Water management is a critical aspect of sustainable development, particularly in regions where water resources are limited and subject to various pressures. The main objective of the project is to improve the efficiency and productivity of the use of water harnessed by the cascade and individual tanks to manage the demand for water for irrigated agriculture in the hotspots area and to enhance the returns per unit volume of water and farm incomes.
The hydrological assessments have been done for 11 river basins using the HEC-HMS model. This Hydrological Analysis Report was used to estimate inflows for the Yala & Maha seasons of the cascades. Accordingly, average annual Inflows of the Cascades were estimated by using the developed Rainfall-Runoff Model which is a developed power equation. Finally, we have a rainfall-runoff relationship for each cascade. This information is being used to prepare the cropping pattern of the cascade. To optimize the cropping pattern of the cascade, a WEAP model was developed. Based on the water availability ( reliability of Inflow and demand) and results of the economic analysis, a suitable cropping pattern for each tank in the pilot cascades was prepared and incorporated into the CMP for decision-making. Also, these hydrological studies were applied to design the spillways of the tanks in the cascade for extreme weather conditions and to prevent hole cascade.
Operation and Maintenance of Irrigation Systems aims to ensure the sustainable operation and maintenance (O&M) of tank systems at the individual tank level and systems. Established Cascade Management Committees and strengthened Farmer Organizations should work on O&M of rehabilitated irrigation systems on sustainability while a monitoring system for water use and availability will be designed and implemented. All these activities are covered under the sub-component 2.2.
Accordingly, the sustainable operation & maintenance and proper water management of the village irrigation systems are essential to improve the water use efficiency in these systems. The main key performance indicator for measuring irrigation system Water Productivity is the water use efficiency, and the Project expects to increase the water use efficiency of the village irrigation systems by 30% in the selected hotspot area.
To achieve the target of water use efficiency, it is necessary to train the officers involved in field-level management of Irrigation systems as well as the farmer Organization. Also, required to prepare an O & M plan and a Water Management Plan for a particular crop season in the system during the training. The project already trained officers in the Implementing Agency Staff & Farmer leaders for water management & O and M activities in the irrigation systems. Also, prepared the O & M handbook for farmer training and a curriculum for TOT training of Implementing Agency Staff. The rest of the Farmers in rehabilitated tank systems are being trained parallel to the next cultivation seasons. Also, needed to complete the O & M plan and water management plan for each tank.
To ensure sustainable Water Management Practices in the cascade systems and individual tanks, water issues from the sluice are to be measured by the appropriate methods which should be handled easily by the Farmer Organization. Accordingly, CSIAP provided a water measuring device, cutthroat flumes for 11 districts to use for better water measuring of canal flows, and training was given to Farmer Leaders. Now, farmers can handle their water issues accurately from the irrigation tanks without interfering with Officials. Our final goal is the operation and maintenance of the tanks sustainably handled by the farmers.
Introducing the improved AWD (Alternate Wetting and Drying) apparatus designed for easy use by farmers. This new device features a top indicator with a scale that is easily readable from a distance, allowing farmers to quickly and accurately determine the optimal time for irrigation. This innovation ensures efficient water management, promoting sustainable farming practices and enhancing crop yield. Various models were tested for suitability and the model given in Figure 1 was selected after carefully considering all the aspects. It is planned to install 1000 nos. for the pilot tanks.
Measuring Water Use Efficiency (WUE) is the main key performance indicator under the water management sub-component. Under this, it has been started to measure the WUE effective from Yala season 2023 and is being continued using 48 pilot tanks covering the project implementation provinces. The project target for the increase of WUE by 30% and, with the calculations carried out until the 2023/2024 Maha season, the average achievement was around a 22% increase of WUE.