Introduction
Irrigation plays a key role in the development of agriculture sector of a country. Agriculture’s share of water is declining at a faster rate because of increasing competition for available water from urban and industrial sectors. Pakistan is also severely affected by water scarcity and is already one of the most water-stressed countries in the world, and is moving to outright water scarcity by 2025 according to the International Water Management Institute (IWMI), due to a high level of population growth. Presently, the water availability per capita has reduced to 1050 m3 (2010) and is seemed to reduce 800 m3 by the year 2025.
Pakistan has been facing water shortages for the last several years due to lesser rains and high temperatures with the result wheat production both in irrigated and rainfed areas is being hampered. Primarily the irrigation system of Pakistan was designed for the cropping intensity of about 70% and this figure is increased up to 200%, which is three folds greater than the designed irrigation supply of canal network due to the food requirement of the growing population. Area irrigated by canals and tubewells for agricultural practices by the year 2008 and 2009 was 19.27 Mha. This drastic change have put a question mark on the agriculture growth and subsequently, agriculture scientists have to turned to advanced techniques such as remote sensing (RS) and geographic information system (GIS) techniques for crop assessment. Performance assessment is regarded as the most pivotal element for improving irrigation management. Irrigation performance indicators range from water distribution to agricultural, economic, social, and environmental aspects.
Efficient utilization of existing water resources is a pressing need for Pakistan in the face of rising population, reduction in present storage capacities, and lack of storage facilities and poor delivery efficiency of 30 to 40% from canal head to rootzone. Groundwater is being heavily exploited unchecked in the country with the result that in large areas over exploitation is taking place as well as poor quality groundwater is causing soil salinity. This situation demands that alternative water management options should be evaluated for long term management of land and water resources. The use of advanced technology tools such as satellite Remote Sensing, Geographic Information System (GIS) techniques, and hydrologic modeling can greatly help improve irrigation management. The Government of Pakistan has started a huge project of 66 billion rupees for watercourse lining throughout the country to conserve the water lost due to the seepage from the earthen watercourses. This project aims to assess the performance of irrigation system and evaluate the impact of multiple activities such as watercourse lining, change in cropping pattern and or groundwater pumping on the surface and groundwater system so that proper measures could be adopted for the sustainable management of land and water resources on regional basis.
Objectives
- To apply an integrated approach of surface and groundwater model for assessing existing irrigation performance in terms of productivity of water using Remote Sensing, GIS and hydrological models.
- To Evaluate and forecast long-term changes in groundwater movement and groundwater quality in response to different irrigation and or agricultural interventions such as watercourse lining, change in cropping pattern, control on groundwater pumpage etc.
- Developing strategies for the efficient management of surface and groundwater resources with respect to quantity and quality to improve productivity of water and sustainability of environment.
Achievements
The data collection is in progress and following data have been collected so far at Khurrianwala and Mungi Distributary study areas:
1. Survey: A field survey was conducted to suggest the management practices in the area. Engineering surveys (topographic survey and profile survey) were carried out for leveling and watercourse improvement.
2. Watercourse Improvement: To calculate the water losses of the selected lined watercourse, the total length of watercourse was divided into three portions i.e. head, middle and tail. Discharge measurements were made within each portion by further selection of three points in each section by cut throat flume. The cut throat flume of size 8" x 3' (throat width x length) was used. Discharge was measured at middle and tail position in the watercourse.
3. Mapping the Study Area through GPS: A detail survey of the study area was conducted to mark the longitudinal and latitudinal position of the fields and the corresponding water course through GPS in degree decimal system. The watercourse survey points were marked at three different points i.e. head middle and tail. The coordinates of the fields and corresponding watercourse were converted into Universal Transverse Mercator (UTM) system.
4. Satellite Images: Available satellite images of LandSAT ETM+ for the year 2000 and 2005 were collected for the performance evaluation of the study area. The available images are in TIFF format. In order to process these images they will be transferred into image format and will be stacked to enhance their visibility and combined layer effect by using ERDAS Imagine. Building a visible color composite image of Landsat 7 bands using ERDAS Imagine will require images with bands 1, 2, 3, 4, 5 and 7.
Results and Expected Benefits
The data collections of the both sites are in progress. The collected data will be analyzed and the results will be presented. The techniques used in this project will be helpful in quantification of the effect of management options practiced in the study area. |