Water accounting and auditing is an essential aspect of planning processes for managing water resources. Water accounting is the systematic examination of the state and trends in the availability, demand, accessibility, and usage of water. 

Water auditing puts trends in water supply, demand, accessibility, and usage in a broader framework of governance, institutions, public and private expenditure, law, and the wider political economy of water. When combined, results from water accounting and auditing facilitate policy development and decision-making. 

The KnoWat project carried out a water accounting and auditing assessment to improve water governance in the Malwathu Oya Southern catchment, in addition to a water productivity study based on WaPOR in an area identified with low water productivity. 

The water accounting study focused on ten sub-watersheds of the Malwathu Oya catchment, for four seasons. For each watershed, water balances were calculated with inputs from the WaPOR database, based on the Soil and Water Assessment Tool (SWOT) which is commonly used for hydrological studies by the Irrigation Department. These water balances were compared with observed hydrological data. 

Results show that the flows calculated based on the model are generally higher than the observed flows, by about 4 to 13 percent. The study concludes that the model replicates the situation on the ground quite well and can be used in future water balance studies. 

The water auditing study focused on three case studies where there is an issue with water management: 

1. Water sharing between agriculture and domestic water and the issues of unavailability of water from a tank in Thuruwila. The study discovered that through an enhanced collaboration between the area’s officials and the farmers, the farmers’ practical knowledge in the high-level discussions could help solve the issues related to water sharing.
2. The Nuwara Wewa feeder canal and the issue of illegal use of water. In this case, irrigation officials believe that the illegally irrigated lands should be legalized because siphoning is difficult to control. 
3. Water management in areas of low water productivity in the Nachchaduwa irrigation scheme, identified by the water productivity analysis based on WaPOR. In the Nachchaduwa irrigation scheme, the study revealed issues with canal’s maintenance and cleaning, which cause flooding and, as a result, low water productivity. In addition to improving canal system, better facilities to access and use of the infrastructure by the farmers should be considered. 

The results of the Water Accounting and Auditing were validated with stakeholders at local and national levels. The information can underpin better decisions on water management in the future.