for irrigation sector to reduce. Paradigm shift towards performance improvement. Audit used as a management tool for conservation; now for water conservation also.
WATER AUDIT Water audit is a systematic and scientific scrutiny of water
accounts of the projects. Elements of water audit includes record of amount of water available water delivered for various sectors losses in the distribution system measures to address water loss
identify reasons for deviation in irrigation performance viz a viz planned. Facilitate effective management of water resources with improved reliability. General guide lines for water audit covering Irrigation, Domestic and Industrial sector prepared by CWC.
WATER AUDIT STEPS Water Supply & Usage Study Process Study System Audit Water Audit Report
WATER SUPPLY & USAGE STUDY Involves preparation of complete layout of
water sources distribution networks service/delivary points location & size of measuring devices return flow of waste/excess water.
Study of water availability Vs past consumption patterns
helps understand present water utilization and projecting future requirement.
PROCESS STUDY Measure discharge at all strategic points Record/estimate losses directly from the structure/gates and
estimate loss in conveyance. SYSTEM AUDIT Study of current water usages and systems for various sectors to check their operational efficiency and level of maintenance. Measurement methodology at intake point, various sub-systems & ultimate user points to be verified periodically for its suitability, efficiency and accuracy. Audit of water release from various points to identify reaches of undue water loss/pilferage. Study of domestic wastewater, return flows from irrigation and effluents from the industries for conformity to environment standards, possibility of recovery of valuable by-products and the opportunity for recycling of waste water.
WATER AUDIT REPORT A water audit report shall contain Amount of water available in reservoir. Amount of water earmarked for different sectors. Amount of water released for various sectors. Amount of water utilised and unutilised. Actual Irrigation performance Vs planned. Water loss in conveyance/leakages from structures and reasons for such water losses Suggested measures to check water loss and improve efficiency.
WATER AUDIT - IRRIGATION SECTOR
Records to be maintained Water account is prerequisite for water audit as it defines the demand for surface water service. Assessment of water demand Compute Crop Water Requirement (C.W.R) of different crops. Assess
flow to be released at outlet/off taking head; distributor/branch head; head regulator (Canal head) etc. by adopting judiciously assumed efficiencies (or computed losses) and area under each crop.
Add water demand of other sectors to get total water demand. Water Release Techniques/measuring
devices for measurement of water delivered can be Velocity Area Method; Weir; Flumes etc. Maintain complete record of water withdrawn for different uses from the reservoir; water flow through the various branches/distributaries; Outlets; Escapes etc.
Records to be maintained Record of rainfall &water availability in reservoirs in beginning of water year and end of Monsoon. Evaporation from reservoirs. Crops sown. Area irrigated and depth of water provided. ANALYSIS Match total water availability with water use for different sectors; evaporation; losses/leakages; unutilised. Compare actual water use for different purposes Vs planned. Compare actual evaporation loss Vs assumed. Actual area irrigated Vs planned. Actual water losses/efficiencies Vs assumed. Identify reasons for deviation & take remedial measures, if required.
VARIOUS PROFORMAE FOR WATER AUDIT Proforma
Discharge drawn at various locations of canal
Water used for different sectors and area irrigated
Discharge letout through scouring sluices or escapes
Annual water account for major and medium irrigation projects
Annual water account for minor irrigation projects
WORKSHOP ON WATER AUDIT Draft ‘Guidelines for Water Audit’, prepared by Central
Water Commission were deliberated upon in a National Level Workshop organized at New Delhi in January, 2004.
Workshop Recommendations Water audit is good management tool for water conservation. Conduct supply side audit and demand side audit. Water audit help Improve WUE of system. Prioritise development and management of water. Water audit be incorporated as a routine exercise of O&M. Appropriate provision of fund may be made for annual water
Water audit bring out changes in demand and supply
scenario. Helps in realistic assessment of ground realities and initiating remedial measures including holistic approach of conjunctive use of ground water and surface water and adoption of micro irrigation for overall improvement of WUE. Water audit shall also include recording/reporting of pollution level of fresh surface water & ground water. Existing laws regarding pollution control be strictly observed. Bulk metering system should be installed at various well defined locations in the system for effective water audit.